Chemistry of Vegetable oils/animal fats as source of energy is very interesting and important for human health.Their metabolic studiesafter intake in human body will be another interesting aspect for further studies to understand the best natural energy source as described in ancient Indian literature like Sushtrut and Charak Samhita.

Chemistry of Vegetable oils /animal fats as source of energy is very interesting and important for human health.Their metabolicstudies after intake in human body will be anotherinteresting aspect for further studies to understand the best natural energy source as described in ancientIndian literature like Sushtrut and Charak Samhita.The complete metabolic oxidation of tri glycerol yields 37 kJ/g energy. Most of the energy derived from fat breakdown comes from oxidation of the constituent fatty acids. Oxidation of fatty acid provides the major content of energy for many human and animaltissues.

Fats and Lipids play significant roles in energy metabolism, as membrane constituents, thermal insulators and biological regulators and remain as the major energy storage form in most cells. The chief contribution of fats and lipids to the diet is their energy value and also satiety value. Fats are also acts as solvents and source for the fat-soluble vitamins such as A, D, E, K and pro vitamin A, the carotene. Fats and other lipids also contribute essential fatty acids to the diet which body cannot synthesize.

It is a well-known fact that soybean, sunflower, ricebran and safflower oils are extracted through different new technologies involving solvent extractions, bleaching, refinement etc by the use of number of harmful chemicals, and antioxidants have been added afterwards.

Study of general chemistry regarding constitutional analysis of lipids and fats suggests that fat containscontaining lower chain saturated fatty acids (SFA) ranging between C4-C14 present in Coconut oil alongwith substantial amounts of Mono and Poly unsaturated fatty acids (MUFA and PUFA)present in Mustard ,Groundnut (MUFA rich ) and Seasam oil (PUFA rich due to essential Linolenic ,linoleic acids) which tend to be liquid at body temperature, are absorbed relatively easily with higher rate, whereas lipids containing mostly long chain saturated fatty acids such as palmitic and stearic acids with higher melting points are digested and absorbed at slow rate. Evidences also suggests that linolenic   and other ω-3 fatty acids act by somehow competing with the metabolism of arachidonic acid (20:4c∆ 9,12,15,18) the principal precursor of a class of biological regulators called Prostaglandins and Thromboxanes [1].

The concept of “Sarve Bhavantu Sukhinah, Sarve Santu Niramaya “ has been accepted by our ancestors and in india our Indian culture is based on idealism of well beings of all creatures of the earth .Edible oils have significant role in diet all around the world . Edible oils are related directly to the health aspects of all the people and also to the growers and consumers. From long time according to the environment of the local region and area, various natural oil seeds like coconut, sesame, mustard, and ground nut have been cultivated as a source of best fat in the different eastern countries specially in India. Literature survey also reveals that traditional and natural edible oils like sesame, mustard, groundnut and coconut are being used   in cooking vegetables, deep frying and for storage purposes as pickles from a long time worldwide specially in eastern countrieslike India, China and Japan. [2,3] Thevirgin oil has been extracted through ecofriendly, cold pressing  technique called ‘Ghani’ which extract the oil from seed very slowly at low speed (which is an important factor to preserve the natural quality, components, specific colour, flavour and odour of the oil) at room temperature between 25-400C.The extracted oil is fresh, healthy, pure, rich in antioxidants and naturally fat-soluble vitamins like A, D,E, K. These oils should be preferred to be chosen for edible purpose as they are more nutritious in all means, easily assimilated and digestive in human body to provide maximum benefits without causing any harmful effecton health.

It may be noted that mostly oil is treated at high temperature during frying and cooking food items or stored for long period as pickles. Rancidity and reversion is found to be the main problem in use of vegetable oils, which is caused due to tendency of unsaturated fatty acids to oxidize. Literature survey reveals that oil containingmore polyunsaturation reacts more rapidly with air and rancidity and reversion like phenomenon takes place readily. Some other reactions like oxidative polymerization and hydrogenation can occur during their thermal abuse and long storage. [4-6]

According to ancient Indian literature of Ayurveda , sesame oil is the best for edible purposes and which has been used as dressing oil on freshly cooked traditional food items made by regional food grains which are very nutritious in all means , though mustard, groundnut and coconut oils are not only healthy but possess medicinal properties as well [ 2,3] whereasSafflower oil is said worst for eaten as an oil.[2,4] In-depth scientific studies of these oils support traditional (Ayurvedic) understanding and indicate that these new oils extracted and treatedchemically are not only undesirable but are harmful to human health, especially in Indian cuisine where they are mostly used for frying and for storage as pickles.

