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management efficacy while reducing the farmer’s re-

liance on and use of various pesticides and increasing

crop yield. Herbicide tolerance in crops allows

farmers to manage weeds more effectively and with

the use of fewer herbicides.

0007 Figure 1 shows the increase in acreage planted

worldwide in genetically improved crops from 1996

to 2001. Thirteen countries (USA, Argentina, Canada,

China, Australia, South Africa, Mexico, Spain,

France, Portugal, Romania, Bulgaria, and Ukraine)

grew nine crops (soybean, corn, cotton, canola,

potato, squash, papaya, tomato, and tobacco) com-

mercially in 2001. Over 65% of the soybeans, 65% of

the cotton, and 25% of the corn grown in the USA in

2000 were genetically improved, while over 95% of

the soybeans grown in Argentina were genetically

improved (James 2001).

Safety Assessment Process and Regulations for

Foods Derived from Genetically Improved Crops

0008 As plant biotechnology products have been de-

veloped, so have national and international regula-

tory oversight measures for them. Appropriate

scientific procedures to assess the safety of products

from crop biotechnology have been developed over

the past decade by scientists and regulatory agencies,

including the United Nations (UN) Food and Agricul-

ture Organization (FAO), the UN World Health Or-

ganization (WHO), the Organization for Economic

Cooperation and Development (OECD), the US Food

and Drug Administration (FDA) and others. There is

general consensus among scientists on the approach

used and information appropriate to assess the safety

of foods and feeds from genetically improved plants.

These procedures focus on the safety of the final

product.

0009The majority of food and feed products from gen-

etically improved plants introduced to date have been

shown to be compositionally and nutritionally com-

parable (i.e., ‘substantially equivalent’) to the parent

crops, with the exception of the introduced trait(s).

Additional safety assessments have focused on the

safety of the expressed protein and any products

resulting from it. The safety of the protein conferring

the desired trait is assessed via internationally

accepted procedures, including characterization of

the function, specificity, and history of consumption

of the same or related proteins, estimation of the level

of consumption of the protein, assessment of digest-

ibility, and appropriate animal toxicology studies.

Special attention is paid to insure that the introduced

protein is not allergenic and does not share physico-

chemical properties of allergenic proteins. Once food

or feed from a crop has been shown to be substan-

tially equivalent to its traditional counterpart except

for the introduced trait, and the trait has been shown

to raise no safety concerns, the crop (following ap-

propriate regulatory review) may be introduced into

the marketplace with the same degree of safety assur-

ance as those products derived from their traditional

counterparts.

1996

100

120

140

1997 1998

M acres

1999 2000 2001

Other crops Canola Cotton

Corn Soybean

3.4

2.9

7.8

12.2

6.2

5.9

20.3

35.5

9.3

8.5

12.3

7.3

24.6

7.0

23.4

79.5

61.6

15.8

fig0001 Figure 1 Worldwide acreage (millions) of genetically improved crops planted in 1996 to 2001. Information derived from James C

(2001) Global Review of Commercialized Transgenic Crops: 2001 Preview ISAAA Brief 24–2001. Ithaca, NY: ISAAA.

2878 GENETICALLY MODIFIED FOODS

0010 Table 2 summarizes the information typically pro-

vided to regulatory authorities to demonstrate the

food, feed, and environmental safety of genetically

improved plants and plant products.

0011 In the USA three federal agencies have the authority

to regulate biotechnology. The FDA maintains

authority to insure the food and feed safety of the

products of plant biotechnology; the US Department

of Agriculture (USDA) has the authority to insure that

these plants do not present any plant pest risks; and

the Environmental Protection Agency (EPA) has the

authority to assess the safety of plants that produce a

pesticidal substance (e.g., plants protected against

insects, fungi, or viruses). The EPA also maintains

authority over herbicides used in conjunction with

herbicide-tolerant plants.

0012In the FDA’s 1992 document Statement of Policy:

Foods Derived from New Plant Varieties, as well as in

the international documents from the FAO, WHO,

OECD, and other organizations, there is a general

consensus that foods derived from genetically im-

proved plants do not pose any unique safety concerns.

The FDA regulates these products in the same way as

food and feed products derived from traditionally

bred plant varieties.

0013Other countries, such as Canada, Japan, Korea,

South Africa, Switzerland, and Australia also have

specific regulations for genetically engineered plant

products. In the European Union, the primary control

is Directive 2001/18 EEC, which regulates the release

of genetically modified organisms (GMO) into the

environment. The foods and feeds produced from

these GMO are regulated via the Novel Foods Regu-

lation, which requires that before a novel food is

marketed, manufacturers must document that the

new food does not present a new safety or nutritional

risk. Other countries are also developing regulations

for these products.

Food Quality Enhancements

0014Although most of the initial genetically improved

plant products have improved agronomic traits, the

first plant biotechnology product marketed in the

USA, the Flavr Savr tomato, was developed to allow

the fruit to ripen longer on the vine and have an

increased shelf-life. Many additional products with

improved quality or nutritional properties are under

development (Table 3).

