029_HANDB OF FRUITS_AND PROSESSING_2006_688

9 Food Additives in Fruit Processing 165

Table 9.8. Classification of Hydrocolloids

Type of Sources Food Applications
No. Hydrocolloid Functions Potato, cereals tapioca, and
Pie fillings
1. Unmodified Thickener arrow root Jams and jellies
Products of chemical
starch Gelling, adhesive, and Pie fillings
modification of natural Canned fruits
film former polysaccharides Fruit-based desserts

2. Modified Bodying and gelling Milk Edible films for
starch Improvement of viscosity packaging of
precut fruits and
and other rheological vegetables
parameters
Thermal resistance Beverages
against higher as well Water-based frozen
as lower temperatures
Modification in gelling fruit desserts
To improve solubility and Beverages
gelling in cold water Emulsifier for citrus

3. Casein Film former with cohesive oils and flavors
and adhesive properties Frozen desserts
Structured fruits
4. Guar gum Stabilizer Guar beans Jams and jellies
Beverages
5. Gum Arabic Stabilizer Exudate from genus Acacia Fruit bars
Emulsifier Fruit snacks and
Irish moss
6. Carrageenan Gelation Fruit wastes desserts
Beverages
7. Pectin Gelation Puddings
Texturization as binder Dry mixes of
Stabilizer
beverages
8. Xanthan gum Stabilizer Fermentation product from Dry drink mixes
Gelation Xanthomonas Fruit-flavored syrups
comprestris
9. Carboxy Thickener
methyl Stabilizer Modified cellulose
cellulose

substances (CDR 121.172.580-CDR121.172.874). lipophilic as well as hydrophilic groups enabling the
Their safety has been promulgated by JECFA and products to bring together the water and oil moieties
EEC. without phase separation.

EMULSIFIERS Apart from phase separation, the other functions
of food emulsifiers are to enhance stability in flavors
Emulsions are necessary for obtaining homogeneity and fats and oils by restricting the onset of rancid-
in liquid foods having a tendency toward phase sep- ity. Emulsions are also used for better crumb texture
aration during processing/storage. Emulsifiers have in baked products due to optimal starch complex-
ing property (Thompson and Buddemeyer, 1954).

166 Part I: Processing Technology

Usually except lecithin most of the emulsifiers are obtain higher juice yields and clarity. The turbid-
used in combinations. The important emulsifiers used ity/cloudiness of fresh fruit juices can be decreased
widely are as follows: with pectinase treatment due to the removal of nega-
r Mono- and diglycerides tively charged pectin deposits on particulate matter,
r Acetylated monoglycerides which ultimately results in the coagulation of turbid-
r Sucrose fatty acid esters ity causing materials (Yamasaki et al., 1967). Enzy-
r Stearoyl-2-lactylates matic treatment of soft fruit pulp facilitates pressing
r Propylene glycol esters and improves juices and anthocyanin pigment yields
r Sorbitan esters (Neubeck, 1975). Pectin degrading enzymes are also
r Diacetyl tartaric acid esters of monoglycerides used to degrade highly esterified apple pectin and
increase juice yields (Devos and Pilnik, 1973). Amy-
(DATEM) lases are often used along with pectinases to clarify
juices such as banana to obtain optimal juice yields.
FDA permits lecithin, mono- and diglycerides, and Similarly, application of cellulases also facilitates
DATEM as GRAS. The other emulsifiers are ap- higher recovery of juices due to the degradation of
proved under the standards of identity at specific cellulosic matrix. Cellulases are also used for waste
levels. In fruit products, emulsifiers find applica- treatments from fruit processing units for the devel-
tions in flavor emulsions, beverages, pie fillings, fruit opment of value-added products. Glucose oxidase in
desserts, and salad dressings (Mahungu and Artz, combination with catalase is used to protect citrus
2002). juices from off-flavor development (Scott, 1975) and
in the prevention of enzymatic browning in frozen
ENZYMES fruits (Somogyi, 1996).

Enzymes are biological catalysts and proteinaceous As far as the regulatory aspects are concerned,
in nature. The use of enzymes in food processing enzymes are considered as direct food additive as
in general and in fruit industries in particular is an per FDA. The source organisms play an important
offshoot of advances in fermentation/biotechnology. role in the affirmation of GRAS status. Pectinases
Enzymes, which exist within the fruits, perform a as well as glucose oxidase derived from Aspergillus
number of functions such as softening, flavor devel- niger are considered as GRAS. Same holds good with
opment, ethylene biosynthesis, etc. Vegetables and ␣-amylase and cellulase derived from A. niger.
fruits are also rich in oxidases, a class of enzymes,
such as PPO and peroxidase, which cause browning VITAMINS
reaction and off-flavor development, which is detri-
mental to the fruit quality (Whitaker, 1996). Vitamins occupy an important place in nutrition and
participate in a variety of biological processes. Fruits
In case of fruit processing, enzymes are used are rich sources of both water-soluble as well as fat-
mainly as processing aids aimed at specific functions, soluble vitamins. Vitamin A precursors in the form of
such as: carotenoids are available in significant proportions in
r improvement in juice extraction yields several fruits. On the other hand, fruits are also rich
r increment in solids recovery sources of vitamin C. Certain fruits, i.e., seabuck-
r improvement in filtration thorn is known to be a good source of vitamin E.
r removal of nonnutritional factors Apart from this, vitamins are usually used as sup-
r flavor enhancement plements. The supplements may be directed toward
r viscosity modifications compensating the processing losses. The processing
r anticlouding operations loss of water-soluble vitamins is significant and sup-
r antifouling operations for membrane plementation is required to maintain the nutritional
balance. Thermally processed fruit extracts need such
concentrations. supplementations due to heavier loss of vitamins dur-
ing heat processing as well as subsequent storage of
Enzymes of commercial importance used in fruit the product (Kanner et al., 1982).
processing are (a) pectinases, (b) cellulases, (c)
amylases, and (d) glucose oxidase. Pectic enzymes, Apart from supplementation, vitamins also have
i.e., pectin methylesterase and polygalacturonase are certain functional properties. Vitamin C is widely
used often in combination with amylases and cel- used as ascorbic acid in dextro- or levo-rotatory forms
lulases in fruit and vegetable juice clarifications to

9 Food Additives in Fruit Processing 167

as a natural antioxidant. Vitamin E (tocopherols) is immunological/physiological hazards. The typical
also known as a potential antioxidant. Ascorbic acid symptoms of health-based hazards include hypersen-
on oxidation can inhibit PPO activity by restrict- sitivity and associated allergic reactions. The allergic
ing the availability of molecular oxygen required for reactions may cause respiratory problems such as
the reaction. Fruit processing unit operations such as asthma. The cross reactions of sulfites and steroid
blanching, thermal processing, and freezing consid- dependency in asthma patients have given rise to
erably reduce vitamin C content. The storage losses novel debates and amendments in regulations, which
add to the processing losses, demanding necessary ultimately resulted in the ban of sulfites in ready-
supplementation (Kacem et al., 1987). The other to-eat fruit- and vegetable-based products (Anon,
functionalities include use of riboflavin-5-phosphate 1990).
as a colorant.
Toxicological research continues to throw light on
The FDA considers vitamins as GRAS and nutri- implications of chemical toxicity hitherto unknown.
tional supplements. Pantothenate is allowed as a food Colorants, antimicrobial compounds, antioxidants,
additive and requires label-mediated expression with antibrowning agents, and sweeteners continue to re-
regards to the concentration used. Some of the com- ceive regulatory restrictions. The advent of functional
mercial forms are marketed as follows: foods, dietary supplements, and transgenic products
offer plethora of challenges to ensure safety to the
r vitamin A as vitamin A acetate; consumers. Food sector is basically a buyers mar-
r thiamine as thiamine hydrochloride; ket, and it is important to keep the “psyche” of the
r pantothenic acid as calcium pantothenate; consumer in a satisfaction mode. Mere toxicologi-
r pyridoxin as pyridoxine hydrochloride; cal certification may not necessarily satisfy the con-
r ascorbic acid as ascorbic acid, calcium ascorbate, sumer. The regulatory authorities, therefore, are strik-
ing a fine balance between consumer safety and the
sodium ascorbate; and manufacturer’s product requirements to keep up op-
r vitamin E as tocopherol acetate, DL-␣-tocopherol. timal quality and commercial feasibility (Branen and
Haggerty, 2002).
SAFETY AND HEALTH
IMPLICATIONS OF FOOD Labeling is being optimally used to overcome
ADDITIVES many problems and at the same time keeps the con-
sumer aware of the compositions involved along with
The safety and health implications of food additives the statutory warnings, if any. The usefulness of ad-
are given utmost importance in framing the stan- vanced labeling can come a long way in bridging the
dards and regulatory measures. The FDA as well as gap among regulator, processor, and consumer.
Codex Alimentarius and other national and interna-
tional bodies stress on the need of ADI as a premier FUTURE TRENDS
aspect to restrict cytotoxicity-induced health hazards.
ADI limits are usually expressed in terms of chemi- The future trends in research and development as well
cal exposure of body on unit body weight basis and as in commercial application involving direct food
are based on authentic risk assessment (Winter and additives may be outlined as follows:
Francis, 1997).
1. Increased stress on natural preservatives, sweet-
The concept of ADI renders more flexibility to eners, colorants, and antioxidants.
maximum limits prescribed for various food cate-
gories with regards to standards of identity. Lowest 2. Minimal or no use of chemical additives with em-
observed effect level (LOEL) and no observed effect phasis on physical conditioning of the products.
level (NOEL) form the bases of risk assessment in
framing the ADI levels. ADI is the NOEL value di- 3. Advanced research on gene products for transgen-
vided by 100 when the NOEL is derived from animal ics and comprehensive studies on the health im-
studies or the NOEL value divided by 10 when the plications thereof.
NOEL relates to human data (Renwick, 1996).
4. Restriction in additive use by adopting hurdle-
The risks involved in overuse or underuse of ad- based processing.
ditives can give rise to several types of risks, i.e., (a)
microbial hazards, (b) nutritional hazards, (c) color 5. Labeling strategies to counter growing toxicolog-
additive hazards, (d) environmental hazards, and (e) ical concerns.

