Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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Other Benefits

0035 Fermented milks and other related products may

have other benefits above and beyond their nutri-

tional content. Traditional products (such as laben

from Syria) have been used therapeutically for

decades for disorders of the stomach, intestine, and

liver, and for stimulating the appetite long before the

existence of bacteria and other microorganisms was

recognized. Both koumiss and kefir are used thera-

peutically in Russia.

0036 The glucose liberated from the lactose hydrolysis

during fermentation is converted into lactic acid,

which contributes to the taste of the products. It

also helps preserve fermented foods by acidifying

the product and preventing or decreasing the growth

of pathogenic organisms. Certain probiotics may

have a similar effect within the human GIT either by

changing the environment (decreasing the pH) or

by colonization resistance (preventing other micro-

organisms from adhering to the GIT), thereby

decreasing the incidence and/or duration of intestinal

infection. It has also been established that some pro-

biotic bacteria are capable of producing bacteriocins

– substances that are toxic to other (usually related)

strains of bacteria. Other probiotic components may

also have beneficial effects on unwanted microorgan-

isms, for example a supernatant of one probiotic has

recently been shown to downregulate Helicobacter

pylori infection in humans.

0037A number of health effects have been established

for probiotics, including reduction of duration of

rotavirus diarrhea, alleviation of the symptoms

of lactose intolerance, reduction of harmful intestinal

microbial enzyme activities, immune enhancement,

and decreased fecal mutagenicity. However, it cannot

be assumed that all probiotic strains of even a spe-

cific species have the same or even any desirable

properties.

0038In some countries where yogurt has not been part

of the normal diet, the consumption of fermented

dairy products is generally low. However, their popu-

larity has increased in recent years (Figures 1 and 2).

Austria

Belgium

Denmark

Finland

France

Germany

Netherlands

Portugal

Spain

Norway

Country

kg per capita

1997

1998

1999

fig0001 Figure 1 Consumption of milk drinks and fermented products, including yogurt: part 1. Aadapted from IDF (2000) The world dairy

situation 2000. Bulletin of the International Dairy Federation 335: 8.

Iceland

Bulgaria

Czech Republic

Slovakia

Slovenia

Hungary

Poland

Ukraine

Canada

Argentina

Australia

South Africa

Country

kg per capita

1997

1998

1999

fig0002 Figure 2 Consumption of milk drinks and fermented products, including yogurt: part 2. Adapted from IDF (2000) The world dairy

situation 2000. Bulletin of the International Dairy Federation 335: 8.

2388 FERMENTED MILKS/Other Relevant Products

This may be due to the wide variety of products

now available, their simple production technology,

their low cost, their long shelf-life, and their healthy

image.

0039 The growth area for fermented milks and related

products appears to be in the added-value and health

sector of the market – probiotic, functional, and for-

tified products. A number of factors will influence the

acceptance and further growth of the market, includ-

ing the introduction of more specialty products,

quality and sensory improvements, development of

fermented products using plant material, genetically

engineered strains, and continued or increased inter-

est in ‘healthy’ foods.

See also: Acidophilus Milk; Cheeses: Types of Cheese;

Fermented Foods: Origins and Applications; Fermented

Milks: Types of Fermented Milks; Lactic Acid Bacteria;

Lactose; Microflora of the Intestine: Role and Effects;

Yogurt: The Product and its Manufacture; Yogurt-based

Products; Dietary Importance

Further Reading

Codex Alimentarius Commission (1975) Codex Standards

for Milk and Milk Products, vol. 12. Codex Stana 11(a).

Rome: FAO/WHO.

Codex Alimentarius Commission (2001) Report of the

Fourth Session of the Codex Committee on Milk and

Milk Products. Rome: FAO/WHO.

Dairy Industry Federation (2000) Yoghurt Code of Practice

for the Composition and Labelling of Yoghurt. London:

Dairy Industry Federation.

FAO (1990) Animal Production and Health Paper. The

Technology of Traditional Milk Products in Developing

Countries. Rome: FAO/WHO.

IDF (1988) Fermented milks and science and technology.

Bulletin of the International Dairy Federation 227:

4–164.

IDF (1997) Standards for fermented milks. IDF-Doc 316.

IDF (2000) The world dairy situation 2000. Bulletin of the

International Dairy Federation 335: 8.

Kiple KF and Conee Ornelas K (eds) (2000) The Cambridge

World History of Food, vol. 1. Dietary Liquids, Milk

and Dairy Products, pp. 692–702.

Kurman JA, Ras˛ic

JLJ and Kroger M (1992) Encyclopedia

of Fermented Fresh Milk Products. New York: Van

Nostrand Reinhold.

Nakazawa Y and Hosono A (1992) Functions of Fermented

Milk Challenges for the Health Sciences. London:

Elsevier Science.

National Dairy Council (1997) Topical Update 8. Nutri-

tional Benefits of Yogurt and Other Fermented Milk

Products. London: National Dairy Council.

O’Brien J (1999) Sugar profiles of cultured dairy products

in the UK. Journal of Human Nutrition and Dietetics 12:

242–250.