0015Carbohydrates Modifications in the composition

and total amount of starch have been achieved via

tbl0002 Table 2 Data typically provided to regulatory agencies to

support the food, feed, and environmental safety of genetically

improved plants and plant products

Food/feed safety assessment

Molecular characterization

Gene source

Transformation system

Insert number

Copy number

Integrity of each inserted genetic element (promoter, coding

sequence, polyadenylation sequence)

Genetic stability

Protein safety assessment

Source

Host/processing

Protein expression levels/consumption

History of use of same/similar protein

Safety to nontarget organisms

Function/specificity/mode of action

Homology to known toxins/allergens

Digestibility

Potential toxicity testing (case by case)

Allergenicity assessment

Marker gene/protein safety

Nutritional equivalence

Identification of key nutrients

Levels of key nutrients relative to traditional counterpart

Anticipated uses relative to historical uses

Nutritional assessment of expressed trait (e.g., modified oil,

carbohydrate, etc.)

In vitro/in vivo nutritional/animal wholesomeness studies

(case by case)

Toxicological assessment

Identification of key antinutrients/toxicants in host or

organisms related to host

Levels of key antinutrients relative to traditional counterpart

Toxicological assessment of expressed trait

Environmental safety assessment

Molecular characterization (as above)

Outcrossing/gene flow (potential/impact)

Weediness

Competitiveness/survivability/dormancy

Morphological/phenotypic characteristics

Insect/disease susceptibility

Impact on nontarget organisms

Agronomic performance

Resistance management (where appropriate)

tbl0003Table 3 Products from plants improved to contain improved

nutritional or quality traits

High-oleic-acid vegetable oils

High-stearate vegetable oils to replace the hydrogenated oils

and reduce trans fatty acids

Canola oil high in beta-carotene

Corn and soy with increased levels of lysine, tryptophan,

methionine

Corn, rice, wheat, and potato with improved starch

characteristics

Rice high in beta-carotene and iron

Sweet potatoes with improved protein quality

Ripening-controlled papayas, cherry tomatoes, bananas,

strawberries, and pineapples

Tomatoes with increased lycopene

Soybean with increased vitamin E

GENETICALLY MODIFIED FOODS 2879

biotechnology. For example, amylose-free, amylopec-

tin-enriched potatoes have been produced by inhibit-

ing the production of granule-bound starch synthase

to produce starch preferred for specific industrial

applications. It was recently reported that by introduc-

ing photosynthetic genes from corn into rice, yield

increases of up to 25% were observed in new rice

varieties. In addition, by redirecting the flow of

carbon from starch biosynthesis, increases in sucrose

content and production of new components like

fructans or other sweeteners also can be realized.

0016 Oils Plant biotechnology efforts have focused

largely on altering the fatty acid composition of

canola, soybeans, corn, and sunflowers, all major

sources of dietary oils, to provide either more oxida-

tively stable oils or oils with enhanced nutritional

characteristics. A genetically improved soybean with

increased levels of oleic acid, a monounsaturated

fatty acid, and reduced levels of polyunsaturated

fatty acids has also been produced. Because this prod-

uct is more stable, it does not require hydrogenation,

thereby eliminating the production of trans fatty

acids which have been linked to cardiovascular

disease. Modification of other fatty acids, such as

stearate, is also being evaluated for improved

human health.

0017 Proteins Foods that provide sufficient quantities

of essential amino acids are critical to meet dietary

needs, especially in developing countries where foods

low in one or more of these amino acids are often

relied upon as staples of the diet. Approaches to

increase the amount of lysine in cereals and methio-

nine in legumes are being assessed. For example, total

lysine content of canola and soybean was increased

two- and fivefold, respectively, by expressing non-

feedback-inhibited forms of two key enzymes in

lysine biosynthesis. A two- to threefold increase in

the total lysine content of corn was also obtained

using the same approach. These changes are import-

ant both from a human nutritional perspective as well

as for improved animal feeds, eliminating or decreas-

ing the need to provide supplemental lysine to animal

rations.

0018 Vitamins/minerals Research efforts to increase the

levels of certain vitamins and minerals in genetically

improved crops are ongoing. In developing countries

where malnutrition is a major concern, enhancing

these components in staple foods may improve nutri-

tional status and reduce disease. These projects

include increasing the levels of beta-carotene, the

precursor of vitamin A, vitamin D, iron, lycopene,

folate, and other nutrients. The most exciting of

these research programs is the production of a variety

of rice with significantly increased levels of beta-

carotene and iron in a more bioavailable form. Con-

sumption of a typical serving of 300 g day

1

of this

rice could help reduce both xerophthalmia and iron-

deficiency anemia, which are devastating nutritional

problems in the developing world. Over 2 million

children die annually from vitamin A-related illness

and over 3.7 billion people globally have a deficiency

in iron intake. A canola variety with greatly increased

levels of beta-carotene in the oil has also been

developed.

0019Eliminating undesirable food components Plant

biotechnology can reduce a number of undesirable

food components, such as one of the major allergenic

proteins in rice or the major allergens in peanut or

soybeans. Other efforts to eliminate allergens in foods

by modifying their amino acid sequences have also

proven successful. Efforts to reduce or eliminate other

undesirable components of foods, e.g., glucosinolates

in canola meal, protease inhibitors in beans, glycoalk-

aloids in potatoes and mycotoxins in corn, are being

evaluated. Components such as caffeine from coffee

beans can be eliminated or reduced to provide a

coffee with no or a very low caffeine level without

using chemical extraction.

Impact of Genetically Improved Crops on

Agriculture

Insect Protection

0020Insect pests, which can cause tremendous damage to

agronomically important crops, typically have been

controlled by a variety of chemical insecticides. Yet

20–30% of total crop product is still lost due to these

pests. Thus, genetically improved plants containing

insecticidal genes from microbes which have been

used safely as microbial insecticides for over four

decades were developed to improve the efficiency of

pest management.

