Polyunsaturated fats/oils

The intermediate m hydrogenation formed by reaction of the unsaturated ester with the hydrogenated surface of the metal catalyst not only can proceed to the saturated fatty acid ester but also can dissociate to the original ester having a cis double bond or to its trans stereoisomer Unlike polyunsaturated vegetable oils which tend to reduce serum cholesterol levels the trans fats produced by partial hydrogenation have cholesterol raising effects similar to those of saturated fats... 

BHA and BHT, which are both fat soluble, are effective ia protecting animal fat from oxidation, and are often added duting the rendering process. Propyl gallate is also effective, but it has limited fat solubiUty, and turns bluish black ia the presence of iron. It is typically used as a synergist ia combination with BHA or BHT. TBHQ is most effective against oxidation ia polyunsaturated vegetable oils (qv), and is often used ia soybean oil (19). 

Trilinolein is a polyunsaturated fat. This type of fat is an antioxidant that has been linked to a number of potential cardiovascular health benefits. It is found in seed oils such as safflower oil and linseed oil. 

Polyunsaturated fats can combine easily with oxygen at the points where there is a double bond between two carbon atoms. This is why they make good antioxidants they combine with the oxygen free radicals so they don t damage other molecules. It is also how oils harden, and is thus important to painters. Oil paints made with linseed oil are almost three-quarters trilinolein. They dry to form a tough plastic film that incorporates the pigments and holds them onto the surface to be painted. 

Gonjugation of polyunsaturated fats Methyl linoleate with tris(triphenylphosphine) chlororhodium. J.Am. Oil Chem. Soc., 48, 21-24. 

Polyunsaturated fats occur widely in the fats and oils that are components of our diet and are widespread in the tissues of the body where they perform numerous vital functions. 

Oxidative rancidity is not necessarily a problem unless a polyunsaturated fat such as sunflower oil has been used. Where such a fat is used oxidative rancidity can occur and, as autoxidation occurs where the reaction becomes self-catalysing as oxygen free radicals react, some very unpleasant tastes can appear very quickly. In general, the effect of oxidation on biscuits at the end of their shelf life is that a cardboard taste starts to appear. 

Mean urine and fecal losses of calcium of subjects while receiving the three test fats are shown on Table II. Apparent calcium absorptions and calcium balances were calculated from this data. Mean fecal calcium losses when safflower oil, soybean oil and apricot kernal oil were fed were 460, 500 and 520 mg/day. With a probability of only P<0.10, these difference were not statistically significant although a strong trend toward increased fecal calcium losses with degree of saturatedness of the dietary fat was shown. Thus, a trend toward increase in calcium absorption with more polyunsaturated fats was illustrated. Coupled with changes in... 

Significantly improve keeping qualities of polyunsaturated fats and oils. 

Sixty to eighty-five percent of the fatty acids in fishery products are either monounsaturated or polyunsaturated. Polyunsaturated fats have been shown to reduce blood cholesterol levels and the same phenomenon exists for fish oils. Epidemiological studies of the Greenland Eskimos show their diet to be high in marine oils and the populaticxi has correspcMidingly low serum cholesterol values (6) (7). 

You can hydrogenate some of the double bonds in any polyunsaturated fat. Hydrogenation, whether complete or partial, results in an increase in the melting point, a fact that makes it possible to convert a liquid oil to a solid fat. (Note that partial hydrogenation may convert some of the cis double bonds into tram double bonds, thereby producing a trans fat.)... 

Diets. Three basic diets were utilized (Table I), a 2% low fat diet (2% linoleic acid methyl esters), a 20% polyunsaturated fat diet containing 20% stripped corn oil, and a high saturated fat diet containing 18% coconut oil and 2% linoleic acid methyl esters to prevent an essential fatty acid deficiency (6 ). All diets were prepared to our specifications by ICN Life Sciences (Cleveland, OH) and analyzed both by ICN and our laboratory for fatty acids, antioxidants and some trace minerals. They are routinely stored in sealed plastic containers at 4°. Antioxidants when added (see Figure 2) were supplemented just prior to feeding and at 0.2% or 0.3% of the diet by weight as specified in each experiment. 

