The Science of Cooking Every Question Answered to Perfect Your Cooking

Is It Possible to Age Meat at Home?

Is it possible to

AGE MEAT AT HOME?

APPLE SWEET Aging lends meat complexity of flavor and aroma,
CHESTNUT but ready-aged meat can be very expensive.
Wood chips
Dry-aging meat is a time- and space-consuming
Choose culinary wood chips process that causes cuts to lose volume, which is why aged
made from hardwood, as these meat is expensive. Leaving meat in cool, humid conditions
are packed with flavorful lignin. gives time for enzymes to break down collagen and muscle
fibers, tenderizing meat and fragmenting large, flavorless
molecules into aromatic, flavorful, smaller ones. In specialized
facilities, large cuts are aged in temperature- and humidity-
controlled rooms for months, but a similar effect can be created
at home with a standard beef roast and a fridge. The timeline
below shows how meat transforms during the aging process.

338°F AGING TIMELINE
(170°C) is the
temperature that wood Dry-aging meat develops complex flavors and
must reach to release tenderizes meat. Below is a summary of the

its flavor. changes happening to beef as it ages.

TIME WHAT HAPPENS
Starting to tenderize
DAYS
01–14 Place a large joint of beef on a rack above
a drip tray containing a little water. Place
in a cool fridge (37–41˚F/3–5˚C). Enzymes
begin to tenderize the meat; at 14 days,
meat has reached 80 percent of its
maximum tenderness.

#4 DAYS Flavors begin to develop
15–28
BATHE IN THE SMOKE As enzymes continue to break down
Leave the meat to smoke in the wok tissues, sweet and nutty flavors begin
for 10 minutes over high heat, then to develop in the meat. Keep the water
remove the wok from the heat and in the tray topped off to help the air in
leave the meat to bathe in the smoke the fridge stay humid, and thereby limit
for a further 20 minutes, or longer for how much the meat dries out.
a stronger flavor. Finish the meat by
grilling, or slicing and stir-frying to give DAYS Optimum tenderness and flavor
it a browned crust. 29–42
The longer meat is left, the more time
the enzymes have to work and the more
flavors will develop. Fat breaks down
to create complex cheese-like flavors.
Before cooking, slice off any mold and
the charcoal-colored crust to reveal a
deep-red meat.

050 // 051 The Science of Meat and Poultry

Should I trim What is the secret to

ALL THE FAT PERFECTLY CRISPY
OFF MEAT? PORK CRACKLING?

Health-wise, the message is to avoid saturated Golden pork crackling is prized by many meat eaters.
animal fat, but fat has other roles in cooking.
Turning the pale, rubbery skin on pork into light and airy
We’re aware of how saturated fats in red meat impact crackling is a challenge, but with the right preparation
and cooking stages, this is actually fairly easy to master.
cholesterol and calories. But fat also carries much of the
How do I create crackling?
flavor of meat, so from a culinary standpoint it’s generally
Many believe that pork crackling is just fat, but it is
better to leave fat on. actually made from the whole layer of pork skin and
contains connective tissue and protein, which give it
There are a couple of strength, in addition to an underlying layer of fat—nearly
half of which is unsaturated. Follow the method below
exceptions. When flash-frying for a perfectly cooked roast with delicious crackling.

a steak Diane, there isn’t COOKING PORK CRACKLING

enough time for the strip of MEAT ENHANCING Several key stages are needed to create crunchy, golden
crackling. Before cooking, skin needs to be dried and
fat to cook, so this remains WHEN HEATED, FAT scored. Cooking is then done in two stages. Roasting a
semi-raw. And large lumps of OXIDIZES, CREATING
fat in stewing steak should NEW FLAVORS, AND #1
be cut out as there may not MELTS, MAKING MEAT
SALT AND DRY
be enough cooking time for MORE TENDER. For successful pork crackling, the skin
of the meat needs to be dried before
the collagen to break down cooking. Rub salt into the roast well
in advance. The salt quickly draws
and the fat to melt. moisture out—pat the moist surface
dry, then place the roast in the cold
Does it matter if you cut meat air of the fridge to dry out.IN PRACTICE

ACROSS THE GRAIN
OR ALONG IT?

You can spot the direction of the muscle fibers on
meat by inspecting the fibers on its surface.

Whether you cut meat “across the grain” or “along it” has
profound effects on tenderness and juiciness. The “grain”
is the direction in which the muscle fibers run. On a piece
of meat, look for the direction of the fibers and lines of
connective tissue on the surface. If you tore the muscle,
it would split along these grains. When you cut meat for
serving, it should be cut across, not along, the grain. Biting
into meat cut this way allows your teeth to exert maximum
force on the tough sheaths of connective tissue that
envelop each strand. The meat breaks apart in the mouth
easily and any soft gelatin or fat is released onto the palate.
Biting into meat cut along the grain takes ten times the
biting force as chewing across the grain.

THE WHOLE HOG

CRACKLING IS EASIER
TO ACHIEVE WITH SPIT-
ROASTING, WHERE ROTATING
ALLOWS MORE CONTROL

OVER COOKING TIME.

“Crackling is made up
of the whole layer of pork

skin and contains
strong connective tissue

and protein.”

belly of pork at a low temperature gives juicy meat,
but the skin will be chewy. For crunchy crackling, a
final cooking stage at a high heat is needed (see below).

#2 #3 #4

INCREASE THE SURFACE AREA COOK SLOWLY, THEN REST INCREASE THE HEAT
Scoring the surface of the skin is Cook the pork on a lower heat, around Once the temperature has increased,
crucial to increase the surface area 375ºF (190ºC), allowing 35 minutes for baste or drizzle oil over the resting
and allow the hot oven air to penetrate each pound until the flesh is nearly roast to increase heat transfer to
further into the skin. Score across the cooked—a knife should have little the skin, then return the meat to
skin, placing the scores a finger’s width resistance when twisted in the meat. the oven for about 20 minutes,
apart. Make sure you score down well At this point, the meat will be juicy, rotating the meat regularly to avoid
into the fat, but not right through to but the fat will be chewy and flabby. hot spots. The remaining moisture
the meat. During cooking, moisture Remove from the oven, cover in foil, in the skin will evaporate, bubbles
escapes through the cuts and fat will and leave to rest, while turning up the of steam will expand, and the
bubble up and fry on the surface. oven to 475ºF (240ºC). surface will brown.

052 // 053 The Science of Meat and Poultry How do I cook the

Should I cook meat from room PERFECT STEAK?

TEMPERATURE? The “perfect” steak may mean different things for
different people, but some key principles hold true.
Many cooks take meat out of the fridge early
with the aim of reducing cooking time. While the perfectly flavored steak is partly dependent
on personal taste, some core guidelines and tips can help
Bringing meat to room temperature before cooking seems you to hone your steak-making skills and make the most
sensible for speeding up cooking. In reality, this makes of your prime cut. Ensure the pan or grill is hot and
little difference and could even pose a health risk. The follow the tips below and guide opposite for steaks
core of a medium-thickness steak takes 2 hours to increase up to 1½in (4cm) thick.
just 41ºF (5ºC), and in this time infection-causing bacteria
may have grown on the surface. Searing meat kills off TOP TIPS FOR COOKING STEAKS
germs on the surface, but won’t eradicate all the toxins
that have infused the meat. Keep the following points in mind when
cooking your steak to optimize flavor and texture:
The only time it is worth warming meat precooking
(but not to room temperature) is when using a thin skillet: LOOK FOR THICK FOR A PERFECT
a cold steak could drop the pan’s temperature to below CUTS WITH GOOD CRISPY FINISH, DAB
the minimum 284˚F (140˚C) needed for browning. MARBLING FOR A WITH SALT AND PAT
MOIST, FLAVOR-
Does searing a steak really DRY 40 MINUTES
FILLED STEAK. BEFORE COOKING.
“SEAL IN” JUICES?
SEAR ON GRILL YOUR STEAK FOR THAT
Searing steak is a well-known practice, but the benefits HIGH HEAT FOR DELICIOUS SMOKY FLAVOR THAT
might not be quite those you were expecting. YOU CAN’T ACHIEVE IN THE KITCHEN.
A DELICIOUS
It’s often thought that cooking meat rapidly at a high CRUST AND FLIP YOUR
temperature “seals” the outside into a crisp, impermeable STEAK OFTEN TO
crust that stops moisture from escaping. Science shows us A SOFT, COOK IT EVENLY.
that the opposite is true—the crust that forms when steak is JUICY CENTER.
cooked rapidly at a high heat isn’t waterproof; in fact, a seared FINISH OFF FOR EXTRA
steak dries out faster than an unseared one, as the high MAXIMIZE CUTS FLAVOR, ADD
JUICINESS THICKER BUTTER IN THE
heat needed to brown the meat’s BY RESTING THAN 1½IN FINAL STAGES
outer layers dries out the STEAK SO (4CM) IN OF COOKING,
inside more rapidly. THE JUICES THE OVEN. SPOONING
However, a seared brown THICKEN. IT OVER THE
crust does make for a far STEAK AS
tastier steak, as the high IT MELTS.
heat triggers the
Maillard reaction (see MAKE YOUR SAUCE IN THE SAME
pp16–17), releasing PAN SO THE GELATIN FROM THE
myriad mouthwatering
flavor molecules. MEAT THICKENS THE SAUCE.

SEARED
STEAK

How Do I Cook the Perfect Steak?

WHEN IS IT DONE?
A meat thermometer is the most accurate way to test
meat, but you can also gauge red meat by color and
texture. The finger test, below, together with how the
meat looks, helps you to judge when steak is done.

“BLUE”/EXTRA-RARE
Seared briefly, for about 1 minute on each
side, the texture and internal chemistry of
meat will be similar to raw. An extra-rare
steak will be soft to the touch, feeling
like the relaxed fleshy muscle at the
base of the thumb. The center of the
steak will reach about 129ºF (54ºC).

RARE
A rare steak feels like the base of the thumb
when the thumb and index finger touch.
It has a juicy texture; while muscle fibers
have firmed and the color is more pink,
much of the moisture remains. Cooked
for about 2.5 minutes on each side, it
reaches 135ºF (57ºC).

MEDIUM–RARE
A medium rare steak has a similar
texture to rare, but is pinker and firmer,
feeling like the base of the thumb
when the thumb and middle finger
touch. Cooked around 3.5 minutes on
each side, the internal temperature is
around 145ºF (63ºC).

MEDIUM
At about 160ºF (71ºC), most of the
proteins clump together and meat is a
light brown color. Firm and moist, it
feels like the base of the thumb when
the thumb and ring finger touch. Cook
for around 5 minutes on each side.

WELL DONE
At 165ºF (74ºC), meat is tougher, drier,
and darker as more proteins coagulate
and force moisture from cells. Meat
feels like the base of the thumb when
the thumb and little finger touch.
Cook for about 6 minutes on each side.

054 // 055 The Science of Meat and Poultry

DATA The Process of ADD THE INGREDIENTS
Put the ingredients in the
How it works SLOW inner cooking pot. Slow
Food is cooked for COOKING cookers don’t reach the high
an extended period of time, temperatures needed for the
immersed in liquid. Maillard reaction (see p16),
so brown onions and meat
Best for in a pan first, if needed.
Tough cuts of meat with
white connective tissue, Cooking at low to moderate temperature over #1
root vegetables, dried beans a long period of time will convert a tough cut
of meat into a melt-in-the-mouth delight.
and other pulses.
What to consider Low-temperature cooking gives
Low temperatures mean you
must preboil dried kidney ample time for chewy collagen in
beans (see p140). Brown
onions and meat beforehand tough meat to be converted into
to give roasted flavors.
velvety gelatin, a reaction that takes
LOWER IS BETTER
place at above 149–158ºF (65–70ºC).
KEEP HEAT LOW. MUSCLE
FIBRES COOK FROM Gelatin breaks down in the
140ºF (60ºC); AS THE
TEMPERATURE RISES, cooking liquid, thickening it
MOISTURE IS
L O S T. and emulsifying flavor-rich

154°F fats to create a rich, luscious
or 68°C is the
temperature at which gravy. Allow the meat to cool
collagen starts to break
in its liquid after
into gelatin.
cooking—any HEAT IS TRAPPED INSIDE #6
THICKENING remaining gelatin will Unless adding flavorings,
pull cooking liquid into avoid removing the lid to
IF THE SAUCE NEEDS the meat, making look inside during cooking
THICKENING AFTER SLOW it extra moist. Lean because this causes steam
cuts with minimal and heat to escape, so the
COOKING, REMOVE THE liquid will need topping up.
MEAT BEFORE BOILING ON
connective tissue will
A STOVETOP.
dry out if slow cooked.

