Fractionation of Anhydrous Milk Fat by Superficial Carbon Dioxide

Milk fat was fractionated with supercritical CO 2 (SC‐CO 2 ) into 8 fractions at temperatures of 50° and 7O°C, over a pressure range of 100–350 bar. Two fractions (L1 and 2) were liquid, 3 fractions (11–3) were semi‐solid and 3 fractions (Sl‐3) were solid at 20°C. The peak melting temperature progressively increased (9.7° to 38.3°C) from fraction L1 to S3. The concentration of short chain (C24‐C34) triglycerides decreased from fraction L1 to S3 while that of long chain (C42‐C54) triglycerides increased gradually. The medium chain triglycerides were more concentrated in fractions L2 and 11–3. The proportion of short (C4‐C8) and medium (ClO‐C12) chain fatty acids decreased and that of long (C14‐C18) chain fatty acids increased gradually from fraction Ll‐S3. The weight average molecular weights and geometric mean‐carbon number of milk fat fractions were in the range from 625.6 to 805.0 and 34.2 to 47.6, respectively, in comparison to 729.3 and 41.O, respectively, for native milk fat, suggesting SC‐CO 2 effected a fair degree of molecular weight separation.