Table 1 - Percentage fatty acid composition of commonly used edible oi

              Table 2- Major component acid (% wt.) of vegetable oils investigated

A perusal of Table -1 & 2 and literature survey suggest that processed oils with a higher percentage of polyunsaturated fatty acids (PUFA) such as soybean, sunflower and safflower (highestcontent of PUFA present) lower both harmfulLDL cholesterol and useful HDL cholesterol. On the other hand natural virgin edible oils rich in monounsaturated fatty acids such as mustard, groundnut, and sesame and oil rich in lower saturated fatty acids ,help in lowering of harmful LDL cholesterol level without affecting useful HDL cholesterol and hence are better for balancing cholesterol profiles.(3-12) Oxidation products present in abused frying fats and oils are the compounds most suspected of impairing the nutritional properties of the oils or involving adverse physiological effects. The recent studies on their health implications include those related to their fate and those focused on their effects in metabolic pathways and the most prevalent diseases [13,14].

Moreover, additional cholesterol-reducing properties are likely to come from the natural plant sterols and stanols contained in oils extracted without heat or solvents [3, 15]. Sesame contains 594mg/100g of soluble phytosterols while groundnut contains 247mg/100g and olive oil 210mg/100g. Soya and corn oils also contain phytosterols when raw (380mg/100g and 580mg/100g respectively), but since these latter need solvent or heat for extraction, the sterols are invariably lost in processing [15].

The natural oils such as sesame, mustard, peanut and coconut are stable, non-drying or semi- drying oils with a low tendency to oxidize in the light. Natural oil seeds rich in oil content contain antioxidants in their natural form which prevent rancidity and reversion (development of ‘off’ odors). In contrast, soybean and safflower oil are drying oils while sunflower oil is a semidrying oil. Thus, due to a higher percentage of PUFAs they are prone to oxidation in the presence of light, temperature, air and metal. In cooking, since edible oils are mainly used forfrying in which oil is subjected to light, high temperature and contact with air and metal, such oils are harmful to health [3]. In the last few years these native edible oils have been supplanted by introducing recent oils such as palm, soybean, sunflower, ricebran and safflower which have never been used in any part for traditional nutritious food of local region in world and India.

In Western countries rancidity and reversion of refined oils such as soybean oil were initially remedied by hydrogenation. More recently, with growing evidence of the harmfulness of trans-fatty acids, rancidity and reversion are increasingly being prevented by the addition of antioxidants [12] However, according to studies conducted on soybean oil by V.K. Tyagi and Pramod Kumar at Kanpur, deterioration of nutritional quality at high frying temperatures is rapid and added antioxidants are almost ineffective at retarding this. [16, 17]

Vegetarians can easily achieve n-6/n-3 ratio and ALNA (α-linolenic acids) intake by using ALNA rich edible oil like yellow Indian mustard as the cooking medium and also by increasing the intake of ALNA rich foods such as sesame, mustard, and groundnut oils freshly extracted throughcold pressing method in the diet.[18-20]

Sesame has been consideredto be an important and best edibleoil seed from ancient times,not only because of its high oil content, but also because of its resistance to oxidative deterioration and its numberof medicinal effects.[2] This oil has been used in India as fresh and raw in different traditional dishes in many states like Rajasthan, Gujrat, Madhyapradesh etc. The studieson the antioxidative constituents in sesame seed and oil revealed four lignanphenols. Among them sesamolinol and sesaminol antioxidants, Sesaminol was also found in high concentration in unroasted sesame oil. In this connection, it has been found that large amountsof sesamol are produced from sesamolin during frying process and contribute to the stabilityof fried food. [21] Further, recent studies also support the Neurological role [22], benefites in regulation of blood pressure [23] of sesame oil. The importantantioxidants sesaminol, sesamolinol, sesamolin and sesaminmaintain the fats including Low Density Lipoproteins (LDL) which cause arteriosclerosis and are believedto promote the integrity of body tissues.These antioxidant lignans have shown hypocholesterolemic and  immunomodulatory effect. [24,25]

Vitamin E,a fat soluble antioxidant, protectsthe body from harmful oxidizingcompounds. Sesame seed oil containsgamma tocopherols alongwith sesaminol and sesamin which possess Vitamin E like activity.[24] Application of sesame oil withturmeric powder in milk on the facial skin, makes it smooth, soft removing pimples.[25] Sesame oil is known for its healing properties and has a reputation as a sedativein Tibetan medicineand also used for millenniain Chinese system of medicine. [25-27] In ayurveda, sesameis known to cure Tridoshas. [2,25] During Abhyanga, a form of massage, the oil is rubbed externally on the skin to improve energy flow and help free the body from impurities. In ayurveda, sesame oil is regarded as an anti bacterial mouthwash and it can also be applied to nostrils to relieve anxietyand insomnia. The pain associated with premenstrual syndrome(PMS) can be overcome by applying the oil on to the abdomen region.[26,27] According to traditional system of medicines, sesame is known to cure bleeding dysentery, burns, ear pain, headache and impotency.

