How Food Works

STORING AND COOKING 48 49
Preservation

CHEMICAL PRESERVATIVES Preservation in action
Different preservation methods work in
differing but often complementary ways.
Each strategy guards against some or most
of the threats, though few can protect
against all of them. Pasteurization (heating
food to destroy harmful microbes) is a safety
measure that also preserves food.

SSAMLTOINKGINAGND KEY
Sunlight
PICK
Oxidation
DRYING
LING Enzymes
Microbes/
FREEZING bacteria
CHILLING Slowed
ANNING
Stopped

FOOD

PASTEURIZING C

HOW LONG CAN
TINNED FOOD LAST?

In theory, canned food should
last indefinitely. In 1974, cans
recovered from the Bertrand,

a steamer that sank in the
Missouri River in 1865, were

found to be edible.

(Airtight conStTaiOneRrI,NkeGpt in darkness)

Chilling HOW LONG CAN
and freezing FOOD STAY FROZEN?

By extending the life of perishable foods—making it possible Bacterial growth should be
to store them for long periods and transport them across great halted indefinitely in frozen
distances—refrigeration and freezing have transformed the food food, but the food’s quality
economy and broadened our diets. deteriorates as freezing breaks
or weakens cells, changing

texture and flavor.

Refrigerator Gas travels Freezing suitability
casing insulates through freezer
and fridge, Vegetables that hold water, such as
cold lettuce and cabbage, get mushy when
Why do we freeze food? lowering the thawed. When the water in their cells
Liquid quickly turns temperature freezes, ice crystals puncture the cell
to cool vapor walls, breaking the food’s structure.
At low enough temperatures the chemical Meat and fish can be frozen because
Expansion device their cells are flexible.
expands liquid and and biochemical processes that cause food

converts it to gas spoilage effectively halt. Freezing water

also removes the liquid essential to many Cell wall
Water
biochemical processes.

Plant cell Animal cell
The wall surrounding The membrane
a plant cell is rigid surrounding an animal
and inflexible. cell is soft and flexible.

Cooling gas Why do we chill food? Cell wall
condenses breached
into liquid Degradation and spoilage of food and drink
is the result of chemical and biochemical
processes caused by free radicals, internal Water freezes Water freezes
enzymes, and microbes. Temperature affects As the water in As the water in the
the rate of these procesess, and chilling food the cell turns to ice, cell turns to ice, the
slows them down. it expands and membrane stretches
ruptures the cell wall. to accommodate it.

CHEESE BANANA

Hot, compressed When chilled, enzymes in Contents
gas loses heat leak out
bananas break down cells
Compressed gas
from pump travels Carbonated drinks and cause browning

through pipes at retain their fizz MILK Cell releases contents Cell retains contents
rear of fridge As the ice thaws, As the ice thaws, the
because carbon Milk the cell contents intact cell membrane
spoilage are released through contracts, keeping all
dioxide bubbles CHICKEN delayed the ruptured wall. of its contents inside.
have less energy by chilling
SODA
BROCCOLIto escapeChilling chicken at
when chilled about 39ºF (4ºC) delays

bacterial growth

PUMP

How fridges work TOMATOE THE FRIDGE IS THE
Gas compressed by MOST COMMON
a pump loses heat Broccoli kept close to 32ºF (0ºC) will Tomatoes lose flavor APPLIANCE. IN THE STORING AND COOKING
through pipes at the retain all its vitamin C for 7 days below 45ºF (7ºC) US, 99.5 PERCENT Chilling and freezing
rear of the fridge. As OF KITCHENS HAVE
it cools, it condenses to A FRIDGE.
liquid, but then reaches
an expansion device,
where it turns to gas again.
This evaporation cools it
rapidly before it enters the
freezer or fridge, where it
chills the food before
returning to the pump.

Importance of thawing Cooked surface Frozen interior HISTORY OF REFRIGERATION

Frozen food is best and most STEAK As early as 1000 bce, the Chinese ICE 50 51
safely thawed by leaving it in the Cooking meat from frozen were cutting blocks of ice to use ICE BOX
refrigerator, sitting it in cold water, It is best to avoid cooking meat from as food-cooling aids, and this
or using a “defrost” microwave frozen. If the insides of the meat was the most important form
setting. It is important to thaw remain uncooked, there is a risk that of cooling technology for the
food all the way through prior any bacteria in the meat that would next 2,800 years. Refrigerated
to cooking, otherwise there is an have been killed by cooking will remain. ships appeared in the late
increased chance of undercooking 1800s, while the first domestic
the inside, while overcooking fridges appeared in 1911.
the outside—particularly when
frying and grilling.

Fermentation

Used across the globe throughout history, fermentation
is a simple form of food preservation requiring no heat
or artificial energy source. In the absence of oxygen,
microbes can convert sugars into acids, alcohol, and gas.

Why do we ferment foods? Fermented cabbage
Sauerkraut, originating from Europe, is
As microbes such as Lactobacillus thrive in an one of the most popular preparations
oxgen-free environment, their success suppresses of fermented cabbage.
the growth of spoilage microbes, generating
preservative by-products and interesting flavors. 2 Teasing out the sugar
Fermentation microbes are often the same as the Salt helps to draw water and
ones found in our gut, so eating fermented cell contents (including sugars) out of
food can be a good way to top up gut flora.

the plant cells, so that the fermenting
microbes can get to work.

1 Salted and soaked Water and sugars drawn
Salt is applied as a brine, out of cells by salt
cutting off oxygen supply to
competing microbes. The cabbage
must be kept below the surface.

SALTY WATER WATER SUGAR
Salt

SHREDDED IN THE 1700S FERMENTED CABBAGE
CABBAGE WAS USED BY SAILORS TO COMBAT
VITAMIN C DEFICIENCY AND SCURVY

Other foods that are fermented Fermented milk CHEESE
Milk has a very short YOGURT
In addition to helping to preserve foods, fermentation shelf-life, but fermented CRÈME FRAÎCHE
can leaven dough through generating gas, and produce dairy products can last
browning reactions, adding color and flavor. Different for months. These range
methods of fermentation are used in breadmaking; from yogurt and crème
alcoholic drinks and vinegar production; making fraiche, fermented for
yogurts and cheeses; pickling fruit and vegetables; just a few hours, to
curing meats; making soy and fish sauces; softening large cheeses prepared
olives and removing their bitterness; and producing over many months.
chocolate from cocoa beans.

MILK

STORING AND COOKING 52 53
Fermentation

3 Fermentation ICELANDIC DELICACY
A succession of fermenting microbes consumes
the sugars, generating a complex mixture of alcohols, Pre-industrial societies used
acids, and flavor compounds. Fermentation also helps fermentation to prevent spoilage
to retain the nutritional value of the cabbage. The of fish, resulting in delicacies of
layer of carbon dioxide gas protects vitamin C from strong odor and flavor. Iceland’s
oxidation, while B vitamins are produced. Hákarl is Greenland shark that has
been gutted and beheaded, buried
in a sandy pit and left to ferment
for six to 12 weeks before
being wind-dried, shaved,
and cut into small pieces.

Flavor compounds Bubbles of HÁKARL
are released carbon dioxide

Microbes 4 Fermented result
consume sugar The delicious and nutritious
FLAVOR sauerkraut is tart and crunchy. Yeast
COMPOUND growth is limited by the process, but
a little growth is acceptable and even
MICROBE generates a distinct, flowery aroma.

SUGAR

SAUERKRAUT

Fermented soy MISO Fermented cucumber CUCUMBER PICKLE
Soybeans have high SOY SAUCE Cucumbers are turned into POI
levels of protein and oil, pickles using lactic acid
which can be extracted TEMPEH bacteria and brine with
as a kind of milk. This is five to eight percent salt
fermented in a similar concentration.
fashion to milk and with
outcomes as equally Fermented taro root
diverse—from the thick Rich in starch but toxic
miso paste used for when raw, taro are used in
soups and seasoning Hawaii to make poi, a
to tempeh, a cultured fermented preparation rich
soybean cake. in flavorful volatile acids.

SOY TARO ROOT

Raw foods VITAMI NC NC

Raw food appeals to many because cooking 23% RAW
can damage or lower levels of vitamins and
minerals. There is a growing trend for raw 6% BOILED
food diets, but eating raw foods does not 31⁄2 oz (100g)
always mean maximum nutrient intake. of CARROTS

Best raw foods 31⁄2 oz (100g) Carrot
of KALE When carrots are boiled,
Vitamin C and flavonoids (see p.110) are vitamin C levels decline
examples of beneficial nutrients that are precipitously since this
particularly vulnerable to heat. The type of vitamin dissolves
best raw foods are likely to be those (is soluble) in boiling water
with high levels of these fragile and is then poured away.
nutrients. For instance, green,
leafy vegetables (see pp.112–13) VITAMI
are rich in vitamin C and other
antioxidants to help the plant 200% RAW
deal with the damaging effect of
sunlight. Raw foods do not tend to 89% BOILED
raise blood sugar levels (see p.141)
since they contain fewer simple sugars.

KEY Raw Kale
A percentage of your daily Cooked This leafy vegetable is rich in vitamin
need of certain vitamins C. The large surface-area-to-volume
and minerals can be ratio of kale and other leafy greens
measured in raw and makes them particularly vulnerable
cooked portions of food. to nutrient loss in boiling water.

RAW FOODISM

DOES COOKING Raw foodism is a typically vegan practice Vitamin Vitamin Selenium
“KILL” FOOD? of eating about 70-100 percent uncooked B12 D
food. Claimed effects range from weight
There are a few plant loss to curing diabetes and cancer. It is Zinc Iron Omega-3
enzymes that remain active based on beliefs that “live foods” have fatty acids
in the stomach, but digestion natural energy, and on misconceptions
changes their shape and they about the role of plant enzymes in NUTRIENTS MISSING FROM
become inactive. They are digestion. For instance, some plant A RAW FOOD DIET
enzymes do help digest certain kinds of
not “alive” in the protein, but most plant enzymes will be
strictest sense. broken down by stomach acid. However,
certain nutrients are missing from a
purely raw food diet.

STORING AND COOKING 54 55
Raw food

A SPECIAL CASE CANNED
TOMATOES
Lycopene is a beneficial carotenoid pigment
4oz (112g) ONE found in tomatoes. Heat weakens plant cell
MACKEREL walls and makes the cell contents more
FILLET accessible for digestion. Lycopene in tomato
cells is released during the heating stage of the
canning process. A can of tomatoes contains
over four times the lycopene of the same
amount of raw tomatoes.

