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Ghee – Product with 30 per cent MUFA and numerous nutritive properties
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Tuesday, 16 July, 2013, 08 : 00 AM [IST]
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B Surendra Nath and Satish Kulkarni
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fiogf49gjkf0d Milk and milk products, since time immemorial, have formed an important part of our diet. Milk is naturally designed as a nutrient dense food source that nourishes and provides immunological protection for mammalian offspring.
Because of their unique nutrient profile, dairy foods are designated as protective foods, that is food in which the concentration of essential nutrients is high in relation to the food's energy value. Therefore, milk and milk products are recognised as important constituents of a well-balanced and nourishing human diet.
Ghee, a major dairy product is the usual Indian name for butterfat made from cream, desi butter or creamery butter. It has an important place in the diet of the people of the Indian sub-continent.
It forms the largest segment of the milk products in India. Nearly 30 per cent of the milk produced in our country is utilised for the production of ghee. The traditional criteria of quality of ghee centre around flavour, texture and colour.
The flavour of ghee is often described as pleasant, nutty, lightly cooked or caramelised aroma. Its taste is described as one that lacks oiliness, blandness, and is sweetly rather than sharply acid.
Local preferences exist in different parts of India both for a raw, buttery, undercooked flavour and for a distinctly overcooked, slightly burnt one. The flavour of ghee is influenced by many factors such as the quality of raw materials, the method of preparation, the ripening of cream and the temperature of clarification.
However, fermentation of milk (as followed in the indigenous process) or cream and heat clarification of cream/butter influence the flavour of ghee to a large extent.
Cow ghee has a golden-yellow colour due to the presence of carotenoid pigments. Buffalo ghee is whitish or light brownish due to the browning that occurs during heat clarification.
Completely-melted ghee and cooling to room temperature assumes a grainy texture due to the formation of fat crystals, which are suspended discretely in a liquid phase.
Granularity is considered as important criteria of quality and even purity by the consumer. Ghee increases the palatability of the foods, in which it is a constituent, through improved appearance, flavour and texture.
Composition of ghee
Ghee is an isolated milk fat. The constituents present in cow and buffalo ghee are shown in Table 1.
Table 1: Chemical composition of cow and buffalo ghee
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Constituent,
Weight percentage
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Cow
ghee
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Buffalo
ghee
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Triglycerides,
%
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98
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98
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Diglycerides,
%
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0.37
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0.4
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Monoglycerides,
%
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0.03
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0.03
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Phospholipids,
%
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0.6
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0.5
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Cholesterol,
mg/100g
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310
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300
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Carotene,
mg/g
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8
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-
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Vitamin
A, RE/g
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9
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9
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Vitamin
D, IU/g
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0.5
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0.4
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Vitamin
E, µg/g
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35
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25
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Vitamin
K, µg/g
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1
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1
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Free
fatty acids (Oleic acid), %
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0.4
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0.5
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Moisture,
%
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0.3
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0.3
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Fatty acid composition of ghee
More than 400 different fatty acids have been identified in ghee (milk fat) ranging from butyric acid- with four carbon atoms – to fatty acids with 26 carbon atoms. Ghee consists of about 65 per cent saturated fatty acids, 30 per cent monounsaturated fatty acids and five per cent polyunsaturated fatty acids.
Though it has a relatively high-level of saturated fatty acids, more than quarter of them are constituted by short- and medium-chain ones, which are readily utilised as a energy source. These acids neither increase blood lipid levels nor are deposited in adipose tissues.
Ghee is not a good source of omega-3-fatty acids, which are known to have important biological functions. About three per cent of the fatty acids in milk fat are constituted by trans-fatty acids which are produced during biohydrogenation of polyunsaturated fatty acids of feed in the rumen.
No harmful effects of the trans-fatty acids of milk fat have been reported. In fact, the chief source of conjugated linoleic acid present in milk is vaccinic acid, a predominant trans fatty acid.
Milk fat is the richest natural source of conjugated linoleic acid (2.5-20 mg/g fat). Anti-carcinogenic, anti-atherosclerotic, anti-diabetic and immunomodulating properties have been attributed to conjugated linoleic acids (CLA).