Dietary Importance

C D Khedkar, College of Dairy Technology, Warud,

(Pusad), Maharashtra, India

G D Khedkar, Dr. Babasaheb Ambedkar Marathwada

University, Aurangabad, Maharashtra, India

N V Chavan, Adarsha College, Hingoli, Maharashtra,

India

S D Kalyankar, Marathwada Agriculture University,

Parbhani, Maharashtra, India

Background

0001During the past 80 years, considerable attention has

been directed sporadically on benefits derived from

the consumption of milk products containing lactic

acid bacteria (LAB). The role of fermented milks

(FM) in human nutrition is well documented. Man

knew the virtues of these fermented foods, even

during the early days of civilization. In earlier days,

these foods were produced by natural fermentations

with the main objective of preserving milk. In Europe,

Asia, and Africa, sour milk was known to be more

stable than fresh milk. It preserved the high-quality

nutrients present in milk in a relatively more stable

form. From prehistoric times, Man learned to use

milk as food, and, although the origin of the art of

preserving dairy products by lactic acid fermentation

is lost in antiquity, biochemical and microbiological

knowledge of fermentation is comparatively recent.

On the Indian subcontinent, the conversion of milk in

every household by souring with the left-overs of the

previous day’s sour milk has been a common practice

ever since the Aryans inhabited the land. In this way,

the life and utility of milk nutrients were extended.

Today, the practice of preserving milk by fermenta-

tion has become a routine household technology, and

these products are almost compulsory on this subcon-

tinent. As far as the Western countries are concerned,

FMs like kefir, koumiss, leben, skyr, crowdiss, and

yogurt produced by lactic fermentation of milk have

been consumed by people either as refreshing bever-

ages or as nutritious or therapeutic foods and dietary

adjuncts.

0002The milk of several species, including the cow,

buffalo, goat, sheep, mare, camel, and reindeer, has

been used for the preparation of FMs. Each type of

FM has its own characteristic texture, body, flavor,

and composition, depending on the type of milk used,

the type of starter cultures (LAB with or without

aroma producers and yeasts), and the procedures

followed in its preparation. The FMs popularly used

in various countries may be classified broadly into

four categories: (1) moderately sour types with a

FERMENTED MILKS/Dietary Importance 2389

pleasant aroma associated with diacetyl, e.g., cul-

tured milk; (2) sour and very sour types owing to

high acid production, e.g., yogurt and dahi; (3) etha-

nol in addition to lactic acid, e.g., koumiss and kefir;

and (4) probiotic fremented milks, e.g., acidophilus

milks especially prepared with human strains of

Lactobacillus acidophilus.

0003 Fermentation with LAB is one of the oldest

methods of food processing and food preservation

used by mankind. In many areas of the world, the

fermentation process is initiated by adventitious indi-

genous microorganisms or through ‘backslopping’

with mixed or unknown cultures. Often, this type of

fermentation may be slow or unpredictable. Never-

theless, it affords a vital means of preserving highly

perishable foods, especially where refrigeration is

lacking. In developed countries, fermentation is initi-

ated with pure starter cultures that have predictable

performance potentials. Recent scientific and techno-

logical advances in starter-culture management and

process control have yielded a variety of products

with superior chemical, physical, nutritional, and

sanitary qualities. A number of FMs, cereals, and

beverages are prepared through the action of lacto-

bacilli. Nearly every civilization has consumed FMs.

Over the past two decades, the per-capita consump-

tion of FMs has increased more than 35-fold owing to

their image as nutritious and healthful foods. Like-

wise, the per-capita production and consumption of

cheeses have seen notable growth in the USA, Europe,

and the Indian subcontinent. Thus, FMs have been,

and still are, of extreme importance in the nutrition of

people throughout the world.

Nutritional Significance of Fermented

Milks

0004Lactobacilli use the nutrients in milk for their own

metabolism and growth, and multiply from one to 10

million cells per milliliter. The microorganisms are

present in the FM, not only as viable cells, but also

as autolyzed cells that give rise to primary and sec-

ondary metabolites and enzymes that they may have

produced during fermentation and storage.

0005The nutritional value (NV) of a FM depends on the

availability and digestibility of nutritive constituents,

and the changes in these constituents resulting from

microbial growth and fermentation processes (Tables

1 and 2). Similarly, the NV of fermented food also

depends on the nutrient content and the bioavailabil-

ity of the nutrients. Generally, the energy value of a

FM is similar to that of the milk from which it was

prepared, yet it is claimed that the FM are more

nutritious (the compositions of milk and yogurt are

given in Table 2). Fermentation makes some of the

nutrients more available for absorption. The inter-

actions between milk nutrients and starters are

detailed below.

tbl0001 Table 1 Changes in milk constituents resulting from

fermentation

Constituents Changes

Milk proteins (3–4.5%) Coagulated into a smooth curd with

casein particles finely dispersed;

partially peptonized (0.1–0.7%) and

utilized for microbial growth, resulting

in the build-up of microbial cell

proteins, increase in non-protein

nitrogen and release of peptides and

amino acids

Lactose (4.5–5%) Utilized (1–2%) by starter bacteria

producing mainly lactic acid (0.6–2%),

volatile acids, flavor compounds, and

may also be formed by

heterofermentative types; alcohol and

may be produced by lactose-

fermenting yeasts

Milk fat (3.5–7%) Fermentation leads to partial digestion of

lipids

Mineral matter

(0.7–0.8%)

No direct appreciable change

Vitamins No change in fat-soluble vitamins A, D,

and E; slight decrease in B-complex

vitamins, depending on the strains

used

Source: Khedkar CD and Khedkar GD (1993) Fermented milks: Dietary

importance. In: Encyclopeadia of Food Science, Technology and Nutrition.