V

51% RAW IRON
30% DRIED ITAMIN B3
30% RAW
Mackerel (81⁄2oz, 240g)
Vitamin B3 levels are
higher in raw compared 2% CANNED
to dried mackerel. This is (101⁄2oz, 296g, )
because as mackerel dries,
oxygen reacts with BOWL OF
vitamin B3, depleting its COCONUT MILK
levels within the fish.
Coconut milk
Iron levels within
freshly squeezed
coconut milk are
higher because the
addition of water
during the canning
process dilutes
the milk.

Limitations of raw foods RAW FOODS WHAT HAPPENS
Brassicas
People on raw food diets can experience If eaten in excessive amounts, brassicas such as broccoli
nutritional deficiencies and even food Green potatoes and kale contain goitrogens—substances that can
poisoning. Many cooking processes can interfere with hormone production in the thyroid gland.
actually enhance the nutritional value of Fava beans
foods. We cook food for safety, practical Salad bars Green parts and sprouts in potatoes contain solanine, a
reasons, or even just to improve flavors toxic alkaloid, which if eaten can cause bouts of nausea
(see pp.60–61, 64–65). Raw foods can pose or diarrhea.
risks to health—through toxins in food that
do not get broken down and pathogens Also known as broad beans, these contain alkaloids that
that are not killed. can cause a condition, known as favism, in which your
red blood cells deteriorate.

Many disease outbreaks E. coli, Salmonella, and
Staphylococcus have been linked to improperly washed
raw vegetables at salad bars.

Food processing IS RAW MILK
SAFE TO DRINK?
“Processed” has become a dirty word in today’s food
culture, but the definition of a processed food can vary Bacteria in raw milk can
greatly. Very few foods do not undergo some degree cause food poisoning.
of processing, much of which is absolutely essential. Pasteurization is a very
Sometimes, though, we can take processing too far. important process that
kills harmful bacteria,
What is food processing?
which makes milk
Processing is generally defined as any change that is made to food or safe to drink.
drink to alter its quality or shelf life. After harvesting crops and
slaughtering livestock, methods of preservation are often put in place
so food can be available at a later date. In addition to preservation, we
change foods from their natural state for three main reasons: to make
food edible, to improve its nutrition, and to make food safer to eat.

GRAIN VITAMIN B1
VITAMIN B2
JUICE
VITAMIN B12
Heated
VITAMIN B3
Rollers IRON
grind grain
into flour Vitamins
and
FLOUR minerals

Cooled

BREAD

WHITE RICE WHITE PASTA PASTEURIZED JUICE
Safety
Edibility Improved nutrition Drinks such as juice and milk are
Processing is necessary to make some Food can be enriched in the factory sometimes required to be processed
foods edible. The edible parts of grain with extra nutrients. In grain products, in order to make them safe to drink.
are extracted and then ground into flour, this is carried out because refining, Pasteurization is a process of heating
which is processed further, by forming which makes white rice from brown, and cooling that kills harmful bacteria.
dough and baking, into bread. removes many nutrients, which must
then be replaced—sometimes by law.

STORING AND COOKING 56 57
Food processing

HIDDEN INGREDIENTS CORN SYRUP TOMATO PASTE

Many highly processed foods are high in added
sugar, salt, fat, and low in dietary fiber—with the aim
of improving their taste and palatability, and to make
them last longer. If levels of these ingredients are
high, some authorities require food producers to
highlight them on the packaging (see p.43). However,
in some countries it is possible to avoid drawing
attention to unhealthy or unpopular ingredients by
listing complex constituents such as tomato paste or
corn syrup (themselves processed from many parts)
singly, without an analytical breakdown.

1 Reconstitution How potato snacks are made
Potatoes are cooked, mashed, The journey from potato to reconstituted snack
dehydrated, and milled into flour. can be a long and convoluted one. A range of
Starches from corn and wheat may be changes are made to a simple potato to make
it look almost unrecognizable—and taste
completely different.

added, and the resulting flour is mixed.

Processed starch 2 Extrusion 3 Frying
added to milled flour A dough is made with The half-cooked

the flour and squeezed through potato snacks are dried and
passed through a continuous
shaped nozzles at high pressure frying machine to assure rapid,
to create partially cooked,
shaped snacks. even cooking.

Mashed, half- Potato Potato snack
cooked potato flour deep-fried in oil

Highly processed foods Half-cooked snack
shaped by nozzle
When we think of processed foods,

we are probably thinking of highly 4 Flavoring
The cooked chips are shaken
processed foods, such as chips, snacks, and chocolate –

in which the main ingredients have themselves been free of excess oil, sprayed or dusted
with flavorings, salt, and other
milled, refined, cooked, or otherwise significantly additives, and finally packaged

altered in ways we cannot do in the kitchen. Highly for distribution.

processed foods are almost always high in calories, Flavorings, salt, and

sugar, and fats, and low in nutrients and fiber. additives sprinkled

onto chips

WITHOUT PROCESSING
50–60 PERCENT OF FRESH FOOD
COULD BE LOST AFTER HARVEST

Main chemical additives Preservatives Sweeteners
Additives are classed into several main groups according These prevent spoilage These alternatives to sugars
to their role, for example, as sweeteners, flavorings, or and prolong shelf life by
preservatives. In most countries, all these additives must slowing the growth of include aspartame and
pass strict safety regulations before they are allowed in microbes and retarding saccharine. They are used
food, although an additive approved in one country to reduce calories, since
may not necessarily be approved in another. natural chemical they are either much lower
reactions that would
5 PERCENT OF THE otherwise make food in calories than sugar,
WORLD’S POPULATION HAS unpleasant or inedible. or can be used in very
A SENSITIVITY TO ONE OR
MORE FOOD ADDITIVES small amounts.

Nutrients Stabilizers Antioxidants
These replace vitamins and These prevent emulsions These are chemicals
minerals destroyed during (foods such as mayonnaise) that inhibit oxidation.
processing, or enrich foods from separating into their They are used to delay
with nutrients they do not oily and watery constituents browning and decay caused
after they have been mixed, by oxidation, prolonging
contain naturally. helping to maintain the shelf life. Ascorbic acid
(vitamin C) is a commonly
food’s texture and
consistency. used example.

Additives WHAT IS A
BATTLE BUTTIE?
Additives are found in a wide variety of processed
foods. They are crucial in extending the shelf life The US Army developed
of foods, replacing lost nutrients, preserving appealing a sandwich that will not
textures, and adding taste and color. become stale for at least two
years. This is due to a packet of
Not all bad iron filings in each sandwich
bag that absorbs the oxygen
Additives can include natural and artificial substances, although the
dividing line between them is fuzzy. Some of the additives are natural that microbes need
substances that have been used since ancient times for enhancing or to grow.
preserving food—sodium chloride (common salt), for example. Newer
additives are tested extensively before being approved for use.

Emulsifiers Flavorings Colors
Emulsions are mixtures of Artificial or natural These are used to add
liquids that do not normally mix, flavorings are added to or improve colors lost
such as oil and water. Emulsifiers replace or enhance in processing or to add
promote such mixing in foods— natural flavors lost in
in mayonnaise, for example. processing. Taste and color to white or
smell are closely linked, dull-looking foods in
so many flavorings also order to make them
have smell components. look fresher and more

attractive.

Acidity regulators Anti-caking agents Leavening agents
These are used to control the These help to prevent These are added to doughs
acid–alkaline balance (pH) of powdered or granulated
foods (such as flour and salt) and batters to help them
food for taste (acid foods from absorbing moisture and rise by promoting the
taste “sharp” or sour; alkaline
ones, bitter), and to inhibit clumping together. production of gas (usually
carbon dioxide); a common
the growth of microbes so
that food remains safe to eat example is baking soda.
when it has a long shelf life.

What’s in a burger? BURGER BUN TASTE BUD TICKLER
PICKLES
There may be more than CHEESE The savory umami flavor comes mainly
you think. Even a 100 from the amino acid glutamic acid, and an
percent meat patty may BURGER PATTY artificial preparation of this acid—
have stabilizers to make KETCHUP monosodium glutamate (MSG)—is widely
sure the meat keeps its used as a flavor enhancer, especially in
shape while cooking and BURGER BUN Asian dishes. In the 1960s, MSG was linked
flavorings such as salt, to symptoms such as migraines and
pepper, and onion powder. palpitations, but later studies
The bun and toppings showed that MSG does not
may also have additives, cause health problems,
to help prevent the except in a few people
growth of microbes and who have a specific
keep them fresh-looking. sensitivity to it.

Cooking BAK LLING
GRI
Heat produces chemical and physical Grilling (applying dry heat from below)
changes in food, making it softer, more is probably the earliest method of cooking,
digestible, and causing the food to release since it can be done with an open fire. Grilling
nutrients. However, sometimes nutrients are with a heat source above the food is called
broiling. Grilling imparts very high temperatures

to foods, enabling browning reactions,
but there is a risk of charring.

degraded when certain foods are cooked. Food surface GRILL
closest to
Why do we cook food? Infrared light
heat source carries heat
Some scientists think that the discovery of cooking cooks first to food
(see pp.8–9) was a key trigger in our evolution.

Cooking improves and generates new flavors, ING/RAOnAoSvTenINtrGansfers heat, from a gas
aromas, and textures. One such example is a
browning reaction, in which sugars in food lose flame or electric element to the food
water when heated, producing flavor. Raw foods
are often tough, fibrous, difficult to chew, and

hard for digestive processes to attack. Unless mainly by convection, as hot air circulates in
cooked, many food components cannot be the oven. Direct infrared radiation from the
broken down by our digestive system. Also,
oven’s hot walls also heats the food.

cooking helps to kill or suppress pathogens Hot air OVEN
and renders many toxins inactive. circulating

ING Steaming transfers heat to food Infrared
radiation
through air convection (as in baking),
STEAM but also through condensation of vapor. Just
as it takes a lot of energy to convert water into
steam, so steam gives up a lot of heat energy
as it condenses back into water as it reaches and

moistens the food.

Steam delivers PAN BOILING Boiling is one of the most efficient
heat to food methods of cooking, since all of the food
Water gives is in direct contact with the heat transfer
off steam medium (water). Browning reactions are not
triggered because of the constant presence of water.