HEAT RADIATES UPWARD #5
Heat from the base unit
spreads across the bottom
and sides of the inner pot.
The heat then passes into the
cooking liquid and directly
into food resting on the base.

A heating element is in the
base or around the sides
(some models have both).

The Process of Slow Cooking

ADD LIQUID SECURE THE LID See inside
Slow cookers are heated from Put the lid on. This will
the bottom, like a pan on the stop heat and steam from White, chewy connective tissue is made of collagen and elastin
stovetop, so can burn if the escaping, allowing the proteins. Collagen begins to denature at 126°F (52°C), then
pot is dry. Add enough liquid temperature inside the contracts and shrinks at 136°F (58°C), squeezing moisture out.
just to cover the food, but not inner pot to reach a steady At around 154°F (68°C), however, collagen breaks apart and
too much as the sauce will temperature and prevent reforms into soft gelatin, giving succulence to the dehydrating
be too thin and lack flavor. the liquid evaporating away. meat (see below). However, elastin does not break down at
normal cooking temperatures, so remains as inedible gristle.
#2 #3
Key At 154°F (68°C),
Collagen molecules collagen strands
Gelatin molecules break apart.

Steam circulates
inside the pot.

#4 Gelatin forms from
broken-down collagen.
SET THE CONTROLS Collagen forms long
Slow cookers mostly operate strands in uncooked meat.
at below the boiling point of
water. “Low,” “medium,” Heat spreads across
and “high” settings usually the bottom and sides
range between 176 and 248°F of the pot.
(80 and 120°C), so check Outer casing houses
your instruction manual. the temperature
controls.

Ceramic inner cooking
pot conducts heat slowly
but distributes it evenly.

056 // 057 The Science of Meat and Poultry

How can I keep

CHICKEN OR TURKEY FROM DRYING OUT?

Different preparation and cooking techniques offer some useful ways to keep these lean meats moist.

Poultry’s delicate white meat is abundant Cooking a chicken or turkey in a conventional home
in bulky and tender “fast-twitch” muscle
(see p34), used for quick, powerful actions, oven is convenient, but the blasting-hot oven
which tends to cook rapidly. There is very
little fat in the breast meat and almost air quickly dehydrates this fragile meat. The
no connective tissue, both of which are
important for ensuring that meat has A LEAN CUT preparation and cooking methods outlined
a juicy, succulent mouthfeel. below, for both whole chickens and smaller
THE LEANEST PART OF pieces, offer a range of solutions for ensuring
A CHICKEN, MOST PRONE that chicken and turkey remain moist and
succulent during cooking.
TO DRYING OUT WHEN
COOKED, IS THE PALE

BREAST MEAT.

OPEN FIRE SOUS VIDE SPATCHCOCKING BRINING

The method The method The method The method
Known as “spit roasting,” Most practical for smaller cuts of This can be done when A whole bird is submerged in
this involves skewering a whole meat, this involves placing the oven-roasting a whole bird.
bird on a spit and roasting cuts an airless bag and immersing The backbone is removed so that salty water overnight.
the butterflied bird can lie flat, How this helps
it over an open flame it in a hot-water bath set at a with the breast in the center and
while it rotates. controlled temperature. the legs on either side. The aim of brining is to force
How this helps How this helps water into uncooked meat. Left
How this helps for several hours, salt penetrates
As the spit rotates, heat This is the most foolproof way to Flattening the bird in this into the meat (in a process called
rays coming from the flames keep poultry moist. Surrounded way helps the meat to cook more diffusion), pulling water with it
by precisely heated water, there is evenly throughout, in a similar way as it does so (a process known as
cook all sides of the meat not much danger of overcooking. that pounding a chicken breast
evenly. Cooking in this way However, sous vide doesn’t brown does (see p42). Speeding cooking osmosis), drawing the water
meat, so for Maillard flavors (see in this way means that the outer toward the center. This is an
is less dehydrating than pp16—17), it needs searing in a layers are less likely to dry out. imperfect method because the
the hot, dry air from a pan or with a blowtorch afterward. salt travels slowly and may not

conventional oven. reach all the muscle.

Heat radiates Heated water The poultry When laid flat, Salty Salt and
evenly over the cooks from retains the center cooks water water work
rotating meat. all sides. moisture. more quickly into the meat.
and dries out less.

ADDING FATS SEPARATING What Does Basting Do?
A BIRD
What does

BASTING DO?

Bathing meat in its own cooking juices is
an effective way to enhance your meat.

Conventional wisdom is that basting meat
during cooking adds moisture, resulting in a
succulent dish; however, this is not the case
(see Myth Buster, below). Regularly ladling
meat with its own oily juices does, however,
add flavor and texture because it increases
the surface temperature to hasten the Maillard
reaction (see pp16—17), releasing rich, meaty
flavors and crisping the skin. The shiny glaze
suggests that the meat is moist, but bear in
mind that oil speeds up cooking, so care is
needed to avoid drying out the outer layers.

The method The method GRAVY BASE
Combine slices of breast meat with Break up a whole bird into
SOME OF THE COOKING
other fat-containing, individual pieces. JUICES, TOGETHER WITH
moist foods. How this helps MEAT FRAGMENTS IN THE
How this helps
Similar to spatchcocking, breaking up PAN, CAN BE USED IN
Even when cooked in a bird, or buying separate cuts, is an A R IC H GR AVY.
ideal conditions, breast meat easy way to avoid overcooking the
meat. Fast-cooking breast can be Basting tool
can still taste dry, which is cooked independently of the darker,
due to its lack of fat. slow-cooking legs and thighs. A whole Meat basters can be
bird is broken down into eight pieces: used to draw up juices,
Combining thinly cut or shredded which are then squirted
meat with moist, fattier foods and two drumsticks, two thighs, two evenly over meat.
meaty, gelatinous sauces offsets breasts, and two wings.

the dryness, giving
a succulent mouthfeel.

Fat- and gelatin- Heat cooks separated MYTH BUSTER
containing liquid helps parts at an even
the meat taste less dry. Myth
rate if they are of a BASTING MEAT KEEPS IT MOIST
similar type of meat.
Truth

Oven-roasted meat is prone to drying out.
Traditional teaching states that basting meat
in its juices moistens meat and increases succulence.
However, little or none, of the basting liquid soaks
into meat; instead it dribbles off or forms a glaze.
The muscle tissue has no capacity to absorb liquid
because it is already saturated with juices and

furthermore is being squeezed by collagen
fibers as they shrink in the heat.

058 // 059 The Science of Meat and Poultry

How can I tell

WHEN MEAT IS DONE?

Some foods, such as eggs, can be cooked to a timer, whereas the art of cooking meat is knowing when to stop.

Each piece of meat is different: its thickness, water content, cooking times. A fast-read digital meat thermometer is the
fat density, amount of stringy connective tissue it has, and easiest way to test whether meat is cooked. You can also
position of bones all affect cooking times. Fat conducts heat gauge red meat by its appearance and feel (see below and p53),
poorly, so fatty cuts take time to cook properly; meat with cooking it to your preferred level of doneness. White meat,
tough white connective tissue also needs slower cooking to such as chicken, needs to be cooked completely, while pork
break tough tissue down into succulent gelatin; and bones needs to be cooked well, but can have a little pinkness. Use
transfer heat quickly to the core of the meat, speeding up the guidelines below to check that meat is cooked correctly.

Poultry WHEN IS RED MEAT DONE?

Red meat, such as lamb and beef, can be cooked to be rare,
medium, or well done, depending on your preference.

COOKED RARE, FOR MEDIUM DONENESS,
MEAT IS FIRMER, MOIST,

RED MEAT WILL BE AND LIGHT BROWN.

RED LIKE BLOOD IN WELL DONE
THE CENTER AND RED MEAT IS DARKER
AND FIRM TO
Red ITS TEXTURE SOFT. THE TOUCH.
meat

Pork

WHEN IS POULTRY DONE? WHEN IS
PORK DONE?
Pierce the flesh with the tip of a thin, sharp knife or a skewer to see if the
juices run clear. If there is no pinkness, the myoglobin pigment has unraveled Unlike chicken, pork does not
and the core temperature has exceeded the safe minimum of 165ºF (74ºC). need to be cooked until white
throughout. This pale meat is
WHEN COOKED OVER WOOD OR IMMATURE BONE cooked when a quick-read digital
CHARCOAL, GASES FROM BURNING MARROW IS RED, SO thermometer reads 145ºF (62ºC).
FUEL CAN PASS INTO THE SURFACE RED ON BONES CAN
OF CHICKEN MEAT TO TRIGGER A PORK MEAT SHOULD
JUST MEAN THAT BE MOSTLY WHITE,
SERIES OF REACTIONS THAT FIX A CHICKEN WAS WITH A HINT OF PINK.
THE RED SUBSTANCE, MYOGLOBIN, KILLED YOUNG.
IN THE OUTERMOST LAYERS OF THE
MEAT INTO A PERMANENTLY PINK

STATE, BUT THE MEAT IS
PERFECTLY COOKED.

What Can I Do with Overcooked Meat?

Why do I need to rest What can I do with

MEAT AFTER OVERCOOKED
COOKING? MEAT?

Resting meat is a concept we are all familiar with, but Like spilled milk, there is no undoing
some confusion surrounds the reasons for doing this. overcooked meat.

Leaving meat to rest has real benefits—meat “bleeds” When meat is overcooked, the proteins have coagulated
less on the plate, slices more cleanly, and tastes juicier. and the fibers have lost their moisture and shriveled,
There are no set rules on how long meat should rest for— resulting in tough, dry meat. However, all is not lost. The
a few minutes at room temperature can be enough for most effective way to salvage overcooked meat is to recreate
a medium-sized steak. In this time, heat from the outer the slow-cooking effect used for stews. Slow-cooked meat
layers spreads into the core, and moisture from the cooler tastes succulent because tough cuts become surrounded by
core diffuses outward, giving a more even temperature and smooth gelatin (see pp54–55), so try shredding overcooked
juiciness. Most importantly, resting lets the meat’s “internal lean cuts and mixing them with a gravy made from meat
gravy” thicken as water between the muscle fibers mingles stock, fats or butter, and silky gelatin. Another way to
with broken-down proteins. As the steak rests and cools, reintroduce succulence is to add dry meat to dishes with
these thickened internal juices form a delicious jus. other sources of moisture, as shown below.

Oil used for frying gives Thick sauces
impression of juiciness. add succulence.

REST TIME (MINS) 10 The longer a steak is rested, the
8 more juice it retains, resulting
6 in a more succulent piece of meat.
4
2 2% 4% 6% 8% 10%
00 % INTERNAL JUICE LOST

Meat weight loss after cooking Add to a fritter Mince for a sauce

The table above shows weight loss through “bleeding” in identically Finely dice meat to use in a Dry meat can be minced
sized beef steaks cut into at different times after cooking. At 2 minutes, fritter with onions and oils. and used in a pasta sauce.
6 percent of weight is lost, while after 10 minutes just 2 percent is lost.

MYTH BUSTER Vegetables add a Fats reintroduce
variety of textures. moisture to blended meat.
Myth
RESTING MEAT LETS TENSE MUSCLES RELAX Use in a stir-fry Blend in a pâté

Truth Thinly slice overcooked meat Meat can be blended and added
and use it in a stir-fry. to fats in a succulent pâté.
After slaughter, muscles go through a period of rigor mortis,
degrading muscle proteins so they are no longer able to contract
and relax. In addition, muscle proteins heated above 122˚F (50˚C)
will have unraveled permanently. Resting thickens juices and allows

some fluid to be reabsorbed into muscle fibers, but does
not actually “relax” the muscles.

060 // 061 The Science of Meat and Poultry

Gelatin creates a
silky-smooth sauce.