0021Approximately four million acres of insect-

protected cotton varieties were grown in the USA in

1999 and 2000. Use of these varieties significantly

reduced the use of chemical insecticides (by over

two million pounds annually in the USA alone), sig-

nificantly increased cotton lint production, and also

increased the number of beneficial insects compared

to fields treated with chemical insecticides due to

increased specificity of the pesticidal protein. US

farmers realized significant economic value, aver-

aging about $40 per acre increase in income. Data

from developing countries show even greater benefits;

for example, insect-protected cotton in China allowed

2880 GENETICALLY MODIFIED FOODS

reduction of chemical insecticide use by approxi-

mately 80% and reduced applications from an aver-

age of 15 to less than one per season and increased

yields by approximately 25%.

0022 Potato plants protected against Colorado potato

beetle, the most damaging potato insect pest, were

planted commercially in 1996. Growers used ap-

proximately 35% less insecticide to control this beetle

compared to growers planting nongenetically pro-

tected varieties. In 1999, two new products were

introduced which combined protection against the

Colorado potato beetle with resistance to either

potato leaf roll virus or to potato virus Y, two major

viral diseases for potato. These products essentially

eliminate the need for chemical insecticide use for

potato production.

0023 In 1999 and 2000 approximately 25% of the corn

planted in the USA was genetically improved to resist

pests. An additional advantage of this genetic modifi-

cation is that the protection of corn ears from pests

also drastically reduces the amount of secondary in-

fection caused by the fungus Fusarium. The ability to

control Fusarium results in up to 95% reduction of

the level of the mycotoxin fumonisin under some

environmental conditions. Fumonisin is known to

cause adverse health effects in swine, horses, rodents,

and humans. Significant reductions in fumonisin on

insect-protected corn have been demonstrated in a

number of countries, including the USA, France,

Italy, and Argentina.

Virus Protection

0024 Virus-resistant plants have been produced by using

genes derived directly from the virus – so-called

pathogen-derived resistance. The first genetically im-

proved plant, tobacco with increased resistance to

tobacco mosaic virus (TMV), resulted from the ex-

pression of the TMV coat protein in tobacco. This

coat protein-mediated resistance has been used exten-

sively to confer viral resistance to numerous food

crops, including tomato, squash, melon, papaya,

sweet potato, and potato. Squash varieties resistant

to zucchini yellow mosaic virus (ZYMV) and water-

melon mosaic virus (WMV) were approved in the

USA in 1995 and marketed. These two viruses rou-

tinely reduce crop yields by 20–80% depending on

production season and growing region. More re-

cently, squash plants resistant to these two viruses

plus a third destructive virus, cucumber mosaic virus

(CMV), were developed. Marketing of these products

will allow the more consistent production of squash

varieties with significant reductions in the use of

chemical insecticides that are typically required to

control virus spread by insects. Coat protein genes

have also been used to confer resistance to papaya

ringspot virus (PRSV) in Hawaii, and to sweet potato

feathery mottle virus (SPFMV) in Kenya. Resistance

to PRSV has essentially saved papaya production in

Hawaii, while resistance to SPFMV has the potential

to increase yields in Kenya by up to 80%, based on

reported yield losses attributed to this virus.

Selectivity to Herbicides

0025Weeds are one of the major agricultural pests that can

devastate a crop. Weeds compete with crops and

reduce yield, decrease harvest efficiency, decrease

seed quality, and serve as a reservoir for pests. Agri-

cultural practices used prior to World War II were

labor-intensive and contributed to soil erosion. These

processes have been replaced by the use of chemical

herbicides that are the most effective, reliable, and

economic method of controlling weeds on a large

scale. Today herbicides are used on essentially 100%

of the acreage of the major agronomic crops in

developed countries.

0026Traditionally, herbicides are selected based on

the weeds to be controlled and the natural resistance

of the crop to the herbicide. Biotechnology provides

an opportunity to modify crops so they tolerate

selected herbicides with preferred environmental

properties, such as glyphosate. These herbicide-

tolerant crops allow the farmer to apply herbicide

to planted fields, killing weeds but leaving the

crop unaffected. This ability provides increased

flexibility and cost savings to growers. In addition,

farmers can move from using preemergent, soil-

incorporated herbicides to postemergent herbicides

that are applied on an ‘as-needed’ basis. This strategy

can reduce the number and total amount of herbicides

used and enables the application of herbicides

that bind tightly to the soil and are less likely to

enter the groundwater, thereby providing environ-

mental benefits and encouraging the use of reduced-

tillage agriculture.

0027Soybeans, canola, cotton, and corn tolerant to

glyphosate, and canola and corn tolerant to phos-

phinotricin are examples of herbicide-tolerant crops

(Table 1). When introduced in 1996, glyphosate-

tolerant soybeans were planted on only 1.5% of the

US soybean acres. Because of exceptional weed con-

trol and crop safety, these soybeans were rapidly

adopted. Approximately 75% of the growers used

only one herbicide application, providing a reduction

in the amount and number of herbicides used

compared to soybeans treated with conventional

herbicide programs. By 1999 greater than 65% of

the US soybeans, and over 95% of Argentinian soy-

beans in 2001, were glyphosate-tolerant.