Convection currents in water
carry heat from source to food

PAN

A GLOWING COAL RADIATES
40 TIMES MORE HEAT ENERGY

THAN THE EQUIVALENT
AREA OF AN OVEN WALL

FRYING STORING AND COOKING 60 61
Cooking
Oil can reach higher temperatures than
water, and in shallow frying it is used to HOW MICROWAVES WORK
conduct heat directly from the source (pan base)
to food. This means browning reactions happen A microwave has a transmitter that sends out waves of
quicker. In this method all of the immersed food around 5in (12cm) in length. They are shorter than radio
surface is in contact with the heat transfer medium (oil). waves, but longer than infrared waves from grills and ovens.
A turntable rotates the food to ensure all parts are cooked.
Bottom surface of food
Heat from flame cooks first
transferred to food
Microwaves Wave guide
through pan bounce off
reflective wall Transmitter, or
PAN “magnetron”
Food
Turntable

Deep frying uses convective heat WAVINMGicrowaves agitate the water in
transfer, but since the medium (oil)
can reach a much higher temperature than foods, generating heat and thereby
water, food can be cooked much more quickly cooking the food. It may seem as though
than frying and browning reactions happen faster. microwaves heat foods from the inside out but
DEEP FRYING they tend to heat all molecules at the same time.
MICRO However, microwaves will cook the wet interior
Convection currents in of dry-cased foods (such as pie) more quickly.
oil carry heat from Oil reaches temperatures
source to food above 212ºF (100ºC) Agitated water molecules Microwave—a wave with a
generate heat frequency of around 2,450MHz

PAN

MICROWAVE

Fast and slow cooking Oven wall during roasting 2,000°F/1,100°C
480°F/250°C 2,900°F/1,600°C
Cooking quickly can minimize damage to
easily degraded nutrients, and can seal the Coal in a barbeque
outside of meat or fish to limit moisture loss,
but it is harder to heat food evenly and the Gas flame in a grill
interior is likely to remain undercooked. Slow
cooking heats through more evenly but can
degrade nutrients and dry out food.

Turning up the heat
Flame grilling and barbecuing are better for
thin foods with high surface area to volume
ratios, since this raises the likelihood that
food will be cooked through.

104ºF (40ºC) 122–140ºF (55–60ºC) 149–167ºF (65–75ºC)

RAW STEAK

PROTEIN Juices may be reddish Oxygen leaves meat
in color but it is not
Protein blood—it is some of Meat turns gray-brown
chains the red pigment as myoglobin changes shape
begin to (myoglobin) leaking out
unravel

1 Proteins change 2 Juices leak out 3 Oxygen leaves
Water begins to escape from Collagen sheaths around muscle Myoglobin, which gives raw
unraveling protein chains in steak and fibers contract, squeezing cells so that and rare meat its red color (see
collects within cells. Under gentle heat, the water they have accumulated pp.68–69), changes shape. This means
muscle fibers within a steak begin to oozes out. Fiber-weakening enzymes the meat loses its color as myoglobin
relax and unfold, while the meat’s own reach high levels of activity but then can no longer hold on to oxygen,
enzymes actively break them down. change shape and stop working. fading from red to pink to gray-brown.

How food cooks

At the molecular level, cooking involves a complex series of interactions

between heat, water, and individual food components, and

between the components themselves. When cooking, DO FOODS LOSE
NUTRIENTS WHEN
the perfect balance between temperature, time, and
the desired change in chemistry must be achieved. COOKED?

What happens when food cooks? Some foods lose a portion
of vitamins when cooked. In
Food, especially meat, is composed of molecules similar to ours— others, the chemical reactions
proteins and fats. Plants mostly comprise of carbohydrates. Heating and release of nutrients while
these molecules changes their nature, causing some to combine into
new molecules, others to break down into smaller ones, and some to cooking can improve
degrade. When heated, large molecules in food, such as enzymes, their nutritional
change shape and stop working. Water is a crucial factor: dry cooking value.
causes water to evaporate; wet cooking can have the opposite effect,
causing food to absorb water, as with rice or pasta.

STORING AND COOKING 62 63
How food cooks

167–194ºF (70–90ºC) 230–239ºF (110–115ºC) 266–284ºF (130–140ºC)

COOKED STEAK BURNED STEAK

Meat shrinks; becomes PROTEIN
tough and fibrous from
loss of juices and fluids Sugar Amino acids
combines recombine
Water evaporates to create
as steam with new protein
protein chain
Carcinogenic
compound

4 Water boils off 5 Maillard reaction 6 Surface chars
Collagen begins to break down At the meat’s surface nearest If meat is exposed to high
and liquefy. In a pan-fried steak, water the heat source, where water has temperatures, such as those from coals
evaporates, and it becomes dense and boiled away, Maillard reactions take or flames on a barbeque, or left to cook
dry. In wet-cooked meat (such as in a place—combining amino acids and for too long, combustion reactions will
stew) the collagen melts, so the meat sugars that turn the meat brown and take place that produce carcinogenic
remains succulent and juicy. provide it with aromas and flavor. compounds (see pp.68–69).

The story of steak Cooking vegetables 1 Pectin
Many changes happen at the molecular Long chains of
level to steak meat as its temperature Vegetables are composed linked sugars (carbohydrates)
rises and cooking progresses from one mainly of carbohydrates, which hold vegetables such as
extreme to the other. are generally much tougher and carrots together—making
more heat resistant than them tough and fibrous.
COOKING WITH A proteins. The cell walls of plants
PRESSURE COOKER in particular are hard to break Pectin molecule
IS EQUIVALENT TO down, although heat will
COOKING WITH AN weaken them, allowing water 2 Bonds broken
OPEN PAN 3.6 MILES from inside the cells to leak out. When heat is
(5.8 KM) BELOW Vegetables turn tender when applied to pectin chains,
SEA LEVEL boiled because pectin (a type of they dissolve at boiling
carbohydrate), which sticks cells point, making carrots tender.
together like bricks with mortar,
dissolves at boiling point. Sugars break apart
Blending cooked vegetables when heated
will eventually break down cell
walls altogether—this is how
vegetable puree is made.

Safe Preventing contamination
cooking At home, you can reduce the risk of
contamination either by rinsing and washing to
As well as transforming food’s flavours remove the dangerous microbes or cooking and
and textures, cooking makes it safe to heating to kill them with elevated temperatures.
eat by destroying toxins and killing
microbes, though if not done properly, WASHING FRUIT AND
it risks making food less safe.
Importance of rinsing VEGET

Fruit, vegetables, and salad can be ABLES
contaminated with Listeria and norovirus,
especially if grown with certain types of fertilizer,
or if prepared by someone with poor hygiene.
Contamination Contaminants confined to the surface of plant
foods can be washed away, which is preferable
Your skin and immune system protect you from harmful to peeling, as the outer layers are
organisms, but if they enter your body via your food, often the most nutritious.
they may cause food poisoning. Unfortunately, the scale
and complexity of modern food production greatly Water
increase the risk of contamination. From farming to
processing and distribution, contamination can happen Bacteria Listeria
at any point in the food production chain. The most washed
common threats are the bacteria Salmonella, E. coli, off leafy
Campylobacter, and Listeria, the parasite trichinosis, greens
and the viruses hepatitis E, hepatitis A, and norovirus.
Norovirus

Killing bacteria WASHING
LEAFY GREENS
Bacteria can be robust and persistent, but few living
things survive being heated to extreme temperatures. WASHING SILVERWARE AND SURFACES
Heat disrupts chemical bonds and drives off water,
causing the bacteria’s cell components to break down, What washing kills
their enzymes to change shape and lose their function, A major source of food contamination is
and their cell walls to breach. As each species of poor kitchen hygiene. Work surfaces and
bacterium has a different composition, they have varying implements can spread germs easily. Soap or
levels of tolerance to heating. disinfectant kills bacteria, but dirty cloths can

SALMONELLA LISTERIA harbor germs.
158ºF (70°C) 165ºF (74°C)

LOW HIGH Campylobacter

TRICHINOSIS E. COLI Bacteria
136ºF (58°C) 154ºF (68°C) removed
by soap
Safe temperatures E. coli
You can remove bacteria from your food by making sure it WASHING
reaches certain temperatures. For example, to kill E. coli you UTENSILS
need to make sure that the center of the food reaches at
least 154ºF (68°C); for Listeria it needs to reach 165ºF (74°C).

STORING AND COOKING 64 65
Safe cooking

YOUR KITCHEN SINK MAY CONTAIN
100,000 TIMES MORE GERMS
THAN YOUR BATHROOM

Appropriate cooking COOKI SHOULD I WASH
NG MEAT CORRECTLY RAW CHICKEN?
There is a high chance of the surface of a piece of meat
being contaminated. It is hard for microbes to enter the Washing chicken may
interior of red meat, so just the outside needs cooking. splash bacteria, such as
Because poultry is more easily penetrated by bacteria, Campylobacter, off the chicken
it needs to be cooked all the way through. and onto surrounding

Bacteria only on surfaces where they
outer surface of meat may proliferate.

Campylobacter Salmonella

Heat penetrates COOKING
meat thoroughly CHICKEN

Heat REHEATING RICE
COOKING
BEEF STEAK Illness associated with reheated
rice is called “fried-rice syndrome,”
REHEATING LEFTOV ER FOOD heat and is caused by the bacteria
Bacillus cereus. Spores in freshly
Sufficient cooked rice that sits at room
Leftovers can be safe to eat. First, limit temperature will grow into bacteria,
microbial contamination by taking leftovers which release toxins that cause
away from the heat source so it can cool vomiting and diarrhea. Reheating
quickly. Hot leftovers in the fridge can raise the rice might kill the bacteria, but their
temperature of surrounding spores may survive.
chilled foods, initiating
Bacteria live microbial growth within BACILLUS
CEREUS
throughout leftovers them. Stirring reheated
BOWL OF
foods from the microwave REHEATED
will help spread the
heat and kill any RICE
leftover bacteria.

Heat Clostridium
REHEATING
MEALS



TYPES
OF FOOD

Red meat

Meat has played a central role in human nutrition for
at least 2 million years. In the modern world, meat—
especially red meat—has accounted for an increasingly
high proportion of our diet, with consequences for obesity,
cardiovascular health, and cancer rates.

Myoglobin and
cytochromes

What makes red meat red? MUSC LE TISSUE

Meat usually refers to muscle, however, the term can also
encompass organ meats. Red meat gets most of its color
from iron-containing myoglobin, a richly pigmented
protein that provides cells with oxygen, similar to
hemoglobin in red blood cells. Energy is supplied to
muscle by fats, which are broken down by cytochromes—
a type of protein in muscle fibers that is also red.

WHY CAN MEAT Muscle fiber
SOMETIMES TASTE
Muscle fiber
METALLIC? In muscles that are constantly
at work—such as leg muscles—
Very lean cuts of red meat there are lots of myoglobin and
lack flavorsome fat, which cytochromes, which provide the
contributes to the typical beef muscle fibers with all the oxygen
taste. This can accentuate the and energy, respectively, that
metallic flavor from the high they need to function.
quantities of iron in red meat,
BOWEL CANCER RISK
especially muscle meat
and liver. Although some large-scale studies have implied that
that consumption of red meat (particularly chargrilled
or barbecued) correlates with a risk of colorectal
(bowel) cancers, the association is weak. Furthermore,
the reason for a link is unclear, and may be because
fatty red meat contributes to obesity (a high BMI is
associated with a risk of colorectal cancer), rather than
the ingested fat itself. An analysis of 27
independent studies found no clear
patterns of a direct relationship
between higher red meat intake
and increased risk of cancers.