What’s the secret of a DEGLAZE PAN SAUCE

TASTY SAUCE? The brown gelatin-containing particles in the
bottom of a roasting pan, known as the “fond,”
The artistry of sauce making is harmonizing are scraped off as hot liquid is added to form PROTEIN
flavors and perfecting texture.
a sauce. Adding stock creates a gravy or As collagen in meat tissues
For a great sauce or jus, the taste, aroma, mouthfeel, meat jus, or wine can be added heats, it breaks down to form
and flavor pairings all need to work together. A sauce can for a tarter taste. gelatin, a protein that dissolves
intensify a main ingredient, such as the rich sauce of a beef Fat globules from
bourguignon, complement and accentuate other flavors, or the butter add and forms into gel-like
even salvage overcooked meat. flavor to the roux. networks, thickening sauces.
Egg proteins are also used
Building a sauce ROUX-BASED SAUCE
as thickeners.
The aim of a sauce is to achieve a smooth consistency This traditional sauce base heats flour into butter
before slowly mixing in liquid to make a smooth STARCH
that is thicker than water but less dense than the sauce. For a béchamel, mix roux with milk. Stock
Starch swells rapidly in water,
main ingredient. The diagram, right, shows how and roux create a sauce velouté; brown so easily clumps. To stop this, sift
roux with veal stock, a sauce
sauces are built from liquids and thickening espagnole. flour, use a low-protein corn
starch, make a paste with water
agents. Starches are the most often used first, or mix with butter for a roux
base. Lengthy cooking makes a
thickeners, but despite their versatility,
brown roux.
they can be heavy and starch molecules

cling to flavor molecules tightly, making

them relatively bland and in need of

additional flavoring. Oil- and fat-based

sauces are more intense because

flavor molecules dissolve

more successfully in fats. Starch granules
swell and leach
molecules that mesh
and thicken the sauce.

“A sauce can help to
intensify a main ingredient,
such as the rich red wine
sauce of a beef bourguignon.”

What’s the Secret of a Tasty Sauce?
Fats in milk and cream can
mix with water because of the
emulsifying molecules that coat them.

SAUCES CREAM CREAMY SAUCE

A sauce brings together the Fats in milk and cream are Cream produces a rich, smooth sauce, thanks to
flavors of a dish and requires encased in globules that tiny milk-fat globules. Flavor molecules dissolve
dissolve in water. Emulsifying well in fats and linger on the tongue. Combine
some key components. proteins present in cream also
help mix other fats evenly with stock for a rich jus, or add cream
THICKENERS to a roux base for a creamy
into a sauce. béchamel sauce.
Thickening is a crucial step in
developing a sauce. Any thickener Finely blended food
can be combined with any liquid particles are well
dispersed.
to create a range of sauces.
FOOD
LIQUIDS PARTICLES

Most classical sauces are water-based. Bits of food, such as meat,
Water is made of tiny, boomerang- veg, or fruits, if broken down
small enough, will thicken a
shaped molecules that slide past each sauce. The consistency of the
other easily. When blended with larger sauce depends on the size
molecules in a thickening agent (see
above), their movement is slowed, so and number of the
particles.
the liquid thickens.
PURÉE
YOU CAN USE:
A classic example of using food particles to
Plain water thicken a sauce is a tomato sauce or purée.
The most simple liquid base, a Fats, such as those in butter and cream, can be
water-based sauce needs extra added to make a richer sauce, but beware

flavorings to enrich it. that thin creams will curdle in the
Stock acid when heated.

Using stock rather than plain water
brings with it the seasonings and
complex flavors already in the stock.

Wine
Slightly thicker than water, wine brings
acidity, astringent tannins, sweetness,

and the bitter harshness of alcohol.
Milk

Fat globules in milk thicken the sauce
if simmered down.
Cream

Richer, and more intense than milk, thick
cream quickly thickens a sauce when

simmered and adds a smooth mouthfeel.

062 // 063 The Science of Meat and Poultry

Is it worth all the effort to

MAKE MY OWN STOCK?

Ask a classically trained chef what raises a good dish into a phenomenal one and they will tell you it is the stock.

The benefits of making your own stock are out of vegetables and meat as they slowly cook.

undeniable: homemade stock lends dishes There are no absolute rules, although it’s

a depth of flavor that no powder or cube best not to salt stock, and keep flavorings

comes close to. The French chef Auguste WHAT IS BOUILLON? simple and subtle so that the stock can
Escoffier, who pioneered classical French be used for a variety of dishes—you can
cooking, insisted that without a good stock SIMPLY THE FRENCH WORD add strong herbs and spices later. A
prepared from fresh ingredients, food would FOR “BROTH”, BOUILLON basic meat or vegetable stock forms the
never be better than distinctly average. foundation of many dishes: it can be
HAS BECOME WIDELY USED
AS A NAME FOR PREMADE thickened with flour into a “roux”; mixed

STOCK POWDER.

Using and making stocks with wine, herbs, and spices; reduced into a

A stock is an extraction of flavors from fresh concentrated, intense jus; enriched with cream or

ingredients. In near-boiling water, flavor molecules diffuse butter; or bulked into a soup.

IN PRACTICE MAKING CHICKEN STOCK use a pressure cooker in place of a saucepan—it allows
water to reach high temperatures without boiling (see p134),
Chopping ingredients into small pieces speeds flavor speeding flavor extraction and keeping liquid clear.
release as it increases their surface area, liberating flavor
molecules and the gelatin from meat and bones. You can

#1 #2 #3

BROWN THE CHICKEN ADD VEGETABLES AND AROMATICS HEAT ON THE STOVE
Break up one whole chicken Place the chicken bones in a large Bring to a boil, then reduce the heat.
carcass into pieces and roast in a pan. Add one diced onion, 2 diced Simmer gently for at least 1½ hours
preheated oven for 20 minutes at carrots, 2 sticks of celery (chopped), (ideally 3–4 hours). Skim off scum that
400°F (200°C). Alternatively, cook the 3 cloves of garlic, ½ tsp whole black rises to the surface. If using a pressure
pieces in a little oil in a frying pan over peppercorns, and a large handful of cooker, cook for 30 minutes to 1 hour.
a medium heat until golden-brown. aromatic herbs, such as parsley, fresh Remove the stock from the heat and
Browning the chicken creates the thyme, or bay leaves. Cover with cold allow it to cool, then skim off the fat
Maillard reaction (see p16), which will water to about 1in (2.5cm) above the and pour through a fine sieve. Use
add intensity of flavor to the stock. level of the stock ingredients. immediately, store in the fridge for up
to 3 days, or freeze for up to 3 months.

Why Do So Many Foods Taste Like Chicken?

Why is it safe to eat

RARE BEEF, BUT NOT CHICKEN OR PORK?

If you enjoy a rare steak, you may wonder why you can’t cook other meats in the same way.

Risk of food poisoning affects some meats more often piled together, easily contaminating all parts of the

than others, and depends on the way an animal is meat with bacteria. Larger animals, such as cows

kept, fed, and handled when it is butchered. OFFICIAL and pigs, are usually handled with more care,
GUIDELINES so are less likely to be cross-contaminated
Take care with chicken with infected material; searing the outside
POULTRY SHOULD BE
Fears of eating undercooked chicken are COOKED TO AT LEAST should kill any bacteria. Pork, in particular
well-founded. Chickens often harbor 165°F (74°C) AND PORK TO from pigs fed on garbage and other animals,
dangerous bacteria such as Salmonella and 145°F (62°C) TO KILL can carry worms that lay their eggs deep inside
Campylobacter. Most bacteria live on, rather HARMFUL BACTERIA. muscle. However, improved feeding practices

than inside, meat, and come from contact mean that most experts believe slightly pink,

with animal feces. In an industrial setting, cooked pork is safe to eat. Cook poultry and pork

carcasses of chickens killed on conveyor lines are to minimum temperatures to kill bacteria (see box).

Why do so many foods Pale There are
fast-twitch few dark
TASTE LIKE muscle fiber slow-twitch
CHICKEN? muscle fibers.

Goose, frog, snake, turtle, salamander, pigeon… all WHITE MEAT MUSCLE Contains little
taste a bit like chicken! There is a logical explanation. or no fat, so
Dark tastes blander
Red meats taste distinctive to us, but when we try slow-twitch than red meat
a white meat for the first time, we often compare it to muscle fiber muscle.
chicken. The clue is in the type of muscle the animal has. Contains
lots of flavor-
A type of muscle generating
enzymes.
Chickens don’t do a great deal of endurance exercise, so
their meat is mostly pale “fast-twitch” muscle, designed There are few, Fats in cells
for brief, powerful movements, such as flapping. Fast- or no, pale and around
twitch muscle is soft, lean, and lacks flavor-giving fat, so it fast-twitch fibers give
tastes bland. Most of the animals that taste like chicken, such slow-twitch
as pigeons or frogs, have a similar ratio of paler muscle. In muscle fibers. muscles extra
contrast, darker, red “slow-twitch” endurance muscle, found flavor.
more in red meats, has more fat and distinctive flavor-giving
substances, making it easier to tell these meats apart. The RED MEAT MUSCLE
flavor molecules in each meat vary between species, but
scientists have charted how meat flavors have been Muscle types and meat flavor
inherited. They have found that many of the animals that
we eat today (except pork, beef, and venison) descend from The two muscle types above show how the
one common chicken-flavored ancestor. composition of muscle in red and white meats
affects the appearance and flavor of the meat.



FISH & SEAFOOD

In focus 066 // 067 The Science of Fish and Seafood

FISH

If you want to experience a wide variety of flavor sensations, look to the seas. KNOW YOUR FISH
There are about five times more species of animals living underwater than
there are mammals on the land. Rich in protein and fats, how relatively
lean or fatty a fish is determines how you
High in protein and essential nutrients, but low designed to work in the cool temperatures of cook it. Fatty fish such as salmon suit a
in saturated fat, fish is a nutrient powerhouse. Its the sea and rivers. This means that proteins in variety of methods, while leaner white fish
subtle flavor profile and delicate texture means it fish unfold and coagulate and cook at a lower and more delicate fish such as trout require
requires careful cooking. Like meat from land- temperature than land animals. Fish shouldn’t gentle cooking methods, such as poaching.
based animals, fish is comprised of be kept in the fridge for as long as meat for
muscle, connective tissue, and similar reasons: the muscle-digesting enzymes OILY FISH
fat, but its tissues are quite in fish thrive at ocean-like temperatures (40°F
different. Its flesh is mostly or 5°C), rapidly spoiling the meat. Putting fish Salmon
muscle, suited for short, in a container of ice (32°F or 0°C) will slow With its oily flesh
powerful bursts of down these enzymes, making fresh fish last and meaty texture,
acceleration, and twice as long. salmon works well
with a range of
Head Eyes FAT: HIGH cooking methods.
Mostly made Bright, clear, bulging eyes are a sign of PROTEIN: MEDIUM Wild salmon is leaner
of bone and freshness in a fish. If eyes are dull, a and firmer in texture
connective tissue, fish is past peak freshness. The eyes are FAT: HIGH than farmed salmon.
which cooks down edible and are prized in some cuisines. PROTEIN: MEDIUM
into gelatin, fish Mackerel
heads add flavor Gills FAT: LOW This small fish has a
and texture to These threadlike filaments PROTEIN: HIGH creamy, slightly salty
stocks and stews. are the organ that lets fish flavor. Sturdy and
extract oxygen from water. firm-fleshed, it can
Gills have a red tinge due be grilled or broiled
to high blood flow, but taste whole. Store it on ice
bitter as a result so are as it spoils quickly.
always best removed.
Fillets Tuna
These are cut from either As a warm-blooded,
side of the fish’s body, active carnivore, tuna
removing the spine. This has dense, flavourful
cut offers the most meat. meat. However, its
flaky flesh dries out
rapidly, so thick slices
cooked rapidly help
keep the silky texture.

Steaks FAT: MEDIUM Trout
Used mainly for large, PROTEIN: HIGH Closely related to
round fish, steaks are cut salmon, trout has an
through the body and earthy flavor and
include vertebrae and flaky, delicate flesh
the stomach cavity. with moderate fat,
Scales so it is best gently
Each scale is made of baked or steamed.
a protective, bone-like
material that encases an WHITE FISH
inner layer of collagen.
Tail fillet They are generally FAT: LOW Cod In Focus: Fish
Muscle here is darker inedible and, unless very PROTEIN: MEDIUM This mild flavored,
small, are best removed white-fleshed fish is
endurance muscle, with gentle scraping. FAT: LOW lean—cod has just
used to power PROTEIN: MEDIUM 0.3 percent fat. Cook
SCIENCE gently and serve with
movement, and is FAT: LOW fat-containing foods
more richly flavored. FISH MUSCLE IS PROTEIN: MEDIUM to add succulence.
ARRANGED IN SHEETS,
Tail WHICH ALLOWS FISH TO FAT: LOW Haddock
Known as the UNDULATE THEIR BODIES PROTEIN: MEDIUM Similar to cod,
caudal fin, this haddock is low in fat
propels the fish THROUGH WATER. and has a high water
content of up to 80
forward. Sheets, or percent, so it can be
myotomes, of fragile when cooked.
Poach it or bake it.
muscle are
separated by a Monkfish
The tight, meaty
thin band of white flesh of
connective tissue. monkfish tail can
withstand the high
COOKING temperatures used in
stir- and pan-frying.
WHEN HEATED, THE The large head is
SHEETS OF FISH MUSCLE usually discarded.