GENETICALLY MODIFIED FOODS 2881

Plants as Production Factories

002 8 Plants provide an unmatched capacity to produce

products with a maximum efficiency and a minimum

of energy – thus, cost-effectively. Plants can be bio-

engineered to produce insecticidal proteins using just

carbon dioxide, water, and nitrogen, thereby reducing

the need for expensive and energy-intensive chemical

insecticide manufacturing. The potato which has

been developed to produce proteins that protect it

from both the Colorado potato beetle and the potato

leaf roll virus is an excellent example. The combin-

ation of these two traits enables potatoes to be grown

without the application of chemical insecticides and

will result in environmental and economic savings.

Approximately 5 million pounds of chemical insecti-

cides are used to control these pests annually in the

USA, and 2.5 million pounds of waste are generated

in the production process. Less than 5% of the ap-

plied insecticide actually reaches the pest. Using the

plant to produce these pesticides is more energy-

efficient and environmentally acceptable.

0029 One of the most exciting applications of plant bio-

technology is the ability to produce edible vaccines in

plants. For example, transgenic potatoes containing

the nontoxic binding subunit of the E. coli entero-

toxin as well as transgenic potatoes which express the

capsid protein of Norwalk virus have been produced.

The expressed proteins function as oral immunogens

in humans which, if effective, could immunize people

against the diarrheal diseases caused by these organ-

isms. Efforts are under way to introduce such vac-

cines into banana, which would be eaten raw and

thus serve as an ideal source to deliver this technology

to developing countries, where inexpensive vaccines

are urgently needed.

0030 Improving crop yields is essential to meeting the

increased food demands of an ever-increasing world

population. Improving crop protection from pests

and increasing crop yields through herbicide toler-

ance are two strategies that will help meet this need.

Biotechnological enhancements of crops can insure

that these changes occur quickly enough to meet

global food needs. At the same time, agricultural

biotechnology has advantages for the environment

in terms of reductions in soil erosion and tilling, and

less agricultural chemical use and run-off. The first

generation of crops developed via biotechnology

provides these agronomic and environmental bene-

fits. The next generation of products is expected to

provide greater direct consumer benefits, such as

enhanced food quality and nutritional value.

Seealso: Biotechnology in Food Production; Food

Safety; Rape Seed Oil/Canola; Retinol:Propertiesand

Determination;Physiology; Rice; Soy (Soya) Beans:The

Crop; Rape Seed Oil/Canola

Further Reading

American Council on Science and Health (2000) Biotech-

nology and Food, 2nd edn. http://www.acsh.org.

Gianessi LP and Carpenter JE (1999) Agricultural Biotech-

nology: Insect Control Benefits. Washington, DC:

National Center for Food and Agricultural Policy,

http://ncfap.org.

Hammond BG and Fuchs RL (1999) Safety evaluation for

new varieties of food crops developed through biotech-

nology. In: Thomas JA (ed.) Biotechnology and Safety

Assessment, pp. 61–79. Philadelphia, PA: Taylor &

Francis.

IFT (2000) Expert report on biotechnology and foods. Food

Technology 54: 124–136; 54 (9): 53–74; 54 (10): 61–80.

James C (2001) Global Review of Commercialized Trans-

genic Crops: 2001 Preview, ISAAA Brief 24: 1–20

Ithaca, NY: ISAAA.

Kendall HW, Beachy R, Eisner T et al. (1997) World Bank:

Bioengineering of Crops. Report of the World Bank

Panel on Transgenic Crops. Environmentally and So-

cially Sustainable Development Studies and Monograph

Series no. 23. http://www.worldbank.org.

Metcalfe DD, Astwood JD, Townsend R, Sampson HA,

Taylor SL and Fuchs RL (1996) Assessment of the aller-

genic potential of foods derived from genetically engin-

eered crop plants. Critical Reviews in Food Science and

Nutrition 36: S165–S186.

Organization for Economic Cooperation and Development

(1997) OECD Documents. Report of the OECD Work-

shop on the Toxicological and Nutritional Testing of

Novel Foods. Paris, 1997; Report of the OECD Task

Force for the Safety of Novel Foods and Feeds – Oki-

nawa, Japan. 2000 http://www.oecd.org/subject/

biotech/report_taskforce.pdf.

Royal Society of London, USA National Academy of Sci-

ences, Brazilian Academy of Sciences, Chinese Academy

of Sciences, Indian National Academy of Sciences,

Mexican Academy of Sciences, and the Third World

Academy of Sciences Transgenic Plants and World Agri-

culture (2000) http://www.royalsoc.ac.uk.

World Health Organization (2000) Safety Aspects of Gen-

etically Modified Foods of Plant Origin. Report of a

Joint FAO/WHO Consultation. Geneva, Switzerland:

World Health Organization.

Geriatrics See Elderly: Nutritional Status; Nutritionally Related Problems; Nutritional Management of

Geriatric Patients

2882 GENETICALLY MODIFIED FOODS

GHEE

G S Rajorhia, National Dairy Research Institute,

Karnal, India

This article is reproduced from Encyclopedia of Food Science,

Introduction

0001 Ghee (synonyms: ghrit, ghritam, havi, rognezard,

samn, samna, maslea) is a milk-fat product originally

produced in India. The origin of gheemaking lies far

beyond recorded history. Indian epics and Vedas

relate it to third-century bc. Ghee is also marketed

in Australia, Armenia, many African and Asian

countries, Belgium, The Netherlands, New Zealand,

the UK, and the USA. ‘Ghee’ is the Indian name for

clarified butterfat, and it is usually prepared from

cows’ milk, buffalo milk, or mixed milks. Milk is

separated into cream, which may be directly con-

verted into ghee, or it can be first converted into

butter and then into ghee. Milk of other mammals,

such as goat, sheep, and camel, can also be used.