6. Consumer awareness and technical strategies to
prevent misuse of food additives.

168 Part I: Processing Technology

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Handbook of Fruits and Fruit Processing
Edited by Y. H. Hui

Copyright © 2006 by Blackwell Publishing

10
Fruit Processing Waste Management

Judit Monspart-Se´nyi

Introduction Environmental Information System
The Impact of Food Production on the Environment Institutional System
Social Participation
Food Industry as an Environmental Polluter International Cooperation
Biological and Economical Environment, Justifying Conclusions
References
Waste Management
Opportunities for Utilizing Food Industry Wastes and INTRODUCTION

By-products Since the middle of the 20th century environmen-
Utilization of By-products for Feeding tal pollution has increased, as a result of technologi-
The Role of Biomass in Waste Utilization cal development and an explosion in the population.
Evaluation of Waste Utilization Techniques Consequently, international, states, and civil organi-
zations joined forces to limit economic development
Wastes and By-products of Fruit Processing that contribute to environmental pollution—water,
Pollution Prevention and Control in Fruit Processing air, soil, and landscape—that endangers human life
Target Pollution Loads (Anon, 2003).
By-product Treatment and Utilization in the Case of
Certain Fruit-based Products The concept of “sustainable development” trig-
Some Example of Research Areas for the Utilization gers the interest of an increasing number of people
Opportunities of Fruit Processing By-products who pay attention to the environment not only in their
workplace but also in their homes.
By-Product Utilization in Apple Processing
What is Pectin? National leaders often refer to cooperation be-
Commercial Production tween the economic sector and the state as an
Application of Pectins essential requirement to success. Thus environmen-
By-products: Coloring and Noncoloring Sweetener tal protection and economic growth are closely re-
By-product: Fodder lated. Economic growth enables the implementation
Other Ways for Apple Pomace Processing of environmental protection. However, within the
(Fiber Utilization) framework of a market economy, economic growth
cannot be sustained without protection of the envi-
Environmental Guidelines for Fruit Processing ronment and the living world. Industry should op-
Waste Management erate in a more efficient way, producing more prod-
Process Description ucts with less input and waste. Moreover, customer
Fruit Waste Characteristics preferences should also be more sustainable (Vermes,
By-products are Produced During Many Steps of the 1998).
Fruit Production Chain
Key Environmental Risks/Liability Factors
Solid Waste Disposal
Refrigerants in Fruit Processing

Means of Modern Waste Management
Feasibility Strategic Principles
Issues of Environmental Policy, Planning,
and Regulation
Research and Technical Development

171

172 Part I: Processing Technology

THE IMPACT OF FOOD Huebner and Kienzle, 2001; Poonam-Nigam et al.,
PRODUCTION ON THE 2001).
ENVIRONMENT
However, because of differences in ownership and
Production and acquisition of food, which is nec- size of individual food industry companies (e.g., in-
essary to sustain life, is, at the same time, contin- creasing role of small and middle scale enterprises),
uously changing the environment. Traditional rural certain branches have different impacts on the envi-
production was environmentally friendly; closed sys- ronment (Woods, 1998).
tems were developed since farmers utilized the by-
products and wastes of food processing. There was a Some technological waste is of animal origin
dynamic balance between nature and humans: plants, (80%), which will not be included in this chap-
animals, and humans formed an ecological system. ter (Williams, 1995; Apellaniz et al., 1996; Anon,
2003). Technological waste of plant origin is usually
However, since the beginning of the industrial not considered dangerous. Wastes may be burned,
revolution, the emphasis of agricultural and in- used for animal feed, or used for human appli-
dustrial development has been on short-term eco- cations. However, there are some wastes of plant
nomic gains instead of ecological equilibrium (Anon, origin that are “dangerous” (Be´ke´si and Pa´ndi,
1996a). 2001)

Today, with improved technology there is more ef- r Asbestos and silica filters used by the beverage
ficient production with greater yields, consequently, industry
there is less attention given to the preservation of
natural resources and utilization of wastes and by- r “Blue precipitate” that is the result of “blue
products (Henningsson et al., 2004). clarification” in wine making (it can be used for
tartaric acid production, but this leads to sewage
Food Industry as an Environmental containing cyanide compounds and disposal is
Polluter still a problem)

Waste management, placement and disposal, are crit- Biological and Economical
ical aspects of food processing. The percentage of Environment, Justifying
by-products and wastes in food processing is 30% Waste Management
(Fehr et al., 2002; Anon, 2001; Tuncel et al., 1995).
The majority of food industry wastes and by-products Agricultural production and further processing can
(of plant origin) is used as animal feed (Adebowale, become one of the most serious sources of pollu-
1985). Only 2–3% is marketed for human use. Some tion (Di Blasi et al., 1997). Because of cheap en-
30% of all production waste are so-called dangerous ergy and raw materials following World War II, lit-
waste (mainly of animal origin), which requires spe- tle attention was given to utilizing by-products. An
cial treatment, for example, the disposal of sludge increase in the number of industrial plants in turn
resulting from sewage treatment (Pa´ndi, 2001). The increased the volume of by-products. Further treat-
food industry is not a heavy environmental pollut- ment and environmentally friendly disposal and dis-
ing industry. Production and packaging wastes are tribution were not the main interest of the industry.
significant, however, because of the size of the food This paradox could be handled by directing wastes
processing industry. The role of food industry is to back into production (Howitt, 1997). This is not a
convert agricultural raw materials of plant and animal new solution, since classic agricultural technology
origin to foodstuffs suitable for human consumption. also utilized by-products, e.g., the fodder industry
This process unavoidably results in wastes and by- used waste from vegetable oil production (Bulla,
products unfit for consumption. Food industry wastes 1994).
can be further classified as technological waste (some
of them are “dangerous”) and sludge and packaging The process is also influenced by economical
wastes. This chapter will deal only with fruit produc- conditions since the expense of converting waste
tion waste, since further processing can decrease the products into useable products will happen only if
burden to the environment. the expenses do not exceed the final selling price.
Such decisions can be supported by operations re-
The amount and ratio of waste depend on the given search to determine inaccurate economic value of
branch of the food industry (Di Blasi et al., 1997; by-products (Cheeseborough, 2000; Henningsson
et al., 2004).

10 Fruit Processing Waste Management 173

OPPORTUNITIES FOR In Europe, the BAT group is working to develop
UTILIZING FOOD INDUSTRY and distribute information on how to avoid pollution
WASTES AND BY-PRODUCTS when using production methods for various com-
mercial products. The aim is to further the utiliza-
Food industry wastes and by-products are geograph- tion of the BAT within selected fields (for exam-
ically scattered, of large volume and low nutritional ple in the field of fruit processing). The object is
value. Consequently, their collection, transportation, to reduce the burden on the environment as much
and processing costs of by-products can exceed the as possible. Due to the diversity of the fruit indus-
selling price. The real difference between the main try, examples of techniques and methods proven suc-
product and by-products is the level of profit. If we cessful in some cases are not necessarily applica-
could produce valuable products from food industry ble directly to other cases. Each technique should
waste through new scientific and technological meth- be assessed case by case, taking into consideration
ods, environmentally polluting by-products could be the age, the scale, and the geographic location of
converted into products with a higher economic value the processing plant, as well as the product port-
than the main product. folio and the type of process. The best strategy is
to establish a working environment, which means
The utility of raw materials—to what extent the defining policies, monitoring environmental impact
valuable components can be converted to the end of specific activity, and setting up goals to enhance
product—depends on the following factors: performance.