SEPARATE INTO THE Sea bass
DELICATE FLAKES TYPICAL This covers a range of
species characterized
OF COOKED FISH. for their thick coat of
scales. The slightly
MUSCLE STRUCTURE sweet, flaky flesh can
be baked, broiled, or
pan-fried.

068 // 069 The Science of Fish and Seafood

How do I know if Why is fish called

FISH IS FRESH? “BRAIN FOOD”?

Fresh fish has a short shelf life, so knowing how Our prehuman ancestors started fishing
to spot-check for freshness can be useful. around two million years ago. Today,
researchers believe that fish nutrients fuelled
Once a fish dies, its digestive enzymes continue to work and bacteria
that is naturally present on the fish start breaking down its flesh. our rapid brain growth.
Because bacteria in fish breed well at lower temperatures, and the
unsaturated oils turn rancid more rapidly than other animal fats, fish Fish is a rich source of iodine and iron,
should ideally be eaten within one week of being caught. Use the essential minerals for healthy brain development
indicators below to help you identify the freshest fish. in childhood. In addition to these brain-fortifying
minerals, the oils in fish also contain essential
Skin and scales Smell omega-3 fats, which act as building blocks for the
These will be metallic- A fresh, slightly briny fatty sheaths that surround nerve cells, coating
looking and bright on smell is ideal. Avoid fish the nerves and allowing them to function
fresh fish, rather than that have an unpleasant, properly. Oily fish, such as salmon, anchovies,
dull, and there should or especially strong, sardines, mackerel, trout, and tuna, have the most
be no patchy or fishy aroma. plentiful supply of brain-fortifying omega-3 fats.
broken scales.
The way in which fish is prepared or cooked
Eyes can affect its levels of essential fats. Canning
Look for fish with fish destroys a large proportion of omega-3s,
and cooking at high temperatures, for example,
bright, shiny, frying, can break down, or oxidize, omega-3s.
bulging eyes and Delicate cooking methods, such as baking and
steaming, are best for preserving these oils.
avoid those
SALMON with milky, Omega-3 levels in fish 2.5g
sunken eyes. 2.0g
The chart shows the levels of
MYTH BUSTER omega-3 fatty acids in different
fish. Women are advised to eat
Myth around 1.1g of omega-3 fats
ALL FISH SMELL “FISHY” each day, and men 1.6g.

Truth = 0.1G OF 1.5g
OMEGA-3 FATS 1.0g
Freshly landed fish actually have a
pleasant grassy smell, but after 2–3 PER 3.5OZ
days this sweet smell vanishes. In (100G)
saltwater fish, the foul-smelling odor
Feel Gills comes from the breakdown of urea 0.5g
The freshest In fresh fish, the and trimethylamine oxide (TAMO).
fish have a firm gills are moist, Freshwater fish don’t have TAMO, but 0.0g
consistency and are bright red, and start to smell over time as bacteria COD SHRIMP SARDINES ALBACORE SALMON TROUT MACKEREL
springy to the touch, clean-looking,
rather than inelastic, produce rancid-smelling gases. TUNA
soft, or squishy. rather than So a freshly caught fish doesn’t
dull or slimy. smell “fishy,” but fishy smells evolve

the less fresh it becomes.

Why Is Fish Called “Brain Food”?

OILY FISH ARE ONE OF THE WORLD’S BEST SOURCES OF OMEGA-3 FATTY
ACIDS, WHICH ARE INCREDIBLY IMPORTANT FOR THE BODY AND BRAIN.

A HEALTHY BRAIN A FISHY DIET MAY EATING FISH HAS
OFFER SOME BEEN SHOWN TO
RESEARCH SHOWS THAT PROTECTION
PEOPLE WHO EAT OILY HELP REDUCE
FISH REGULARLY HAVE AGAINST DEMENTIA. MENTAL FATIGUE.
LESS BRAIN SHRINKAGE
RESEARCH SUGGESTS THAT A DIET RICH IN FISH OILS
IN OLD AGE. BOOSTS MENTAL PROWESS AND REACTION TIMES.

EVIDENCE REVEALS BRAIN-FORTIFYING
FISH OILS CAN IMPROVE
FISH OIL SUPPLEMENTS
CONCENTRATION IN GIVEN TO PREMATURE
CHILDREN WITH ADHD. BABIES HELP ENSURE

EATING OILY FISH NORMAL BRAIN
MAY IMPROVE D E V E L O P M E N T.

SLEEP QUALITY.

FATTY ACIDS Brain-boosting
IMPROVE BLOOD nutrients
FLOW TO THE BRAIN.
A SAFE LIMIT For those low in
omega-3, research shows
FISH SOAK UP POLLUTANTS, that fish has marked
S U C H AS M ERC U RY, F R O M brain-boosting benefits,
THE SEA, SO EAT NO MORE helping to keep our
mental faculties sharp
THAN FOUR SERVINGS and functioning well.
OF OILY FISH
A WEEK.

SUPER FISH

MACKEREL HAS AN
IMPRESSIVE 2.6G OF
OMEGA-3 FATTY ACIDS

PER 3.5OZ (100G).

070 // 071 The Science of Fish and Seafood

Why does salmon come in

VARYING SHADES OF ORANGE?

It’s a natural assumption that the color of a salmon is an indicator of its quality.

If you’ve ever eaten too many carrots, you’ll appreciate the red astaxanthin pigment, giving them unusally

how the color of the food you eat can affect the pale flesh compared to other wild salmon.

color of your skin. The pigment in carrots—a Farmed salmon are consistently

substance called carotene—can turn skin A COMMON COLOR brighter and more orange than their wild

orange. In just the same way, a natural THE PIGMENT ASTAXANTHIN, counterparts. Although farmed salmon
pigment, astaxanthin, in the food that salmon WHICH GIVES SHELLFISH don’t have the chance to hunt shellfish,
eat, which also comes from the carotene fish farmers add astaxanthin to their pellet
family, turns their flesh orange (see below). THEIR ORANGE COLOR, ALSO feed, to give them a striking pink-orange
GIVES FLAMINGOS THEIR

PINK PLUMAGE. glow. This is intended to appeal to

Shades of orange consumers, where the commonly held belief

The color of wild salmon can vary, depending on the is that the redder the salmon, the fresher, better

food that they are able to hunt. Some types of King tasting, and higher quality the fish will be. The delicious

Salmon are an exception as these are unable to process pale-fleshed King salmon disproves this belief.

The astaxanthin pigment Krill, shrimp, and other tiny
in algae and plankton is a crustaceans feed on microalgae
concentrated bright red color. and absorb astaxanthin.

ALGAE AND PLANKTON KRILL AND SHRIMP SALMON
Carnivorous salmon
The seafood Astaxanthin eat krill and shrimp.
food chain in algae Unlike other fish, they store
astaxanthin obtained from
This illustration shows This common green algae, their diet in their muscles,
how a red-colored known as Haematococcus turning their flesh orange.
pigment, astaxanthin,
travels through the algae, is one type of algae
food chain, affecting that contains a high
the color of both
crustaceans and salmon. amount of the red pigment
astaxanthin in its cells.
Red pigment in cells
Green algae cells

Is Farmed Fish as Good as Wild?

Is farmed fish

AS GOOD AS WILD?

Feeding practices, lifestyle, and slaughter conditions all need to be considered when assessing fish.

While rearing cattle, sheep, pigs, and chicken on pesticides, and fed artificial dyes to make their flesh

farms seems quite normal, there’s a tendency to brighter (see opposite) raise concerns, but many

feel that breeding fish in a pen is less natural. salmon farms are leading the way in raising

Fish are one of the last major foods that are CHANGING TIDES standards. In terms of ethical practices,

mostly caught from the wild, and wild fish BY 2030, NEARLY TWO- wild salmon has drawbacks, with other fish
are believed to be tastier, more natural, and THIRDS OF ALL SEAFOOD sometimes being injured and killed in nets,
healthier compared to fish that do not have WILL BE FARMED RATHER and sustainability is uncertain. Looking
free access to the seas. However, while there for “responsibly sourced” wild fish and
THAN CAUGHT IN

are small differences in taste and texture (see THE WILD. purchasing farmed fish that are certified

below), these can be hard to discern. Stories of as meeting the highest standards can help

farmed fish being given antibiotics, doused in to counter concerns and ensure a quality purchase.

KNOW THE DIFFERENCE

WILD SALMON FARMED SALMON

Muscle fibers in wild fish Carefully controlled feeding
tend to be denser than those means farmed salmon grow
in farmed fish, giving their well. In some farms, food is
flesh a slightly firmer texture. sprayed on the water; when
Fighting tides, chasing prey, and eating slows, feeding is halted
fleeing predators tone muscles. so that fish are kept hungry
Wild salmon have lower fat and efficient, as in the wild.
levels overall than farmed Farmed fish feed is highly
salmon, but a higher proportion controlled to maximize fish
of healthy essential omega-3 fats. growth, and typically contains
Wild salmon experience more soy, fish meal, and fish oils.
stress in the last moments of life Capture is efficient, so
and may fight against a trawler’s there is minimal struggling,
net. As with other animals who have meaning that flavor isn’t
a stressful slaughter, lactic acid can diminished by a stressful
build up in their muscles, resulting in death. Caught fish are placed
a metallic aftertaste when we eat them. in cold water, then stunned
before being quickly killed.

072 // 073 The Science of Fish and Seafood

Is it better to buy shrimp

WITH THEIR HEADS ON?

Shrimp are the most widely eaten seafood in the world, and are available to buy in many different forms.

Anatomy This gland Shrimp are sold whole, with the head removed, the shell split,
of a shrimp contains or completely peeled. Normally, we would assume that a whole,
digestive unadulterated fish offers the fullest, freshest flavor experience,
A shrimp’s digestive organs enzymes. but this is not necessarily the case with shrimp.
sit just behind its head, above The stomach is positioned
the gills. These include a at the base of the head. Why shrimp heads affect taste
gland that releases spoiling
enzymes after death. Soon after death, substances from a shrimp’s digestive system
start to leak out into its flesh. Enzymes in these juices
quickly begin to eat away at the flesh, causing it to
turn mushy. Most of these enzymes come from the
hepatopancreas, a small gland in the base of the head, so
taking off the head as soon as possible slows the degradation
of the shrimp. Unless they are very fresh, shrimp that
have had their heads removed before shipping to the store
will have the best meat. If you are eating freshly caught
shrimp, however, those with their heads on
will retain more moisture and flavor when

cooked. The shells and most of the head
are inedible, but can be used to make
a flavorful stock.

Is it better to buy shrimp

RAW OR PRECOOKED,
FRESH OR FROZEN?

When shrimp are caught, whether in the ocean or on a shrimp farm,
time is of the essence—they can spoil within just a few hours.

Because shrimp spoil quickly shrimp farms, are simmered more

(see above), they are often –4°F gently, but nevertheless tend
processed in the moments to be overdone and dry.
after being caught. They Unless your shrimp are

may be rapidly frozen at (–20°C) is the maximum freshly caught, choose
sea, chilled on ice for temperature at which frozen, shell-on shrimp
processing on shore, or shrimp are rapidly with the head off for
cooked at sea by briskly frozen after the best flavor and
boiling them in seawater. freshness. Shrimp that
catch.
Shrimp that are cooked on are “individually quick SHRIMP
CURRY
shore, or are harvested from frozen” (IQF) are the best quality.

“ Called “insects of the sea”
because of their segmented body
and “exoskeleton” shell, shrimp
are the baby-sized relatives of
lobsters and crabs. They are the
most widely eaten seafood
”in the world.

074 // 075 The Science of Fish and Seafood

Why do we

EAT OYSTERS RAW?

Cooking breaks down proteins in animal flesh, but this is
a bad thing when it comes to molluscs, such as oysters.

The flavor of most foods improves and clams traps these tasty
with cooking: proteins break down molecules in the tangle of
into their component parts (amino cooking, coagulating
acids) to stimulate the taste buds, muscle proteins, masking
starches break down into sweeter them from the taste buds.
sugars, tough fibers weaken, textures The only way to release
firm, and excess moisture is driven them again would be by
off. This is not true for shellfish cooking for long enough
such as oysters and razor clams; their to break apart the proteins.
flavor ebbs away with each minute But by that time, the
of cooking. shellfish would have the
consistency of rubber.
Molluscs, unlike most fish (see
pp66–7), use flavor-containing amino Common oysters
acids, especially glutamate, to help
them survive the dehydrating effects Each oyster species has a specific
of the salty sea. Glutamate stimulates flavor profile, but this can vary
the umami taste receptors on the depending on where they were
tongue (see pp14–15), giving them a farmed. The species below are the
savory, meaty flavor. Cooking oysters most commonly available to buy.