For pharmaceutical applications, sesame oil is used as a solvent for intramuscular injections and has nutritive, demulcent, and emollient properties and as a laxative. It was used to cure toothaches and gum diseases in 4th century. It is also used for the treatment of blurred vision. dizziness and headaches. The oil is more efficient than isotonic chloride solution in curing nasal mucosa dryness due to winter. The high polyunsaturated fat content in oil reduces cholesterol. Sesame oil has been used by Indians as an antibacterial mouthwash, to relieve anxiety and insomnia. Malignant melanoma growth was selectively inhibited due to the presence of large amount of linoleate in triglyceride form in sesame oil. [28] The antioxidant and health promoting propertyof sesame lignans (sesamin and sesamolin) increases both hepaticmitochondrial and peroxisomal fatty acid oxidationrate. Consumption of sesame seed increases plasma gamma-tocopherol and enhances vitamin-E activity which can prevent cancer and heart disease. Sesame seed contains cephalin which has hemostat activity. Fibres from sesame are used as an antidiabetic, antitumor, antiulcer, cancer preventive and cardioprotective. [28]

Sesame oil contains Mg,Cu, Ca,Fe, Zn and vitamin B6 which are very useful metals and vitamins Copper provides relief for rheumatoid , arthiritis , Mg supports vascular and respiratory health calcium helps prevent colon cancer phytic acid present in seed to protectcolon cancer,

osteoporosis, migrainand PMS.Zn promotesbone health. Sesame contains high quality protein (25%) and is rich in Methionine [essential Amino acid] and seed is highly beneficial in the treatment of Piles. [29-32]

The amount of monounsaturated content (25 and 61%) Table-2, as isomers and absence of conjugated double bonds in mustard and groundnut are another importantcriteria for establishing their stability upon deep-frying. The content of octadienoic acid (Linoleic) amountedto 51% in Soyabean & 72% in Sunflower where as only 18% in mustard and groundnut. Besides this the content octadecatrienoic acid (Linolenic) was 9 % in soyabean oil where as the trieneswere totally absent in other oils. The contents of octadecenoic, hexadecenoic (Mono unsaturated) and saturated fatty acids were 24, 28, 45 % and 16, 0, 12 % in soyabean, sunflower and sesame respectively. The higher amount of polyunsaturated fatty acid present in refined soyabeanand sunflower oils make these oils more susceptible to oxidative polymerization under frying conditions. Previous studies by various scientists show that the rate of cyclization, branching and polymerization of fatty acids is faster at higher temperature of frying than at lower temperatures.The results of various studies also suggest that antioxidants are almost ineffective in retarding the degree of polymerization in soyabean and sunflower at frying temperature. Studies of various parameters also suggest that the decrease in the iodine value of oil could be due to the constant destruction of double bonds with the development of polymeric fractions. Soyabean oil becauseof more methylene interrupted unsaturated groups provides more active centers for conjugation which in turn facilitate the formation of polymers.[3]

The peroxide value of the frying oil increases indicative of degree of deterioration and was also observed by many scientists [3,16,17]. All the above results indicate and suggest a higher degree of deterioration due to presence of higher poly unsaturation in conjugation and ineffectiveness of antioxidants at higher temperatures in refined soyabean, sunflower and safflower oils. Some chain cleavage productsfrom fatty acids disturbs endothelial cells and inducesseveral genotoxic effectsin hepatocytes and lymphocytes. Soyabean,sunflower and safflowerare prone to be more susceptible towards oxidation during frying and longer storage, thus found to be more harmfulfor cooking at high temperature.