r Nature and quality of raw material The application of this principle contributes to de-
r Type, characteristics, and quality criteria of the creased quantity of waste and water consumption
and has several environmental advantages. Never-
finished product theless, the amount of food processing wastes and
r Technological process by-products—that are the most important issues of
r Technical level and condition of the machinery food processing environmental strategies—is signif-
r Human factors icant even if this principle is applied properly (Pere´di-
Va´sa´rhelyi, 2004).
The difference between the useful components of
the raw material and the end product is called the pro- Utilization of By-products
duction loss. The role of waste utilization is important for Feeding
in terms of environmental protection, too. Food in-
dustry wastes are usually organic substances and can Feed production has become a new industry. More
pollute our environment if not disposed prudently. and more plants are processing by-products as raw
All in all, food industry wastes and by-products are materials, many of which were not used in traditional
substances that originate from production and can feeding technologies. The finished products (feed)
be further utilized in other ways. For example, fruit thus produced can be full (value) mixtures or con-
wastes from cleaning and seeding are used for feed centrates to be mixed at local fodder-plants. Some-
without further treatment. times these products are patented and producers en-
close directions for use, which is usually controlled.
Solid and liquid food industry wastes and by- Factories preparing, producing, and using the feed
products possess long traditions. Although large- are interdependent and operate in a complex ecolog-
scale industry methods are not always efficient, the ical system that can build on agricultural and indus-
technical development of food companies conform trial production plants to utilize waste (Adebowale,
more and more to the BAT principle, applied in 1985).
Europe (Anon, 1996b). The term “BAT” (best avail-
able techniques) is defined in Article 2(11) of the EC There is no sharp distinction between the two alter-
Directive (Integrated Pollution Prevention and Con- natives as plants (e.g., forage mixers) processing for
trol) as “the most effective and advanced stage in only one company can be involved in production or
the development of activities and their methods of paid work. On the other hand, vertical integration can
operation which indicate the practical suitability of also establish complex systems. Disposition can be
particular techniques for providing in principle the the top priority in waste management in addition to
basis for emission limit values designed to prevent profitability (Subburamu et al., 1992).
and, where that is not practicable, generally to re-
duce emissions and the impact on the environment
as a whole.”

174 Part I: Processing Technology

The Role of Biomass in Waste r Concentrated or widely scattered origin?
Utilization r Seasonal or continuous availability?
r Quantity (large or small)?
Biomass production and utilization are of great im- r Concentration of valuable substances (high or
portance both in the short and the long run. Biomass
refers to all organisms (microorganisms, plants, and low)?
animals), both living and recently dead; products of
biotechnology-related industries; all biological prod- The ideal utilization choice is usually determined
ucts, wastes and by-products (human, animal, pro- by complex evaluation and short-run economical
cessing industry, etc.). Food industry production, analysis.
where the agricultural raw materials become food-
stuffs, is a primary source of biomass transformation According to international experiences, by-
(Hammond et al., 1996; Stabnikova et al., in press). product utilization and waste-free technologies are
most sophisticated in developed countries, where
Evaluating the potential of biomass production food production is also on a high level. In less devel-
and utilization and developing a system that in- oped countries the use of such technologies commen-
cludes relevant recommendations for practical ap- surate with the financial resources (Polpraser, 1996),
plications has been discussed in scientific litera- thus
ture (Mahadevaswamy and Venkataraman, 1990; r the easiest use for by-products of plant origin is
Viswanath et al., 1992; Bouallagui et al., 2004). Ani-
mal feeding is such a potential utilization. Mass feed plant fertilizer
production takes substantial amounts of land; how- r biogas production and burning combined with
ever, these areas could be used for plant production
for export, meanwhile by-products could be partially energy recovery are still not widespread
substituted for feed. The profitability of ruminant r the use of food industry by-products (bran, coarse
farming requires a cost decrease without a decline
in production. or oleaginous seeds, and feed yeast) as a feed
supplement is a cheap and simple procedure
Evaluation of Waste Utilization r by-products with high water content need to be
Techniques dried or concentrated prior to further processing
r primarily by-products, rich in protein, are used
The above enumeration expresses the value of uti- for feeding, and
lization procedures. The highest new values can be r human application is the most expensive, due to
obtained by the introduction of by-products in human high requirements for equipment and energy.
nutrition; meanwhile burning (if its energy is not uti- Fruit processing (e.g., pectin production) is a
lized) is primarily “waste elimination.” Primary con- good example to illustrate this kind of utilization
ditions for the introduction and implementation of
technologies selected for utilization are as follows: WASTES AND BY-PRODUCTS
r Preserving and storing by-products of different OF FRUIT PROCESSING

origins geographically. This means that they are The aim of fruit processing is to transform fresh fruits
decentralized. To gather them, distant transport is into preserved products. Therefore, the selection and
required. elimination of components unsuitable for human con-
r Reasonable solutions for transport. This means to sumption, lead to by-products and wastes. There is
achieve cost effectiveness. That is, the best traffic no sharp limit between the two categories as indus-
logistics for the minimum cost and the most tries processing substances of biological origin are
effective transportation technology. in close cooperation; the by-product of one industry
r Ensuring the space, building, machinery, can be a valuable secondary raw material for another.
equipment, energy, and personnel requirements of
processing. Apple processing is a good example for the afore-
mentioned principle. Although apples (canned ap-
Before making a decision to utilize by-products, ples, apple juice, etc.) are the finished product, and
an evaluation of the by-products should be made on the by-product, apple pomace, is the secondary raw
the following issues: material of pectin production. However, if this by-
product goes to the refuse, it becomes waste and pol-
lutes the environment. Generally, in Hungary as well
as the rest of the world, the majority (60–65%) of

10 Fruit Processing Waste Management 175

food industry by-products become waste and a bur- combined with recovery) (Prema Viswanath et al.,
den to the environment (Szenes, 1995). 1992; Mahadevaswamy and Venkataraman,
1990).
In order to meet stringent environmental require-
ments, modern fruit processing should minimize the Pollution Prevention and Control
amount of by-products and waste, decrease energy in Fruit Processing
utilization, produce high-quality foodstuffs without
polluting the soil, air, and spas (Barta et al., 1997). Reductions in wastewater volumes up to 95% have
been reported through implementation of good prac-
Fruit processing wastes differ from other wastes tices. Where possible, adopt the following measures:
r Use clean raw fruit, reducing the concentration of
r they are organic and therefore, decompose. Most
go back into the soil, due to natural biomass dirt and organics (including pesticides) in the
circulation, or decompose without pollution; effluent.
r Use dry methods such as vibration or air jets to
r they are large in volume with high water content. clean raw fruit. Dry peeling methods reduce the
In spite of the high volume their origin is effluent volume (up to 35%) and pollutant
scattered, making gathering and utilization concentration (organic load reduced up to 25%).
difficult and expensive; and r Separate and recirculate processed wastewaters.
r Use countercurrent systems where washing is
r they tend to deteriorate, thus limiting the storage necessary.
period, even under appropriate circumstances, r Use steam instead of hot water to reduce the
which include low temperatures, controlled quantity of wastewater to be treated.
humidity, and storage in dark and dry places. r Remove solid wastes without the use of water.
r Reuse concentrated wastewaters and solid wastes
Apart from the main finished product, unused sub- for production of by-products.
stances are considered as waste and by-products.
These can be utilized in different ways depending As an example, recirculation of processed water
on their texture and content. from fruit preparation reduces the organic load by
75% and water consumption by 95%. Similarly, the
Certain by-products can be valuable resources for liquid waste load (in terms of biochemical oxygen
human nutrition if special technologies are used. demand, BOD) from apple juice processing can be
They include reduced by 80%.

r precooling techniques (Brosnan and Sun, 2001) Good water management should be adopted, where
r solid-state production (Zheng and Shetty, 2000) feasible, to achieve the levels of consumption pre-
r Gas chromatic evaluation of residues (Pugliese sented in Table 10.1 (Anon, 1998).

et al., 2004) Target Pollution Loads
r the beneficial effects of grinding, soaking, and
Implementation of cleaner production processes
cooking on the degradation of dangerous matters and pollution prevention measures can yield both
in fruit waste (Tuncel et al., 1995)
r Others Table 10.1. Water Usage in the Fruit
Processing Industry
Some examples are
Product Category Water Use (cubic meters
r pectin from apple pomace per metric ton of product)
r aromas and coloring agents from fruit waste
r oils from seeds Canned fruit 2.5–4.0
r tartaric acid from wine lees Frozen fruit 5.0–6.0
Fruit juices
Also, further processing of by-products can trans- Jams 6.5
fer their valuable compounds into new products: Baby food 6.0
6.0–9.0
r Distillery wastes can be added to feed after Source: Anon, 1998.
appropriate treatment.

r Household and gardening wastes are utilized for
soil improvements.

r All organic by-products can be utilized in a
profitable way, if used for biogas production
(methane production) or burning (especially if

176 Part I: Processing Technology

Table 10.2. Target Loads Per Unit of Production, Fruit Processing Industry
Fruit

Product Waste Volume BOD (kg/U) Solid Waste
(m3/U) (kg/t product)

Apricots 29.0 15.0

Apples 90

All products 3.7 5.0

All except juice 5.4 6.4

Juice 2.9 2.0

Cranberries 5.8 2.8 10

Citrus 10.0 3.2

Sweet cherries 7.8 9.6

Sour cherries 12.0 17.0

Bing cherries 20.0 22.0

Dried fruit 13.0 12.0

Grapefruit

Canned 72.0 11.0

Pressed 1.6 1.9

Olives 38.0 44.0 20

Peaches 180

Canned 13.0 14.0

Frozen 5.4 12.0 200

Pears 12.0 21.0

Pineapples 13.0 10.0

Plums 5.0 4.1

Raisins 2.8 6.0

Strawberries 13.0 5.3 60

Source: Anon, 1998.