Polyunsaturated Fat Saturated Fat (20% Corn Oil) (18% Coconut oil + 2% Linoleic acid)... 

In this experiment, the type of fat as well as the amount was changed because earlier studies had shown that saturated fats were less effective promoters of mammary carcinogenesis than polyunsaturated fats. Lard, however, has a higher content of linoleic acid than either butter or coconut oil and increased the tumor yield almost as much as polyunsaturated fats when fed at the 207, level... 

Polyunsaturated aliphatic alkohols, aldehydes, ketones, and esters occur as fragrance components in fats, oils, fruits and plants 158). As an example the synthesis of ethyl (2 ,4Z)-2,4-decadienoate (232, pear ester ), which is responsible for the aroma of bartlett pears 161) is given. 2,4-Diunsaturated ester 232 may be obtained by a number of highly stereoselective syntheses, a lot of them making use of the Wittig reaction. Ohloff and Pawlak condensed 4,5-epoxy-( )-2-pentenal 228 with the ylide generated from 229 (butyllithium/ether) to the alkadiene epoxide 230 which was oxidized with periodic acid to the 2,4-decadienal 231. 231 is subsequently converted with MnOj/NaCN in ethanol to the pear ester 232162) [75 % (Z)-amount of the C-4 double bond] (Scheme 44). 

A role for milk fat in cancer risk has not been examined adequately in epidemiological studies, because milk fat is not consumed as a single dietary item, but as a component of dairy products and dairy products also contain non-lipid components with anti-cancer potential (Parodi, 2001a, b). On the other hand, seven studies were found in the literature, where milk fat or butter diets were compared with diets containing equal amounts of polyunsaturated vegetable oils or margarine in animal models of colon, breast, and skin cancer. All seven studies showed that there was less tumor development with milk fat-based diets (Parodi, 2004). 

This reaction is put to good use in the manufacture of margarines. One of the ingredients in many margarines is hydrogenated vegetable oil. When polyunsaturated fats are hydrogenated they become more solid. This means... 

Kathy boasted that she kept her cholesterol down and kept slim with a diet that included a special margarine. It never has that effect for me , said Sandy. Mind you, she did have a full cooked breakfast and five pieces of toast and marmalade. The polyunsaturated fat got lost in the crowd of harmful fats. Generally speaking fats are mostly saturated hydrocarbon compounds. Oils , on the other hand, do contain many C=C bonds and are said to be unsaturated . Natural vegetable oils contain many C=C bonds they are polyunsaturated. Poly means many. 

Polyunsaturated fats and oils are susceptible to oxidation when stored in metal containers, at elevated temperatures, and/or in open containers. Oxidation can be minimized by storing them in closed, nonmetal containers with minimal headspace or flushed with nitrogen gas. 

A polyunsaturated fat such as linoleic acid is more likely to be found in peanut oil. Additional Problems... 

Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end. They can be classified on the basis of the length of the hydrocarbon chain (Table 2.2) and whether there are any double bonds. Trivial names of fatty acids such as butyric, lauric, oleic and palmitic acids are in common use in the food industry. A form of short-hand is used to refer to triglycerides where POS is palmitic, oleic, stearic. If the chain length is the same an unsaturated fat will always have a lower melting point. Another classification of fats that is used is in terms of the degree of unsaturation of the fatty acids. Saturated fats are fats without any double bonds. Many animal fats are saturated, but some vegetable fats, e.g. coconut oil, are saturated also. Mono-unsaturated fats include oils like olive oil but also some partially hydrogenated fats. Polyunsaturated fats have many double bonds and include sunflower oil. Because they are... 

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