TYPES OF FOOD 68 69
Red meat

Red meat and nutrition

Red meat is a complete protein source, providing all of the essential
amino acids that our bodies cannot create. It is also a rich source of
iron and B vitamins. Significant health concerns remain, however.
The red meat we consume tends to be high in fat—the higher the
fat content, the greater the flavor and tenderness of the meat.
Higher fat content means a greater number of calories, more
saturated fats, and the health risks associated with them.
CA M RE FATTY
CH CE ACIDS
PHEASANT
D BLOOD CELLS LL CONSTITUENTS Enzyme breaks MUSCL
fats down to
fatty acids

E CELL

The body needs iron to make We need the amino acids provided AMINO
oxygen-carrying hemoglobin by meat to construct the proteins ACIDS
in the blood, as well as that make up our cells, including
Enzyme breaks Enzyme breaks
myoglobin in our their membranes and all proteins down glycogen down
own muscles. the cell machinery. to amino acids to glucose

USCLES OLESTEROL Producing flavor GLUCOSE

Hanging is common for
any wild-caught meat,
including gamebirds such
as pheasant. Enzymes within
cells start to attack other cell
components. Proteins are
The fat-burning nature of red broken down into savory
Our own muscle fibers are built muscle means that red meat is amino acids, glycogen into
from protein that we can only high in saturated fats and sweet glucose, and fats into
make if we get the right balance aromatic fatty acids.
cholesterol, which can affect
and supply of amino acids our cardiovascular health
in our diet. (see pp.214–15).

RCINOGENS Hanging meat

Carcinogens are naturally found SINCE 1961, Meat should be hung after
in many foods, but in such small GLOBAL PORK slaughtering to prevent excessive
quantities that they are offset CONSUMPTION toughness. Meat cut immediately
HAS INCREASED on slaughtering will be very tender,
by other nutrients. Smoking BY 336 PERCENT but within hours muscles contract
or charring meat can also irreversibly. To minimize these
produce carcinogens. effects, carcasses are hung in
such a way that the muscles are
stretched by gravity. Longer
hanging periods (such as a week)
allow enzymes in the meat’s own
muscles to get to work tenderizing
and producing flavors.

White meat

White meats include chicken, turkey, duck, and
pigeon—some definitions include veal, piglet, rabbit,
certain game birds, and frog. The different function and
physiology of white meat gives it unique characteristics
of flavor and nutritional value, which in turn have
led to an explosion in global production and
consumption of poultry.

What makes white meat white? Myoglobin and EN BREAST
cytochromes
White muscles are specialized for short bursts of intense (oxygen-carrying
action (they are full of what are known as “fast-twitch pigments)
fibers”). They burn glycogen (made of linked glucose
molecules) and can work without oxygen for brief periods, CHICK
although they must rest in between bursts of activity.
Muscle fiber
This means they have less oxygen-carrying pigments Light meat
(red pigments that deliver oxygen to muscle) White muscle cells do not need as
than red meat. Chicken legs, which always rich a bloody supply as red muscle
support the body, will have slightly more red cells, so they contain less oxygen-
pigments, giving dark meat. Also, these carrying red pigments—making
redder muscle fibers have their own white meat lighter in color.
fat supply, making dark meat
more flavorful.

UPSIDE-DOWN ROASTING

In Western cultures, there is a chef’s trick to Fat from back
roasting chickens and turkeys—place them drips into meat
breast-down in the oven. This is
because most of the bird’s fat is HEAT
located on its back, so when
placed upside down and
cooked, the fat trickles into the
bird’s meat—providing a rich
flavor and moist texture. If
cooked breast upward, the
flavorsome fat just pools at the
bottom of the pan and is wasted!

TYPES OF FOOD 70 71
White meat

Pasture-raised or caged chickens? VITAMIN E
OMEGA-3 FA
Nutritionists argue that there is a nutritional difference
between hens raised inside in cages and those allowed
to roam and feed outside in pastures. Pasture-raised
chickens have a different diet, a more active foraging
strategy, and lower stress levels than caged, barn-raised,
or free-range chickens (see pp.232–33). There is evidence
that this not only improves the amount of essential fatty
acids and vitamins in the meat, but also reduces the
levels of unhealthy fatty acids.

OMEGA-6 FATTY ACID ATURATED FATTY ACID
TTY ACIDS
SS
S

-32.9% -51.9% +90.8% +406.8%

Nutritional differences KEY IN THE US, TURKEY
According to a study comparing Caged chickens CONSUMPTION
pasture-raised and caged HAS DOUBLED IN
chicken, the pasture-raised Pasture-raised THE PAST 25 YEARS
poultry had less omega-6 fatty chickens
acids and more beneficial
omega-3 (especially when fed
on soybeans), less fat overall
(including saturated fat), and
much more vitamin E.

RESTORATIVE PROPERTIES OF CHICKEN SOUP DOES TURKEY
MAKE YOU DROWSY?
In several cultures, most notably in
Ashkenazi Jews, chicken soup has long No, not at all—this is a myth
been described as particularly effective that stems from the fact that
against colds. One study was conducted there is an amino acid called
in which blood samples of those who ate tryptophan found in turkey
chicken soup and had a cold were analyzed.
The study found that chicken soup did that is used to create the
have anti-inflammatory and decongestant sleep-inducing hormone
properties that eased symptoms such as
runny noses, as well as promoting good melatonin.
digestion, boosting fluid intake, and
providing healthy nutrients.

Cuts of meat Fat within
muscle
The nutrition, taste, texture, nutrition,
and even the cooking method of a piece Fatty meat takes
of meat is ultimately determined by its longer to cook
original location on the animal’s body—
and how active that part was in life.

Taste and texture STEWING

Each cut encompasses a different set of muscles on the Muscle
animal. The guiding principle behind evaluating different fiber
cuts of meat is that more active muscles (such as those
found on the legs) have thicker fibers and more Fatty meat CHUCK STEAK
connective tissue, and so will have tougher
and chewier meat. More active muscle will Fattier cuts of meat can benefit from slow cooking
also have more fat, however, and so may to render down their fat. Globules of fat are
be more flavorsome. Butchers divide most scattered in-between muscle fibers that would
animals into a broadly similar set of cuts, have provided the muscle with energy (see p.68).
with the same terminology applying to
cows, sheep, goats, and pigs—the CHUCK
French have the most types of cut RIB EYE
when it comes to beef.

TONGUE CHEEK NECK

Connective
tissue

Tough meat CUFOTSRFERLEOGM
takes longer to
become tender

RIBS

BRISKET BRISKET

BRAISING Muscle
fiber

Tough meat BRISKET MEAT

Cuts from the breast, such as brisket, have higher
levels of connective tissue that supported much
of the animal’s weight when it was alive. Brisket is
cooked for longer and often in liquid to dissolve
the connective tissue and make the meat less tough.

TYPES OF FOOD 72 73
Cuts of meat

Muscle fiber OFFAL

Lean tender meat Offal (the internal organs of an animal, not including
can be cooked in muscle or bone) comes in many forms, and each
organ has its own distinctive flavor and texture. Offal
a shorter time generally has more connective tissue and tends to
need slow, thorough cooking; livers are a popular
FRYING exception. A lot of offal and organ meat has high
levels of nutrients and essential fatty acids, and
low levels of harmful fat. For instance, liver and
kidney can be particularly high in iron and folate
(vitamin B9).

Lean meat SIRLOIN STEAK Kidney Tongue

Less active muscles such as those found in
sirloin cuts need less of an embedded energy
supply and so will have less fat or no fat at all;
hence they are known as lean, or tender, cuts.
Heart Liver Feet

RUMP 45HOURS IS

SIRLOIN THE MAXIMUM TIME IT CAN
TAKE TO COOK PIGS’ FEET—AFTER
TAIL WHICH EVEN THE BONE IS EDIBLE
CUHTINS DFRLOEGM

FLANK

LEG WHY CAN’T WE
EAT RAW MEAT?

It is thought that our teeth and
stomachs evolved to be better

at digesting the more easily
available nutrients in safer,
cooked meat, but we are able
to eat very fresh raw beef

(like steak tartare).

Processed meats Grinding
Surfaces are the risk zones
Since ancient times, meat has been processed to extend for meat contamination, and
its lifespan and to add flavors and aromas that can only grinding radically increases
be produced through the unique biochemical processes meat’s surface area. Producers
involved—resulting in a wide range of products. therefore ensure any bacteria
are killed by blanching the
Why do we alter meat? Meat mixtures meat (very briefly heating and
Meat mixtures were cooling it) before grinding.
Meat is metabolically active. It is fragile on the cellular traditionally a way to
level and rich in moisture and nutrients, so it is at high maximize use of every GROUND MEAT
risk of rapid spoiling. Spoiling includes fats going part of a valuable animal
rancid (oxidizing), and growth of microbes from animal carcass so that nothing
hides and intestines if they contaminated the meat went to waste. Today,
during butchering. Processing meat helps to delay or meat mixtures are
halt spoilage and generates complex and interesting thought of as cheaper,
flavors and textures. It can also mean turning whole lower quality products,
meat into ground and reconstituted forms, sometimes often with negative
known as meat mixtures. These bring their own health impacts.
culinary possibilities, but also their own health risks.

THERE IS A 42 PER-
CENT HIGHER RISK
OF DEVELOPING
HEART DISEASE FOR
EVERY HOT DOG
YOU EAT PER DAY

Methods of preservation MEAT MEAT Dead
ANTIOXIDANT bacteria
Curing encompasses a range of
preservation techniques, including CARCINOGEN SALT
the traditional methods of smoking ANTIMICROBIAL
and salting (which can often be Moisture drawn out
used together). In modern times, Smoking
preservative chemicals such as Smoke contains antimicrobial and Salting of surrounding meat
potassium nitrate are also used. antioxidant compounds and helps to
Bacteria in the meat process it into prevent fat from going rancid. However, Adding salt to meat draws water out of cells,
nitrite, which reacts with oxygen in smoke also contains carcinogenic depriving microbes of the moisture they
the meat to form nitric oxide. This (cancer-causing) compounds. need to thrive. High salt levels cause protein
binds with the iron in the meat to filaments to spread out so that they no longer
prevent oxygen from affecting fat scatter light, making meat translucent.
and making it rancid. Meat gains
a rosy color and a piquant flavor.