Cream or butter is heated at a temperature sufficient

to evaporate nearly all the moisture content, and to

produce the characteristic flavor. Heating destroys

most of the microorganisms and enzymes. Low

water activity hampers the growth of organisms

that survive heat treatment or those recontaminat-

ing the product. The suspended curd particles are

either filtered off or removed by centrifugation.

The clear butterfat is cooled to develop a special

physical structure by a controlled crystallization

process. (See Buffalo: Milk; Milk: Dietary Import-

ance; Sheep: Milk.)

Mode of Ghee Utilization

0002 The butterfat in milk is largely used in the form of

ghee, as this method of utilization admirably suits the

climatic conditions and food habits prevailing in the

tropics and the subtropics. It does away with the need

for elaborate arrangements which would otherwise

be required for the manufacture and storage of table

butter. It is an effective way of avoiding the risk of

microbial and chemical deterioration incidental to

holding butter at relatively high temperatures.

0003 There are regional and seasonal variations in the

mode of ghee utilization which can largely be influ-

enced by local food habits, price structure, number of

festivals, and image of the product as a nutritional

supplement. A major portion of ghee is utilized for

culinary purposes. This may cover its extensive use

for the direct dressing of food articles, such as

unleavened breads, cooked rice, and lentils (dhal),

for flavoring, and as a cooking and frying medium.

About 60–70% of the total ghee in India is used for

direct dressing, and almost 15–20% for the cooking

and frying of foods. A significant quantity of ghee is

used by confectioners and bakers. Ghee is recognized

as a sacred article, and approximately 5–7% is used

in religious rites, such as the burning of ghee dips,

lighting of the sacred fire in yaganas, preparation of

sacred offerings and prasadam, and even for crema-

tion of dead bodies. It is conjectured that ahutis

(burning of ghee in religious functions) purifies the

air. This practice is considered environmentally safe.

Other usages of ghee of minor significance include

ladies’ hair dressing, body massage of wrestlers, ath-

letes, and invalids, and in the formulation of indigen-

ous pharmaceutical drugs. Ghee is also used for

flavoring snuff by mixing and grinding to a very fine

powder.

Method of Manufacture

0004The methods of ghee manufacture vary according to

the base material used (milk, cream, butter), inter-

mediate treatment of raw materials, and handling of

the semifinished or fully formed ghee. There are four

methods for the production of ghee which are essen-

tially based on batch operation:

0005the indigenous milk–butter process

0006direct cream (DC) method

0007the creamery butter (CB) method

0008prestratification (PS) method

These methods are suitable for the different scales of

production.

Indigenous Milk–Butter Process

0009The indigenous methods of gheemaking usually

involve: (1) direct churning of raw milk; (2) lactic

acid fermentation of heat-treated milk followed

by churning; or (3) removal of thick clotted-cream

layers (malai); from continuously heated milk at

temperatures around 80



C followed by grinding of

clotted cream, its dispersal in water and, finally,

churning. In methods (1) and (2), milk is churned

every day. Hand-driven wooden beaters are usually

employed for separating the butter. After accumulat-

ing sufficient quantity over a period of a few days, the

butter is melted in a metal pan or earthenware vessel

on an open fire until almost all the moisture has been

GHEE 2883

removed. The extent of frothing may be used as an

index to judge when to terminate heating. After

heating, the contents are left undisturbed. When the

curd particles have settled at the bottom of the pan,

the clear fat is carefully decanted off into ghee storage

vessels.

0010 The traditional gheemaking practice contributes

about 90% of the total ghee production in India.

This method leaves behind a large quantity of butter-

milk of varying quality, and also leads to low fat

recoveries (75–85%). This is why modern dairies

do not use the indigenous method of gheemaking.

However, village ghee constitutes the major share of

the base material used for the blending operations at

ghee grading and packing centers functioning under

the Agricultural Marketing Grading (AGMARK)

scheme in India. (See Lactic Acid Bacteria.)

Direct Cream Method

0011 The small dairies use a technologically improved

method for gheemaking which involves the separ-

ation of cream from milk by centrifugation. This

process omits the need for production of butter be-

cause cream is directly converted into ghee. The fresh

cream, cultured cream, or washed cream is heated to

115



C in a stainless-steel, jacketed ghee kettle fitted

with an agitator, steam control valve, pressure and

temperature gages and a movable, hollow, stainless-

steel tube centrally bored for emptying out the con-

tents. Alternatively, provision can be made for a

tilting device on the ghee kettle to decant off the

product. Heating is discontinued as soon as the

color of the ghee residue turns to golden yellow or

light brown. One of the limitations of the DC method

is that it requires a long heating time to remove the

moisture. A high content of serum solids in the cream

may also produce a highly caramelized flavor in

the ghee, and lead to about 4–6% loss of butterfat

in the ghee residue or during handling operations,

depending upon the fat percentage in the cream. The

use of plastic cream or washed cream with about

75–80% fat is recommended for minimizing both

fat loss and steam consumption. The final product

will have a less intense cooked flavor when low-

solids not fat (SNF) cream is used.

Creamery Butter Method

0012 Most dairies use unsalted CB or white butter as a raw

material for gheemaking. A typical plant assembly for

the CB method comprises the following: (1) a cream

separator; (2) butter churn; (3) butter-melting outfits;

(4) steam-jacketed, stainless-steel ghee kettle with

agitator and process controls; (5) ghee filtration

devices, such as disk filters or oil clarifier; (6) storage

tanks for cream, butter, and ghee; (7) pumps and

pipelines interconnecting these facilities; (8) crystal-

lization tanks; and (9) product filling and packaging

lines.

