Nutritional aspects of fats and oils

3 (linolenic acid and/or docosahexaenoic acid). The advent of hydrogenation to produce such products as margarines has introduced the unnatural trans fatty acids. Due to the concern over fat consumption, the development of fat substitutes for foods is an active area of research. Medium-chain triglycerides have been used as an alternative source of fat energy for those individuals unable to digest normal fats in the diet. These topics are discussed in detail in this chapter. 

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By far the most telling negative nutritional aspect of milk fat is the belief that its content of saturated fatty acids and cholesterol elevate plasma cholesterol levels, which is a risk factor for coronary heart disease (CHD). During the early 1950s, it was found that the type of fat in the diet could influence plasma cholesterol level. Ahrens et al. (1957) showed that diets containing saturated fats, such as beef, lard and milk fat, produced higher plasma cholesterol levels than diets containing unsaturated fat like safflower and corn oil when they were fed under strict metabolic-ward conditions. Later, Connor (1961) reported that the level of cholesterol in the diet also influenced plasma cholesterol level. 

In recent years, new developments in deodorization technology were mainly determined by the strong demand from edible oil refiners to reduce the capital and operating cost of deodorizers and the increased importance of the nutritional aspects of food oils and fats. 

Petroselinic add (Z)-6-octadecenoic acid]. H3C-(CH2),o-CH=CH-(CH2)4-COOH, C,gH3402, Mr 282.47, mp. 32-33°C, bp. 215-217°C (0.2-0.3 kPa) soluble in organic solvents. P. was first found as the glycerol ester in the seed oil of parsley (Petro-selinum crispum), it is a characteristic component of the seed oils of umbelliferous and ivy plants. The fatty acids of these seed oils contain up to 87% P. (e.g. fat coriander oil, 75-80%). P. is also used as a starting material in oleochemistry. For nutritional-physiological aspects, see Lit.. ... 

A note on health aspects is appropriate because the lauric oils are more than 80% saturated. This is much more than the major liquid oils such as soyabean, sunflower and rapeseed, which are respectively only 16%, 12% and 7% saturated. Nutritionally this may be thought of as a great disadvantage but such simple comparisons can be misleading. Lauric oils are only used in foods where a sharp melting hard fat is needed. When liquid oils are hydrogenated to a similar consistency, they contain not only more saturates but also trans fatty acids, which some recent studies have shown to be even more objectionable with regard to serum cholesterol profiles than the saturated ones (Byers 1997, Pietinen et al. 1998). 

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