economic and environmental benefits. The target Solid Fruit Wastes
loads per unit of production are shown in Table 10.2
(Anon, 1998). The data refer to the waste loads aris- There are possible ways to use some solid fruit
ing from the production processes before the imple- wastes, which are discussed below. However, it is
mentation of pollution control measures. These levels stressed that a full financial evaluation should be done
are derived from the average loads recorded in a major before the implementation of any of the suggestions.
study of the industry and should be used as maximum
levels of unit pollution in the design of new plants. One major goal in using fruit wastes is to ensure
a reasonable microbiological quality in them. This
By-product Treatment and means that one should process waste products on the
Utilization in the Case of Certain same day that they become available. It is not ad-
Fruit-based Products visable to store wastes until the end of the week’s
production before processing them. Even with this
The processing of fruits produces two types of waste: precaution, the wastes being used will most likely
solid waste [e.g., peel/skin (Larrauri et al., 1997; Negi contain moldy fruit (discarded during processing),
et al., 2003; Ferna´ndez et al., 2004), seeds (Noguchi insects, leaves, stems, soils, etc. This will contami-
and Tanaka, 2004), and stones (Lussier et al., 1994)] nate any products derived from such wastes.
and liquid waste [juice (Gil et al., 2000) and wash
water]. A serious waste disposal problem can attract Therefore, some preliminary separation is needed
flies and rats in the processing room, if not corrected during processing, such as
properly. If there is no plan to use the waste products,
they should be buried or fed to animals in distant r peel and waste pulp in one bin
locations. r moldy parts, leaves, soil, etc in a second bin,

which may be discarded
r stones, seeds, etc., in a third bin

10 Fruit Processing Waste Management 177

Possible Products tain amount of experimentation is needed to establish
oil yields and suitability of the equipment. Solvent
The six main products from wastes include extraction is not recommended for small-scale appli-
cations. However, steam distillation of citrus peel oils
r candied peel is well established for small-scale operations.
r oils
r pectin The crude oil may be sold to be refined elsewhere,
r re-formed fruit pieces but it is likely that the producer is responsible for the
r enzymes initial refining.
r wine/vinegar
Pectin. This is a gelling agent used in jams and
Each is discussed below. some sweets and occurs in most fruits, ranging from a
low to a high level. Commercially, pectin is extracted
Candied Peel. Peel from citrus fruits (orange, from citrus peel and apple pomace, the residue left af-
lemon, and grapefruit) can be candied for use in, for ter apple juice has been removed. Other tropical fruits
example, baked goods and snack food. In addition, may contain high levels of pectin, passion fruit be-
shreds of peel are used in marmalades, similar to ing a notable example. The utilization of the “shells”
the process of candying. That is, boil the slices or remaining after pulp removal may permit pectin ex-
shreds of peel in a 20%-sugar syrup for 15–21 min traction.
and progressively increase the sugar concentration in
the syrup to 65–70 Brix (percentage of sugar moni- In most developing countries, pectin is imported
tored by a refractometer) during soaking of the food from Europe or United States. This may look like a
for 4–5 days. It is then removed, rinsed, and given a good market or opportunity for processors in these
final drying in the sun or in the hot air drier. This can countries to provide pectin locally to substitute for
serve as a secondary product for a fruit juice or jam imports. However, there are major problems:
processor. This assumes that a large food company is
interested in buying the candied peel as an ingredient r In countries where this has been tried, it has not
for their products. In one application, candied melon been possible to produce pectin at a cost lower
skin has been used to substitute for sultanas in baked than that for imported products.
goods and, in another, candied root vegetables have
found a similar market. r It is difficult to produce pectin powder on a small
scale, although liquid pectin is possible.
Oils. The stones of some fruits (e.g., mango, apri-
cot, and peach) contain appreciable quantities of oil r There are many types of pectin, each with specific
or fat, some of which have specialized markets for properties suitable for a particular application.
culinary or perfumery/toiletry applications. Palm ker- For example, pectin for jams as a preserve differs
nel oil is well known as a cooking and industrial oil. from that used in jam as an ingredient in baked
In addition, some seeds (e.g., grape, papaya, and pas- goods.
sion fruit) contain oil with a specialized market. Of
course, for any commercial product in any country, Re-formed Fruit Pieces. Fruit pulp can be recov-
the goal is to identify the import/export agents in- ered and formed into fruit pieces. Although the pro-
terested in such products. After that, the processor’s cess is relatively simple, the demand for this product
responsibility is to produce the oil to satisfy the cus- is low. Therefore, a thorough evaluation of the poten-
tomer in terms of sufficient quantity and stringent tial market is recommended before investing in the
quality standards. Obviously, the manufacturer has enterprise (Kilham, 1997).
to secure proper equipment to produce the oils at a
reasonable cost. The process involves preparing a concentrate by
boiling the fruit pulp, followed by sterilization. Sugar
The process involves grinding the seeds and nuts may also be added. A gelling agent, sodium alginate,
to release the oil without a significant rise in temper- is then combined with the cooled pulp and then mixed
ature, which would spoil their delicate flavors, with with a strong solution of calcium chloride. All ingre-
the exception of palm kernel oil. Generally, a powered dients are safe for human consumption, being legal
hammer mill is needed for nut and kernels. A press food additives in most countries. The calcium and
is needed to extract the oil. Since the existing manual the alginate combine to form a solid gel structure and
presses have not been tried for this application, a cer- the pulp can therefore be re-formed into fruit pieces.
The most common way is to pour the mixture into
fruit-shaped moulds and allow it to set.

178 Part I: Processing Technology

It is also possible to allow drops of the fruit/alginate r an assessment of the economics of production
mixture to fall into a bath of calcium chloride solu- r a basic familiarity with the production technique
tion where they form small grains of re-formed fruit, r a reasonable capital investment in equipment
which can be used in baked goods. Commercially, the r a fairly large amount of waste available to make
most common product of this type is glaced cherries.
utilization or harvesting worthwhile
Enzymes. Commercially, the three most important
enzymes from fruit are papain (from papaya), brome- For small-scale operations, where reducing pollu-
lain (from pineapple), and ficin (from figs). Each is a tion or increasing waste disposal is more important
protein-degrading enzyme used in such applications than process economics, the most likely solution is
as meat tenderizers, and washing powders and is also to use wastes as animal feeds.
used in leather tanning and beer brewing. However,
it is unlikely to be economical to harvest these en- Some Example of Research Areas for
zymes from fruit processing waste. Currently, even the Utilization Opportunities of
the more efficient process of collecting enzymes from Fruit Processing By-products
fresh whole fruit is no longer economical. Changes
in both large-scale production with higher quality Several valuable substances—fibers, coloring agents,
standards and use of biotechnology to produce “syn- gelling agents—can be extracted from the wastes of
thetic” enzymes mean that small-scale producers will fruit-based products. The way and goal of utilization
be unlikely to compete effectively. In addition, there is determined by the economic efficiency of extrac-
are proposals to phase out the use of these enzymes tion and the market potential. It is not easy to collect
in food products in Europe and United States. Their data about the quantity of fruit waste and widespread
market is therefore declining. Consequently, it is not treatment techniques.
cost effective to harvest enzymes from fruits process-
ing waste. The following literatures review the types of
by-products, modern treatment technologies, and
Wine/Vinegar. Although products such as wine or approaches of utilization. It does not deal with tra-
vinegar should be produced from fresh, high-quality ditional methods, which can be found in standard
fruit juices in order to obtain high-quality products, literature:
it is technically feasible to produce them from both
solid and liquid fruit wastes. Solid wastes should be r Fruit stones constitute a significant waste disposal
shredded and then boiled for 20–30 min to extract problem for the fruit processing industry.
the sugars from the fruit and to sterilize the liquid. High-quality activated carbon can be produced
Several batches of waste may be boiled in the same from waste cherry stones (Lussier et al., 1994).
liquid to increase the sugar concentration. This is then
filtered through boiled cloth to remove the solids and r Fruit processing wastes including apple,
cooled in preparation for inoculation with yeast. Liq- cranberry, and strawberry pomace were used as
uid wastes should be separated during production to substrates for polygalacturonase production by
ensure that fruit juice is kept separate from wash wa- Lentinus edodes through solid-state fermentation
ter. For example, the juice could be drained from a (Zheng and Shetty, 2000).
peeling/slicing table into a separate drum. The juice
is then boiled for 10–15 min and treated as above. r Watermelon peel constitutes 44% of the whole
fruit weight. In the study of Madhuri and
The liquid is then inoculated with “wine” yeast Kamini-Devi (2003), the potential to produce
and not bread or beer yeast and fermented in the preserved products such as pickles, tutti-fruiti,
normal way for wine production. This can then vadiyams, and cheese using the white portion of
undergo the standard second fermentation to produce watermelon rind was investigated.
fruit vinegar.
r Fruit wastes (pineapple, mixed fruit, and maosmi)
In summary, each of the above uses of fruit waste were investigated as possible substrates for citric
requires acid production by solid-state fermentation using
Aspergillus niger (Kumar et al., 2003).
r a good knowledge of the potential market for the
products and the quality standards required r In 1996, a laboratory study was conducted by
Hammond et al., to assess ethanol production
potential from banana waste.

r Citrus junos is one of the important citrus fruits in
Japan. The fruit juice is an ingredient used in
sauces and salad dressings for its special flavor.