Sausage-making Mechanically reconstituting 74 75
To make sausages, chopped meat Most reconstituted ham is made
and usually some filler, such as by pressing together pieces of Injections of salty water
bread crumbs and spices, are pork (not necessarily muscle Many bacon and ham
stuffed into tubes traditionally meat) that have been blasted off products are injected with
made from animal intestines. the bone by jets of high-pressure a solution of water, sugars,
The fat in sausages keeps them water. This is just one method of preservatives, flavorings, and
from drying out when cooking. what they call “mechanical additives to bulk them out
recovery” of meat. and save money. Some bacon
strips are 50 percent water.
High-pressure
water blasts meat

off bone

Different parts Different parts of meat results Solution injected
of meat in in ham’s patchy color into bacon
sausage
results in
mottled color

Meat flecks pressed
together into ham slices

SAUSAGES RECONSTITUTED HAM BACON

WHY DOES PRESERVATIVE HEALTH CONCERNS
RECONSTITUTED HAM
HAVE A RIND OF FAT? Nitrite has been a popular preservative for
the flavor and color it adds to meat, and is
Manufacturers of re-formed often used in salamis. It is especially good
ham often add a coating of fat to at delaying the growth of bacteria that
produce toxins that cause botulism.
give an illusion of authenticity However, nitrite can react with amino
to their product, as if it has acids in the meat to produce
been cut directly off carcinogenic compounds called
the carcass! nitrosamines. Although there is
little hard evidence that nitrites
in cured meats increase cancer
risk, its use is now often
carefully regulated.

Meat substitutes

Consumers prize meat for its flavor, texture, and 1 Fungus, glucose,
nutritional value, but many are concerned by the and minerals added
negative health, environmental, and ethical impacts A starter culture of the fungus Fusarium
of meat consumption and production. One solution is added to a fermentation tank. It needs
to these problems is the use of increasingly popular food to metabolize into protein, so
meat substitutes. sterilized glucose syrup is
added to the tank, along
with trace minerals.

Trace
minerals added

HOW MYCOPROTEIN IS MADE Glucose added

Starter culture
of fungi added

5 Mycoprotein
grows
For about six weeks the
mycoprotein continues to
cycle around the fermenter
and grow. Eventually, it 4 Cooling down
collects in a chamber and The rapid growth of the
fungus, and its constant metabolism,
is then harvested. generate lots of heat. Coils of cooling

water help to maintain the optimum
temperature for fungal growth.

Oxygen Nitrogen

2 Ammonia and air added MYCOPROTEIN COLLECTS
Fungal growth is boosted
by adding nitrate from ammonia
and oxygen from air. These gases
are bubbled through the mixture
to help mix it.
COOLING SYSTEM

Using meat substitutes HEAT DRYING AND
TREATMENT CHILLING
Although meat substitutes might
seem like a modern trend related to 6 Finished products
health benefits, they have actually Harvested mycoprotein
been popular since ancient times is heated to neutralize harmful SAUSAGE
through cultural and religious substances, spun in a centrifuge SLICES
prohibitions against meat. For to dry, and is then chilled. The
example, tofu was created in ancient mixture is also treated to make
China by vegetarian Buddhists. Today it more closely resemble muscle
the primary sources of meat substitute fibers, flavored, and shaped
are soy-based products, gluten-based into meatlike products, such HARVESTED
products from grains, the use of other as sausages or slices. MYCOPROTEIN
protein sources such as nuts, and, as
shown here, the controlled growth
of mycoproteins from fungi.

TYPES OF FOOD 76 77
Meat substitutes

IN 10TH CENTURY Versatility of soy
CHINA, TOFU WAS
COMMONLY KNOWN Soy is rich in proteins and oils, which makes
AS “SMALL MUTTON” it an extremely useful base for meat substitutes.
Fermenting the soy releases its rich cargo of
3 Waste gases nutrients and these can then be processed in
The air and ammonia similar fashion to milk and dairy products. Many
different soya products have been developed.

bubbled through the mixture, Gases
along with waste gases released

produced by the metabolism
of the fungus, are extracted
from the fermenting vessel.

Tofu Thousand layers tofu
Tofu, or bean curd, is made by A process of freezing then
curdling soy milk to produce thawing tofu creates a product
curds, which are then broken with a spongy network that

down to release water and resembles many layers.
pressed into blocks.
Mycoprotein (fungus)
starts to grow

SOYBEANS

Textured vegetable protein Tofu skin
Made from the by-products of Heating soy milk creates a thin

soy-bean oil processing, but solid skin that traps oil.
textured vegetable protein Fibrous and chewy, it is
dried as sheets
is a versatile meat or sticks.
alternative.

IS MYCOPROTEIN
VEGAN?

Although pure mycoprotein
probably would be vegan,
most marketed products are
not because they use egg
white as a binder and milk

ingredients during
processing.

OMEGA 3 FATS (PERCENTAGE BY WEIGHT) 0
0.5
1.0
1.5

2.0 1.0

2.5

1.6 1.6
2.0 2.1

HERRING
SALMON
MACKEREL
BLUEFIN TUNA
TROUT
Oily fish 184 BILLION TONS
One of the richest known sources TOTAL GLOBAL FISH
of vital omega-3 fats, oily fish have PRODUCTION IN 2014
oil throughout their tissues and
more oil overall than white fish.
They tend to be warmer-water
species or more active fish, such
as trout, tuna, and salmon.

Oily fish and white fish SASHIMI

Fish are high in protein, rich in nutrients such as iodine, calcium, and Fish sashimi, thin slices of raw fish
B and D vitamins, and low in cholesterol. Fish are often divided into oily prepared Japanese-style, is popular
(or fatty) and white fish. Oily fish have more fat than white fish and are worldwide. However, because the
particularly rich in omega-3 fatty acids (see pp.28–29), notably EPA and fish is raw, there is the risk that it
DHA. These two omega-3s can be made in the human body from another may be contaminated with
omega-3, alpha linolenic acid (ALA), but only in small amounts—so EPA parasites or microbes, and the fish
and DHA are best obtained from the diet. White fish have less fat than
oily fish. They also contain omega-3s, but less than oily fish. must therefore come from
high-grade sources and be
Fish prepared carefully.

The largest single source of wild food in the human
diet as well as the product of a rapidly growing
branch of farming, fish are a source of important
nutrients such as protein and omega-3 fatty acids.

0.2 0.3 TYPES OF FOOD 78 79
0.4 Fish
0
0.5 0.5
1.0
FLOUNDER
HALIBUT 0.6 1.5

SNAPPER 2.0
COD 2.5

CATFISH
KEY
Oily fish Fat under skin Fat between
White fish muscle blocks
Omega-3 fats (% by weight) High fat
concentration Dark Where’s the fat?
in dark muscle muscle In fish, fat is generally stored
White in thin layers under the skin
White fish Spine muscle and between muscle blocks.
White fish have less oil and omega-3s than oily It is also present in strips of
fish, and the oil tends to be concentrated in the Gut cavity WHITE FISH dark muscle that run along
liver rather than throughout their body tissues. White the body. These strips are
White fish include all flatfish, such as halibut muscle larger and fattier in oily fish
and flounder, as well as some cold-water OILY FISH and smaller and less fatty
ocean fish, such as cod, monkfish, and mullet. in white fish.

Concentration of toxins Volcano MERCURY
Factory Mine
The ocean is the ultimate repository FOOD CHAIN
of much of the pollution generated HEAVY
by natural and manmade sources. METALS
Pollutants that are not readily
broken down naturally, such as Large Tuna Mackerel
mercury, heavy metals, and shark Krill
persistent organic pollutants (POPs,
see pp.202–03), may be present in HIGH LEVEL MEDIUM LEVEL LOW LEVEL
low levels in small prey animals but OF MERCURY OF MERCURY OF MERCURY
accumulate through the food chain,
becoming concentrated in top
predators, such as sharks.

Toxins in the food chain
Persistent pollutants become concentrated
as they move up the food chain. Sharks,
swordfish, and other top predators may
contain dangerous levels of these pollutants.

Shellfish WHY DOES
COOKING CRUSTACEANS
Colossal heaps of discarded shells at prehistoric sites
attest to the historic importance of shellfish in the TURN THEM RED?
human diet, and today this diverse group of aquatic
organisms is still a valuable source of nutrition. The shells of crustaceans
contain carotenoid pigments
The value of shellfish linked to proteins. Cooking
alters the proteins, releasing
Shellfish—crustaceans such as crabs and shrimp, and mollusks such as
oysters and octopus—are a superfood category all of their own, being an the reddish-colored
excellent source of lean protein. They are also rich in B vitamins, iodine, carotenoids.
and calcium. From a flavor point of view, seafood is rich in tasty amino
acids, such as glycine, which tastes sweet, and umami (savory) glutamate.

APHRODISIACS ABOUT ONE-THIRD
OF THE WARM-WATER
Raw oysters have a historic SHRIMP HARVEST
reputation as an aphrodisiac, and IS FARMED RATHER
20% there is some evidence that this THAN FROM
reputation may be justified. They WILD STOCKS
are high in zinc, which aids male
fertility, and have also been
found to contain amino acids
that can trigger the release of sex
hormones in men and women.
15%

PERCENTAGE OF FAT, BY WEIGHT High protein, low fat
Compared to the meat of land animals, most crustaceans and
mollusks offer high protein for little fat. Their meat protein
also offers a contrast in texture with land-animal red meat,
because it is white muscle packaged with high levels of the
10% protein collagen, making it firm and moist. In contrast, red Crab meat contains
a similar proportion
meat contains high levels of the protein myoglobin, which
give the meat its red color, and lower levels of collagen. of protein and fat
to shrimp

Scallops have little fat

5% but also a fairly small
amount of protein
OYSTER

SCALLOP SQUID CRAB SHRIMP
20%
0 15%
10% PERCENTAGE OF PROTEIN, BY WEIGHT

TYPES OF FOOD 80 81
Shellfish

When to eat shellfish Toxic algae Nontoxic KEY
algae Safe
Many types of shellfish are best High levels of Dangerous
avoided at certain times of the year, algal toxins Lower levels
for a number of reasons. First, many of algal toxins Seasonal toxicity
species breed in the summer and The summer months
expend their energy reserves during SPRING SUMMER FALL WINTER are often the worst
this period, becoming meager and for toxic blooms of
less tasty. Second, summer is also algae and for harmful
the period when toxin levels are microorganisms,
highest. The best period for eating which proliferate in
many shellfish is during the winter warmer waters and
months, when they are fattening up in can accumulate in
preparation for the breeding season filter feeders, such
and when toxin levels are low. as many mollusks
and crustaceans.

LAMB Lamb has a high Shellfish poisoning
percentage of fat in
relation to protein Many shellfish feed by filtering
out food particles from the water.
BEEF However, they also trap toxins
and microbes, which may build
up and, if enough contaminated
shellfish are eaten, may cause
poisoning. The toxins are not
destroyed by cooking. Symptoms
of the main types of shellfish
poisoning are outlined below.