Academic Press, London, pp. 1810–1814.

tbl0002 Table 2 Composition of milk and yogurt (per 100 g)

Nutrients Whole milk Whole-milk

plain yogurt

Low-fat

plain yogurt

Very-low-fat/low-calorie

flavoredyogurt

Greek yogurt Plain fromage frais

Energy (kcal) 66 79 56 41 115 113

Protein (g) 3.1 5.7 5.1 4.3 6.4 6.8

Fat (g) 3.9 3.0 0.8 0.2 9.1 7.1

Calcium (mg) 115 200 190 130 150 89

Zinc (mg) 0.4 0.7 0.6 0.4 0.5 0.3

Phosphorus (mg) 92 170 160 110 130 110

Magnesium (mg) 11 19 19 13 12 08

Source: Buttriss J (1997) Nutritional properties of fermented milk products. International Journal of Dairy Technology 50 (1):21–27.

2390 FERMENTED MILKS/Dietary Importance

Predigestion of Protein and Protein

Quality

0006 The proteins in milk are of an excellent quality bio-

logically, and both caseins and whey proteins are well

endowed with essential amino acids (EAA). The fact

that the protein content of FM, like yogurt, is often

elevated by concentration or addition of skim milk

solids means that it is an even more attractive source

of protein than liquid milk. It is important that the

proteins in FMs are totally digestible, because some

degree of initial proteolysis is caused by the starter

organisms. The extent of this breakdown depends on

the strains of bacteria being employed, but, in gen-

eral, at least some release of amino acids and peptides

can be expected during incubation and storage. FM

products contain significantly higher levels of free

amino acids (FAA) than milk, because the heat treat-

ment and proteolytic activity of the starter organisms.

The native milk proteins, which form a hard curd in

the stomach, are converted into a soft curd containing

finely dispersed casein particles resulting from the

action of starter organisms in the FM. The FM pro-

teins are useful to children, old people, and those with

stomach ulcers, because the soft curd in FM is easier

to digest than the milk.

0007 It has been observed that rats fed with diets con-

taining FM products had a higher feed consumption,

greater weight gains, and a more efficient utilization

of their feed. Some medical practitioners advocate the

use of dahi and buttermilk by children not only for

treatment of common intestinal ailments but also for

their general nutrition. In tropical countries like

India, where milk is exposed to heavy bacterial con-

tamination because of the tropical atmosphere and

low standards of hygiene, leading to rapid spoilage, it

is better to convert milk into FM in order to preserve

its NV.

Predigestion of Milk Fat and Fat Quality

0008 Although much of the FM sold in industrialized coun-

tries is produced from skim milk, traditional mater-

ials have always contained some 3–4% milk fat. It has

been proposed that the digestibility of fat is improved

via the action of the bacteria present during the fer-

mentation process, but whether this effect really

exists is highly debatable. The overall energy content

of FM reflects both the fat content of the milk from

which it was made and whether or not ingredients

such as cream or sugar have been added. Humans

have a double requirement for lipids. Lipids act as a

storage fat, which is composed of saturated fatty

acids, and serve as a source of energy or as a pro-

tection for vital organs. In addition, they play an

important role by acting as structural fat, which,

together with proteins, forms many of the essential

membranes in animal cells, particularly in areas like

brain and nerve cells. These are essential to many

physiological processes. Some essential nutrients are

fat-soluble and are found primarily in foods that

contain fat. These nutrients are essential fatty acids

(EFA) and fat-soluble vitamins. Shahani and Chan-

dan (1979) cited the fact that the LAB possess lipase

activity, as evidenced by lipids in cultured products

being partially degraded. Their assays for lipase ac-

tivity, however, were performed using culture organ-

isms with tributyrin emulsions as a substrate, and

they did not prove that the bacterial lipases acted on

lipids in the cultured products. A significant increase

in free fatty acids over the milk has been observed in

FM. The lactic acid fermentation and enzymic deg-

radation of amino acids also produce small quantities

of volatile fatty acids.