0013First, the butter mass is melted at 60



C. The

molten butter is pumped into the ghee boiler, and

the steam pressure increased to raise the temperature

to 90



C. This temperature remains constant as long

as the moisture is being driven off. The scum which

collects on the top surface of the product is removed

from time to time with the help of a perforated

ladle. The temperature gradually rises and the heating

at the last stage is carefully controlled. The endpoint

shows the disappearance of effervescence, appear-

ance of finer air bubbles on the surface of fat, and

browning of the curd particles. At this stage, the

typical ghee aroma is also produced. The final

temperature of clarification is adjusted to 110



C. In

some cases, heating beyond this temperature is

carried out in order to generate a marked ‘cooked’

flavor, relished by a sizeable section of consumers.

The ghee is then pumped, via an oil filter or clarifier,

into settling tanks which are cooled by recirculating

water at 60



C. The residue is packed in suitable

containers at 60



Prestratification Method

0014The PS method consists of keeping molten butter

undisturbed in a ghee boiler at a temperature of

80–85



C for 30 min for stratifying the mass into

three distinct layers. The top layer is composed of

floating, denatured protein particles and impurities,

the middle layer of almost clear fat, and the bottom

layer of buttermilk serum. This division helps in

mechanical removal of the bottom layer of butter-

milk, carrying about 80% of the moisture and 70%

of the SNF contained in butter. Removal of the but-

termilk eliminates the need for prolonged heating for

evaporation of the moisture, and results in the forma-

tion of a significantly low quantity of ghee residue,

into which a portion of ghee can become absorbed

and from where it is irrecoverable.

0015The middle layer of fat is heated, usually to 110



along with some denatured curd particles floating on

the top. This process is essential to promote develop-

ment of a more chracteristic aroma. This method

offers the advantages of economy in fuel consumption

up to 35–50%, saving in time and labor up to 45%,

and production of ghee with lower free fatty acid

(FFA) levels and acidity. The provisions of pressure

gage, safety valves, temperature regulators, and con-

densate outlet pipe make the PS process capable of

producing ghee of better quality, and amenable to

process controls. Stratification also helps in the pro-

duction of ghee with a milder flavor. Its application is

limited to batch-scale operation.

2884 GHEE

Continuous Gheemaking (Figure 1)

0016 To overcome the problems of low heat transfer coef-

ficients in batch methods of gheemaking, limitations

of scale of operation and excessive exposure of the

plant operators to the stresses of heat and humidity, a

continuous gheemaking machine was designed using

the principles of hydrodynamics and heat transfer in a

horizontal, straight-sided, thin-film, scraped-surface

heat exchanger. The rate of water evaporation is

75–80 kg h

1

2

of surface area at a steam pressure

in the jacket between 450 and 500 kPa. The rotor

is provided with four variable-clearance blades

revolving at a speed of 2.45 m s

1

. The capacity of

the prototype developed is 500 kg h

1

ghee.

0017 Butter, heated in a tank to 75



C, is pumped into the

heat exchanger, with the flow rate adjusted with a

rotameter. The rotor drive is switched on, and steam

allowed to flow into the jacket. The centrifugal action

of the rotor causes the product to spread uniformly as

a thin film on the heating surface. The turbulence

induced by the blade action causes rapid evaporation

of water from the product film. The vapors removed

via vapor outlets are used for preheating the butter in

a tank. During the warm-up period, the partially

concentrated fat is diverted into a balance tank.

After attaining the desired temperature, ghee is col-

lected in a tank and subsequently passed through a

residue separator or clarifier.

Quality of Ghee

0018 The quality attributes of ghee are affected by many

factors, such as quality of base material, extent of

lactic acid fermentation, time and temperature of

heating, rate of cooling, package type, filling condi-

tions, presence of oxygen and contaminants such as

iron and copper, exposure to sunlight and tempera-

ture, and duration of storage. These factors should be

controlled to produce ghee of premium quality.

0019The consumers of ghee always look for most desir-

able flavor, texture, and color, and freedom from

suspended serum residues. They also want an assur-

ance of purity, freshness, and wholesomeness. The

above attributes are assigned relative weightings by

consumers in the overall assessment of quality. A

perfect score of 60 for flavor, 25 for texture, 10 for

color, and 5 for freedom from suspended impurities is

recommended for the judging of ghee. The preference

for quality is also determined by the end use.

Flavor

0020Aroma and taste constitute the flavor of ghee. A

perfect ghee flavor is characterized by a multitude of

sensory perceptions which are pleasant, enjoyable,

and lingering in the mouth. Consumers always resist

any change in the flavor of ghee as this is one charac-

teristic which predominantly determines acceptabil-

ity. There are regional preferences for flavor in ghee.

The preferred ghee flavors range from ‘slightly curdy’

to ‘pronounced curdy’, cooked to caramelized and, at

times, slightly oxidized in some quarters of the popu-

lation. The village-produced ghee is characterized by

a curdy flavor which lingers in the mouth. (See Sens-

ory Evaluation: Taste.)

0021The quality and the amount of SNF present in the

base material, as well as the intensity of heating sep-

arately and cumulatively, affect the flavor of ghee.