CHICKEN Paralytic shellfish poisoning
Numbness and tingling, loss
Octopus meat is one of coordination, difficulty
of the best sources of speaking, nausea, vomiting.
May be fatal.
low-fat protein Amnesiac shellfish poisoning
Memory problems, which
LOBSTER OCTOPUS may be long term, or even
permanent brain damage.
25% 30% May be fatal.
PERCENTAGE OF PROTEIN, BY WEIGHT Neurotoxic shellfish poisoning
Nausea, vomiting, slurred speech.
No known fatalities.

Diarrheal shellfish poisoning
Diarrhea, nausea, vomiting,
abdominal pain. No known
fatalities.

Eggs SHELL

After a decade or more in the shadow of a EGG W HITE
health scare in the developed world, eggs
are reemerging as what many consider to Inside chicken eggs
be the perfect food. Handy self-contained Eggs provide an almost perfect
packages of healthy protein, eggs are rich balance of proteins, along with
in almost every desirable nutrient. omega-6 fatty acids, and the
antioxidants zeaxanthin and
Nutrition powerhouse EGG INGREDIENTS lutein. In fact, they contain every
Icon sizes show total nutritionally essential vitamin
The egg white, or albumen, amount of each nutrient. and mineral with the exceptions
contains 90 percent of an egg’s of vitamins C and B3 (niacin).
water and half of its protein. The 0.1–9 mcg
most plentiful protein in egg white 0.01–9.9 mg YOLK
is ovalbumin. Accounting for
around one-third of the mass of 10 mg–0.9 g MAGNESIUM
the egg is the yolk, which contains
half the egg’s overall protein, 1–5 g VITAMIN A
three-quarters of the calories, and
all the iron, thiamin (vitamin B1), Rich in protein, FAT VITAMIN D
fat, cholesterol, and vitamins A, D, but low in fat and ZINC
E, and K. In fact, eggs are one of VITAMIN K
the few food sources of vitamin D. cholesterol, egg
Also present in the egg yolk are white is extremely
essential fatty acids. useful in cooking

The yolk contains SELENIUM
the vast majority of
the egg’s rich load of
vitamins, minerals, and
other trace nutrients

PROTEIN

EGGS AS EMULSIFIERS POTASSIUM IRON
VITAMIN E
Emulsifiers blend substances that are unmixable, such as
oil and water. The result is an emulsion—tiny droplets of
one substance suspended in the other. Egg proteins can
create emulsions useful in cooking, such as mayonnaise,
which is an emulsion of oil in vinegar or lemon juice.

MAYONNAISE Water-loving PROTEIN
IN CLOSE-UP part of egg
Oil protein
Vinegar faces the
water-based
Oil-loving part of egg fluid outside
protein surrounds and
isolates a tiny droplet

TYPES OF FOOD 82 83
Eggs

Cooking eggs RAW EGG

Eggs are versatile cooking 179
ingredients, but the quality of an Curled THE NUMBER OF
egg diminishes over time, partly protein EGGS PER PERSON
because the shell is highly porous, AVAILABLE FOR
allowing moisture to escape. As an In a raw, unbeaten egg, the protein chains CONSUMPTION
egg dehydrates, it becomes more are folded and curled up, enabling GLOBALLY
alkaline, which makes the egg them to remain separate, self- IN 2014
white runnier and the membrane contained units suspended
around the yolk weaker. Freshness, in water; the egg
therefore, is essential in making the remains liquid.
best fried and poached eggs.
BEATING EGGS BAKING EGGS
Eggs have proteins that harden
when heated or beaten, resulting in Trapped air
a range of useful cooking effects. bubble

COOKING EGGS

Uncurled Uncurled Air bubble
protein with protein expands

cross-links Whisking or beating eggs is another way The scaffolding provided by long,
to put energy into the system. As with interlinked egg proteins helps to give
Heating gives energy to the protein
chains, which shake themselves out into heating, the protein chains acquire cake mixtures structural integrity,
energy and unravel and interlink, allowing the trapped air bubbles
long chains that can cross-link. Cross-
linked protein assemblages cause trapping bubbles of air to to expand without breaking
the egg to harden and form a foam. or bursting open.
become opaque.

WHAT’S THE A BAD REPUTATION
DIFFERENCE BETWEEN
WHITE AND BROWN EGGS? In recent years, eggs have experienced
bad press, but most concerns are
The color of a chicken egg in unfounded. For instance, egg yolk is
no way reflects differences in high in cholesterol, but contrary to what
taste or nutritional value. It is scientists once thought, dietary cholesterol
does not greatly affect blood cholesterol
merely determined by the levels. Salmonella contamination, which has
breed of the hen that hit the headlines in some countries, is in fact
produced it. the main risk in eating eggs, but the risk is
now very low thanks to hen vaccination.
Vulnerable people (such as the elderly)
can further lower the risk of becoming ill by
cooking or pasteurization of their eggs.

Milk and lactose DOES MILK
REALLY HELP WITH
Humans are unique among mammals in continuing to consume
milk after infancy, but our ability to cope—to a greater or lesser BRITTLE BONES?
degree—with the milk-sugar (lactose) opens up for us a
delicious and nutritious world of dairy products. Milk is rich in calcium and
phosphate—two minerals that
help to contribute to healthy

bones. For those who can’t
tolerate milk, other foods can

supply these important
minerals.

HEATING Most harmful
bacteria killed by heat

0.7% VITAMINS
AND MINERALS

COWS’ MILK 3.4% PROTEIN
3.7% FAT

4.8% LACTOSE

87.4% WATER COOLING Cooling stops the milk
from caramelizing
What’s in milk?
How pasteurization works
Milk evolved as a starter food for mammalian
infants, providing a rich, dense source of nutrients In the 1860s the French chemist Louis
including sugars and fats for energy, and protein, Pasteur investigated microbial activity in
fats, minerals, and vitamins for building and growing food and developed a heat treatment that
bodies. Babies can survive for months on milk alone, and killed potentially harmful microbes without
adults almost can, although milk is lacking in vitamin B12, significantly affecting flavor. This process
vitamin C, fiber, and iron. The milk of different species tends is applied to milk to make it safe to drink.
to contain the same nutrients but in different proportions.

Diversity of dairy products

The varied composition of milk gives it great value, both as a food
source in its own right and as the base for a wonderful range of dairy
products, both fermented and unfermented. Processing is important
for milk products with medium-to-long shelf life, because even
pasteurized milk contains high levels of bacteria and will spoil quickly.

How cream is made CENTRIFUGAL CREAM REINDEER MILK IS ONE
Cream forms naturally in fresh, untreated SEPARATOR OF THE RICHEST MILKS
milk, because it is an emulsion that will AVAILABLE: 17 PERCENT FAT
separate under gravity. In industrial AND 11 PERCENT PROTEIN
production, a centrifugal separator will
spin milk at high speeds in order to
separate the cream.

How ice cream is made LACTOSE TOLERANCE
Milk is not simply frozen—if it were, the
fat and protein would coagulate. Instead, FREEZING ICE CREAM Bovine milk-drinking is a behavior that has
it is frozen and spun at the same time in become widespread relatively late in human
order to force air into the mixture. This evolution, and so the genes that make it
freezes the ice crystals at a steady rate, possible are unevenly distributed among
producing a smooth, consistent texture. world populations. In most people, the level
of lactase, the enzyme that allows us to digest
How condensed milk is made lactose, decreases rapidly after infancy, so that TYPES OF FOOD
Boiling milk to evaporate half its adults can become lactose intolerant. However, Milk and lactose
water leaves behind condensed milk. in some parts of the world, especially in
Its shelf life is prolonged as spoilage Scandinavia, populations have evolved to
microbes cannot survive with much continue making lactase into adulthood.
of the water removed. Sugar is often
added to improve taste. WATER CONDENSED Lactose tolerant Lactose intolerant
EVAPORATED MILK
How powdered milk is made SPRAY-DRIED SCANDINAVIA 98% CHINA 8% 84 85
Continuing to evaporate the water POWDERED LACTOSE TOLERANT LACTOSE TOLERANT
until about 90 percent is lost results MILK
in a highly concentrated syrup,
which is then freeze-dried or

spray-dried by scattering tiny
droplets into hot air. Powdered
milk is proof against microbial

attack but can go rancid.

Yogurt and IS THERE ANOTHER
live cultures WAY TO BOOST GUT FLORA?

Milk contains agents of extraordinary People with digestive problems
transformation—bacteria that can produce a due to too few microbes in the
galaxy of fermentation products that improve
nutrition. The same microbes that produce gut can gain those essential
yogurt may also benefit your gut, promoting bacteria by undergoing a fecal
a healthy balance and diversity of gut flora. transplant. Feces of someone
with rich gut flora are liquidized
What is yogurt?
and inserted into the colon
Yogurt is curdled (separated) milk. The fat droplets that are usually of the patient.
dispersed within milk have been captured by unraveled protein
chains, creating the thicker, clumpier composition of yogurt. This
change in structure is caused by bacteria (such as Lactobacillus)
that acidify the milk. Yogurt was probably first made by accident –
today, it is produced on a large scale using industrial methods.

1 Incubated milk KEY 2 Yogurt is made Milk thickens
Initially the milk is boiled to Bacteria Lactose is fermented into into yogurt
Lactose sugar lactic acid by the bacteria. This
concentrate proteins. The milk is Protein causes protein chains to unravel Lactic acid
then allowed to cool partially and Fat provides
bacteria are introduced to begin and mesh together, capturing sour taste
some fats and water—and also
fermentation—they begin to provides the sour taste of yogurt.
consume the sugar lactose.

Lactic acid is Fat globules
released from form
bacteria fermenting
lactose sugar

Protein uncurls
due to release

of lactic acid

TYPES OF FOOD 86 87
Yogurt and live cultures

Do live cultures survive digestion? YOGURT WITH Live culture
LIVE CULTURE survives digestion
Live cultures in both yogurts and probiotic
supplements are carefully selected and tested to in the stomach
ensure they do survive the acidic conditions of
our stomach. Some supplements are even coated STOMACH
in substances that protect them until they reach
the alkaline conditions of the small intestine.