10 Fruit Processing Waste Management 179

After juice extraction, the fruit pulp is usually BY-PRODUCT UTILIZATION IN
dumped as waste at a large cost. The APPLE PROCESSING
manipulation of food processing wastes is now
becoming a very serious environmental issue. The In the temperate zone, apples are the most signifi-
peel of C. junos fruit was found to possess potent cant fruit economically. Apple production achieves
allelopathic activity and a methanol extract of the approximately 10% of the world’s fruit production,
peel inhibited the growth of several weed species with one fourth produced in Europe.
(Fujihara and Shimizu, 2003).
r A method is described by Drunen and There are opportunities for the utilization of apple
Hranisavljevic (2003) for the enrichment of fruit press cakes
products with beneficial substances (e.g., r drying
antioxidants) extracted from processing waste, r feeding
e.g., fruit peel. r composting
r Progress is described in an ongoing project in r storing
European Union (EU) (QLKI-1999-00124) on
anthocyanin bioactivities. The investigation However—both environmentally and economically
covers the functional properties and the effects of —the best technique is drying for pectin extraction.
anthocyanins and anthocyanin-rich food
ingredients on heart disease. This study aims to What is Pectin?
use such compounds as colorants and in the
development of new anthocyanin-rich functional Pectin for use in food is defined as a polymer contain-
foods (Anon, 2002). ing galacturonic acid units (at least 65%). The acid
groups may be free, combined as a methyl ester, or as
sodium, potassium, calcium, or ammonium salts, and
in some pectins amide groups may also be present.

Successful Waste Utilization in Wine Making Commercial Production

Among food industry by-products of fruit or veg- Process details vary between different companies, but
etable origin the products of wine industry are out- the general process is as follows:
standing. Grape marc and wine lees are the basic
by-products of wine making. Depending on the vari- The pectin factory receives apple residues [pomace
ety, ripeness, vintage, and harvesting time, 100 kg of (Carson et al., 1994)] or citrus–orange peels from a
grapes produces 15–20 kg of grape marc. number of juice producers (El-Nawawi and Heikal,
1996). In most cases this material has been washed
The majority of grape marc goes to refuse; a small and dried, so it can be transported and stored without
percentage is burned or used as compost. Unfortu- spoilage.
nately, it is also used for wine adulteration. Grape
marc contains seeds that possess valuable substances If the raw material is dry, it can be assessed and
such as oil, proteins, and tannins. Grape seed oil is selected from storage when the need arises. If wet
the most valuable because of its health-protecting and citrus peel is needed, it has to be used immediately
cholesterol-lowering effects. This oil can be obtained on receipt because of rapid deterioration (Kim et al.,
by pressing or extraction. It has the main advantage 2004).
of being pesticide free. Due to its valuable fatty acid
content it can be used as a foodstuff, lubricant, and The raw material is added to hot water containing
raw material for cosmetics as well. In the world’s a processing aid, usually a mineral acid, although
vine-producing lands, the quantity of marc has been others such as enzymes could be used (Schieber et al.,
registered since 2001. In Hungary, after the EU ac- 2003). Water alone will extract only a very limited
cession, like in other wine-producing countries, the amount of pectin.
by-products need be distilled or further utilized. EU
requirements, for instance, are that grape marc be After pectin is extracted, the remaining solids are
withdrawn from circulation within the framework of separated, and the solution clarified and concentrated
a controlled process, and then used for feed, organic by removing some of the water. The solids can be
manure, oil, distilled spirits, and tartaric acid produc- separated by filter, centrifuge, or other means. The
tion (Szenes, 1995). solution is then filtered again for further clarification
if necessary.

Either immediately or after a holding period to
modify the pectin, the concentrated liquid is mixed

180 Part I: Processing Technology

with an alcohol to precipitate the pectin. The pectin r confectionery in fruit jellies, neutral jellies;
can be partly de-esterified at this stage, or earlier or r beverages
later in the process. r nutritional and health products
r pharmaceutical and medical applications
The precipitate is separated, washed with more al-
cohol to remove impurities, and dried. The alcohol This wide range of applications explains the need
wash may contain salts or alkalis to convert the pectin for many different types of commercial pectin, which
to a partial salt form (sodium, potassium, calcium, are sold according to their application, for example
and ammonium).
r rapid set pectin traditionally used for jams and
The alcohol (usually isopropanol) is recovered marmalades
very efficiently and reused to precipitate further
pectin. r Slow set pectin used for jellies and some jams and
preserves, especially for vacuum cooking at lower
Before or after drying, the pectin may be treated temperatures. It is also important for higher sugar
with ammonia to produce an amidated pectin if re- products like bakery and biscuit, jams, sugar
quired (Braddock, 1999). Amidated pectins are pre- confectionery, etc.
ferred for some applications.
r stabilizing pectin used for stabilizing acidic
The dry solid is ground to a powder, tested, and protein products such as yogurts, whey, and soya
blended with sugar or dextrose to a standard gelling drinks during thermal processing
power or a product with other functional property
such as viscosity or stabilizing effect. r Low methyl ester aminated pectin used in a wide
range of low-sugar products, reduced sugar
Pectins are also blended with other approved food preserves, fruit preparations for yogurts, dessert
additives for use in commercial applications. gels and toppings, and savory applications such as
sauces and marinades. It can also be used in
The various raw materials yield different amounts low-acid and high-sugar products such as
of extractable pectin: Pomace, 10–15%; Sugar beet preserves containing low-acid fruits (figs and
chips, 10–20%; Sunflower-infructescence, 15–25%; bananas) and confectionery
and Citrus peels, 20–35%.

Application of Pectins By-products: Coloring and
Noncoloring Sweetener
Pectin is one of the most versatile stabilizers avail-
able. Its gelling, thickening, and stabilizing proper- After distilling the alcohol used for the precipitation
ties make it an essential additive in the production of of pectin and fruit extracts, such as sugar and fruit
many food products. acids, the natural flavors will remain. For example,
apple extract obtained from pomace will be used as
Traditionally, pectin was primarily used in the pro- sweetening agents for the preservation of freshness
duction of jams and fruit jellies—industrially as well and/or coloring of food. A further possibility is to
as domestically and in low- as well as high-sugar ferment it to form apple ethanol.
products. It produces the desired texture, limits the
creation of water/juice on top of the surface as well At a further processing stage, special technologies
as an even distribution of fruit in the product. With are used to remove dark natural coloring agents, min-
the change in lifestyle, pectin is primarily sold for eral substances, and fruit acids from these fruit ex-
industrial use. In some European markets it is still tracts. The resulting products will only contain the
sold to the consumers as an integrated component in sugars of the respective raw material that has been
gelling sugar, though. processed. They will be used by the food industry as
sweetening agents (Khachatourians et al., 2001)
Product and application development by the major
pectin producers has over the years resulted in a large By-product: Fodder
expansion of the opportunities and applicability of
pectin. Pectin is a key stabilizer and is used in many After pectin is extracted, the various residues of the
food products as original raw material are dried and pressed into pel-
lets. Due to their high energy content and nutritive
r fruit applications in jams, jellies, and desserts; value, these products are in demand as fodder. The
r bakery fillings and toppings in fruit preparations residual moisture and the fodder value of these prod-
ucts are checked continuously so as to ensure that
for dairy applications
r dairy applications in acidified milk and protein

drinks, yogurts (thickening)

10 Fruit Processing Waste Management 181

products of uniform quality are obtained (Bennett fiber helps to prevent several diseases. They found
and Bendigo, 2002). a relationship, for example, between the fiber con-
tent of the food and serum cholesterol of consumers.
Other Ways for Apple Pomace Significant intestinal diseases can be cured and pre-
Processing (Fiber Utilization) vented with an increase in food fiber.