Technologies have been developed in the author’s

laboratory to produce ghee with desired flavors of

both ‘curdy’ and ‘cooked’ types.

0022The flavor of ghee is mainly contributed by the heat

interaction products formed between the unfermen-

ted serum portion, comprising the native carbohy-

drate and protein system, and by metabolic products

of the starter culture when ripened cream is used for

gheemaking. The most important flavor components

of ghee are as follows: FFAs, 6–12 mg g

1

fresh

ghee; methyl ketones, 6–12 p.p.m.; a complex mix-

ture of 44 lactones, both d-lactones and g-lactones,

29–43 p.p.m.; aldehydes, ketones, and alcohols.

About 34 monocarbonyls were found in the flavor

volatiles of ghee. The ‘curdy’ flavor in ghee could be

produced by mixing of desi ghee with dairy ghee in

varying proportions, by the addition of lactic cultures

to butter at heating, by incubating the molten butter

with a lactic culture, or by the addition of ‘lassi’

powder at the time of heating. ‘Cooked’ flavor could

be simulated by clarifying butter at temperatures of

115



C for 10 min, or 120



C for 5 min, or 125



without any holding time. (See Flavor (Flavour) Com-

pounds: Structures and Characteristics.)

fig0001 Figure 1 A continuous ghee plant. Courtesy of NDRI, Karnal,

India.

GHEE 2885

Texture

0023 Granulation of ghee is an important criterion for its

selection; a good grainy texture is very much appreci-

ated by consumers, and such a ghee develops a lower

degree of rancidity than ghee kept in the liquid state.

Milk fat has the unique property of forming grains

because it is made up of a wide variety of complex

triacylglycerol mixtures with varying melting points.

The texture of ghee will depend on the source of the

fat (animal species), method of preparation, tempera-

ture of clarification, rate of cooling, amount of FFAs,

rate of seeding, and storage temperature. The pres-

ence of FFAs markedly increases the grain size, but

the quantity of grains is only increased to a limited

extent. Seeding with grains of ghee at the rate of 2%

by weight of ghee improves grain formation. The

grain shape becomes needle-like, in contrast to the

spherical shapes obtained without seeding. The large

number of fatty acid residues present in ghee results in

a wide variety of crystallization patterns.

0024 The maximum amount of solid fraction (about 74%)

is obtained at 28



Cin20–24 h from buffaloes’ ghee,

closely followed by cows’ ghee (69.5%) and a distinct

low in goats’ ghee (30%). There can be significant dif-

ferences in the melting curves of fat from the milk of

buffaloes, cows, and goats. The changes in the condi-

tions of cooling can have a pronounced effect on ghee

texture. If ghee is cooled rapidly, a larger number of very

fine crystals will be formed, all consisting of a mixture of

high- and low-melting fats, leading to a smooth, grease-

like character. Slow cooling of ghee from a temperature

higher than the melting point will lead to the formation

of few crystals with a high melting point. As cooling

proceeds, more and more fat solidifies, forming a mass

of large crystals suspended in liquid fat.

Color

0025 Buffaloes’ ghee appears whitish in color owing to the

absence of carotene, which imparts a yellow color to

cows’ ghee. In the village method of gheemaking, the

development of a greenish-yellow tinge in buffaloes’

ghee is caused by the action of lactic acid bacteria.

Ghee produced by the DC method has a brownish

color compared to that prepared by the CB process.

Stratification results in a light color. A more intense

heating in the presence of a high SNF content will

result in a darker color, especially if the raw material

has been fermented. (See Colorants (Colourants):

Properties and Determination of Natural Pigments.)

Shelf-Life of Ghee

0026 Although ghee has a better capacity to resist spoilage

by elemental and microbial attack than any other

milk product, it is common knowledge that, upon

prolonged storage at ambient temperature, it under-

goes oxidative changes. Reaction of oxygen with the

‘unsaturated fat’ is a major cause of spoilage. It gives

rise to a typical, strong and disagreeable odor.

Production of off-flavors accompanies the loss of nu-

tritive value. (See Oxidation of Food Components.)

0027Autooxidation of ghee is aggravated by metallic

contamination and sunlight. The ‘acceleration’ effect

of light is dependent on its wavelength, and visible

light accelerates the decomposition of hydroperox-

ides. The effect of ultraviolet light on ghee is more

pronounced than the impact of other rays. High-

energy radiations, such as b- and g-rays, exert a

pronounced acceleration effect because they split

hydroperoxides and also generate free radicals from

molecules of unoxidized substrate.

0028The durability of ghee is affected by the degree of

unsaturation of the fat, the temperature at which the

ghee is stored, the manner in which the milk for

gheemaking was handled, uncontrolled fermentation

during curdling, uneven heating during manufacture,

and insanitary conditions of the vessels used for the

production and storage of ghee.

0029A number of synthetic antioxidants, such as

gallates (ethyl, propyl, octyl), butylated hydroxyto-

luene (BHT), butylated hydroxyanisole (BHA), ter-

tiary butyl hydroquinone (TBHQ), ascorbic acid,

a-tocopherol, phospholipids, and some natural anti-

oxidants, namely curry leaves, betel leaves, soya bean

powder, safflower, and amla (Phyllanthus amblica),

can be added in small amounts (permitted legally by

different countries) with a view to either complete

prevention or partial retardation of the oxidation of

fat during storage. (See Antioxidants: Natural Anti-

oxidants; Synthetic Antioxidants.)

