Physico-chemical Properties of Milkfat Fractions Extracted with Supercritical Carbon Dioxide at Different Pressures
Dilek Büyükbeşe1, Dérick Rousseau2, Ahmet Kaya1
1. University of Gaziantep, Gaziantep, Turkey
2. Ryerson University, Toronto, Ontario, Canada

Milkfat was sequentially fractionated with supercritical carbon dioxide (CO2) at 40oC using pressures of 100, 150 and then 200 bar. Fractions were continuously collected every hour for 6 hours at each pressure and evaluated for extraction yield, fatty acid composition, thermal transition temperatures and shear crystallization. The mass of the fractions collected at 100, 150 and 200 bar were 34, 26 and 33 g/100 g milkfat, respectively. The remaining raffinate represented ~7 % of the milkfat. As a function of time within each successive pressure, there was a decrease in the proportion of short chain (C4–C8), medium chain (C10–C14) and total saturated fatty acids and an increase in long chain (C18–C18:2) and total unsaturated fatty acids. The raffinate exhibited a higher melting point and a yellower appearance than the fractions than those obtained at lower CO2 pressure. Fractions produced at 100 bar were liquid at room temperature and had lower melting points than at high pressures. All fractions at 100 and 150 bar were colorless. Shear crystallization showed a distinct relationship between composition and nucleation/crystallization onset temperatures. This study showed that the composition and crystallization behavior of fractionated milkfat can be greatly tailored based on supercritical CO2 pressure.