Predigestion of Lactose

0009The milk carbohydrate, lactose, causes intestinal

problems in a number of persons who are lactose-

intolerant. These persons are deficient in the intes-

tinal enzyme, b-galactosidase, and thus must restrict

their intake of milk and dairy products. Milk does not

contain this enzyme. Lactose intolerance is normally

defined as the occurrence of gastrointestinal symp-

toms after administration of a single test dose, about

50 g of lactose in aqueous solution. In a large propor-

tion of the world’s population, b-galactosidase activ-

ity is low or absent. This enzyme is present in

sufficient quantities in lactic fermented milks. Conse-

quently, the lactose level in FM can be lower than in

milk, although this is not always the case, as skimmed

milk powder or non-fat milk solids are sometimes

added during the manufacture of some of these prod-

ucts; during fermentation, 20–50% of the lactose in

milk is hydrolyzed to its component monosacchar-

ides, glucose and galactose, by the starter culture

organisms. The production of b-galactosidase in-

creases during the fermentation of yogurt, reaching

a maximum after 4 h of incubation. This enzyme may

be released from the microbial culture during diges-

tion, thus indicating that it may be present in

the intestine of persons consuming FM. Lactose-

intolerant subjects have a much lower rise in blood

glucose and thus a much lower lactose utilization

efficiency. A lower lactose content would presumably

help tolerance of the product to those with a reduced

ability to digest lactose. But clearly, the explanation is

not this simple, because FM with a fairly high lactose

content is also better tolerated by such individuals

than the equivalent amount of lactose in milk. Lactic

FERMENTED MILKS/Dietary Importance 2391

acid is produced as a byproduct of the fermentation

process. It acts as a preservative, influencing the phys-

ical properties of casein curd by inducing a finer

suspension, which improves the digestibility of

casein. It also improves the utilization of calcium

and other minerals, and inhibits the growth of poten-

tially harmful bacteria.

Effect of Fermentation on Vitamin Content

0010 Milk is a rich source of vitamins, particularly A, D,

and some B-complex vitamins. Breed, diet, climate,

geographical location, age and stage of lactation and

other factors can influence the vitamin content of the

milk and, in turn, affect the vitamin content of

the FM. There is conflicting evidence about whether

there is an increase, decrease, or no change in the level

of vitamins during the fermentation of milk. Various

manufacturing treatments may affect the content

of labile vitamins, whereas there is metabolism of

vitamins by the LAB during the log-growth phase

and their subsequent synthesis by the same bacteria.

An indication of the changes, resulting from heat

treatment, fermentation, and storage, is given by the

International Dairy Federation (1983). The vitamin

content of FM varies with the type of milk used

(particularly the fat content of the milk, which influ-

ences the amount of vitamin A and other fat-soluble

vitamins present), with the strain of bacteria and with

fermentation conditions. Vitamin C is heat- and light-

labile, but it is more stable in the acidic conditions

of FM than in normal milk. The levels of some B-

complex vitamins are reduced, owing to the require-

ment of some of the LAB. Losses of up to 90% of

vitamin B

have been reported with specific bacterial

strains, but losses are not always this great and can be

reduced considerably by the use of a ‘supplementary

culture’ capable of synthesizing significant amounts

of vitamin B

. However, several cultures are able to

synthesize the folic acid, increasing the level of this

vitamin present in the final product; e.g., Propioni-

bacterium freudenreichii ssp. Shermanii, which is

used as a starter culture in some of the cheeses, is

known to synthesize vitamin B

0011 In the current climate, in which there are concerns

about the folate intake of women during the early

stages of pregnancy, this aspect may prove to be a

nutritional advantage. Increases in vitamin B and P

(riboflavenoid) group vitamins have been observed in

kefir, as a result of the activity of yeasts and acetic

acid bacteria. Fermentation has been reported to in-

crease folic acid in buttermilk, sour cream, yogurt,

bifidus milk, kumiss, dahi, lassi, laben, skyr, and kefir.

The effect of fermentation on the vitamin content is

given in Table 3.

Effect of Fermentation on Mineral

Absorption

0012Most experiments performed recently did not con-

firm the improved absorption of calcium because of

the more acid pH in the intestine following consump-

tion of FM. When the bioavailability of essential

minerals and trace elements was investigated in rat

experiments using diets based on milk, yogurt, pas-

teurized yogurt, and a commercial diet, it was ob-

served that the bioavailability (as measured by

intestinal absorption, urinary excretion, and bone

content) of calcium, phosphorus, magnesium, and

zinc from all diets was superior to that from the

commercial diet. In experiments with albino rats,

the availability of calcium and phosphorus from FM

was increased by about 7 and 11%, respectively, com-

pared with milk. These results are explained by the

fact that colloidal calcium complexes and lactic acid,

both present in FM, enhance calcium absorption.

0013Bioactive peptides derived from the tryptic hydro-

lysates of casein, known as caseinophosphopeptides

(CPP) possess physicochemical properties that enable

chelation of various bi- and trivalent minerals to be

carried out, thereby enhancing mineral solubility in

the lower small intestine. It has been suggested that

moderate and exchangeable binding of calcium to

CPP is responsible for the high absorbability of cal-

cium from milk. Results of experiments conducted at

the University of Melbourne School of Dental Studies

have proved that there is a significant reduction in the

tooth decay in laboratory animals fed with CPP.

Nutritional Significance of Single-cell

Proteins in Fermented Milks

0014In recent years, the nutritional importance of micro-

bial cell protein has received considerable attention.