ATLANTIC EUROPEAN KUMAMOTO PACIFIC

A commonly Native to Europe These oysters Now cultivated
cultivated variety in the and distinguished by their originate in Japan, but are around the world, Pacific
US, Atlantic oysters are the now popular around the oysters are native to the
only species native to the flat, shallow shape, world. They are smaller Asian Pacific. They were
numbers have depleted in than most other oysters, introduced to the US and
East Coast of North natural breeding grounds and take longer to reach
America. They have a maturity. Their shells are then Europe as native
distinctive, teardrop- over the 19th and 20th stocks in these
centuries. Hard to find deep and fluted. depleted areas.
shaped shell. Taste Taste
Taste outside Europe.
Taste Milder than other varieties, Flavor varies, but Pacific
They have a salty, clean they have melon aromas oysters are generally less
flavor with savory and They have a mild, slightly and a soft texture. salty than other species.
mineral notes. Crisp texture. metallic flavor, and are

almost crunchy in texture.

“While cooking improves the When Is the Best Season for Oysters?
flavor of most foods, this is not
When is the best
true for oysters and clams.”
SEASON FOR
Eating raw safely OYSTERS?

Raw oysters and clams are far from risk-free. Molluscs, such Many people argue that oysters should not be eaten in
as oysters and clams, are filter feeders, drawing in water and summer, and this may have once been prudent advice.
filtering it for plankton and algae. This process can also trap
harmful microbes, creating a small, infectious cesspool. There is an adage that oysters should not be eaten during
the summer months (May until August). This saying may
Many of these microbes come from sewage contamination, be rooted in a desire to avoid food poisoning. Algae are in
but most store-bought oysters are from protected, inland their most vigorous growth during summer, flooding the
waters that are monitored for bacteria and harmful chemicals. water with toxins that can cause food poisoning if
Oysters are also “purged” before sale—kept in a tank of clean ingested—summer “red tides” are when large numbers
saltwater so they can naturally cleanse themselves. of algal blooms discolor coastal waters.

To avoid risk, eat molluscs from a reputable source. They Another traditional reason to avoid oysters in summer
should be stored very cold (ideally on ice) and eaten promptly. is because it is their breeding season. During this part
Avoid eating raw fish if you have immune system problems. of the year, oysters expend all of their energy reserves
producing eggs, making them small, soft, and flimsy,
and dramatically reducing their flavor.

Oyster farming

Thankfully, this advice can now be cast out to sea. Most
oysters purchased in stores today are farmed oysters that
come from well-maintained waters. Commercial farms will
also select oyster breeds that have a very short spawning
period—or are sterilized so that they never spawn. Oysters
can now be savored year round—regardless of whether or
not you decide to cook them.

MYTH BUSTER

Myth
OYSTERS ARE AN APHRODISIAC

Truth

Those looking to explain this myth often point to the high
zinc content of oysters, a mineral used to create the key

sex-drive hormone, testosterone. By this logic, oysters may
help the zinc deficient, but no more than any other

zinc-rich foods. There are two other substances in oysters
rarely found in other foods that help create sex hormones:
aspartic acid and NMDA. However, experiments on mice
using these substances have been inconclusive, and, in any

case, an excess of zinc could dampen libido by causing a
surge in the “hormone of satisfaction”, prolactin.

076 // 077 The Science of Fish and Seafood

DATA The process of

How it works PAN-FRYING
A hot frying pan, glazed
with oil, transfers heat quickly Heating food in a frying pan glazed with a little oil is one of the simplest
and evenly into food. High and most effective ways to cook meat or fish—but how does it work?
temperatures create a crisp,
Frying is great for cooking flavorful food pp16–17). Oils lubricate food and let flavor
browned exterior. quickly. Liquid fats heat up twice as quickly molecules from food seep across the pan,
Best for as water and reach higher temperatures. while adding their own buttery or fresh
These high heats let food develop a crisp, notes. This diagram puts a spotlight on the
Fish fillets; thin cuts of meat, aromatic crust via the Maillard reaction (see process to help you fry food to perfection.
such as steak, pork chops,

or chicken breasts; potatoes.
What to consider

Timing is key. As heat travels
through food slowly, the

outside can easily burn before
the center cooks.

A THICKER CUT OIL THE PAN PLACE FOOD IN THE PAN
Add at least 1 tbsp sunflower oil or Add the food to the pan. It should
AS HEAT TRAVELS SLOWLY other oil or fat with a high smoke sizzle right away, as surface moisture
THROUGH MEAT AND FISH, point (see pp192–193) to the pan. evaporates from the food, indicating
Oil transfers heat to the food and the oil is above 212ºF (100ºC). For
FILLETS THICKER THAN prevents it from directly bonding an aromatic crust, water must be
1½IN (4CM) SHOULD with the metal of the frying pan. driven off quickly so that food cooks
BE FINISHED IN Heat until the oil begins to shimmer. above 284ºF (140ºC).
THE OVEN.
#2 #3
75%
Do not overcrowd the pan; otherwise the
hotter cooking temperature of the pan will drop and the fish will
temperatures are used
for pan-frying compared steam in its own moisture rather than fry.

to boiling.

SPEEDY TECHNIQUE TURN ON THE HEAT #1
Place a heavy-bottomed frying
OIL REACHES HIGHER pan over medium-high heat, and
TEMPERATURES THAN THE heat for at least 1 minute without
BOILING POINT OF WATER, oil to allow the metal to warm up.
SO PAN-FRYING IS A QUICK

COOKING METHOD.

The Process of Pan-frying

HOW TO SAUTÉ See inside Key
Film of oil cooking the fish
FOR SAUTÉING, SMALL When food is first placed into hot oil, the Heat traveling from the oil
PIECES OF FOOD THINLY water-repelling oil lubricates and coats the Steam
base of the food, letting heat spread evenly
COATED IN OIL ARE across the food. Heat moves relatively Heat moves
TOSSED IN A HIGH-SIDED slowly through the food compared slowly through
to the rate at which the surface to the center.
PAN AT A HIGH dries and cooks.
H E AT. Dehydration creates
a crispy surface.
FLIP AND COOK THROUGH
Flip the food regularly, to allow Repelled steam
even cooking. Fish should “sizzles” off the
ideally be flipped only once, surface of the fish,
after 3–4 minutes, because helping to prevent
fish muscle is fragile (see it from sticking.
p86). Once the food is cooked
as desired, remove from the
pan and serve immediately.

#4

If the pan gets too
cold, the food will
stick to the surface.

A heavy-bottomed “The high
frying pan spreads temperatures used in
and retains heat well. pan-frying dehydrate
the surface of foods,
Place the pan on
a burner at least creating a crisp,
two-thirds the browned exterior.”
pan’s width
to help heat
spread evenly.

078 // 079 The Science of Fish and Seafood

How can I

PRESERVE FISH AT HOME?

Curing is one of the oldest methods of preserving fish—and it’s simple to achieve in your own kitchen.

The best fish is tender and moist, but if we don’t salt is considerably faster than air drying and is easy

have a freezer and want to save fresh fish for to do at home. Covering fish in a blanket of

eating another day by refrigerating it, the salt forces the protein molecules in the flesh

moisture that gives it a smooth mouthfeel soon TEXTURE to unravel, just as if they had been cooked.

turns the flesh into a damp breeding ground for CURED FISH HAS A FIRM, Salt slowly seeps in as moisture is drawn out,
bacteria. Before refrigerators, salting and drying DRY TEXTURE; HOME- resulting in firm, flavorful fish. This method
seafood was the norm for keeping microbes at CURED SALMON HAS is known as dry curing. Including sugar in
bay. Norwegian tørrfisk (stockfish) keeps this the curing mix adds sweetness and also
A TEXTURE REMINISCENT

historical tradition alive today: whole, gutted OF SMOKED SALMON. helps preserve the fish. You can also wet-cure

cod are simply hung on racks and left out to fish by immersing them in a densely salted

dry. This method is impractical for the home solution, which retains more moisture. A wet

cook, as it requires outdoor drying space, takes months cure is often used with smaller fish or with fish that

to complete, and can be very smelly. Preserving fish with are going to be smoked.

IN PRACTICE HOW TO DRY-CURE SALMON are present. To add extra flavor to the outside of the fish,
include citrus zest, peppercorns, herbs, or toasted spices
Choose the freshest fish for curing—buy sushi-grade fish, in the curing mix and put in a food processor to combine.
or purchase your fillet from a reputable source and freeze
it for 24 hours before defrosting to kill any parasites that

#1 #2 #3

PREPARE THE CURING MIX MAXIMIZE CONTACT WITH SALT CHECK THE CURE
Combine 1lb 2oz (500g) fine salt and Cover the dish with plastic wrap and Uncover the fish and check its texture—
1lb 2oz (500g) extra-fine sugar to make place a heavy object on top of the fish it should feel firm. If it is still mushy,
a curing mix. Cover the base of a flat to flatten it. This presses the fish down recover the fish with the curing mix
shallow dish with half the curing mix. into the curing mix and helps create and plastic wrap and weight it before
Place one clean, dry, 1lb 9oz (700g) a firm texture. Leave to cure in the returning to the fridge for 24 hours.
skinned salmon fillet in the dish, and fridge—allow 24 hours of curing for Once ready, rinse the fish and pat it
cover it with the remaining curing mix. each 1in (2.5cm) thickness of fish. dry. Refrigerate and eat within 3 days.

Serving cured fish What Happens When You Salt-Bake Fish?

Acids released during the curing process What happens when you
give fish an intense tangy taste, so it is
best served in thin slices. You may want SALT-BAKE
to discard the saltier outer layer. FISH?

This ancient cooking technique
is simpler than it looks.

Of all the ways to cook fish, covering
it in salt before baking seems one of the
most extravagant. A whole fish, such as a
sea bass, sea bream, or snapper, is seasoned
before being encased in salt moistened
with egg white, then baked. The salty,
golden-brown shell is cracked open to
reveal a perfectly cooked fish.

How it works

The salt covering acts very much like
pastry, parchment, or foil covering,
preventing water from escaping. The fish
steams in its own moisture, rather than
being cooked by the hot, dry oven air.
Egg white proteins solidify as they cook,
which helps hold the salt shell around the
fish during baking. As salt diffuses into fish
very slowly, very little penetrates the flesh
in the time it takes to cook—this means that

it tastes similar to other
forms of baked fish.

400°F

(200°C) is the optimum
temperature for salt

baking fish.

SALT BAKING
ORIGINS

THE EARLIEST RECORDS
OF SALT BAKING ARE

FOUND IN TUNISIA IN THE
4TH CENTURY
BCE.

080 // 081 The Science of Fish and Seafood

Is it better to buy fresh or

FROZEN FISH?

Freezing fish halts the growth of bacteria and microbes,
and muscle-digesting enzymes in fish are stalled.

Fragile fish oils quickly turn rancid crystal damage is negligible, FLAVOR TRANSFER
and natural bacteria that coat them and texture and taste are almost
breed well in the fridge (see p68). identical to a fresh fish. But FLAVOR MOLECULES FROM
low-powered home freezing will PARCHMENT-BAKED FISH
Fish can be frozen with more damage delicate fish proteins. SEEP OUT INTO THE LIQUID
success than other meats as their BROTH AND CAN BE KEPT
flexible muscle membranes suffer So, if fish has been caught very
less damage from sharp ice crystals. recently and kept on ice, fresh is FOR A SAUCE BASE.
If “flash frozen” (see below), ice best, otherwise buy it prefrozen.
KNOW THE DIFFERENCE
KNOW THE DIFFERENCE
Parchment
Flash-freezing fish Home freezing fish Baking fish in parchment, en papillote,
Industrial blast freezers freeze fish Low-powered home freezers freeze traps in moisture and gives a similar
rapidly to limit ice crystal formation. slowly, allowing ice crystals to form. effect to slow-poaching fish (see p83).