After adding wine yeast to the apple pomace, remain- The nutritional effect of dietary fiber components
ing from fruit juice and apple pulp production, the is due to their physical and chemical properties. The
marc is fermented at 30◦C in solid phase, resulting human body does not have enzymes to digest fibers.
in a liquid with a 4–5% ethyl alcohol content. Then Fibers are resistant to digestion by gastric juices, only
it is concentrated to 10% by means of vacuum distil- some bacterium can decompose a certain quantity.
lation. With further fermentation high-quality apple Consequently, fibers possess slight nutritive value,
vinegar can be obtained. but they play an important role in digestion (Barta
et al., 1989).
If we add “A. niger” mold and methyl alcohol to
the apple pomace, its sugar content will decrease by ENVIRONMENTAL GUIDELINES
81% in 5 days. Meanwhile, from 1 kg of apple marc FOR FRUIT PROCESSING WASTE
we can extract 90 g of citric acid or a yield of 88%, if MANAGEMENT
expressed in sugar. If apple marc is treated with a thin
alkali solution we get two fractions: fibers comprising Process Description
of alpha-cellulose pentosanes (26%) and pectin (10–
18%). Both fractions can be used for apple products Fruits can be processed in many different ways de-
as a thickener and a calorie-free texture modifier. pending on raw materials and end products. The
techniques most frequently used are canning or bot-
The Importance of Dietary Fibers tling accompanied by heat treatment, refrigeration or
and Fiber Sources freezing, fermentation, drying, pickling, and chemi-
cal preservation. In most cases the aim is to lengthen
In civilized societies, there is a preference for re- the shelf life (to reduce the perishability) of the prod-
fined and cleaned foodstuffs. However, consumers uct, but there are often secondary objectives related
deprive themselves of many substances that are con- to consumer acceptance, for example, convenience
sidered healthy. A lack of fiber, for example, would (preparation and recipes), appeals (packaging and
result in diseases and abnormalities, which are un- presentation), eating quality, novelty, or new prod-
known in uncivilized societies. Nutrition scientists ucts (juices, purees, jams, or wine).
are researching the degree to which refined food will
trigger health problems (Barta, 1993). There are on- The manufacturing steps include some or all of
going efforts to add back important substances, such the following: receipt and weighing of raw materials,
as dietary fibers (Larrauri, 1999; Miguel and Belloso, storage, washing, grading, peeling, cutting, crush-
1999), coloring matters, aromas, volatile compounds, ing, filtrations, heating, cooling, preservation, pick-
vitamins, etc. These substances have been removed ling, drying, concentration, fermentation, packag-
or cleared during operations to purify the food for ing (cans, jars, vacuum packs, tetra-paks, etc.) and
a convenient “end product.” They may also be the storage. This includes grading and packing of fresh
result of a negative effect from an essential process- fruit for market. Common examples of processed
ing. However, some of such “removed” substances fruit products include fruit juices (apple, orange,
are very important for a healthy human life. Exam- etc.), canned peaches and pears, dried fruits (apri-
ples include fibers or vitamins (Ramadan and Mo¨rsel, cots, prunes, dates, raisins, etc.), and wine and fruit
2003), which are added back, for health reasons or purees for commercial applications.
legal requirements, after removal during processing.
Today, fiber products are very important dietary sup- Fruit Waste Characteristics
plements. The indigestible parts of plant cell wall,
such as cellulose and lignin, were considered as un- The fruit industry typically generates large volumes
necessary parts of foodstuffs that decrease the energy, of effluents and solid waste. The effluents contain
compositional, and sometimes even the sensory val- high organic loads, cleansing and blanching agents,
ues. After gaining further information, this approach salt, and suspended solids such as fibers and soil par-
changed and scientists ascertained that plant-based ticles. They may also contain pesticide residues from
the washing of raw materials or discarded fruits. Odor

182 Part I: Processing Technology

problems can occur with poor management of solid r Potential for minimizing water use and/or
wastes and effluents. recycling water for washing.

By-products are Produced During r Integrity of the drainage system to prevent
Many Steps of the Fruit Production contamination of surface or ground water. Check
Chain drains, pipes, screens, interceptors, etc.

Such by-products may come from r Potential for the use of wastewater treatment plant
r overstock merchandize (facility/municipal); check type, effectiveness,
r screenings, tops, stems, pulps, pomace, skins, monitoring final effluent disposal to sewers or
lagoons.
hulls, peels, meals, seeds, fines, green chop,
pressed cake, dried fruit, and fresh fruit waste r Regulatory compliance like discharge permits,
r unsold merchandize because of passed “sell by” impact statement, enforcement, costs, etc.
date
r rinse water or cooking materials Solid Waste Disposal
r below standard (size, color, and texture)
merchandize The following considerations are important:
r trimmings r Production of large volumes of bulky perishable
r fruit harvest
solid waste such as peels, stems, shells, rinds,
The by-products can result from the processing pulps, seeds, pods, rejected raw material, etc.
of almonds, apples, apricots, bananas, cantaloupe, r The need to separate solid from liquid waste by
coconuts, dates, figs, grapes, grapefruits, lemons, screening, sedimentation, flotation, etc.
melons, nectarines, pecans, oranges, peaches, pears, r The cost of transporting waste to approved
pineapples, plums, prunes, pumpkins, raisins, tanger- disposal sites.
ines, walnuts, and many others. r Microbial action in stored solid waste can
produce odors.
Key Environmental Risks/Liability r Vermin (e.g., rats) and insects may be attracted to
Factors solid waste storage areas (Cholos and
Cheremisinoff, 2003).
The risk/liability factors associated with water supply
and wastewater management are as follows: Issues related to the above considerations are
r Sources of processing and potable water are r Permits and charges are usually required for solid

municipal, abstraction wells, and boreholes. The waste disposal.
quality of water is important; pretreatment may be r Approval or licensing of solid waste disposal
required depending on the initial quality and
intended use. contractors.
r Large volumes of water are needed for washing r Security of access to solid waste disposal sites.
raw materials, factory cleaning, and transport of r Potential for process adjustment to minimize solid
materials within the factory.
r Pollutants in wastewaters include detergents, waste production.
pesticides, suspended solids, dissolves solids, r Plans to utilize solid waste for fuel, fertilizer, or
nutrients, and microbes.
r Seasonality of production can place heavy animal feed.
demands on treatment/disposal systems during r Potential treatment of solid waste (e.g., drying) to
the peak season.
facilitate disposal.
Other issues to consider include r Compliance with solid waste disposal regulations
r Permits and fees for the usage of water.
r Availability of acceptable water during the peak and sanitary regulations in importing countries
may be expensive or difficult.
processing season(s).
Refrigerants in Fruit Processing

Fruit processing plants will usually have large
cold storage facilities. The refrigerants used may
be ozone-depleting chemicals, such as CFCs, the
production of which is being phased out under
the Montreal Protocol. Ammonia, which has no
such restriction, is also used as a refrigerant. The

10 Fruit Processing Waste Management 183

release of ammonia into atmosphere, due to leaks Institutional System
from cooling equipment, is a primary health and
safety concern. The institutional system of environment protection
should be decentralized by financing and strength-
MEANS OF MODERN WASTE ening the organization of regional institutions (Read
MANAGEMENT et al., 1997). The system of horizontal relationships,
the activity of professional organizations, environ-
Feasibility Strategic Principles ment protection units, and the branches involved also
need to be strengthened.
Sustainable development means a sustainable use of
the environment to improve the quality of human Social Participation
life without exceeding the availability of natural re-
sources. Prevention is of strategic importance. It is The implementation of environmental projects re-
the main direction of regulatory, research, and devel- quires social participation. The importance of educa-
opment activities (Hollingdele, 2000). tion, training, and information spreading is consid-
erable, in order to make people aware of the proper
Issues of Environmental policy, solutions’ and their decisions’ environmental conse-
Planning, and Regulation quences. Furthermore, the conditions of environmen-
tally conscious, healthy lifestyle need to be ensured
Modern environmental policy requires a prudent, and communicated (Fehr et al., 2002).
target-oriented, integrated approach and universal
planning involving every region. Environmental reg- International Cooperation
ulation needs to be efficient regarding the cost
compared to environmental protection achievements. The compliance of countries to future environmental
Regulation should be based on general legal princi- standards is of crucial importance. On the one hand,
ples and enforcement by the “polluter pays” prin- it should be accomplished by maintaining the exist-
ciple. Environmental fines should be allocated for ing environmental and regulatory advantages. On the
solving problems with appropriate interventions other hand, it needs a reasonable adaptation of inter-
(Sherwood et al., 1995). national (e.g., EU) requirements, tailored to condi-
tions unique to each country (Di Blasi et al., 1997).
Research and Technical
Development Studying the situation of fruit processing wastes
and by-products, it can be stated that processing
Research and technical development is of strategic wastes should be further utilized as secondary raw
importance, providing the knowledge, procedures, materials (for feeding or even for human applica-
methods, and technologies necessary for the imple- tions). As far as packaging materials are concerned,
mentation of the given tasks. the amount needs to be decreased, moreover selective
collection and reuse needs to be organized, with spe-
Environmental Information System cial regard to the principles of a “closed-loop econ-
omy” approach.
Environmental data collection and processing are just
partly done in many countries. Therefore, it is neces- CONCLUSIONS
sary to
r develop an environmental information system The latest research and development have resulted
in new methods of modern waste management so-
involving central systems and professional lutions around the world. Biotechnological (biocon-
systems as well version) procedures (e.g., aerobe composting, bio-
r establish an environmental database within the gas production) are outstanding in this respect and
given countries and their commercial partners, too can successfully be applied. However, in the future
r work out recommendations concerning the index more extensive applications will become necessary
numbers and the content of environmental reports in the field of, e.g., animal feed supplementation,
(Woodard et al., in Press) soil conditioning products, and energetic ingredient
production.