0030The antioxidative properties of curry and betel

leaves are attributed to their phenolic compounds,

predominantly hydroxychavicol. These leaves also

contain ascorbic acid, which may act synergistically.

Curry leaves and betel leaves also contain many

amino acids which serve as antioxidants. Studies

have proved that the age-old practice of boiling

betel and curry leaves with desi butter at the time of

clarification helps to improve the flavor, color, and

shelf-life of ghee.

Increasing the Durability of Ghee

1. 0031Ghee should be prepared from a good-quality

cream or butter.

0032If possible, oxygen should be replaced by nitrogen

gas.

0033Some permitted antioxidants should be added

before crystallization.

2886 GHEE

4.0034 Feeding of green fodders and cottonseeds to

lactating cows or buffaloes helps to increase the

keeping quality.

0035 Transparent containers should not be used for

packaging ghee.

0036 Ghee should be stored in a cool, dark place,

preferably at temperatures below 20



Packaging of Ghee

0037 Ghee is generally packed in lacquered tin cans of

various capacities ranging from 250 g to 15 kg. Tin

cans protect the product against tampering, and

allow transport to far-off places without any signifi-

cant wastage; they can be printed with attractive and

colorful designs. However, tin cans are very expen-

sive. Some plants do pack ghee in metallized, polyes-

ter pouches, but these also work out to be expensive

owing to the aluminum coating. High-density poly-

ethylene and polypropylene are known to have low

water vapor transmission rates and are inexpensive.

Such films can be laminated with other suitable, basic

packaging materials. Ghee packed in flexible pouches

should be placed in cartons that contain some cush-

ioning matter to absorb vibrations during transporta-

tion or rough handling. Ghee can also be packaged in

polymer-coated cellophane, polyester, nylon-6, food-

grade polyvinyl chloride (PVC) or various laminates.

0038 Bulk transport of ghee in tankers, and distribution

at the consuming centers in retail containers, could be

ideal for interstate or intercontinental marketing. A

suitable pumping device is needed to transfer the ghee

from the bulk tank without affecting the texture and

granular structure of the ghee. Bulk dispensing of

ghee, as used for milk, could also become an alterna-

tive system for retailing.

Chemical Composition of Ghee

0039 Ghee is largely made up of triacylglycerols (98%) and

other minor constituents, such as (1) diacylglycerols

(1–2%), (2) monoacylglycerols (0.1–0.2%), (3) FFAs

(1–10 mg 100 g

1

), (4) phospholipids (0–80 mg

100 g

1

), (5) cholesterol (0.25–0.4%), (6) fat-soluble

vitamins, (7) carbonyls (4–6 mgg

1

), (8) glyceryl

ethers (0.8 mmol g

1

), and (9) alcohol (1.8–2.3 mmol

1

). (See Cholesterol: Properties and Determination;

Fatty Acids: Properties; Phospholipids: Properties and

Occurrence; Triglycerides: Structures and Properties;

Vitamins: Overview.)

0040 The presence of about 500 fatty acids in milk fat

has been reported and the majority possess even-

numbered carbon chains, C

4–18

. The total proportion

of polyunsaturated fatty acids is only 3–4% in ghee.

Buffaloes’ ghee is richer in butyric, palmitic, stearic,

tetraenoic, and pentaenoic acids than the fat of cows’

milk. The levels of other short-chain fatty acids (cap-

roic to myristic) are higher in cows’ ghee than in

buffaloes’ ghee. The fatty acid composition greatly

influences the fat constants and rheological proper-

ties, such as melting and crystallization behavior,

solubility, surface activity, and ability to form emul-

sions. Table 1 shows the major analytical constants

for buffaloes’ ghee and cows’ ghee.

Nutritive Value of Ghee

0041Milk fat performs many definite functions in the

human diets. It is a rich source of fat-soluble vitamins,

essential fatty acids, and other growth-promoting

factors. It is believed that ghee improves mental

power, physical appearance, and longevity. It in-

creases the capacity to work and enhances the body’s

resistance to stresses such as cold and undernourish-

ment. Ghee is used as a curative agent for wounds,

ulcers, and eye ailments. The conjugated linoleic acid

content of milk fat, which is known to be anticarcino-

genic, increases substantially during the manufacture

of ghee. Addition of ghee to foods improves the satiety

value and consumers enjoy the feeling of eating. (See

Fatty Acids: Dietary Importance.)

Anhydrous Milk Fat (AMF)

0042AMF (anhydrous butterfat, butter oil) is composed of

the products exclusively obtained from prime-quality

milk, cream, or butter, and resulting from the removal

of almost the entire water and SNF contents. The

highest-grade AMF suitable for the production of

recombined milk and other milk products is produced

from fresh milk or cream (rather than from butter)

which has not undergone any appreciable microbio-

logical or chemical changes. The moisture content,

FFA level, and peroxide value must be very low to

guarantee keeping quality. The essential compos-

itional and quality factors for the different grades of

AMF products are given in Table 2.

0043Anhydrous milk fat is obtained from prime-quality

raw materials to which no neutralizing substances

have been added. The maximum copper content is

0.05 p.p.m., and that of iron 0.2 p.p.m. The peroxide

tbl0001Table 1 Average analytical constants of ghee

Constant Buffalo Cow

Butyrorefractometer reading 42.0 43.2

Saponification value 230.1 227.3

Reichert–Miessl value 32.3 26.7

Polenske value 1.41 1.76

Kirschner value 28.5 22.1

Iodine value 29.4 33.7

Melting point 32–43 28–41

GHEE 2887