Freezing often starts on board The liquid in fish is a salty mix What is it? Fish is baked in a
ships to halt spoilage, with fish of proteins and minerals. The salt tightly sealed parchment or foil
cooled to around –22ºF (-30ºC). lowers the freezing point, which pouch. Parchment typically has
Once on shore, industrial freezer slows home freezing even further, a nonstick silicone coating, giving
chambers blast fish with –40ºF increasing damage to muscle proteins insulation that slows heat transfer
(–40ºC) air to finish freezing rapidly. from slowly expanding ice crystals. from the pan. Most foil isn’t
nonstick and transfers heat
Can I cook fish more rapidly.
Best for: Ideal for cooking fillets.
FROM FROZEN? Herbs, spices, and vegetables can
be added to suffuse the outer layers.
Cooking from frozen increases cooking time, but has benefits, too.
Uncovered
Cooking smaller fish from frozen Ice crystals melt slowly in fish, As with oven roasting meats, the outer layers
works perfectly well. Large cuts of increasing cooking time, but this of fish baked without a covering can dry, but
fish, and whole fish, run the risk of delay can help to achieve crisp skin this can be a good method for whole fish.
being uncooked in the center and without the center overcooking.
burnt on the outside, so should be How the fish cooks: Fish is baked
thawed before cooking. If you do thaw fish, do this in the oven without a covering, with
either on a rack in the fridge with added oils and flavorings. Cooking is
Thin- to medium-thickness a drip tray beneath, or put fish in slow and the outer layers dry as heat
fillets cooked from frozen can a sealed bag in a bowl of icy water. moves into the center.
rival fresh fish in taste and Water speeds thawing, and Best for: This is ideal for whole fish.
texture, and may even surpass keeping it very cold helps Although the outer layers of the fish
them if a crispy skin is called for. prevent bacteria from breeding. dry, as the surface temperature soars,
the skin is crisped and browned while
the center cooks gently.

Should I Bake Fish in Parchment or Uncovered?

Should I bake fish

IN PARCHMENT OR UNCOVERED?

Different methods for baking fish can have very different results.

The two main ways to bake fish have different results, parchment with a similar result; but, unlike parchment,
so deciding on a method (see below) depends on your foil isn’t usually nonstick and heat travels through the metal
desired result. Fish cooked in parchment paper, known as quickly, so any part of the fish that isn’t oiled may stick to
“en papillote,” is an impressive dish to serve: a paper package the foil. Cooking fish in parchment produces succulent flesh
is brought to the table and cut open, revealing a feast of and is an effective way to infuse fish with flavors.
seafood amidst a burst of aromatic steam. It’s a showy dish,
yet remarkably simple: fish is baked in parchment paper so Whole fish can also be baked uncovered to excellent effect
that it cooks in its own juices. Foil can be substituted for as the high heat crisps the fish skin at 284ºF (140ºC) while
the center of the fish cooks gently, retaining moisture.

Cooking fish
in parchment

Heat is trapped inside
the tightly sealed

package in sauna-like
conditions, minimizing
moisture loss from the
fish. The heat circulates

and steams the fish in
its own juices, plus any

added liquid, at about
212ºF (100ºC).

Trapped
steam circulates.
Hot oven air

Cooking fish
uncovered

The hot oven air
doesn’t transfer heat
efficiently throughout
the fish. The surface
layers gradually dry
out as moisture leaves
the top layers and heat
inches slowly toward
the center of the fish.

Moisture escapes.
Heat slowly travels
into the fish.

082 // 083 The Science of Fish and Seafood

How can I keep fish moist

WITH DIFFERENT COOKING METHODS?

The makeup of fish is geared toward survival in cool waters; with delicate muscles and internal
chemistry suited to colder climes, care needs to be taken not to overcook fish.

Many cooks find fish unforgiving because SOUS VIDE PAN-FRIED
they don’t realize how quickly its muscle
proteins unravel and coagulate during Flesh is moist and Fish is flipped to cook the
cooking. In fish, this happens at 104–122ºF succulent after cooking. flesh from both sides.
(40–50ºC), compared to 122–140ºF (50–60ºC)
in red meat. Above this heat, muscle cells and 171ºF (77ºC)
connective tissue shrink, expelling fluid and 154ºF (68ºC)
turning the flesh dry and fibrous. 140ºF (60ºC)

Achieving an “even” cook 129ºF (54ºC)

The surface of fish cooks before the inside, 140ºF (60ºC)
154ºF (68ºC)
the difference in temperature being termed 171ºF (77ºC)

a “temperature gradient,” which Residual heat continues to travel into the
center after fish is removed from the pan.
is greater when cooking at high 140ºF (60ºC) Pan-frying fish at a high temperature
cooks the outer edges before the center.
heats. When removed from “Carryover” cooking continues once the
fish has been taken out of the pan, so it
the heat, residual heat A USEFUL CUT can be easy to overcook fish.
in the fish goes on
Best fish
moving inwards, TO HELP A TAPERING PIECE Pan-frying suits tender fillets and delicate
fish where quick cooking helps prevent
cooking the fish as it OF FISH COOK EVENLY, muscles disintegrating with overcooking.

goes. This is known as SCORE IT EVERY .4–.8IN Surrounded by water, fish Halibut • Dover sole • Cod
carryover cooking and IN THE THICKER PARTS. cooks evenly throughout. Salmon • Seabass • Tuna • Mackerel
is more dramatic in

high-heat gradients, for Cooking fish slowly in a low-

example, with pan-frying, so it’s temperature sous vide bath (see p84)

best to take fish out of a hot pan just cooks the outer layers at a similar rate
before you think it’s done. Slower cooking to the center, giving an even cook and
methods, such as poaching and sous vide, moist, juicy flesh.

achieve more evenly cooked fish. The chart, Best fish
right, uses three different cooking methods: Seafood with plenty of connective tissue and
sous vide, pan-fried, and poaching, to show meatier fish benefit from the slow cooking of
how fish cooks with different heat gradients.
sous vide.

There are several ways to check if fish is Octopus • Squid • Salmon • Dover sole
done: flesh will be firm and not shiny, a bone Haddock • Monkfish
can be pulled out without tugging, or a digital

thermometer reads 140ºF (60ºC) in the centre.

“Naturally delicate, HADDOCK SEABASS
fish need to be

cooked with care.”

Can Fish Turn Soggy If Poached Slowly?

Can fish turn soggy if

POACHED SLOWLY?

Poached fish can be a delicate, flavorful dish; you should understand
the anatomy of fish muscle in order to improve your poaching technique.

A delicate meat, fish requires careful water to a boil. At a rolling boil, timing

POACHED cooking (see left). Poaching offers the becomes difficult and the outside layers

The temperature gradient cook an easy, fuss-free way to cook of the fish can overcook and flake off in
between the center and the
edge is relatively small. fish slowly and steadily. However, a the turbulent water.

171ºF (77ºC) common worry with poaching is Flavor infusion
155ºF (68ºC)
140ºF (60ºC) that fish will become mushy and
155ºF (68ºC)
171ºF (77ºC) waterlogged if left sitting in 70% Ingredients such as
As with sous vide (left), cooking is water for a long period
fairly even and flesh is tender. of time. In fact, fish vegetables, lemon, and
Poaching fish in water is best muscle is unable to herbs can be added to
done at a gentle simmer (see right). absorb much liquid at
Poaching has a lower temperature all because its cells are of the weight of fish the poaching water to
gradient than frying, so fish is cooked
more evenly throughout. infuse extra flavor into
muscle cells is water, the fish. However, these
Best fish so cells are unable to
This is a versatile method that works for already saturated with flavorings don’t carry
many types of fish, but is particularly effective absorb more.
water and so have little especially well in water
for meatier varieities.
Salmon • Halibut • Trout • Dover sole space to absorb more and won’t penetrate far

Turbot • Tuna liquid from the poaching water. into the fish, so the results

TURBOT Poaching does help to keep fish can be disappointing. Poaching in

moist because water cannot evaporate fish stock, vegetable stock, or wine

from the surface of the fish. A common rather than plain water is a slightly more

mistake when poaching is to bring the effective way to to flavor the surface.

KNOW THE DIFFERENCE

Deep poaching Shallow poaching
With deep poaching, a pan of liquid is For shallow poaching, a wide pan of liquid
brought to a gentle simmer of 160–185ºF is brought to a gentle simmer of 185–199ºF
(71–85ºC) and the fish is completely (85–93ºC). The fish is partially submerged
submerged in the liquid. in liquid—to just one-third of the way up.

Deep poaching is a very gentle The smaller amount of liquid
way to cook fish, helping to used in shallow poaching can be
ensure that it remains tender. flavored and reserved and used
With sufficient liquid, all of the to make a concentrated, intense
ingredients are fully submerged sauce after cooking that is
and can infuse some of their infused with flavor molecules
flavors into the liquid and from the fish.
outermost layers of the fish.
Timing is less reliable with
Completely covered in the shallow poaching because some
poaching liquid, fish is evenly of the fish is out of the water.
cooked throughout, and the Lightly covering the surface
cooking time is a reliable with a sheet of parchment paper
10–15 minutes. traps steam to help cook the
top of the fish.

084 // 085 The Science of Fish and Seafood

DATA The Process of

How it works SOUS VIDE
Food is placed in an airless
bag and heated in water at a Done correctly, the texture and freshness of food cooked
controlled low temperature. sous vide—meaning “under vacuum”—is unparalleled.

Best for The French-created practice of sous vide cooking is increasingly popular.
Fish fillets, chicken breasts, The equipment needed for sous vide may appear high tech, but the
pork chops, steaks, lobster, principles are simple—food is cooked at low temperature for a fairly long
time inside a sealed, airless bag. Two pieces of equipment are needed to
eggs, carrots. cook sous vide: a vacuum sealer that extracts air from, and seals, the cooking
What to consider bag, and a water bath to cook at a precise temperature. A thermometer-
As with other low-temperature controlled heater keeps the water a steady temperature that matches the
cooking techniques, food isn’t desired final temperature of the food. The results are incredibly consistent
browned, so if you want a and food is cooked evenly throughout.
seared edge or crispy skin, you
will need to sear food before See inside Flesh is
or after sous vide cooking. cooked
Heat from the water bath through
105ºF penetrates the food’s surface evenly.
from all directions. The airless Food is
(41ºC) is the heat setting bag stops moisture entering or heated from
for rare salmon; 140ºF leaving and the core of the all directions.
(60ºC), for well-done food gradually reaches the same
temperature as the edges, so
salmon. there’s no temperature gradient
(see p82). Food is cooked
LOW AND SLOW evenly, with no dried edges
or undercooked centres.
MEAT AND FISH CAN BE
LEFT AT A DESIGNATED Key
TEMPERATURE FOR THREE Heat from water travels into food
HOURS WITHOUT FEAR OF
Water temperature held at 60ºC (140ºF)
OVERCOOKING.
KNOW THE DIFFERENCE
FRESH ONLY
Sous vide Poaching
SOUS VIDE CAN INTENSIFY Sealed and held at a constant temperature, Food is immersed in liquid and simmered
GOOD AND BAD AROMAS, it’s almost impossible to overcook food. at a higher temperature than sous vide.
SO USE FISH AND MEAT
THAT ARE VERY FRESH, Cooking time: Food is cooked Cooking time: Food cooks faster
slowly in water only and flavoring and can be easily overcooked. It can
WITHOUT A HINT OF is added to the sealed bag. be poached in a variety of liquids,
SPOILAGE. including water, stock, milk, or wine.
Flavor: Vacuum-sealed bags
hold in flavor and moisture. The Flavor: While flavors from the liquid
Low pressure in the bag helps to can suffuse the fish during cooking,
draw the aromas and flavors of flavor can also be lost from the food
the juices into the meat. into the cooking liquid.

The Process of Sous Vide

AFTER COOKING Heat penetrates the food
Once cooked, remove the evenly from all directions.
bag. Let food cool briefly in
the bag to allow moisture
inside the flesh to thicken.

#4

#3 PLACE FOOD ON THE RACK
Place the bag in the cooking
rack and then close the lid to the
sous vide cooker. Suspended
in the water, the food is heated
evenly from all directions.

#2 VACUUM-PACKED
Prepare your fish, trimming and
adding flavorings and seasoning,
then place in the sous vide bag,
ensuring the bag isn’t overfilled,
then vacuum-seal the bag.

#1 A specially fitted
rack keeps food
SET TEMPERATURE submerged and
AND TIME can accommodate
Set the temperature to cook several portions.
food to the desired level of A countertop
doneness. Water is held at appliance
this heat during cooking. contains a
built-in heating
element.