When FM is consumed, a large number of bacterial

cells (about 10

CFU g

1

) and the products released

from these cells enter the digestive tract. Most of the

tbl0003Table 3 Effect of fermentation on vitamin content (mg per 100 g)

Vitamins Whole

milk

Buttermilk Sour

cream

Yogurt Cottage

cheese

Thiamin 30 34 35 44 21

Riboflavin 170 154 149 214 165

Niacin 100 58 67 114 128

Pantothenic acid 300 275 360 591 215

Vitamin B

40 34 16 49 68

Folacin 6 trace 11 11 12

Vitamin B

0.40 0.22 0.30 0.56 0.63

Department of Health (1991) Dietary Reference Values for Food, Energy and

Nutrients for United Kingdom. Report on Health and Social Subjects. London:

HMSO.

2392 FERMENTED MILKS/Dietary Importance

living cells are inactivated in the stomach by the

action of hydrochloric acid and pepsin. It has been

estimated that about 60% of the microbial cell

nitrogen content (excluding cell wall material and

nucleic acids) can be utilized by the body. The EAA

content of microbial cell proteins in FM ranges

from 2.0 to 6.5 mg per 100 g of product. The cells of

some bacteria were found to be rich in methionine,

lysine, and cystine. Studies on amino acid patterns of

acid hydrolysates of microbial cell proteins have

revealed the presence of all the known amino acids.

Cells of mixed cultures contained higher concentra-

tions of many amino acids than those found in cells of

individual cultures. There were also considerable

species variations in the pattern of amino acids in

the microbial cells. When the cells were subjected to

proteolytic enzymes, simulating to some extent the

conditions during passage in the alimentary canal,

significant differences were found between species

with regard to the extent of hydrolysis and concen-

tration of EAA released. Cells of Lactobacillus acid-

ophilus and of mixed cultures of Streptococcus

salivarius ssp. thermophilus and Lactobacillus del-

brueckii ssp. bulgaricus released the highest concen-

trations of EAA. The biological activity of many

EAA in FM protein is much higher than that of cor-

responding amino acids in milk. These results indi-

cate that the microbial cells of starter bacteria

consumed along with FM are likely to be hydrolyzed

partially or fully in the digestive tract, releasing EAA,

and some of the starter cultures are more useful than

others in this respect.

Biological Value of Fermented Milks

0015 The cumulative effect of the available EAA from milk

proteins and from microbial proteins is reflected in

the protein quality (biological value) of the total pro-

tein content isolated from FM prepared with different

cultures. The protein quality of Indian FM, dahi was

assessed by microbiological assay using Streptococcus

zymogenes as the test organism. It was found to be

higher (3–30%) than that of milk used for preparing

dahi. Samples prepared by using mixed cultures of

Lactococcus lactis ssp. lactis, Lc. lactis ssp. cremoris,

Str. salivaricus ssp. thermophilus, and Lb. delbrueckii

ssp. bulgaricus gave higher values than those contain-

ing other cultures. Incorporation of the culture of

Propinobacterium freudenreichii ssp. Shermanii,

along with the starter cultures, produced a further

improvement in protein quality. It has also been

found that there is increased secretion of digestive

enzymes by salivary glands when stimulated by the

curd particles, and that the FM proteins are twice as

digestible as milk proteins.

Biopeptides in Fermented Milks

0016Several of the peptides derived from milk proteins

represent ‘extranutritional’ substances, which display

significant physiological influence. During the micro-

bial fermentations milk proteins undergo controlled

proteolysis under the combined influence of native

microflora (comprising several spore-producers) and

the starter bacteria. In addition, proteinases produced

by the starter organisms could complement the com-

plex enzyme system of starter microorganisms,

leading to the accumulation of beneficial peptides.

Cheeses and processed cheese products, therefore,

offer the potential for developing specialized func-

tional food products displaying prophylactic proper-

ties, besides their natural nutritional virtues. This

represents a hitherto unexplored area of food re-

search, which has tremendous future potential, from

both an academic and commercial perspective.

0017The folklores regarding the nutritional, healthful,

and therapeutic aspects of FM have been amply sub-

stantiated through recent biochemical, nutritional,

and physiological research. With the growing aware-

ness of beneficial attributes of such products, there

has been a tremendous growth of market for probio-

tic FM products in the Western countries, especially

in Japan and developing countries. Prospects for the

genetic modification of starter organisms to enhance

the NV and probiotic attributes have opened challen-

ging vistas for the new product development and

diversification. FM as a potential carrier for natural

source of biological peptides is a fascinating area for

technological development.

See also: Acidophilus Milk; Dahi; Fermented Milks:

Dietary Importance; Yogurt: The Product and its

Manufacture; Yogurt-based Products; Dietary Importance

Further Reading

Buttriss J (1997) Nutritional properties of fermented milk

products. International Journal of Dairy Technology

50(1): 21–27.

Department of Health (1991) Dietary Reference Values for

Food, Energy and Nutrients for United Kingdom.

Report on Health and Social Subjects. London: HMSO.

International Dairy Federation (1983) Cultured Foods in

Human Nutrition. Doc. 159, pp. 18–28.