Milk fat is characterised not only by the kind and amount of fatty acids, but also by the distribution of fatty acids on the glycerol moiety.
For example, the short-chain fatty acids occur in external positions and long-chain fatty acids are found in position two. This arrangement contributes to the ease of digestibility and absorption of milk fat compared to other fats, especially those with large proportions of long-chain fatty acids.
The levels of the major fatty acids of cow and buffalo ghee are shown in Table 2.
Table 2: Fatty acid composition of ghee
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Fatty
acid, Weight percentage
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Cow
ghee
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Buffalo
ghee
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Butyric
acid
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3.2
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4.4
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Caproic
acid
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2.1
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1.5
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Caprylic
acid
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1.2
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0.8
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Capric
acid
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2.6
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1.3
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Lauric
acid
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2.8
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1.8
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Myristic
acid
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11.9
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10.8
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Palmitic
acid
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30.6
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33.1
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Stearic
acid
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10.1
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12.0
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Oleic
acid
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27.4
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27.2
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Liloleic
acid
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1.5
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1.5
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Linolenic
acid
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0.6
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0.5
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Nutritive virtues of ghee
The nutritive value of milk fat (ghee) has been debated on grounds of health considerations. Though the debate on the role of fat in the diet was raised with laudable objective of reducing the incidence of coronary disease, the scientific findings have often been misinterpreted. The role of milk fat with respect to its constituents is discussed below:
Cholesterol
Many risk factors, both genetic and environmental, contribute to the development of coronary heart diseases (CHDs). A direct relation exists between elevated blood cholesterol and CHD risk, especially for middle-aged persons.
Therefore, a lot of attention is given to blood cholesterol level, which is considered as major modifiable risk factor. In this context, two important classes of lipoproteins of blood, viz. low-density lipoproteins (LDL) and high-density lipoproteins (HDL) have been studied with regard to their relation with CHD risk.
An elevated level of blood LDL cholesterol is associated with an increased risk of CHD (therefore ‘bad’ cholesterol) and in contrast a high level of blood HDL cholesterol reduces the risk of CHD (therefore ‘good’ cholesterol).
A high intake of total and saturated fat and cholesterol is believed to elevate total and LDL cholesterol level in blood. Therefore, it is generally recommended to limit the intake of cholesterol to less than 300mg/day and to keep the saturated fat contributing to less than 10 per cent of daily calories.
Cholesterol is a natural substance in body tissues; 1-4g is synthesised in the body daily, 10-12g is present in blood, and 100-150g in the human body. It is a structural component of cellular and sub-cellular membranes and nervous tissue.
It also serves as a precursor of bile acids, steroid hormones and vitamin D and is involved in many metabolic processes. Most of our daily need of cholesterol is made in the body itself, and the remainder is obtained from the diet. Metabolic control of the body’s synthesis of cholesterol ensures that production rises or falls to compensate for our dietary intake.
Individuals vary in their blood cholesterol response to dietary cholesterol. It was found that reducing dietary cholesterol may lower blood cholesterol levels in the 15-20 per cent of the population, which lacks precise feedback.
Control of endogenous cholesterol synthesis due to an inherited defect-familial hypercholesterolemia. But, for the 80-85 per cent of the population which compensates by decreasing cholesterol synthesis in response to increased dietary cholesterol, it would have little or no effect.
Most of the scientific data also suggest a relatively small effect of dietary cholesterol on plasma, total and LDL cholesterol. Hence, the recommendation to reduce cholesterol intake will have questionable benefit for the normal person.
In the majority of health subjects, very low fat diets appear to be of little benefit with regard to coronary disease risk profiles and may even have adverse metabolic consequences. At present, there is no biological marker to identify individuals who are or are not sensitive to dietary cholesterol.
In any case, milk and dairy foods do not contribute to the cholesterol level in blood to any great extent as the daily limit (300mg) of cholesterol is provided by 2.5-1itre cow milk, 150g butter, 100g ghee or two eggs.
Thus, whilst cholesterol in the body is of importance, the impact of cholesterol in the diet has largely been overemphasised, and milk fat has received an unwarranted blame.
