A comparison of physical and chemical properties of milk fat fractions obtained by two processing technologies

Milk fat fractions from supercritical carbon dioxide (SC-CO2) extraction were compared with commercial melt crystallization (MC) fractions for their physical and chemical properties. The fractions were analyzed for fatty acids, triacylglycerols, cholesterol, total carotenoid content, and volatile compounds. The fractions were also evaluated for solid 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 fractionation technique used. SC-CO2 separated fractions based on molecular weight rather than on melting point, which is the driving force for the MC process. The differences among the fractions were quantified from their SFC and DSC curves, Triacylglycerol profiles by high-performance liquid chromatography showed that the SC-CO2 fractions were distinctly different from each other and from MC fractions. The SC-CO2 solid fraction (super stearin) was the most unique. It had a high concentration of long-chain, unsaturated fatty acid-containing triacylglycerols in a narrow range of high molecular weight, indicating a homogeneity of this fraction that has not been attainable by other techniques. It was also enriched in beta-carotene and was devoid of volatile compounds. As compared to liquid MC fractions, the liquid SC-CO2 Fraction had a high concentration of low-melting triacylglycerols and was enriched in volatile compounds. With SC-CO2, it is thus possible to simultaneously fractionate and produce a flavor-rich concentrate at no extra processing cost.