Khedkar CD and Khedkar GD (1993) Fermented milks:

Dietary importance. In: Encyclopeadia of Food Science,

Technology and Nutrition. Academic Press, London,

pp. 1810–1814.

Mathur BN (1998) Nutrition and probiotic aspects of

cheese and fermented milk products. In: Advances in

Cheese and Fermented Milk Products: A Compendium

of Short Term Course Notes, Karnal, India: National

Dairy Research Institute, pp. 210–217.

FERMENTED MILKS/Dietary Importance 2393

Shahani KM and Chandan RC (1979) Nutritional and

healthful aspects of cultured and culture-containing

dairy foods. Journal of Dairy Science 62: 1685–1694.

Yamauchi K (1992) Biologically functional proteins of milk

and peptides derived from milk proteins. IDF Bulletin

272: 51–58.

Fiber See Dietary Fiber: Properties and Sources; Determination; Physiological Effects; Effects of Fiber on

Absorption; Bran; Energy Value

FIGS

K K Sinha, T.M. Bhagalpur University, Bhagalpur,

India

Background

0001 Along with date, vinifera grape, and olive, the fig was

an important food crop for the ancient civilization of

the eastern Mediterranean region. It has been referred

to in many legends and songs of historical and mytho-

logical background. It has also been mentioned fre-

quently in the Bible. Theophrastus was also familiar

with its several varieties, as is indicated in his ‘En-

quiry into Plants.’

0002 The edible or common fig, Ficus carica L., is a

member of the family Moraceae, which includes more

than 1000 species distributed throughout the world.

Some well-recognized ornamental species of the genus

Ficus include Ficus benghalensis L. (Indian banyan), F.

elastica Roxb. (Indian rubber fig), F. pumila L.

(Climbing fig) and F. religiosa L. (Peepal tree).

0003 The fig is thought to be a native of southern parts of

Arabian peninsula, Italy, the Balkan peninsula, and

Russia. It was brought into cultivation probably in the

southern parts of the Arabian peninsula by 3000 bc.

Later on, it spread into Iraq, Syria, and Turkey, and

into all the Mediterranean countries. During the age

of exploration by Columbus, the fig was taken into

most subtropical areas of the western hemisphere. It

is widely cultivated in the tropical, subtropical, and

warm temperate areas of the world. The major pro-

duction is found in the Mediterranean region, from

Turkey in the east to Spain and Portugal in the west. It

is also grown commercially in parts of the USA and

Chile and, to a small extent, in Arabia, Iran, India,

China, and Japan.

0004 Greece is now the leading fig-producing country,

followed by Algeria, Morocco, Syria, and Italy.

Turkey is, however, the largest producer of dried figs.

General Habit

0005The fig is a small to moderate-sized deciduous tree,

5–8 m high, with a short twisted trunk crowned with

irregular branches. Shoots can also develop fre-

quently at the base of the trunk. The bark is pale

gray. Leaves are broad, ovate or nearly orbicular,

more or less deeply (3–5) lobed, rough above, and

pubescent below, long stalked, leaf blade 10–25 cm

long, dark green with pronounced venation. The

female fig plants have larger, denser, and more

spreading crowns of leaves than males. Moreover,

leaf fall begins earlier in males.

Fruit Morphology

0006Fruits are mostly solitary, axillary, green, yellow

brown, purplish, or even black, depending on the

cultivar and more or less pear-shaped with either a

velvety or glabrous skin. Normally, these fruits are of

moderate size, but in certain cultivars, these may be

up to 6 cm in diameter. The plastid pigments in the

fruit skin of fig are chlorophyl a and b, b-carotene,

lutein, violaxanthin, and neoxanthin.

0007The edible fig is a multiple fruit that is botanically

known as syconium. It consists of a fleshy hollow

receptacle with a narrow aperture at the tip and

numerous small flowers lining the inner surface. The

true fruits, which are small achenes, are borne on

short stalks on the inside of the syconium (Figure 1).

Types and Cultivars

0008Depending upon the nature of the flowers and the

method of pollination, figs can be cronologically dis-

tinguished into four different classes:

0009Common fig or Adriatic fig

0010Caprifig

0011Smyrna fig

0012San Pedro fig.

2394 FIGS

Common Fig

0013 In this type, the individual flowers are pistillate

(female), and consequently, the fruits develop without

pollination and fertilization (parthenocarpic) andhave

no seeds. Two crops are produced annually. The first

crop (brebas) is larger and more juicy, and is usually

eaten fresh. The fruits are borne on the old wood. The

second crop is produced in the axils of the leaves, and

the fruits are used fresh or dried. Some common culti-

vars of this type are Kadota (Dottato), Mission, Adri-

atic, Brown Turkey, Celeste, and Conadria.

Caprifig

0014 The caprifigs are wild figs that grow naturally in the

Mediterranean region and Western Asia and probably

represent the primitive type. Although the fruits do

not have any commercial value, they are cultivated in

most fig-raising countries, as they are essential for the

development of Smyrna fig. The life history of the

caprifig is closely connected with that of a small

wasp (Blastophaga psenes), which brings about

cross-pollination.