184 Part I: Processing Technology

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Handbook of Fruits and Fruit Processing
Edited by Y. H. Hui

Copyright © 2006 by Blackwell Publishing

Part II
Products Manufacturing

Handbook of Fruits and Fruit Processing
Edited by Y. H. Hui

Copyright © 2006 by Blackwell Publishing

11
Manufacturing Jams and Jellies

H. S. Vibhakara and A. S. Bawa

Introduction The preparation of jams and jellies was developed
Ingredients for Jams and Jellies as an art by the housewife, and served as a means
Types and Varieties of Fruits of preserving fruit, corresponding to the time, when
Peels the fruits were being harvested. Science as applied to
Gelling Agents jam manufacture seems often to be regarded by the
Sweetening Agents general public as synonymous with sophistication.
Acidulants Factory-made jam must conform to certain specifi-
Coloring and Flavoring Agents cations and standards, not essential for a home-made
Product Type and Recipes jam, for instance; it must be of a consistency firm
Methods of Manufacture enough to meet the demands of confectioneries and
to withstand handling during transport.
Fruit Preparation
Fruits for Jelly The consistency depends upon the presence of
Boiling pectin. Hence, scientific jam manufacture is largely
Filling based on the correct application of knowledge about
Packaging Materials pectin and the laws governing the formation of the
Future Research Needs pectin–sugar–acid gel. Jam and jelly products were
References prepared with a high concentration of dissolved
solids so that fermentation could not occur. However,
INTRODUCTION only pectin and sugar are not sufficient for the forma-
tion of the products. Equally important is the acidity
Fruits have been part of man’s food since times im- of the fruit, resulting in a definite equilibrium in the
memorial. Among the preserved fruits, jams and jel- “pectin–acid–sugar” system (Breverman, 1963).
lies constitute important products and afford means of
utilizing a large amount of sound cull fruits unsuitable Pectin is the most essential thing in the forma-
for other purposes. It is an older method than canning tion of jam and jelly. Lack of knowledge about the
and freezing (Peckham, 1964; Thakur et al., 1997). requirements necessary for the pectin gel formation,
Historically, jams and jellies may have originated as frequently contributes to products of undesirable con-
an early effort to preserve fruits for consumption in sistency. The preservation industry awaited the ac-
the off-season. As sugar manufacture became more cumulation of sufficient information on the chem-
affordable, the popularity and availability of these istry of pectin and its gels to control the consistency
fruit products increased (Anon, 1983). Jams in their under commercial conditions. As the knowledge of
various forms are probably the easiest by-products pectin chemistry increased, production grew and to
made of citrus fruits. The earliest published record some extent replaced home-prepared products. Con-
of jelly making appeared in the later part of the 18th sequently, the jam and jelly industry assumed con-
century. siderable magnitude.

189

190 Part II: Products Manufacturing

INGREDIENTS FOR JAMS Figure 11.1. Gel network in jams and jellies (the
AND JELLIES hatched areas represents junction zones).

Definition and standards of identity for various fruit polymeric molecules cross-linked to form a tangled,
preserves and jellies have been issued by the Food interconnected molecular network (Fig. 11.1) im-
and Drug Administration under the Food, Drug and mersed in a liquid medium (Oakenfull, 1991). The
Cosmetic Act under which ingredients for jams and water, as a solvent, influences the nature and magni-
jellies have been discussed. A brief outline of these tude of the intermolecular forces that maintain the in-
standards has been presented here. The U.S. stan- tegrity of the polymer network; the polymer network
dards for Grades were established by the production holds the water, preventing it from flowing away in
and marketing administration (Anon, 1974, 1975). acid medium; pectin with sugar affects the pectin wa-
ter equilibrium and forms a network of fibers through-
Jellies are viscous or semi-solid foods made from out the jelly (Mitchell, 1979; Rees, 1969; Thakur
a mixture of not less than 45 parts by weight of sac- et al., 1997). This structure is capable of support-
charine ingredient. The mixture is concentrated by ing liquids. Figure 11.2 shows the factors affecting
heat to such a point that the soluble solids content the strength of the network.
of the finished jelly is not less than 65%. Spices,
sodium citrate, sodium potassium tartrate, sodium TYPES AND VARIETIES
benzoate, benzoic acid, mint flavor, and harmless ar- OF FRUITS
tificial green coloring may be optional ingredients.
Optimal saccharine ingredients are corn sugar, in- A jam manufacturer can choose a fruit from among
vert sugar syrup, sucrose, honey, or combinations of the following five categories:
these. Pectin and designated organic acids may be
added to compensate for deficiencies of these sub- 1. Fresh fruit
stances in fruit juice. Inducement for adding pectin 2. Frozen, chilled, or cold stored fruit
or acid in quantities greater than required to supply 3. Fruit or fruit pulp preserved by heat
the natural deficiency of the fruit juice is eliminated
by fixing the minimum fruit juice content. The name
of the fruit or fruits present as well as spices, chemi-
cal preservatives, honey, or corn syrup used must be
indicated on the label.

Standards for jams and preserves are similar to
those for jelly except that fruits are used rather than
fruit juice ingredients, and mint flavor and green col-
oring are not optional ingredients. The fruit mixture
is concentrated by heat to such an extent that the total
soluble solids content is not less than 65% for certain
specified fruits, and 68% for others.

It is extremely difficult to account for the behavior
of gels formation. Gels are a form of matter interme-
diate between a solid and a liquid. They consist of

Strength of the jelly

Concentration of Pectin (%) Acidity Concentration of sugar %

0.5–1.5 pH value 64 –71

(depends upon type of 2.7–3.6 (weak jelly-crystal

Figure 11.2. Factors affecting the jelly pectin) (hard jelly-no jelly) formation)
strength.
Optimum (1.0) Optimum (3.0) Optimum (67.5)

11 Manufacturing Jams and Jellies 191

4. Sulfited fruit or fruit pulp, i.e., fruit preserved with example, strawberries require sometime light crush-
sulfur dioxide ing, plums require heating with minimum of water
until soft. When it is required, cherries are similarly
5. Dried dehydrated fruits treated. Currants are passed through machines that
remove the stalks, gooseberries are whirled in ma-
Fresh fruits generally give the best jams. As pectin chine (Morries, 1951).
is the main ingredient in the fruit that gives a set
to the jam, it is preferable to use a slightly under- Sour and bitter oranges are utilized by hand or ma-
ripe fruit that is rich in pectin along with the ripe chine and the peel cut of any desirable size or shape
fruit to secure the desirable gelling effect in the jam. by special machines. Sometimes admixture of cer-
Apple, pear, sapota, apricot, loquat, peach, papaya, tain proportion of grapefruit or lemons is used, peel
karonda, plum, strawberry, mango, tomato, grapes, of which constitutes only a quarter to a half if utilized
and muskmelon have been used for preparation of in proportion to the total weight of fruit. These slices
jams. It can be prepared from a single fruit or a mix- need to be softened either by prolonged boiling, or
ture of two or more. more rapidly by heating. The slices may be covered
with water and cooked until tender, the water being
In jelly making, pectin is the most essential con- changed at least twice during cooking. It can be done
stituent. Although there is difference of opinion about in autoclaves under pressure of 1 atm. More rapid
the exact nature of pectin, it is generally accepted softening is attained by boiling the peel in a solu-
that pectin forms jellies, when mixed and boiled with tion of carbonate of soda or ammonium hydroxide,
proper amounts of sugar, acid, and water. All these which removes from the cell wall certain substances
constituents must be present in a particular propor- that otherwise render the peel tough after boiling with
tion for making a good jelly (Kratz, 1993, 1995). sugar. Ammonia is less drastic in its action than that
of soda and is preferable for use since less danger of
Guava, sour apple, plum, grapes, karonda, wood the peel breaking up into small fragments, which is
apple, loquat, papaya, and gooseberry are gener- due to the fact that soda dissolves both hemicelluloses
ally used for preparation of jelly. Apricot, pineapple, and pectic subtances, whereas the former are said to
strawberry, raspberry, etc. can be used but only after be insoluble in ammonia. It would appear that some
addition of pectin powder, because these fruits have more research is required as to the precise causes of
low pectin content. Fruits can be divided into four the softening.
groups on the basis of their pectin and acid contents
(NIIR Board, 2002). The time required to soften peel in an autoclave
depends on the size of the slices and on the pressure
1. Rich in pectin and acid: sour and crab apple, grape, and temperature employed. Some discoloration may
sour guava, lemon, orange (sour), plum (sour), occur if too high pressure is used. To avoid handling
jamun. the peel after it has been softened, Morris (1935)
suggested placing the peel intended for softening in
2. Rich in pectin but low in acid: apple (low acid perforated baskets of non-corrosible metal, each con-
varieties), unripe banana, sour cherry, fig (unripe), taining sufficient peel for one batch. After having
pear, ripe guava, peel or orange, and grapefruit. been cooked in ammonium hydroxide or soda, the
peels may be re-cooked for a short time with a weak
3. Low in pectin but rich in acid: apricot (sour), sweet solution of citric acid to remove any traces of the
cherry, sour peach, pineapple, and strawberry. hydroxide.

