ALTERATION OF PLASMA-LIPIDS IN THE RAT BY FRACTIONATION OF MODIFIED MILK-FAT (BUTTERFAT)

Our objective was to determine the nutritional effects of defined fat fractions of modified milk fat, or butterfat (anhydrous butter without the milk fat globule membrane) on lipid and lipoprotein cholesterol c oncentrations in plasma of rats fed diets containing 16% fat and two a mounts of cholesterol. Five dietary fats were compared: 1) intact butt erfat, 2) a liquid butterfat fraction enriched in oleic acid and unsat urated triacylglycerols with <40 carbon atoms, 3) a solid butterfat fr action enriched in palmitic and stearic acids, 4) corn oil, and 5) pal m oil. The extent of diet-induced hypercholesterolemia was the greates t with palm oil, followed by solid butterfat, corn oil, intact butterf at, and the lowest with liquid butterfat. Triacylglycerol concentratio ns in plasma were greater for rats fed palm oil than for those fed cor n oil or liquid or intact butterfat. Among the high cholesterol dietar y groups, ingestion of the liquid butterfat diet resulted in similar l ipoprotein cholesterol and very low density lipoprotein concentrations relative to the corn oil diet, and ingestion of the solid butterfat d iet resulted in similar lipoprotein cholesterol and very low density l ipoprotein concentrations relative to the palm oil diet. These results suggest that changes in the triacylglycerol and fatty acid compositio n of butterfat by fractionation processes may improve its nutritional profile.