086 // 087 The Science of Fish and Seafood

How do I cook fish to have CHOOSING FISH

CRISPY, GOLDEN SKIN? AVOID RUBBERY- OR
THIN-SKINNED FISH. SEA
The crisp crunch of perfectly browned skin is the ideal BASS, SNAPPER, SALMON,
counterbalance to soft, flaky fish meat.
FLOUNDER, AND COD
Achieving a crisp, golden-brown skin is all excess moisture instead of kick-starting the ALL CRISP WELL.
about cooking over a very high heat. This Maillard reaction, and the flesh may overcook
causes moisture to sizzle away, allowing the before the skin is dry enough to brown. If
skin to reach 284ºF (140ºC), the minimum the pan is not hot enough and there is no
temperature needed to trigger the Maillard sizzling, a chemical reaction occurs between
reaction (see pp16–17)—a chemical reaction proteins in the skin and metal atoms in the
between amino acids and sugars that crisps pan, causing them to fuse together and the
the skin and creates a delicious flavor and fish to stick. Thoroughly drying the fish skin
brown color. If the skin is not dry enough, and using an oil with a high smoke point on
heat energy will be expended driving off a high heat will help fish skin crisp beautifully.

IN PRACTICE PAN-FRYING FISH better than a thin-based frying pan. For larger cuts of fish
that are too thick to cook through on the stove, transfer
Pan-frying a skin-on fillet is a quick and delicious way the browned fish into a preheated oven to finish cooking.
to yield fish with crispy skin and moist, flaky flesh. Use
a heavy-bottomed frying pan or skillet; this will hold heat

#1 #2 #3

DEHYDRATE FISH SKIN WITH SALT HEAT OIL TO BELOW SMOKE POINT PRESS, FLIP, AND COOK THROUGH
Rub fine sea salt across the surface of Heat a heavy-bottomed frying pan As it cooks, collagen fibers shrink,
a piece of descaled, medium-sized fish over high heat. Add 1 tbsp sunflower causing the fish to buckle, so keep on
fillet with the skin on. Cover both sides oil (or other oil with a high smoke pressing down to make sure the fillet
with salt. Place it in a dish, cover with point—see pp192–3), and heat to just remains flat. Fry the fish until the flesh
plastic wrap, and refrigerate 2–3 hours below smoke point. Place the fish in is opaque two-thirds of the way through.
to allow the salt to draw out moisture. the pan; the skin should start sizzling Carefully flip over to finish cooking.
Dry it thoroughly by dabbing it with immediately. Use a fish spatula to Once the fish is cooked through, serve
a paper towel. apply even pressure to make sure that immediately, with the skin side up to
heat passes evenly across the skin. preserve the crispiness of the skin.

RED SNAPPER Why Don’t You Need to Rest Fish?
Mucus layer
produced by Why don’t you

glands will crisp NEED TO REST
during cooking. FISH?

Scale Fish muscle has a different structure than meat
muscle, so it must be treated differently.
Collagen DID YOU KNOW?
fibers shrink Some cooks suggest that fish should be rested
when cooked. in the same way you would rest meat after cooking.
There is no harm in doing this, but unless it is
Layer of subcutaneous The anatomy Muscle a large whole fish (see box below), it is unlikely to
fat prevents the flesh of fish skin tissue make very much difference in your finished dish.
from cooking too
quickly. Muscle moisture and temperature

Fish skin is very different from the flesh: rich in fat Resting red and white meat helps increase its
(up to a tenth of its weight), toughened by the hardy juiciness slightly by giving time for the liquid
inside the muscle to cool and thicken up (see p59).
protein collagen, and heavy with moisture. Fish During resting, fragmented proteins in meat mix
skin also produces a layer of slimy mucus, designed with moisture to form an unctuous jus within the
meat. Fish contain fewer of these proteins, so
to insulate the living creature, in addition to a resting does not have the same effect. Furthermore,
layer of inedible bony scales. having little connective tissue and no stringy
sinews, fish has a more delicate texture than
meat from land-dwelling animals. This means
that any increase in juiciness caused by resting
would be very difficult to discern.

Resting fish, like resting meat, also helps to
even temperature throughout the flesh. However,
because most fish are thin, this effect is negligible.
When serving fish, the priority is to serve it while
still warm, rather than to achieve an even temperature.

Whole fish can benefit from resting

Although for most fish, resting is unnecessary,
some large whole fish will benefit from a few
minutes’ resting.

Reduces flaking
Allowing a whole, dense fish—such as tuna or monkfish—
to rest for 5 minutes or so before serving allows proteins
in the fish flesh to firm up, reducing flaking and making
slicing cleaner.

Conserves heat
Whole fish hold heat better than fillets, as the flesh is still
enclosed by skin—this means that there’s less danger of
the fish cooling too much during resting.

Can I eat

SASHIMI SAFELY?

Knowing how sashimi is prepared can ease worries about safety.

Sashimi, as with any animal’s flesh and, if ingested, can
uncooked food, is never burrow into our intestines, causing
risk-free, but stringent persistent diarrhea and pain.
controls mean properly Freezing kills these pathogens and
prepared sashimi poses a “sashimi- or sushi-grade fish” is a
low risk of infection. term used to indicate that fish has
been frozen to at least –4ºF(–20ºC)
Tuna used in “Sashimi-grade” fish before sale. Reassuringly, the types
sashimi has a low of tuna served as sashimi (bluefin,
infection risk. Fish used for sashimi are line yellowfin, albacore, and bigeye)
Highest-quality fish caught individually, quickly killed dwell in very deep, cold waters,
Only well-sourced, top-quality fish, properly (to reduce lactic acid buildup, which away from worms.
stored and prepared with the utmost care, is degrades fish), then placed on ice
used in authentic sashimi dishes. to prevent bacteria from growing. To Eating sashimi in a reputable
help grade fish, fish farmers, traders, sushi restaurant that prides itself on
and producers use a chemical test selecting only the finest-quality fish,
to measure how much the energy storing it at very cold temperatures,
stores have been depleted, then and being fastidious about hygiene
value each fish based on freshness. is extremely safe. To enjoy sashimi
at home without anxiety, it is
A bigger risk than bacteria comes important to do the same.
from worms: these invade the living

How does

CITRUS JUICE “COOK” RAW FISH?

“Ceviche”—cooking raw fish with lemon juice—can be a useful addition to a cook’s repertoire.

The ceviche technique, which muscle and causing them to unravel, Getting the timing right
originated in South America, requires or “denature,” in much the same way
nothing more than mixing raw fish that they do when cooked. The length of time fish needs to “cook”
with citrus juice and leaving this to ceviche-style depends on the texture you
sit, ideally in the fridge, to “cook.” For acid to cook fish, it needs to wish to achieve.
The science behind this mysterious have a pH of less than 4.8 for proteins
alchemy is actually quite easy to to denature—lemon and lime juice Ceviche cooking guidelines
understand. have a pH of about 2.5. The citrus Cut a skinless fillet of fish into cubes or thin slices
penetrates the surface, “cooking” it, of around 1in (2cm), then follow these timing
The acid effect gradually turning the shiny, uncooked guidelines. Leaving fish for longer than 25 minutes
flesh into firm, white meat. The acidity will create a chalky, completely cooked consistency.
The acid in citrus juice works on gives the fish a tartness and tang.
fish proteins in a similar way to For extra sweetness, add fruit juice • Rare–medium: 10–15 mins
heat, disturbing the structure of or tomatoes, or chili can be added • Medium: 15–25 mins
the proteins within the delicate fish to the mix to provide some heat. • Medium–well done: 25 mins

“ Most fresh fish should be
edible uncooked, but industrial-
scale fish production means that
contamination is common in
many fish, where quality control
is less stringent than it is
for sashimi-grade
”fish.

090 // 091 The Science of Fish and Seafood

Why do shellfish

CHANGE COLOR
WHEN COOKED?

Heat reveals a previously hidden color.

Crustaceans are one of the most successful classes

of animal; they have existed in our seas for more than 200

million years. One reason for their longevity is their ability

to blend into their surroundings—the grayish-blue

color of a shrimp, for example, is hard to spot in

the murky depths of the ocean. Yet cook

them, and a wonderful color transformation HIDDEN TALENTS
takes place as their natural camouflage
blooms orange-pink. THE DRAMATIC COLOR
CHANGE OF SHELLFISH

Where does the orange-pink OCCURS AS THEIR
color come from? NATURAL CAMOUFLAGE

C O O K S AWAY.

Lobster, crab, shrimp, prawns, and other

crustaceans are orange-pink when cooked for the

same reason that flamingos are pink and salmon are

orange (see p70). A red pigment, called astaxanthin, is

produced in the plankton and algae on which crustaceans

feed, which accumulates in their shell and flesh. No one is

sure exactly why crustaceans store this pigment, although

it may protect them against UV damage from the sun if

they are in shallow waters. Crustaceans hide this

orange-pink color when they are alive to keep

them concealed from predators.

Cooking reveals the orange color, but

should not be a guide for doneness.

Larger shellfish, such as lobster and crab,

will change color before they are fully

cooked. Always make sure the cooked

meat is white, firm, and opaque.

Blue Crustacyanin proteins
crustacyanin clamp around each
end of an astaxanthin
This is a protein that crustaceans’ molecule to hide it.
bodies produce when they are alive.
The blue crustacyanin attaches to
the pigment astaxanthin (see right)
and holds it in check, hiding it. This
conceals the animal from predators
because it takes on the muted hue
of crustacyanin instead.

What Are the Rules When Cooking Mussels?

Astaxanthin molecules What are the rules
are revealed when
crustacyanin proteins WHEN COOKING
unravel on cooking. MUSSELS?

Red With a little know-how, you’ll find that mussels are one of the
astaxanthin easiest seafoods to prepare, and one of the quickest to cook.

This strongly colored pigment comes from the Mussels should be cooked alive MYTH BUSTER
crustaceans’ diet and is hidden in its body by
the protein crustacyanin (see left). The heat because they spoil quickly after Myth
of cooking causes the protein molecules to they die. If you don’t intend to cook NEVER EAT MUSSELS THAT REMAIN
unwind and lose their original shape, which your live mussels immediately, store
forces crustacyanin to release astaxanthin and them on ice or in a bowl covered with CLOSED AFTER COOKING.
let its true color shine through. a damp cloth in the coldest part of
the fridge (storing them in water Truth
will kill them). Before cooking, be
wary of any open mussels: those The meaty morsel inside a mollusc
that are already open and do not shell cooks as it sits in simmering
close when tapped are dead and water, regardless of whether the shells
should be thrown away. While open. The two shells are held shut by
cooking, don’t pluck out mussels as two adductor muscles, which are some
soon as they open—research shows of the strongest muscles in the animal
that early openers are usually not kingdom. When heated, these muscles
fully cooked. If ever in any doubt, slowly weaken as the proteins cook,
always let your senses guide you. but within any batch of mussels, some
Infected or dead mussels will smell specimens will have stronger adductor
bad and may have a tacky surface. muscles than others—their shells may
not pop open, but if you pry them open

they will be cooked.

PREPARING MUSSELS Mussels use their
“beards,” or byssus
Follow a few simple rules to make
sure you have only the cleanest, threads, to attach
freshest mussels in your cooking pot. themselves to a surface.

MYTH BUSTER 1 2 3

Myth CHECK FOR CLEAN AND RINSE REMOVE THE
LOBSTERS CRY OUT WHEN PLUNGED FRESHNESS IN COLD WATER BEARD LAST
Discard mussels that Scrape off any Pinch the stringy
INTO BOILING WATER. are broken or cracked, barnacles with a knife, beard and pull it away
or that are open and do then scrub with a from the top of the
Truth not close when tapped brush under cold shell to the hinge at
(see above). running water. the bottom.
Lobsters can’t cry out because they have
no vocal cords, but you may hear the sound
of trapped air escaping from the shell. To
cook a lobster kindly, freeze it for 2 hours

to render it unconscious first.



EGGS &DAIRY

In focus 094 // 095 The Science of Cooking Eggs and Dairy

EGGS

The egg is a nutritional and culinary wonder, and
a near-essential ingredient in any cook’s larder.

Eggs are one of the most versatile mainly made of water, with some protein— KNOW YOUR EGGS
ingredients in the kitchen—able to bind, coat, when vigorously beaten, egg white proteins
clarify, thicken, and aerate food. They owe unravel to form an airy structure that can be The basic structure of bird’s eggs remains
their incredible powers to their combination combined with sugar to make meringue or consistent across different species—fatty
of proteins, fats, and emulsifiers. folded into cakes to add volume. Added whole, yolk suspended in a watery white, encased
eggs provide structure, moisture, and flavor. in a hard shell. However, the ratio of fats
Yolks are rich in fat, and these fats are And because eggs are designed to provide to proteins varies, having an impact on
suspended inside microscopically sized for a growing chick, they are a nutrient-rich the eggs’ flavor. The size of the egg
globules coated in an emulsifier called lecithin. ingredient unto themselves, and happen to and porousness of the shell also varies. For
Lecithin helps fats and water to mix, making contain amino acids in near-perfect proportions this reason, different eggs are best suited
egg yolks the vital binding ingredient for oil for human health. for different culinary purposes. Here is a
and vinegar in mayonnaise. Egg whites are summary of some of the key varieties.