Fatty acids
Since the “lipid hypothesis” states that saturated fatty acids increase and polyunsaturated fatty acids (PUFAs) decrease plasma cholesterol, demand is often made that saturated fats should be replaced with fats rich in PUFAs.
It is clearly demonstrated that the different saturated fatty acids are by no means equivalent in their influence on blood cholesterol. Palmitic, myristic and lauric acids raise blood total, LDL and HDL cholesterol levels, whereas stearic and short- and medium-chain saturated fatty acids have little or no effect on the total and LDL cholesterol levels in the blood.
Short- and medium-chain saturated fatty acids are absorbed directly from the intestine into the portal circulation and are not transported to the adipose tissues through the bloodstream.
Although milk fat contains a high level of saturated fatty acids, the higher proportion of stearic acid and short- and medium-chain fatty acids makes it less harmful by not increasing the blood cholesterol levels as much as other saturated fats do.
Monounsaturated fatty acids (MUFAs) once thought to have a neutral effect on blood cholesterol levels were shown to be effective in lowering total and LDL cholesterol in blood without lowering HDL cholesterol.
In addition to potentially maintaining HDL V levels, a MUFA-rich diet is preferable to a PUFA-rich diet because it may slow down the progressing atherosclerosis by generating an LDL resistant to oxidation.
Also, MUFAs may not lower apo A1, which is associated with HDL as much as a PUFA-rich diet. In this regard, it is interesting to note that ghee has about 30 per cent MUFAs. Conjugated linoleic acid and sphingolipids of milk fat have also been shown to have effect that protect against coronary heart disease.
In-vitro and experimental animal studies indicated that conjugated linoleic acid at very low concentrations inhibits the growth of tumours at a number of sites, particularly the mammary glands.
Possible mechanisms whereby CLA intake inhibits carcinogenesis include reduction of cell proliferation, induction of apoptosiis, regulation of gene expression and modification of the immune response.
Animal products, specifically dairy products (butter, ghee) are the principal dietary source of these acids. Further, 90 per cent of the conjugated linoleic acids in milk fat in the Cis-9, trans-11, 18:2 isomeric form, called rumenic acid, that is, thought to be the biologically active isomer of CLA.
Studies on experimental animal and cell culture studies indicate that sphingolipds, an important constituent of milk lipids, may protect against some cancers including those of the colon, breast and prostrate by inhibiting cell growth and inducing cell death.
Butyric acid, a short-chain fatty acid, present in milk fat, may protect against cancer, according to in vitro and experimental animal studies. In a variety of human cancer cell lines, including those of the colon, breast and prostate, physiological concentrations of butyric acid inhibit the proliferation and induce differentiation and programmed cell death.
Ghee – An ayurvedic medicine
Ghee is an integral part of the practice of ayurvedic herbal formulation. In ayurveda, ghee is considered a premier rasayana – a food that helps maintain good health, vitality and longevity. It is a considered as yogavahi, that is, it helps in carrying the healing benefit of herbs, spices and other food constituents to the cells and tissues of the body.
Ghee is also considered as medha rasayana, i.e. good for mental alertness and memory. Eating ghee is believed to enhance virility and sexual potency. The ayurvedic texts say that ghee helps balance excess stomach acid, and helps maintain/repair the mucus lining the stomach.
Conclusion
Ghee is an important dairy product with qualities that make it a supreme cooking and frying medium. It has beneficial effects when consumed in moderate amounts as component of balanced diet. Several constituents, such as conjugated linoleic acid, butyric acid, oleic acid, sphingolipids, etc. present in ghee have known health benefits.
Scientific findings suggest that dietary cholesterol has little influence on plasma cholesterol in 80-85 per cent of the population. In any case, ghee is not a rich source of cholesterol. Further, all the saturated fatty acids of ghee are not atherogenic.
Nearly a quarter of them (short- and medium-chain fatty acids) are directly absorbed through portal circulation for energy production. Monounsaturated fatty acids, present in ghee also bring about desirable changes in blood cholesterol without side effects. Hence, ghee should continue to be an important constituent of our diet.
(The authors are scientists, Southern Regional Station,
National Dairy Research Institute, Bangalore)
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