NTRODUCTION
Mustard is undoubtedly the major cooking oil in Indian households. Today, mustard is one of the major edible oils in an Indian market. It is an ecofriendly crop, which is an added benefit of growing mustard crop. It accumulates toxic metals like cesium-137 and strontium-90 chlorides from soil into the body and concentrates these into the various parts of the plant (Swern D., 1979). If unabsorbed from the environment, these may lead to genetic toxicity. The northern India has been a consumer of mustard leaves as a vegetable. Mustard seeds are used as a condiment, for flavoring curries and vegetables. The mustard oil has various non-edible uses also, such as in massaging body and hair in new borns as well as in adults. It is used as a remedy for stomach and skin diseases (fungal infections). Mustard oil is employed to impart soft and pliable texture to skin and helps during the tanning process.

Brassica juncea is the brown and oriental mustard. Sinapis alba is the yellow mustard. The basic composition of mustard oil is monounsaturated fatty acids (erucic acid, oleic acid), polyunsaturated fatty acids (linolenic and linoleic), proteins (25%), isothiocyanates, phenolics, phytin and dithiol thiones. 

Table 1: Percentage variation in fatty acids composition in mustard species

Mustard oil also contains 490mg/ 100gm of calcium. The percent fraction of various fatty acids in mustard oil is given in Table-1.

SATURATED AND UNSATURATED FATTY ACIDS

Saturated fatty acids are those fatty acids, which have no double bonds in the carbon chain. Examples are palmitic acid (16:0) and stearic acid (18:0). Unsaturated fatty acids are those which contain one or more than one double bonds in the carbon chain.

MONOSATURATED AND POLYUNSATURATED FATTY ACIDS

Fatty acids with only one double bond are called monounsaturated fatty acids (MUFA).

Example : Oleic acid (18:1) and Erucic acid (22:1)

Fatty acids containing more than one double bond are called polyunsaturated fatty acids (PUFA). Examples are linolenic (18:2), linolenic acid (18:3) and eicosanoic acid (20:4).

ISOMERIC FORMS OF FATTY ACIDS

Fatty acids with the same molecular formula and the same number of double bonds may differ in the location of the double bond(s). This is called position isomerism. The orientation of the two hydrogen atoms attached to the two carbon atoms joined by the double bonds called geometric isomerism. If both hydrogen atoms are on one side of the double bond this known as cis isomer, while presence one hydrogen atom on either side of the bond is called Trans isomer. Cis forms of fatty acids get easily metabolized while trans forms of fatty acids are not synthesized due to change in physical properties . It is mainly produced during hydrogenation of oils.

The metabolism of fatty acid is a complex process. Therefore, we have compared beneficial or harmful effects of various edible oils having different percentage composition of saturated and unsaturated fatty acids on health profile (Gardner et al., 1995). Some of the PURFA are required in small quantities for normal health and a prolonged absence of any one of them in diet leads to specific deficiency diseases. On the other hand it is very important to note that the ratio of n-3 and n-6 is very essential for healthy heart. A comparative account of fatty acid composition of various vegetable oils is given in Table 2.

Table 2: Approximate fatty acid composition of common fats and oils (g/100g)

Based on the above Table we can say that :

The edible oils and fats like ghee, vanaspati, red palm oil and soybean oil are very high in SFA. Even olive oil has a high in SFA. Even olive oil has a higher amount of SFA as compared to mustard oil which has a lower amount of SFA.

The MUFA content of soybean oil is lower, with a high amount of linoleic acid (disturbing the prescribed ratio of n-6 to n-3 acids), PUFA being the predominant fatty acid. Mustard oil contains a high amount of MUFA as compared to its PUFA and SFA content (having the desired ration of n-6 to n-3 fatty acids).

The red palm oil is deficient in alpha-linolenic acid, which is an essential fatty acid. Olive oil contains comparatively lesser amount of essential fatty acids as compared to mustard oil. Moreover, sunflower and safflower oils also have a very high percentage of linoleic acid whereas linolenic acid content is very low. However, the ratio of omega fatty acids, n-6 to n-3 is within desirable proportions in mustard oil.