Probiotic foods PROBIOTIC BENEFICIAL EFFECTS
IN YOGURT
Probiotic (pro meaning “for,” biotic meaning Lactobacillus Studies suggest it may reduce the risk of developing
“life”) are bacteria that, when eaten, can live rhamnosus allergies, aid in weight loss in obese women, treat
on in our gut and become part of our gut Lactococcus severe gastroenteritis in children, and reduce risk
flora—a community of beneficial microbes lactis of rhinovirus infections in unborn infants.
(see p.25). Some bacteria in yogurt, such as Lactobacillus
bifidobacteria (also present in the infant gut plantarum Studies suggest that this species may aid in treatment
and gained from breast milk), Lactobacillus Lactobacillus of antibiotic-associated diarrhea, produce an
fermentum, L. casei, and L. acidophilus, all acidophilus antibacterial and potentially anti-tumor compound,
colonize the human gut, helping to suppress Bifidobacterium and protect against an infection that causes diarrhea.
bad bacteria by outcompeting them and bifidum
making the gut environment unfavorable Bifidobacterium Studies suggest it may prevent endotoxin (toxins in
for them, shielding the intestinal wall, and animalis lactis bacteria) production, has antifungal properties, and
producing antibiotics. They also suppress can reduce symptoms of irritable bowel syndrome.
immunity and reduce inflammation, help
to reduce cholesterol (see p.25), and even This is commonly used against common causes of
suppress carcinogens. travelers’ diarrhea. Studies suggest it may help reduce
the hospital stay of children with severe diarrhea and
THE 100 TRILLION shows antifungal properties.
BACTERIA IN YOUR
GUT OUTNUMBER This is one of the first bacteria to colonize the infant
THE CELLS OF YOUR gut after delivery. Studies suggest it may reduce the
BODY BY 10 TO 1 hospital stay of children with severe diarrhea; and it
helps with reducing cholesterol levels.

Studies suggest this strain may help treat a type of
constipation in adults, reduce microbes in dental
plaque, reduce the risk of upper respiratory illness,
and reduce total cholesterol.

TRAVELING LIVE CULTURES KEFIR GRAINS

Kefir is a mildly alcoholic, yogurtlike drink made from fermented
milk in eastern Europe, the Caucasus, and other regions. It is
made using remarkable cultures known as “grains” (but they are
not grains), which look like small cauliflower florets and combine
live microbes with dairy proteins, fats, and sugars. These have
been passed down through families and communities, and
carried great distances by migrants. Starter cultures for many
other traditional dairy fermentations have similarly been carried
by migrants to new homes across the world.

Cheese MILK

A single form of processing can

lead to an astonishing profusion of

products, as with the transformation ACID AND HEAT

of milk into cheese. Cheese can take RENNETRAenNneDt (CanULTURE In cheeses like
thousands of forms, from soft and paneer and queso
sinuous to rock hard and pungent. enzyme produced in fresco, rennet and
calves’ stomachs) and cultures are not used.
How cheese is made starter bacteria are added. Instead, acid and heat are
They act on the milk’s used to coagulate the milk.
Milk has a short shelf life. Turning it into casein protein, curdling it. D
S
cheese is a way of concentrating and

preserving its nutritious value, mainly by

removing water that supports spoilage CURDS Queso fresco
microbes. Curdling the milk makes it
possible to remove much of its water, When casein
while salting and acidifying the pressed protein molecules have their
curds helps preserve them further. The ends clipped by the enzymes in
result is a solid mix of protein and fat, rennet, they can bond to one another
with milk and microbe enzymes roped in and coagulate, trapping water and fat
droplets in a mesh to give a gel, known as curds.

to break down the contents into flavor- Curdling WATERY Casein proteins
filled fragments. is driven WHEY in milk are
by the active the only ones
THERE ARE AT LEAST enzymes acted on by
400 COMPOUNDS in rennet the enzymes

THAT CAN AFFECT BRINED SOLID CURD WASHMEDedAiumN-DorPRESSE
THE FLAVOUR
OF CHEESE Salt inhibits the semi-hard cheeses like
microbes that cause Edam and Gouda are made
Variety of cheese spoilage, firms protein by washing curds in water to
The type of cheese produced from milk depends on structure, and adds flavor. remove acidity and calcium,
how it is processed; the use and degree of pressing, Brining the whole cheese then pressing or “knitting”
drying, washing, or cooking; whether mold is added, produces cheese such as
and length of aging. The protein and fat content of them together.
the milk itself (and the animal it came from) also feta or halloumi.
determine the kinds of cheese that it can become.

Halloumi Edam

DOES CHEESE STRETCHED MICROBES HEATED
GIVE YOU NIGHTMARES?
Curds soaked Microbes are For harder
There is no hard evidence in hot water, then added at different cheeses more of the
that this is true, but high fat stretched by kneading and stages in cheese watery whey is forced out
content meals can disturb pulling, produce a fibrous or production, depending on of the curds by heating.
stringy cheese. Some, like the desired outcome. The longer it lasts, the
digestion and thus sleep, mozarella, are eaten fresh.
which might lead to a higher drier the cheese.
Mozzarella
chance of remembering EDDARHEaDrdA, dNryD PRES
dreams. AGED
cheeses are made by
GRASS-FED CHEESE Ripening or CH cutting curd into small SED
affinage of a cheese loaves that are stacked,
Grass-fed cheese is made with milk from is an art of its own.
cows fed only on grass. It is naturally rich Provolone is aged after milled, and pressed
in vitamin K and calcium, and higher in stretching to develop (“cheddaring”).
conjugated linoleic acid—a type of fatty
acid associated with a wide variety of its flavor.
health benefits, including immune and
inflammatory system support, improved Provolone Red TYPES OF FOOD
bone mass, improved blood sugar Cheese
regulation, reduced body fat, reduced SURFACE RIPENED INTERNALLY RIPENELDeicester
risk of heart attack, and maintenance
of lean body mass. Working inward Blue molds
from the cheese surface such as Penicillium
VITAMIN K FATTY where they form a rind, white roqueforti grow in small cavities
CALCIUM ACID molds such as Penicillium in the cheese, produced by
camemberti break down proteins piercing. They break down milk fats
and cause calcium phosphate ions into shorter molecules, to produce 88 89
to migrate from the center, distinctive blue-cheese flavors.
liquefying the cheese. Pierced cheese

Rind

Camembert Stilton

Starchy foods

Although they can be rather tasteless and bland, starchy foods,
such as potatoes, yams, rice, wheat, and pulses, are a primary
staple of most people’s diets, providing a large proportion of energy
requirements as well as other nutrients, such as protein and fiber.

Types of starchy foods What is starch?

Starch is used by plants to store energy, either in Starch is a carbohydrate formed from long chains
the plant cells themselves for short-term storage, of identical glucose units linked together. There are
or in roots, tubers, fruits, or seeds for long-term two types of starch: amylose, made of straight chains
storage. It is these long-term stores that are the of glucose molecules, and amylopectin, made of
starchy foods we are familiar with—potatoes and branching chains. The relative proportions of amylose
rice, for example. However, starchy foods also and amylopectin in a starchy food affects how quickly
include processed foods, such as flour, bread, it is digested and, therefore, its glycemic index.
noodles, and pasta. Most authorities recommend
that starchy foods make up the main source of Straight chain Branched chain
carbohydrate in our diets. of glucose of glucose

Rice is the seed
of a grass

AMYLOSE AMYLOPECTIN

LONG-GRAIN RIC The potato plant is a POTATO
type of nightshade

E

AMYLOPECTIN AMYLOPECTIN
80% 79%

AMYLOSE AMYLOSE
20% 21%

Grains Tubers
Rice, wheat, oats, barley, and Potatoes, yams, sweet potatoes,
other grains are high in starch, and other tuberous vegetables
especially when the parts with get their distinctive cooked
more fiber and protein—the textures from their starch
germ and bran—are removed. granules. When raw, the starch
Grain starches typically consist is packed into hard granules,
of 15–28 percent amylose, but when heated, the granules
although short-grain rice has soak up water, swell, and turn
almost none, which is why it into a gel, giving a tender but
becomes sticky when cooked. dry texture.

TYPES OF FOOD 90 91
Starchy foods

BLOOD GLUCOSE LEVEL HIGH GI Blood glucose rises Glycemic index
and falls dramatically
Glycemic index (GI) is a measure of how quickly
Blood glucose a carbohydrate-containing food raises your blood
rises steadily but sugar level when that food is eaten by itself.
remains low Carbohydrates that are digested quickly and cause
a rapid increase have a high GI; examples include
LOW GI sugar and starchy foods with a lot of amylopectin,
such as potatoes and white rice. Amylopectin is
HOURS 1 2 more easily digested than amylose, as it has more
chain ends for enzymes to work on. But a food’s
Blood glucose levels GI by itself is not a good indicator of whether that
Foods with a high glycemic index (GI) produce a large, rapid rise food is healthy; for example, chips have a lower GI
in blood sugar followed by a similarly rapid fall, leaving us feeling than boiled potatoes but are very high in fat.
hungry. Low GI foods do not cause this “sugar spike,” but produce
a slower, smaller increase, followed by a gradual decrease.

GLOBALLY, EACH In botanical terms,
PERSON EATS AN bananas are berries
AVERAGE OF 73LB (33KG)
OF POTATOES A YEAR BANANA

Peas are the fruits PEAS
of the annual plant
Pisum sativum

AMYLOPECTIN AMYLOPECTIN
66% 70–75%

AMYLOSE AMYLOSE
33% 25–30%

Legumes and pulses Fruit
Peas, beans, and pulses tend to Designed to attract animals that
have a higher proportion of amylose will spread the seeds, fruits build
in their starch content than other up starch stores, which break
starchy foods. Amylose is smaller down into sugars when the fruit
than amylopectin so the individual ripens. A dramatic example is
amylose chains can pack more tightly the banana (though commercial
than amylopectin chains can. As a varieties do not have seeds).
result, more cooking is needed to It changes from 70–80 percent
separate the chains and soften starch when green to less than
these vegetables. 1 percent starch when ripe.

Grains MINERALS PHYTOCH

Grains are the most important food Bran EMICALS
group globally in terms of supplying An outer coating of tough,
calories and nutrients for the majority fibrous material, the bran is rich FIBER
of the world’s population. in fiber, minerals, B vitamins, and
phenolic phytochemicals (which
Types of grain
form part of the seed’s
Also known as cereals, grains are the edible defense system).
seeds of plants of the grass family. The
grains we eat most commonly, either by B VITAMI MINS NS
themselves or as ingredients in other
foods, are rice, wheat, corn, oats, ENDOSPERM BRAN PROTEIN CARBOHY
barley, rye, and millet. Amaranth,
buckwheat, and quinoa are also Endosperm DRATE
commonly thought of as grains, The endosperm, or kernel,
although botanically they of a grain is rich in starch, and FATS
are not related to true significant amounts of proteins,
grains. Nutritionally, fats, and B vitamins, although the
all of them are high in amounts vary according to the
carbohydrate, much
of it as complex, slow- type of grain.
release starches.
B VITA
Anatomy of a grain
Grains are seeds, designed GERM
to protect and nurture embryonic
plants. They consist of three main MINERALS PHYTOCH
elements: the germ (the plant
embryo), the endosperm (the EMICALS
energy store), and the bran (the
protective outer layer). Many of
the most valuable nutrients are
in the germ and bran, which are
removed during refining.