Ground nuts and its oil are a good source possessing 30 essential nutrients and phyto nutrients like niacin, fiber,folate ,Mg , Mn and P and vitamin E 25% protein antioxidant polyphenols called p -coumaric acid – roasting can increase peanuts p - coumaric acid levels , boosting their over all antioxidant content by as much as 22% . They are significant source of resvertrol and co-enzyme Q.10 Resvertrol anti-oxidant is a chemical studied for potential antiaging effects and also associated with reduced cardiovascular disease and reduce cancer risk. [33-35]

Similarly mustard seeds and its oil are also possess very good nutritional value as well as medicinal values .Number of scientific studies and Charak Samhita and Sushrut Samhita (Indian Ayurvedic Literature) suggest that the Glucosinolates , essential fatty acids like linoliec acid ((A) and α-linoliec acid (alna),antioxidants etc. are required by the body and should be taken from external sources from food or from supplements.The genus Brassica consist of 150 species which are cultivated as oil seed crops or as vegetables and fodder crops . Black mustard is used more as acondiment . B.Juncea or Indian mustard is used as an condiment or as an oilseed. The chemical composition of the spices documented shows that they contain fat, nitrogenous substances, fiber , volatile ,oil and isothio cyanates and related compounds .Protective effect against carcinogens probably due to isothiocyanate content which by virtue of its potent effect and enzymes ,enhances solubilization and elimination of carcinogens. [2,36]

Benzyl isothiocyanates and indole 3- carbinol, which are present in cruciferous vegetables in high amountsinduce the conjugating system and are more effectiveinhibitors. The antimutagenic effects of mustard were also assessed by various scientists.[37]. Mustard (B. campustris ) and sesame are considered anti carcinogenic based on cyto toxic and tissue culture studies.

The coconut oil also very good for human health. Recent studies about coconut oil suggest that due to presence of short chain fatty acids as major components and lauric acid is the most prominent medium chain fatty acid MCFA   along with natural antioxidants such as vitamin E and polyphenols present in the coconut oil (Cocos nucifera L.), oral supplementation with coconut oil combined with exercise training improved impaired BRS and reduced oxidative stress in SHR.[38].Other study shows that the lauric acid MCFA digested easily and converted into energy in the liver directly.This makes MCFAs do not take part in the synthesis of cholesterol or deposit fat in body. Many scientists Valente et al. showed that MCFAs in coconut oil can control overweight condition for women. On the other hand, antibacterial ability of MCFAs is one of the remarkableabilities which is concerned by many authors.[39]

Literature survey reveals that coconut oil also showed potential neuroprotective effects.[40] The potential neuroprotective effects of virgin coconut oil (VCO) on inflammasome and oxidative stress in Alzheimer's model has also been reportedby scientists [41]. Recently,virgin coconut oil (VCO) has been growingin popularity due to its potential Cardioprotective Effects. The chemicalproperties and the manufacturing processof VCO make this oil healthier than its copra-derived counterpart.[42]

Thus the plantkingdom and dietary substances appear to open up new fields of investigation in cancer research. [2,43-44]

Studies related to n-6/n-3 ratio and ALNA (alpha linolenic acid)were done by various methods on untreated (raw state) oils whereas traditional cooking processes the oil is treated at high temperature atleastonce and the composition of the oils containing higher PUFA value distorted due to uptake of oxygen and various chemical reactions and become harmful to human health.[2,45-56].

Sesame ,mustard (rapeseed) groundnut(peanut ) and Coconut, are natural oil seeds with highest content of naturally stable healthy oil.They arestable naturally due to presence of abundant amount of natural antioxidants . All these oils have a lesser tendency to oxidize and deteriorate in presence of sunlight, temperature , air and metal which prevents them from rancidity & reversion, while refined soyabean and safflower oils are drying oils and sunflower oil is semi drying. Due to higherpercentage of polyunsaturated fatty acids (PUFA) and presence of double bond they have greater tendency to oxidize in presence of sunlight, temperature, air and metal. Sesame (Til ), mustard, groundnut and coconut oils are easy to process at small scale decentralized levels with eco-friendly and health friendly technologies. The oil extracted through cold pressing technologies is fresh, nutritious, unadulterated and is with natural flavour of taste. Other oils have being extracted by using hydrocarbon solvents such as Hexane, The other processes like bleaching and refinement also include number of hazardous chemicals. In the process of refining using alkaline solution, bleaching and finally de-odorizingprocess, most of the useful lecithin, tocopherols, vitamins andPhytosterols are removedduring various treatments given to the oils. Thus, It may be emphasis that the selection of the oil in the diet should be done carefully.

In fact, greater relianceon a natural means of protection from a diseaserather than chemoprevention appears to be a more promising approach towards human beings all over the world and particularly in developed and developing countries. Promotion of these healthy oils may be supported by policies with referenceto human health.