Canola oil is thought to be beneficial but it is not easily available in India.

In order to help out the consumers, it is essential for scientists to make them aware of the benefits and/or the harms of different components of edible oils.

COMPARING SOYBEAN OIL AND MUSTARD OIL

SFA in soybean oil is 13.1% while mustard oil has 8%. It is a well known fact that saturated fatty acids are not good for heart. The percentage of saturated fatty acids is higher in soybean as  compared to mustard oil while percentage of unsaturated fatty acids is higher in mustard oil, which is a desirable quality.

Soybean has 12% palmitic acid, which is higher than recommended value by Food Chemical Codex, 1996 D.A., 1999). Soybean oil contains trypsin inhibitors, thus causing inhibition of protein digestion.

Moreover, soybean oil probably contains d tocopherol that cannot be metabolized in human beings hence the antioxidant properties of that oil are negligible in that effect.

COMPARING MUSTARD OIL AND RED PALM OIL

Red palm oil is supposed to be protective against cancer due to presence of high content of carotenoids (specially b-carotene), tocopherols and tocotrienols (Hariharan et al., 1996). Unfortunately, most of these beneficial properties are lost during the process of refining.

Various studies have indicated that red palm oil has a protective effect in hypercholesterolemia. However, regular intake of red palm oil may lead to a-linolenic fatty acid (essential fatty acid) deficiency, which is important for the structural and functional integrity of cells.

COMPARING MUSTARD OIL AND CANOLA OIL

Canola oil is not presently permitted in infant formulations in US due to lack of information concerning the effects of feeding canola oil to newborn. It has previously been reported that there is a transient decrease in platelet counts and an increase in platelet size in newborn piglets fed on canola oil for 4 weeks. (Sheila et al., 1999).

On the above comparative statement we have shown percentage of various fatty acids (approximately ) in different vegetable oils (Table 3)

Table 3 : Comparison of fatty acid distribution in mustard oil and other common edible oils.

Good and bad cholesterols : LDL Cholesterol carries about 60-80% of the plasma cholesterol, which is used by tissues to build up cells, and some is returned back to liver. The excess amount of cholesterol is deposited in artery walls, which causes plaques and atherosclerosis. Hence this is called “bad cholesterol”. Even free fatty acids are considered as bad for health because these can increase LDL cholesterol. HDL Cholesterol is produced in liver, intestine and released  in blood stream. HDL picks up cholesterol and picks up cholesterol and brings it back to liver for reprocessing or excretion (Gurr 1992). HDL probably also removes deposited cholesterol from artery walls along with excess cholesterol from fat-loaded cells. Thus HDL is called “good cholesterol”. Levels below 40 mg/d1 are considered to indicate a risk situation. The low level of HDL is associated with obesity, lack of exercise and high intake of fat.

COMPARATIVE ACCOUNT OF MUSTARD OIL AND OTHER OILS

Comparing oils on the basis of SFA. The dietary consumption of saturated fats has, in recent years, been regularly cited as a major factor in the pathogenesis of atherosclerosis and its associated sequelae, namely, ischemic heart diseases (HD) and peripheral vascular diseases, increasing serum cholesterol, thrombogenic and hyperlipidemic. Palmitic acid is the prime offender among all SFAs. According to FCC Standards Palmitic acid level should be less than 6% (Table 4 ) which is within an appreciable range in mustard oil while in most other oils it is higher than that except in Canola oil. However, it is now generally recognized that the replacement of saturated fats by vegetable oils containing high levels of polyunsaturated fatty acid may also render the individuals susceptible to cardiovascular diseases (Lawson H, 1997).   

Comparing oils on the basis of PUFA Polyunsaturated fatty acid rich groundnut oil has been shown to be proatherogenic. Dietary PUFA may induce the growth of colon and breast cancers and influence the levels of immunoglobulins. High PUFA is shown to depress the response of lymphocytes to mitogens and antigens.

