A COMPARISON OF PHYSICAL AND CHEMICAL-PROPERTIES OF MILK-FAT FRACTIONS OBTAINED BY 2 PROCESSING TECHNOLOGIES

Milk fat fractions from supercritical carbon dioxide (SC-CO2) extracti on were compared with commercial melt crystallization (MC) fractions f or their physical and chemical properties. The fractions were analyzed for fatty acids, triacylglycerols, cholesterol, total carotenoid cont ent, and volatile compounds. The fractions were also evaluated for sol id fat content (SFC) by pulsed nuclear magnetic resonance and thermal profiles by differential scanning calorimeter (DSC). The distribution of fatty acids and triacylglycerols in the fractions depended on the f ractionation technique used. SC-CO2 separated fractions based on molec ular weight rather than on melting point, which is the driving force f or the MC process. The differences among the fractions were quantified from their SFC and DSC curves, Triacylglycerol profiles by high-perfo rmance liquid chromatography showed that the SC-CO2 fractions were dis tinctly different from each other and from MC fractions. The SC-CO2 so lid fraction (super stearin) was the most unique. It had a high concen tration of long-chain, unsaturated fatty acid-containing triacylglycer ols in a narrow range of high molecular weight, indicating a homogenei ty of this fraction that has not been attainable by other techniques. It was also enriched in beta-carotene and was devoid of volatile compo unds. As compared to liquid MC fractions, the liquid SC-CO2 Fraction h ad a high concentration of low-melting triacylglycerols and was enrich ed in volatile compounds. With SC-CO2, it is thus possible to simultan eously fractionate and produce a flavor-rich concentrate at no extra p rocessing cost.