0015Caprifigs produce three crops of fruit in a year.

The spring crop (Profichi) contains staminate (male)

flowers and the so-called gall flowers. These are

similar to pistillate flowers but have short-styled

ovaries. The fig wasp enters the young figs and lays

eggs in the gall flowers. In about 2 months, the new

generation of wasps hatches out and emerges from the

fig having pollen grains throughout the body surfaces.

By this time, the summer crop of figs (Mammoni) are

produced, which contain mostly gall flowers. The

wasps again enter these figs and deposit eggs in most

of them. Although these flowers are pollinated by

wasps, the presence of the larvae without eggs may

develop fertile seeds. Late in the season, the winter

crop of figs (Mamme) is developed and remain on the

tree over winter after the wasps visit on them. The

larvae mature in April, when a new crop of spring fig

is ready to receive the wasps, and the annual cycle is

resumed.

Female

(long style)

flower

Female

(short style)

flower

Male flower

Scales

(a)

(b) (c)

Ostiole (opening)

fig0001 Figure 1 Longitudinal sections of fig fruits. (a) Edible fig fruit. (b) Edible fig fruit (diagrammatic). (c) Capri fig fruit (diagrammatic).

FIGS 2395

Smyrna Fig

0016 No staminate flowers are produced in Smyrna figs,

and these are absolutely dependent on cross-

pollination from caprifigs. This process is known

as ‘caprification’ and is brought about artificially.

Branches of caprifigs of the spring crop are suspended

on the Smyrna tree. The wasps coming from Spring

crop enter the developing Smyrna figs and affect pol-

lination. The ovaries of Smyrna figs have longer styles

that prevent the wasp from depositing eggs at the

proper site. The ovules thus develop normally after

fertilization. Smyrna figs have a superior nutty flavor

owing to the presence of fertile seeds. They are the

most important fig of commercial value and are

extensively cultivated in Asia Minor, Greece, Algeria,

and parts of Portugal and California. Early attempts

to cultivate Smyrna figs in California and other places

met with continued failure until the spring crop of

caprifigs and the fig wasp were introduced. Cali-

myrna is the most common and widely grown cultivar

of Smyrna type. Some cultivars like Krymskii 43 and

Bianco Grosso have also been recommended for

cultivation in Southern Uzbekistan.

San Pedro Fig

0017 This is an intermediate type of fig that has two crops

annually. Like the common fig, the first crop (breba) is

completely parthenocarpic and does not require pol-

lination and fertilization of flowers, but the second

crop develops only when the flowers are pollinated,

as in the case of Smyrna fig. San Pedro, King, and

Gentile are some of the common cultivars of this type.

0018 The common fig is the only type that is grown in

India. It is considered to be a hybrid between the

imported F. carica and the indigenous species. A

large number of cultivated forms are known in which

the fruits vary in shape, size, color of skin, color and

flavor of flesh, and period of ripening. Some of the

cultivars grown in India are Black Ischia, Brown

Turkey, Turkish White, Kabul, and Marseilles. The

figs grown in many parts of India are named after the

locality and exhibit no special distinction to warrant

varietal names. Poona fig is of a medium size, bell-

shaped and light purple in color with a rosy flesh. In

South India, Poona fig and Marseilles are commonly

cultivated, the latter thriving well on the hills above

1500 m. The fruits of Marseilles are medium-sized

and pale green on the rind with a whitish sweet flesh.

Fig Cultivation

Soil

0019 The fig tree does not require a very rich soil for

cultivation. Alluvial or loamy soil or yellow or

reddish brown colour, with a rocky or murum bed,

prevents the roots from penetrating deep into the soil,

and favors the side-growth of rootlets, which is very

desirable. Fig trees also thrive well in clayey soil, but

the land must be well drained. Rich black soil is

unsuited to fig trees because the plant grows tall and

runs to leaf, and the fruit is considerably inferior in

both size and taste.

0020The fig is also one of the salt- and drought-tolerant

crops. It can tolerate a fairly high level of sulfate or

chloride salts, but it can be injured when even a small

amount of sodium carbonate is present in the soil. In

highly alkaline soil, the leaves show tip burn, and

there is considerable leaf fall. A red loam with a live

substratum and about a meter deep is considered best

for figs in South India.

0021Heavy and poorly drained soils usually produce

fruits of inferior quality. Soils with a high lime content

produce fruits of better quality suitable for drying.

Climate

0022The fig is a subtropical fruit. In the dormant condi-

tion, the mature trees can withstand temperatures as

low as 12 to 9.5



C depending upon the cultivar,

but the young trees may have to be protected during

winter because they are not very hardy. Low tempera-

tures of about 1.5–4.5



C at the time when the trees

are not dormant are very much damaging. Similarly,

early autumn frost or spring frost when the plant

starts sprouting causes considerable damage to the

tree. In India, the temperature of commercial fig

growing areas in Southern and Western parts of the

country seldom falls below 4–5



C, and therefore,

there is no damage resulting from low temperatures.