The undesirable effect of PUFA is increased susceptibility for peroxidation. Lipid peroxidation is an oxidative deterioration of PUFA with the formation of highly toxic products such as peroxides and aldehydes. (Lauridson C. et al., 1999) It is suggested that dietary ingestion of thermally or autoxidatively stressed PUFA rich culinary oils is more harmful compared with those similarly treated oils rich in saturated fatty acids or MUFA (Prabhu H. R., 2000)

Mustard oil has a lower percentage of PUFA as compared to other commonly used vegetable oils.

Yet a series of PUFA which is the Omega fatty acid series is recently found to be very good for health. Omega (n-3 and n-6) fatty acids are potent inhibitors of cancer. These may also lessen the severity of some autoimmune diseases. The omega (n-6 and n-3) fatty acids when substituted for saturated fatty acid lower serum, total cholesterol and LDL cholesterol (Freese et al., 19997). These also lower serum triglycerides. In addition to this, these have an antioxidant activity that fends off artery damage from LDL cholesterol, thus benefiting the arteries. It is , therefore, used as a biological marker for healthy heart. Omega 3 and Omega 6 fatty acids show platelet aggregations. Oils with Omega or n-3 PUFA reduce plasma triglycerides and increase blood-clotting time. PUFA have a positive role in vascular diseases, inflammation, and allergic diseases and in platelet aggregation. It is also suggested that saturated fatty acids are prothrombogenic compared to PUFA. Omega-3 fatty acid is antithrombogenic whereas w-6 fatty acid is anti-atherogenic. The n-3 and n-6 fatty acid deficiencies are represented in Table 4.

Mustard oil contains 9-15% omega 3 fatty acids, which is much higher than most of the commonly consumed edible oils. It is 10.5% in canola oil, 7.8% in soybean oil while corn oil has 1.5%. A ratio of n-6: n-3 (4:5) is effective in reducing the risk of heart diseases (Enas A.E., 1996) and this ration may be met through mustard oils

Comparison on the basis of MUFA content : Monounsaturated  fatty acids are beneficial for heart. Clinical studies have reported that the substitution of monounsaturated fatty acids in place of saturated fatty acids resulted in a reduction of total cholesterol and LDL cholesterol, perhaps without reduction in HDL  cholesterol. The monounsaturated fatty acids are, therefore, metabolically more favorable than saturated or polyunsaturated fatty acids (Bonanone et al., 1992) . Oleic acid has been shown to have a protective role during oxidative modification of lipoprotein  in in vitro studies. Oxidized LDL accelerates cell production leading to arterial injury. Monounsaturated fatty acids, therefore, may protect and lower bad cholesterol (LDL). It increases good cholesterol (HDL). The American Heart Association has suggested that the ratio of monounsaturated fatty acids to polyunsaturated fatty acids should be 1:5. Monounsaturated fatty acids content of S.alba is higher (oleic acid: 16-18%) and polyunsaturated fatty acids content is lower (linoleic and linolenic: 7-10 and 9-12% respectively).

ANTIOXIDANTS IN MUSTARD OIL

Antioxidants are compounds that protect against oxidation and peroxidation caused by free radicals. Free radicals cause damage to the nuclear material, cell death and tumor formation. High doses of antioxidants are required for scavenging free radicals. Various studies have shown a relationship between antioxidants and CAD. High doses are recommended for CAD patients. Antioxidants are crucial for healthier life and to prevent disorders like atherosclerosis, dementia, skin disorder, arthritis and neurological disorders. They also keep a constant watch on growth and development of foetus during pregnancy. Diets rich in PUFA increase the requirement for antioxidants. Mustard oil contains adequate amount of alpha tocopherol and thus acts as a potent antioxidant for human health.

Beneficial role of erucic acid present in mustard oil : It is very beneficial in the genetic disease Adrenoleukodystrophy (ALD). This is the disease among children linked to X-chromosome. Only sons contract the severe form called childhood ALD. The child builds up unusual body fat with very long chain fatty acids. Saturated fatty acids accumulate in the  body cells and destroy myelin which coats and insulates  nerve fibers. This results in loss of neurosensory functions and ultimately breathing (Peter M, 1993). To treat this disorder “Oleic-Erucic Acid” formulation is used.

