Fat Content and Composition of Animal Products Proceedings of a Symposium (1976) / Chapter Skim
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Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs
Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs
Pages 200-237
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From page 200... ...
and between blood cholesterol levels and heart disease (Figure 2) has made the American consumer wary of the fat in meat, milk, and eggs.
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From page 201... ...
In ruminants, however, if increased amounts of polyunsaturated fats are fed, they are utilized by microorganisms in the rumen or metabolized by these organisms to form saturated and mono-unsaturated fatty acids; as a result, the meat and milk fat do not show any increase in polyunsaturated fat. The data in Table 2 demonstrate that although the normal plant diet of the ruminant is primarily polyunsaturated, both meat and milk fat normally TABLE 1 Contribution of Fat from Various Food Groups a Percentage of Fat Contributed by 1947-19491968 Change (% )
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From page 202... ...
. Recently, a process was developed that represents a breakthrough in the attempt to increase the polyunsaturated, fatty-acid content of TABLE 2 Fatty Acid Composition of Pasture Grass and Bovine Milk and Meat Fat a Weight in Lipid ( % )
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From page 203... ...
It can be seen that ruminant fat contains more saturated fatty acids and less polyunsaturated fatty acids than do swine and poultry fat. Of the three major dietary components fats, proteins, and carbohydrates most attention has been given to the effects of feeding fats upon the fatty-acid and cholesterol composition of the animal.
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From page 204... ...
A wide variety of plant and fish oils, containing large quantities of polyunsaturated fatty acids, were fed to pigs; and the polyunsaturated fats were promptly absorbed and incorporated into their body fat. Most of these studies were conducted with growing pigs (8-28 weeks)
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From page 205... ...
Particularly because of the marked resistance to change of the saturated fatty acids in egg lipids, most compositional changes in response to dietary fats occur in the relative proportions of 18:2 and 18:1. To the extent that generalizations between species are valid in these two monogastric animals, the chicken and the pig, it is apparent that the body fat of swine and poultry will reflect either greater saturation or unsaturation, depending upon the composition of the diet.
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From page 206... ...
206 to Go ~o o _ ~ Go ~o ++ + 4 Ct 4 o _~ o U
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From page 208... ...
The time course of egg cholesterol changes thus appears to agree well with the time course of changes in egg fatty-acid composition (Reiser, l951b)
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From page 209... ...
Alteration of Fatty Acid and Sterol Composition in Lipids TABLE 7 Effect of Dietary Agents on Egg Cholesterola 209 Group Agent Effect References Oils Corn Safflower Linseed + o 39 32,63,80,122,143, 158, 220 7, 80, 209, 219, 220 220,222 80, 219 222 Soybean + 80, 209 0 7,51 Coconut + 7, 220 0 32 Cottonseed 0 167 Lard 0 32,63 Tallow 0 39, 51, 63, 80, 122, 158, 220 Rapeseed 0 122 Sterols Cholesterol + 32, 52, 53, 60, 64, 90, 102, 135, 182, 220, 226 0 121, 136 Sitosterol - 36 0 220 Protein 0 39, 63, 143, 158 Surface Active Tween 0 220 Lecithin 0 220 Cholestyramine 0 111, 134 Tween-cholesterol + 220 Lecithin-cholesterol + 220 Fiber Cellulose + 135 Cellulose - 216 Pectin - 216 Vitamins Niacin 0 220 Vitamin C 0 155 Vitamin A + 182 0 60, 220 Drugs Clofibrate 0 220 MER-29 - 25 Azasterols - 184 Diethyl-aminoethyl diphenyl valerate - 146 Probucol - 146, 147 Hormones D-thyroxine + 220 a CODE: + = increase,-= decrease, and 0 = no change.
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From page 210... ...
Many of the substances that have been used in attempts to alter egg cholesterol are agents that reduce serum cholesterol in other species. Review of the serum cholesterol changes of the studies summarized in Table 7 indicated that there was no simple direct relationship between plasma and egg cholesterol concentration.