Air cell GOOSE EGG
Air seeps into the egg through the porous
shell, forming a bubble at one end of the The facts
egg—a small air cell indicates freshness. Goose eggs are the
largest commonly
Shell used eggs. Their large
Hard and brittle, the shell protects yolks are rich in fat,
its contents from damage. It is and and carry hints
perforated with tiny pores to allow of flavor from the
gases to pass in and out of the egg. geese’s foraged diet.
The protein-packed
Thin albumen whites are thick and
Making up about 40 firm in texture.
percent of the egg white.
the white closest to the How to prepare
shell is thin-textured, and Their high fat content
cooks slowly. A small adds body and flavor
amount of thin albumen to cakes, soufflés, and
also surrounds the yolk. quiches, while their
whites make robust
W E I G H T: meringues and
51⁄8OZ (144G) pavlovas. They also
KCALS: 266 make rich omelets.

DUCK EGG

W E I G H T: The facts
21⁄4OZ (70G) Very porous shells
KCALS: 130 mean duck eggs should be
stored away from strong
aromas. They have a higher
yolk-to-white ratio than
chicken eggs, making
them richer tasting.
How to prepare
Pickling, brining, salting,
and curing all work well
with duck eggs. Their high
fat content lends succulence
to cakes and bakes.

Thick albumen CHICKEN EGG
About 60 percent of
the albumen—the The facts
thick part of the By far the most
white—is made of commonly used egg,
water and protein. As chicken eggs have a good
the egg ages, the thick balance of yolk and white
albumen shrinks. that suits many different
culinary uses. Their yolks
Yolk W E I G H T: are relatively small compared
The yolk comprises fat 13⁄4OZ (50G) to other types of egg, with a
globules wrapped in KCALS: 71 higher proportion of white.
lecithin. It is made of How to prepare
minutely thin, concentric Use as a binding agent in
rings, separated by thin baking or an emulsifier in
membranes. mayonnaise, or cook as it is.

QUAIL EGG

Germinal disc LAYING DOZENS W E I G H T: The facts In Focus: Eggs
This just-visible spot 1⁄4OZ (9G) Tiny and attractively
is where the egg cell IN A YEAR, A LAYING HEN KCALS: 14 speckled, quail eggs have
develops into a chick PRODUCES EGGS EQUAL TO a subtle, earthy flavor.
in a fertilized egg. The firm whites and hard
Chalazae EIGHT TIMES HER OWN shells can be tricky to peel.
These twisting columns of thick BODY WEIGHT. How to prepare
albumen secure the yolk. They are Fry, hard-boil, or pickle
most visible in very fresh eggs. quail eggs for use in
snacks, hors d’oeuvres,
or bento boxes.

096 // 097 The Science of Eggs and Dairy

ONE EGGS ARE A Should I limit how many
LARGE EGG RICH SOURCE OF
CHOLINE, A VITAL EGGS I EAT?
HAS JUST
75 CALORIES— NUTRIENT FOR Forming a compact source of nutrients,
FEWER THAN BRAIN HEALTH. eggs are often referred to as a “complete” food.

A SLICE OF
BREAD.

1 CHICKEN EGG CONTAINS: EGG YOLKS Tightly packed with protein, energy, fats, vitamins, and
30% rda SELENIUM CONTAIN AROUND minerals, eggs are seen as providing a complete source
25% rda FOLATE of nutrition in one neat package. However, in the 1950s,
5G FAT. THIS concerns about cholesterol in eggs affecting heart health,
20% rda VITAMIN B12 IS MOSTLY closely followed by egg-borne salmonella scares, fractured
16% rda VITAMIN A UNSATURATED AND
12% rda VITAMIN E INCLUDES A TYPE OF our trust in the benefits and safety of eggs.
FAT CALLED LINOLEIC
7% rda IRON ACID, ESSENTIAL FOR What we know today
OVERALL HEALTH.
Today, we know that many of the fears about the
EGGS ARE A SOURCE OF THE dangers of eggs aren’t true and their safety has
DISEASE-FIGHTING CAROTENOIDS improved greatly in the past 20 years. Salmonella

LUTEIN AND ZEAXANTHIN. food poisoning from eggs is now far less of a problem
than it was 30 years ago, and in some countries it has
EGG YOLKS CONTAIN THE EGG WHITES been virtually eradicated. Worries about cholesterol
SUBSTANCE LECITHIN, ARE LOW IN levels in eggs have also receded as research has
WHICH PREVENTS CALORIES shown that dietary sources of cholesterol are far
CHOLESTEROL FROM
BEING ABSORBED. AND ARE less of a problem for the majority of people than
FAT-FREE. was once thought (see Myth Buster, below).

AN EGG CONTAINS 7g HIGH-QUALITY In terms of nutrition, eggs are hard to beat,
PROTEIN, WITH MORE PROTEIN FOUND providing a host of nutrients and antioxidants, as
shown, left. Today, nearly all international healthy
IN THE WHITE THAN THE YOLK. eating guidelines have removed restrictions on
the number of eggs that should be eaten each
week, and studies suggest that children and
healthy adults can happily eat an egg a day.

SOME CHICKENS DUCK, GOOSE, AND MYTH BUSTER
HAVE DIETS QUAIL EGGS ARE MORE
Myth
SUPPLEMENTED CONCENTRATED EGGS RAISE CHOLESTEROL LEVELS
WITH FLAXSEED IN VITAMIN B12
AND SOMETIMES AND IRON THAN Truth
CHICKEN EGGS.
FISH OILS TO Eggs are high in cholesterol, but eating cholesterol-rich foods isn’t
ADD EXTRA as risky as was once thought. High levels of “bad” LDL cholesterol
OMEGA-3 TO
THEIR EGGS. in the blood can clog arteries, increasing the risk of serious health
issues. But it’s foods high in saturated fats, such as fatty meats, creams,
EGG WHITES CONTAIN 60%
OF THE EGG’S PROTEIN, WHILE butter, and cheese, that cause the body to overproduce cholesterol,
MANY OF AN EGG’S FAT-SOLUBLE while dietary cholesterol has limited impact. Egg yolks also contain
VITAMINS ARE LOCATED IN
THE CHOLESTEROL AND a substance that prevents the cholesterol it contains from being
FAT IN ITS YOLK. absorbed. Generally, only those with genetically inherited high

cholesterol levels should limit their egg intake.

Is It Safe to Eat Raw Eggs?

Are there more nutrients in ORGANIC FREE-RANGE INDOOR-
FARMED
FREE-RANGE
EGGS? Conditions Conditions Conditions
Chickens have free The amount of Chickens kept inside
Eggs are produced on a scale never before seen, and and easy access to outdoor access
can offer us a safe, cheap, and highly nutritious food. outdoors and are able free-range chickens and fed on grain.
to feed on pasture. have varies, with
Chickens have fared badly from industrial-scale farming. some spending Nutrients
Birds are often housed in cramped wire cages in barns or sheds Nutrients much time in a barn. Forced to lay eggs
where temperature and lighting conditions force them to lay Amounts vary, but
eggs all year round. Fed a supplemented grain mix designed eggs can have up to Nutrients at high rates in
for optimal egg producing, an indoor-farmed hen can convert double the amount of There is wide stressful conditions,
41/2lb (2kg) of feed into an incredible 21/4lb (1kg) of eggs. omega-3 and vitamin variation, but eggs these chickens’ eggs
E, 25 percent less have similar nutrient have fewer vitamins
The life of an animal affects the quality of the food it saturated fat, and values to those from and omega-3 fats
provides (see p40), so it’s no surprise that while indoor-farmed organic chickens. and more saturated
hens lay more eggs, each egg is nutritionally inferior to eggs more minerals. fats than eggs from
from free-roaming chickens (see right). Flavor differences are free-roaming chickens.
subtle, but for the cook, eggs from a reputable local outlet
where chickens lead a pastured life are best for nutrition.

Is it safe to eat Protective cuticle layer
Salmonella bacteria
RAW EGGS? The tiniest crack
can let Salmonella
Uncooked eggs are a key ingredient for many classic access the egg.
dishes, such as mayonnaise, aioli, and mousse. Porous egg shell

The biggest worry with recipes that use raw eggs or runny Infection-
yolks is ingesting Salmonella bacteria along with the egg, fighting proteins
which causes food poisoning. in the white
offer some
The control of Salmonella protection.

Eggs pick up Salmonella when they come into contact with The egg’s protective
infected feces. The shell has a protective coating (see right), outer case
so provided it doesn’t crack, its contents should be safe. Strict
regulations now mean that infected eggs are rare. In the US, Salmonella is usually present on the
eggs are sometimes given a protective mineral oil coating, shell of an egg that has come into
and in Europe chickens are vaccinated. Many countries grade contact with infected feces. The harmful
eggs to indicate that they’ve met safety regulations. Cooking bacteria may penetrate the core, but the
kills bacteria, and in most countries raw eggs are often safe, but shell has a bug-proof coating (the cuticle)
food safety guidelines vary between nations. Pasteurized so provided that the shell doesn’t crack,
eggs—heated briefly to destroy bacteria—are sold where raw its contents are fairly safe. Any egg with
eggs are off the menu, though these are slightly less flavorful. the tiniest crack should be discarded.

098 // 099 The Science of Eggs and Dairy

Where is the best place to

STORE MY EGGS?

The storage of eggs, while seeming like a trivial issue, can be a surprising source of disagreement.

Where you store your eggs can depend on where you USE WHERE WHY
live. In the US, chickens aren’t routinely vaccinated against
Salmonella, so refrigerating is advised to slow the growth Fridge Chilled is best if separating yolks for
of bacteria. European advice is to keep eggs in a cool Separated mayonnaise because the yolks stay firmer.
pantry because it is thought that condensation in a fridge can
encourage bacteria to proliferate. This difference may be Boiled Fridge A boiled egg will take slightly longer to cook
partly due to rates of Salmonella, which historically are slightly or room if chilled, although the end result is identical.
lower in Europe, while in the US, eggs are washed and
sprayed with a chemical sanitizer to remove bugs, although Fridge Whether eggs are room temperature or
this can also strip off the protective antibacterial cuticle layer Scrambled or room chilled makes little difference for scrambling.
(see p97), making them more vulnerable. Aside from official A cold egg lowers the temperature of the pan
guidelines, how you want to use your eggs can influence Fried Room and the oil, so frying can take a little longer.
storage. The table, right, shows how keeping eggs in the For poaching, a cold egg reduces the water
fridge or at room temperature can affect their efficiency for Room temperature, slowing cooking a little and
different cooking methods and uses. Poached making the white more likely to spread.
For foaming yolks for a cake or whisking whites
Storing eggs in the fridge Room for meringue, room temperature lets proteins
unwind and mesh together more easily. Cakes
If you chill eggs, avoid using the egg Cakes have a slightly finer, more even consistency.
holders in a refrigerator door. Opening
and shutting the door shakes the eggs,
speeding the thinning of the white.
Keep them toward the back in an
airtight container to slow moisture loss.

Sulfur S Proteins in fresh eggs Why do rotten eggs
CO2
CO2 is contained Each protein type has a SMELL BAD?
within eggs. CO2 CO2 CO2 unique shape, and many of
H2S the egg white proteins keep Proteins in egg white break down as eggs age.
their form with the help
CO2 CO2 of powerful sulfur atoms. The strong smell of rotten eggs comes mostly from the
While contained in the whites and is due to hydrogen sulfide, a gas so noxious that
egg white, the sulfur atoms it was used as a chemical weapon in World War I. The gas
don’t give off an aroma. is created when certain sulfur-containing proteins in the
egg white unravel. When cooked to above 140ºF (60ºC),
With the loss of The aging egg sulfur starts to break free, which creates the eggy smell of
abceicdoimc eCsOa2lktaheliengeg. As eggs age, carbon dioxide hydrogen sulfide. The sulfurous-smelling sulfide vapor is
also released when an egg ages. The illustration, left, shows
Sulfur converts p(CoOre2s) escapes through tiny how changing levels of carbon dioxide degrade the egg
to hydrogen in the shell. The eggs white proteins, causing the release of the repulsive-smelling
sulfide as become more alkaline, and hydrogen sulfide gas.
CO2 escapes. this change in acidity forces
proteins to unravel and let
go of sulfur atoms, which
turn into a foul-smelling
hydrogen sulfide gas.