Harmful Effects of Erucic Acid : Erucic acid may be a harmful compound regarding its negative effect on health of  heart. Feeding a high erucic acid rapeseed oil (HEAR), with 20%, 22:1, n-9 led to an even greater platelet reduction and increased platelet size through out the 4 wk trial (Kramer et al., 1998).

Positive role of Isothiocyanates : Both mustard and canola contain significant s amounts of glucosinolates. These are sulfur-containing molecules produced from amino acids by the secondary metabolism. Previously it was thought that glucosinolates are carcinogenic but recent studies have shown that glucosinolates have a positive role. High content of glucosinolate is desirable in mustard, as they are precursors of flavor components, also called “essential oil. When mustard seeds are crushed, exposed to water, vinegar, or grape juice, an enzyme called myrosinase (thioglucoside gluochydrolase) hydrolyses glucosinolates to isothiocyanates. Isothiocyanates give pungency to mustard oil. Both allyl isothiocyantes from B.juncea and aromatic PHBIT (parahyroxy benzyl isothiocyanate ) from S.alba are quiet effective antifungals. However, PHBIT is more effective. Allyl isothiocyanates destroys mycotoxin-producing moulds like Aspergillus flavus, Pencillium citrinum and Fusarium graminarium and Neurosproa yeast. An antibacterial activity and an anticarcinogenic activity are also exhibited. Dithiol thiones are also present which are anti mutagenic agents. However, it is still not very clear that the glucosinolates are carcinogenic or are protective against chemical carcinogens.

Beneficial roles of Phenolics : These have an antioxidant activity life tocopherols, phospholipids and amino acids. These retard oxidation of oil. Low pungency Ground Mustard oils (LPGMS) control oxidative rancidity in pork.

Role of Phytins: It is present in mustard oil (2.3%). It has cariostatic property.

NEW DIMENSIONS IN THE FIELD OF MUSTARD OIL RESEACH AND IT’S PROMOTION

The scientists have developed a new bioengineered variety of mustard oil that can be called as (²00²) oil regarding the near zero erucic acid and near zero glucosinolate contents. A newer type of mustard oil called (²00²) rapeseed oil has been extracted from a bioengineered variety of mustard. The good thing about this variety is that it has a very low amount of erucic acid (less than 2%). The low erucic acid varieties are called LEAR (Low Erucic Acid Rapeseed). These also have a lower glucosinolate content: <30 micro moles/g. Increased oleic acid and decreased linoleic acid in B.juncea has been controlled by a single gene and is highly heritable.

CONCLUSION

Mustard is a very important crop in India. It is clear that the mustard has been used for the past many decades and the consumption of mustard oil is still being used mainly in India. Though self-sufficiency is achieved in production of mustard species in India, emphasis is to be given on productivity aspects.

Mustard oil has very low amount of saturated fatty acids while palm oil, palmolein and coconut oil contain very high amounts of saturated fatty acids i.e., more than 50%. Even peanut and cottonseed oil contain more than 20% saturated fatty acids. In other oils also it is around 10% or more, thus mustard oil remains superior to others. Mustard oil contains70% of MUFA while olive oil and peanut oil contain about 70% and 50% respectively . Other oils like corn oil, cottonseed oil, palm oil, palmolein oil, safflower oil, soybean oil and sunflower oil contain less than 50% of MUFA. However, coconut oil contains only 7.8% of MUFA. Mustard oil contains 15.2% of PUFA while safflower oil, corn oil, soybean oil, sunflower oil contain more than 50% of PUFA. Other oils like olive oil, palm oil and coconut oil contain less than 10% of PUFA. Finally, we can conclude in this article, the edibility cycle of mustard oil benefits associated with specific fatty acids (mainly higher content of MUFA and desirable concentration of linoleic and linolenic acid) and possibly another components, other than fatty acids in the oil rather than to specific effects of MUFA itself.

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