4. Low in pectin and acid: ripe apricot, peach (ripe), GELLING AGENTS
pomegranate, raspberry, and any other over-ripe
fruit. Gelling agents are used in the food industry in a wide
range of products both traditional and novel, and this
Types and varieties of fruits selected should be used use is increasing rapidly with the increase of con-
without undue delay for making jam and jelly be- venience foods. An ideal gelling agent should not
cause, if kept for a long time, degradation of pectin interfere with the odor, flavor, or taste of the prod-
proceeds rapidly. uct to which it is added (Fishman and Jen, 1986).
Improvements to existing and development of new
PEELS ones require basic understanding of the processes

Apart from the sorting and removal of leaves, stalks,
and undesirable portions of the fruit, which can only
be done by hand, most fruits require treatment of
some kind before they enter the boiling pan. For

192 Part II: Products Manufacturing

of gelatin and the properties of gels at the molec- polysaccharides with water are by themselves im-
ular level (Doublier and Thibault, 1984; May and portant factors in the gelation process. Both types of
Stainsby, 1986). polymers are strongly hydrated in aqueous solution,
so that some water molecules are so tightly bound
Gels are a form of matter intermediate be- that they fail to freeze even at temperatures as low as
tween a solid and a liquid. They consist of poly- −60◦C (Eagland, 1975). Although the formation of
meric molecules cross-linked to form a tangled, a stable intermolecular junction is a critical require-
interconnected molecular network immersed in a ment for gelation, some limitation on the interchain
liquid medium (Flory, 1953). The polymer net- association is also necessary to give a hydrated net-
work holds the water, preventing it from flowing work rather than an insoluble precipitate (Axelos and
away (Oakenfull, 1987; Meyer, 1960). In gels, the Thibault, 1991).
molecules are held together by a combination of weak
intermolecular forces such as hydrogen bonds, elec- It is important to know the condition for the onset of
trostatic forces, Vanderwaals forces, and hydropho- gelation in technological processes involving gelling
bic interactions. The cross-linkages are not point in- food products. Several methods are used to char-
teractions but involve extensive segments from two acterize this change in consistency (Doesburg and
or more polymer molecules, usually in well-defined Grevers, 1960; Walter and Sherman, 1981; Beveridge
structures called junction zones (Rees, 1969). The and Timber, 1989; Dhame, 1992; Rao, 1992; Rao and
gelation process is essentially the formation of these Cooley, 1993). Physically, the critical stage of gela-
junction zones (Fig. 11.1). tion may be monitored from the loss of fluidity or
from the rise of the elastic property of the growing
The physical characterizations of gel are the network (Shomer, 1991). Table 11.1 gives different
consequence of the formation of a continuous types of jelling agents used in the manufacture of
three-dimensional network of cross-linked polymer jellies.
molecules on a molecular level; an aqueous gel con-
sists of three elements (Jarvis, 1984): Gelatin is a water-soluble protein formed by initial
degradation of collagen from animal skin and bones.
1. Junction zones where polymer molecules are Gelatin jellies have a rather soft or rubbery texture.
joined together. For these, it is normal to use an additional gelling
agent such as thin boiling starch. This involves the
2. Interjunction segments of polymers those are rel- texture incidentally. Gelatin gels forms reversibly on
atively mobile. cooling a gelatin solution. It is now well established
that the protein molecules are cross-linked to form a
3. Water entrapped in the polymer network. network by junction zones, where the protein chain

Gels are always formed in an aqueous envi-
ronment. Thus, the interactions of protein and

Table 11.1. Different Types of Jelling Agents Used in the Manufacture of Jellies

Type of Gelling Origin Use
Agent

Gelatin A protein of animal origin extracted Generally, must not be boiled. To be
Agar/Alginates from bones and purified added to warm syrup for setting
on cooling
Extracted from various sea weeds
Various products such as neutral
Gum Arabic/Acacia Exudates from trees jellies, weakened by boiling in
acid solution
Starch/Modified starch Seeds and various roots
Used to produce hard gums, and as
Pectin Fruit residues particularly citrus and an extender and thickener in
apple pomace products, e.g., Marshmallow

These have been completely and
partly replaced by other jelling
agents in gums—Turkish delight
Glazer

Used largely in acid fruit jellies but
with low melting point is used in
neutral jellies

11 Manufacturing Jams and Jellies 193

have partly refolded in the collagen triple helix struc- relatively higher proportion of oligosaccharides
ture (Veis, 1964). chain on their backbone, and the side chains are much
longer than those of the pectin of the middle lamella
Agar/alginates are the major structural polysaccha- (Sakai et al., 1993).
rides of algae. Agar jellies have a very soft texture.
Straight agar jellies have a characteristic “shortness” Pectins are primarily a polymer of d-galacturonic
that may be modified by the addition of gelatin, gum acid (homopolymer of [1 → 4] ␣-d-galacto pyra-
Arabic, pectin, starch, etc. Alginates with a high ra- nosyluronic acid units with varying degrees of
tio of poly-␤-d-mannuronic acid (M) and poly-␣-l- carboxyl groups methylated estrified) and rhamno-
guluronic acid (G) form weak, forbid gels, whereas galacturonan (hetero polymer of repeating [1 → 2]
low M/G alginates give transparent, stiff, brittle gels, ␣-l-rhamnosyl [1-l] ␣-d-galactosyluronic acid dis-
and the gel strength depends on the nature of the di- accharide units), making it an ␣-d-galacturonan (Lau
valent cation (Smidsred, 1974). et al., 1985). The molecule is formed by l-1,4-
glycosidic linkages between the pyranose rings of
Gum Arabic is the most water-soluble of the natu- d-galacturonic acid units. As both hydroxyl groups
ral gums (up to 50%) and their solutions are of rela- of d-galacturonic acid at carbon atoms 1 and 4 are
tively low viscosity. Other advantages of gum Arabic on the axial position, the polymer formed is 1,4-
are its absence of odor, color, and taste. Hard jellies polysaccharide (Sakai et al., 1993; Oakenfull, 1991).
can be produced with gum Arabic.
The chemical structure of galacturonic acid and its
Unmodified starches, produced by wet milling of methyl ester are shown in Figure 11.3 and the link-
field corn, supply the major amount of thickening ma- ages between different galacturonic acids and their
terial. Modified starch is starch that has undergone methyl esters in pectic and pectinic acid are shown
one of the varieties of treatment to alter its physi- in Figure 11.4 (Swaminathan, 1987).
cal property and/or functionality (Mauro et al., 1991;
Furcsik and Mauro, 1991). They are used to extend Pectic acid is composed mostly of colloidal poly-
the bodying or gelling effect of normal starches, to galacturonic acid molecules, and is essentially free
modify gelling tendencies, and to improve texture. from methyl ester groups. The salts of pectic acids
Starch is an essentially linear polymer of ␣-(1 → 4) are either normal or acid pectates, whereas pectinic
linked d-glucose (Wolfram and EI Khadem, 1965). acid ones are colloidal polygalacturonic acids con-
Starch gels consequently have a composite structure taining more than a negligible portion of methyl es-
of open, porous amylopectin molecules threaded by ter groups. Pectinic acid under suitable conditions is
an amylose matrix. Thus, actual gel-forming poly- capable of forming gels with sugar and acid or, if suit-
mer in starch is amylose. The molecular weight dis- ably low in methoxyl content, with certain metallic
tribution of amylose depends on the plant source and ions. The salts of pectinic acids are either normal or
molecular weights of several millions with broad dis- acid pectinates.
tribution have been reported (Rao et al., 1993).
Studies on esterified residue in pectin claimed that
Pectin is the most frequently used hydrocolloids they are randomly distributed (Garnier et al., 1993;
in processed fruits. Jams and jellies are the major De vries et al., 1986) or non-randomly distributed
food type using larger amounts of pectin. Pectin is (Mort et al., 1993a,b). However, ion exchange chro-
a class of complex hetero polysaccharides found in matography showed a random distribution of change
the cell walls of higher plants, where they function in citrus pectin that had undergone acid catalyzed
as a hydrating agent and cementing material for the deesterification (Garnier et al., 1993). Such disparate
cellulosic network (Muralikrishna and Taranathan, findings may, impart, be due to the length of galactur-
1994). onate residues being examined or due to differences
in pectin source (Baker et al., 1996).
When pectin-rich plant materials are heated with
acidified water, the protopectin is liberated and is Polygalactoronic acid could be considered as a rod
hydrolyzed into pectin that is readily soluble in water. in solution, whereas pectins are segmented rods with
It happens in plant tissues during ripening of fruits flexibility at the rhamnose tees (Fry, 1986). The size,
with the aid of an enzyme protopectinase. As the charge density, charge distribution, and degree of sub-
ripening of fruit proceeds, more and more of the in- stitution of pectin molecules can be changed biolog-
soluble protopectin is converted into soluble pectin ically or chemically (Kerstez, 1951; Kratz, 1993).
(Woodmansee et al., 1959). Their composition varies
with the source and conditions of extraction, location, The most unique and outstanding property of
and other environment factors (Chang et al., 1994). pectin is their ability to form gel in the presence
Pectic substances in the primary cell wall have a of Ca2+ ions in sugar and acid solution (Gordon
et al., 2000; Halliday and Bailey, 1954). Degree of