WHOLE GRAIN VS. REFINED GRAIN Germ
The germ is the most
Whole grains contain all parts Endosperm Endosperm nutritionally rich and flavorful PROTEINS
of the grain. Refined grains, Bran part of a grain, containing large
Germ amounts of fats, proteins, vitamins,
minerals, and phytochemicals.
REFINED GRAIN
such as white rice and white B VITAMIN

flour, have had the bran and

germ removed. Refining may also S VITAMIN A
FATS
involve bleaching to make the

grain whiter. After refining, grains

may be enriched to add back

nutrients previously removed. WHOLE GRAIN

TYPES OF FOOD 92 93
Grains

100,000 ENERGY SOURCE

THE NUMBER OF DISTINCT Globally, we get far more of our
VARIETIES OF RICE calories from grains than from any
other type of food: overall, they
Types of rice provide more than half of the total
calories we humans eat. Around 60
Rice is the largest source of calories for humans worldwide. On percent of the calories eaten by people
average, it contributes about 21 percent of the total calorie intake in developing countries come directly
of every person on the planet, although there are large regional from grains. In the developed world,
variations. For example, in southeast Asian countries such as the figure is about 30 percent,
Vietnam and Cambodia, rice provides up to 80 percent of the although many more of the total
calories eaten by each person. There are two main subspecies: calories consumed come indirectly
japonica and indica, with javanica being a subtype of japonica. from grains via the feed eaten by
animals we then eat.

Oils, fats, sugars Other foods Grains
19.1%
2.8% 51%

Japonica Indica Javanica Roots and Fruits, vegetables, Meat, fish,
Originating in China Long-grain indica rice Grown mainly in tubers pulses, nuts 8.2% milk, eggs
but now grown in many is grown in lowland highland tropical zones 5.3% 13.5%
temperate and subtropical tropical and subtropical in Indonesia and the
regions, japonica rice is regions. It has a high Philippines, javanica rice,
short-grain and has a low amylose content so like japonica, has a low
amylose content (see p.90). takes longer to cook. amylose content.

Nutrient content of grains WHITE RICE Carbohydrate 80%
7% 65%
Overall, whole grains are a good source of calories,
carbohydrates, fiber, proteins, B vitamins, and AMARANTH Protein
phytochemicals. Most grains contain about 70–75 0.7%
percent carbohydrate, 4–18 percent fiber, 10–15
percent protein, and 1–5 percent fat. However, Fat
there is a lot of variation between the different
grains in their specific nutrient content, as shown Carbohydrate
by white rice and amaranth. 14%

Amaranth vs white rice Protein
Compared with most other grains, amaranth 7%
contains relatively little carbohydrate but
lots of fat, whereas white rice is high in Fat
carbohydrate and low in fat.

Bread Unleavened bread

Consisting at its most basic of a cooked Developed before leavening, and still popular
mixture of flour and water—often with in many forms today, unleavened breads were
salt added, and sometimes with yeast a natural development of the use of cereals to
or a raising agent, such as baking make porridge or grain mash. They were made
soda—bread is one of the oldest types simply by baking the porridge or mash without
of prepared food and remains an using any raising agents, producing a flat bread.
important staple even today.
UNLEAVENED BREAD ORIGIN
Making leavened bread Tortilla Latin America
Johnnycake North America
Leavened bread is made with a raising agent—most Souri North Africa
commonly yeast—that causes the dough to develop Pita Greece
bubbles of gas, expand, and rise. Mixing flour and Baladi Egypt
water causes proteins in the flour to form a network of Bouri Saudi Arabia
gluten (see pp.98–99) in the dough. The yeast ferments Matzoh Middle East
the starch and sugars in the dough into alcohol and Lavash Middle East
carbon dioxide gas, which gets trapped in the gluten Chapati India
network. When the fermented dough is baked, the heat Roti India
drives off the alcohol and carbon dioxide, leaving the
familar spongelike structure of bread.

Salt Gluten proteins Air bubble Strengthened
STARCH gluten network

STARCH ENZYME

Loose MALTOSE
network
of gluten 1 Mixing ingredients 2 Kneading the dough
proteins Flour, water, salt, and yeast are mixed to form Kneading the dough makes the gluten

dough. When mixed with water, the gluten proteins in network stronger. It also incorporates air into
the flour form a loose network. The starch in the flour is
broken down to maltose (a sugar) by enzymes in the flour. the dough, producing small bubbles that get
trapped in the gluten network.

TYPES OF FOOD 94 95
Bread

Sourdough bread Wild yeast DON’T BURN IT!

The first leavened breads were Bacteria Acrylamide is a cancer-causing
probably sourdoughs—breads process chemical produced when bread
made with a starter culture maltose and other starchy foods, such as
consisting of wild yeasts and potatoes, are cooked at high
specific bacteria. The wild yeasts SOURDOUGH temperature and start to brown.
cannot process the maltose sugar CULTURE The amount of acrylamide can be
in the dough; this is done instead minimized by cooking food to the
by the bacteria, which produce Commercially lightest acceptable color.
lactic acid as a byproduct. As a cultured yeast
result, the bread has a slightly BURNED
acidic, sour flavor, but it is can process TOAST
generally more flavorful, denser, maltose
and longer lasting than other
types of leavened bread. YEAST
CULTURE

THE FIRST PRESLICED, WRAPPED
BREAD WAS PRODUCED IN 1928,
BY US INVENTOR OTTO
ROHWEDDER

Alcohol evaporated Gas bubbles
out by heat of baking expand

MALTOSE ALCOHOL Sugar combines
with protein

CRUST

GLUCOSE

YEAST

Yeast “burns” Amino acids
glucose recombine to create
new protein chain

CARBON
DIOXIDE

3 Fermenting 4 Baking
After kneading, the dough is left to ferment. Baking causes the alcohol to evaporate,
In this process, the yeast produces enzymes that
convert the maltose sugar into the simpler sugar, drives off the carbon dioxide, and causes the
bubbles to expand and interlock, forming a
glucose. The yeast then “burns” this glucose for spongy texture. On the surface, Maillard
energy, producing carbon dioxide gas and alcohol.
The gas helps to enlarge the air bubbles in the reactions occur (see p.63), combining amino
acids and sugars to form a brown crust.
dough, making it rise.

Noodles SHOULD I COOK MY
and pasta PASTA AL DENTE?
Pasta cooked al dente—firm to
Noodles have a long history in east Asia, where the bite—is broken down in the
they are a staple food in many countries. Pasta, body more slowly than pasta
a specific type of noodle, is a traditional Italian cooked until it is soft. As a result,
staple but has become popular worldwide. it releases sugar more slowly
and so has a lower glycemic
What is the difference? NOODLES index, which may reduce
spikes in blood sugar.
Noodles—sheets, ribbons, and other shapes
of cooked dough—may be made from various PASTA
flours. The flour is mixed with water, eggs, or
both to create the dough, which is then shaped
and cooked. Pasta is a type of wheat noodle
made specifically from durum wheat flour,
which can be made into complex shapes
because of its high gluten content (see p.98).

Flour varieties BUCKWHEAT RICE FLOUR MUNG BEAN DURUM WHEAT
Many types of flour are FLOUR FLOUR FLOUR
used to make noodles,
including flour from
unusual sources, such as
roots of the kudzu plant,
mung beans, and corms
of the konjac plant (all
native to Asia). Of the
types shown here, all
are gluten-free except
for wheat and durum
wheat flour.

POTATO FLOUR KUDZU FLOUR KONJAC FLOUR WHEAT FLOUR

How instant 1 Preparing dough 2 Cooking and cooling 3 Dehydrating
noodles are made Flour, water, salt, and The raw noodles are Water is removed
cooked by steaming for a
The key stage in making kansui (an alkaline liquid) are few minutes, then cooled by air drying or frying
instant noodles is the middle kneaded to make dough, which is and the resulting instant
one. Cooking then cooling rolled then cut into thin noodles. to harden them. noodles are then packaged.
raw noodles makes them
more absorbent than Sheet Noodles being Instant
normal noodles. This of dough steamed noodles
means that they retain
more water and so have a Raw
shorter cooking time when noodles
being prepared for eating.

TYPES OF FOOD 96 97
Noodles and pasta
ORATIVE
LONG
RIBBON DEC
T CUTSPAGHETTI

FARFALLE

CONCHIGLIE VERMICELLI
ANGEL HAIR
RUOTE Pasta shapes
RADIATORI FUSILLI
Pasta shapes and patterns
FETTUCCINI combine aesthetics, function, CANELLONI
and culture. Some shapes and

types are associated with
specific regions, such as penne
with Campania in southern Italy,

and farfalle with Lombardy in
northwest Italy. Some shapes

are particularly suitable for
holding sauces: shell-shaped

conchiglie, for instance, are
good for thick meat or
cream sauces and can
even be stuffed.

TAGLIATELLE MACARONI

LINGUINI

LASAGNE PENNE RIGATONI

SHOR

BRONZE-DIE PASTA Bronze die 15.8

Pasta shapes are made by Rough-surfaced MILLION TONS (14.3
pressing the dough through pasta shape MILLION METRIC TONS)
perforated plates called dies. OF PASTA ARE PRODUCED
Dies made of bronze are WORLDWIDE EVERY YEAR
prized because they have a
rough surface that imparts a
coarseness to the pasta that
is good for holding sauces;
bronze-die pasta also
cooks more quickly.

Gluten GLIADIN
MOLECULE
Found in many grains, including
wheat, gluten is a vital ingredient in
a huge range of breads, pasta, and other
dough products. However, some people
are sensitive to gluten and suffer health
problems when they eat it.

What is gluten?

Gluten is an enormous composite protein—the largest
known—that consists of a strong, stretchy mesh of
smaller proteins linked by molecular bonds. These smaller
proteins are glutenin, which has a long, chainlike shape,
and gliadins, which are shorter and round. The glutenin
is what gives gluten its elasticity, whereas the gliadins
give it strength. It is this combination of stretchiness and
strength, together with its meshlike structure that can
trap bubbles of gas, that makes gluten important in
bread-making (see pp.94–95).
GLUTEN
IS THERE GLUTEN- LEIN MOLECU Glutenin
FREE WHEAT? molecules
STRETCHED GLUTEN can uncoil if
No, all wheat contains gluten. stretched,
However, there is a type of giving gluten
its stretchiness
wheat starch that is gluten-free.
It is made by thoroughly Molecular bond forms
washing wheat flour between gliadin and
with water to remove glutenin molecules,
the gluten. helping to create
a molecular mesh
MOLECULAR
BOND

Structure of gluten
Gluten is a resilient, rubbery substance that
forms when glutenin and gliadin molecules in
flour are mixed with water; this happens when
making dough, for example. The molecules
bond together to form a mesh that can trap
bubbles of gas—as occurs when dough is
kneaded. Because the mesh is stretchy, the
gas bubbles can expand without breaking it.