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From page 211... ...
A SYNOPSIS OF ALTERATIONS IN THE FATTY ACID COMPOSITION OF MILK. INFLUENCE OF UNPROTECTED DIETARY SUPPLEMENTS Table 8 summarizes data on the alterations in milk fatty-acid composition that can be effected by unprotected dietary materials.
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213 cr.
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INFLUENCE OF PROTECTED LIPIDS. A summary of the alterations that occur in milk fatty acids as a result of feeding protected lipid-containing materials is presented in Table 9.
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From page 216... ...
A SYNOPSIS OF DAIRY PRODUCTS CONTAINING INCREASED POLYUNSATURATED FATTY ACIDS A wide variety of dairy products have been prepared from milk containing increased amounts of linoleic acid. These products reflect the milk from which they are made in composition and, generally, are characterized by large increases in 18:2, increases in 18:1 and 18:0, and decreases in saturated C~-16 fatty acids.
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From page 218... ...
Although changes in fatty-acid composition induced by breed, age, sex, season, and growth are not described, these factors also exert influences of about the same order of magnitude. These studies have been needed, and the development of gas chromatography has stimulated an explosion in lipid research because of the relative ease with which fatty acids can be determined.
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From page 219... ...
The two cheaper seed supplements that have been developed, sunflower seed-1 Onto casein-formaldehyde and sunflower seed-soybean (70:301-formaldehyde, were found to be very effective in producing polyunsaturated beef, lamb, and mutton. THE EFFECT OF PROTECTED FEEDS UPON CHOLESTEROL CONTENT OF MEAT, MILK,AND DAIRY PRODUCTS We have previously demonstrated that very large increases in plasma cholesterol occur, from a level of 140 mg % to 380 mg %, when protected lipids are fed to lactating cows (Bitmap et al., 19731.
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From page 221... ...
221 as to I_ o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~cr.
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From page 222... ...
The chicken we have every Sunday is different from those our mothers enjoyed 30 years ago and different from the chickens our grandmothers ate 60 years ago. The rapidly growing chicken of today, fed on fish meal and animal tallow, undoubtedly tastes different from a 1930 bird.
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From page 223... ...
future. I have summarized those researches that indicate which foods of animal origin can be altered in fatty-acid composition and have describ~d the limits of these alterations.
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From page 224... ...
1971. Metabolism of fatty acids by mammary glands of cows fed normal, re
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1974a. Effects of feeding formaldehyde treated soybean preparations upon milk fat polyunsaturated fatty acids.
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1959. Interconversions of polyunsaturated fatty acids by the laying hen.
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1970. Effect of dietary fat on the fatty acid composition of turkey egg yolks.
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1926b. The effect of food fat upon body fats, as shown by the separation of the individual fatty acids of the body fat.
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1943. The influence of dietary fat of varying unsaturation on the component acids of cow milk fats.
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From page 230... ...
1964. Changes observed in egg yolk cholesterol, serum cholesterol, and serum glutamic oxalacetic transaminase by feeding cholesterol and vegetable oil to mature hens.
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From page 231... ...
1972. InDuence of dietary fat on rumen fatty acids, plasma lipid, and milk fat composition in the cow.
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From page 232... ...
1974. Increased polyunsaturated fatty acid yields in milk of cows fed protected fat.
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From page 233... ...
1972. Milk fat with increased polyunsaturated fatty acids.
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1959. Effect of feeding cod-liver oil and unsaturated fatty acids on rumen volatile fatty acids and milk fat content.
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1970. The effect of polyunsaturated fatty acids on milk fat secretion.
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From page 236... ...
1963. Effect of dietary and injected fat on the fatty acid composition of bovine depot fat and milk fat.
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From page 237... ...
1973. Cheddar cheese with increased polyunsaturated fatty acids.
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