In Northern India, where the temperature falls to

freezing, the plants remain dormant at that time and

normally are not damaged. Figs grow well when the

temperature range is 15.5–21



0023The climate also greatly influences the character-

istics of fig fruits. It affects the shape and size of

the fruit, as well as the color of the skin and pulp,

quality, and tendency towards parthenocarpy. The

best-quality figs are produced in regions with a dry

climate, especially at the time of fruit development

and maturation. High humidity coupled with a low

temperature usually results in fruit splitting and a

lower fruit quality. Fruits exposed to warm breezes

in hot areas, though slightly sweeter, remain small in

size. By contrast, mild temperatures result in large,

succulent fruits.

Propagation

0024The plant is readily propagated by cuttings, although

all types of budding and grafting as well as air-layering

2396 FIGS

are successful. Hardwood cuttings, 20–30 cm long

and 0.5–0.7 cm thick, taken from 1–2-year-old shoots

in late summer are selected for this purpose. These

cuttings are treated with root-promoting substances,

stored in packing material like sawdust at room tem-

perature for about 4 weeks, and then planted. Cut-

tings taken from the base of the shoot and lower part

of the crown give better results. In about 2 months,

they begin to throw roots and shoots and make a few

leaves. If they are properly taken care of, the plants

become fit after a year for transplantation, otherwise

they may take a further 10–12 months. After a 12–15

months, they are transplanted into orchards. The

spacing varies depending upon the size of the tree,

variety, and type of culture adopted.

0025 Figs can also be air-layered successfully, and mon-

soon is the best time for it. One-year-old branches, if

layered in June, can be planted in the field in August–

September. Top working to change the variety of

established trees is sometimes possible and may be

done by shield or patch budding or cleft or bark

grafting. Micropropagation of figs is also possible.

Pruning and Training

0026 Fig trees are pruned annually and trained to the de-

sired height and shape to keep the plant most pro-

ductive and to facilitate harvesting and other orchard

operations. As the tree normally bears two crops in a

year, the first pruning is done on the wood of the

previous season and the second on new wood of

the current season; the time and the amount of

pruning are adjusted according to the type, habit

of growth, and bearing capacity of the tree. The

main aim of pruning is to induce the growth of fruit

bearing wood and so improve the yield of fruits. In

addition, pruning increases the fruit weight in early

cultivars. Besides pruning, some special methods like

notching are also adopted to stimulate the production

of laterals on vigorous upright branches.

Irrigation and Manuring

0027 Fig is fairly drought-resistant, and it is seldom irri-

gated in many fig-growing countries. However,

reports from Cairo indicate a greater shoot growth

and yield of fruits in irrigated fig plants. In some

cases, fruits from irrigated trees have been found to

13–16% heavier. In India, the fig is irrigated only

during dry months. However, care should be taken

that at the time of ripening of fruits, no irrigation is

given, because that may result in the production of

insipid fruits. Excessive water in the soil may also

cause splitting of fruits. The plant also responds to

manuring, but the type and amount of manure vary in

different areas.

Fruit Development and Harvesting

0028The fig tree begins to bear a fair crop from the second

or third year after planting, though rooted cuttings

and layered plants are known to bear fruits even in

the first year of planting. Under favorable conditions,

the trees continue to bear fruits for 12–15 years, after

which they show a marked decline in yield. Normally,

the trees bear two crops in a year, but in some types,

even a third crop is obtained.

0029The figs commonly grown in India are partheno-

carpic in nature and do not need any cross-pollination

with wild caprifig (caprification), which is very

common practice in other countries. However, fruit

setting is also inhibited under certain conditions. It

has been suggested that parthenocarpy is favored or

inhibited in a given type by climatic condition of the

growing area. The parthenocarpic fruits develop to a

normal size and have a desired sugar content, but as

they are completely seedless, the baking industries do

not want to use it, because they lack the crunchy

quality imparted by fig seeds.

0030As fresh figs are extremely perishable, fully ripe

fruits cannot be transported to distant markets. It is

better to harvest the crop when the fruits are slightly

immature (ripened). Ripe fruits are picked either from

the tree by twisting the neck at the stem end or by

cutting it or gathered after they drop on the ground.

In the major fig-growing countries, special devices are

employed for collecting fruits from the tree, and the

pickers are protected against the acrid juice.

Drying

0031Fresh figs do not keep well even under cold storage



C) for more than a month. Fully matured figs can

be either frozen or dried if they have to retain their

flavor and color for several months. Details of the

process of drying and curing differ in different

countries depending largely upon the variations in

varieties cultivated.

0032Dried figs are the most important fruit product of

fig. In one method of drying, the fruits are firstly

subjected to sulfur fumigation and then dried in an

electric drier at a temperature of 70–72



C. In another

method, the fruits are initially soaked in boiling salt

water for 30 s, then dried for few hours in the sun and

for 8 days in the shade.

Pests, Diseases, and Disorders

0033The following major pests have been reported from

fig trees:

0034Stem-boring beetles (Batocera rufomaculata,

B. rubrus)

0035Leaf defoliators (Adoratus duvauceli, A. versutus)

FIGS 2397