Fractionation of Butter Oil by Supercritical Carbon Dioxide1,2

Abstract

The use of supercritical CO2 to fractionate butter oil into various triglyceride groups with unique physical and chemical properties was investigated. Experiments were conducted at 40°C and at 10.3, 13.8, 17.2, 20.7, 24.1, and 27.6MPa in a continuous flow extraction system. Solubility of butter oil triglycerides in supercritical CO2 of various temperatures (35, 40, 50, and 60°C) and pressures (10.3, 13.8, 17.2, 20.7, 24.1, and 27.6MPa) was also studied. Triglyceride extractability was enhanced by raising the pressure and lowering the temperature of extraction. The mean molecular weight of fractions, estimated by high performance gel permeation chromatography, ranged from 703amu (atomic mass unit; 40°C, 10.3MPa) to 794amu (40°C 27.6MPa). The fatty acid composition of triglycerides, determined by HPLC, showed that fractions extracted at lower pressure contained higher concentrations of short-chain C4 to c8) and medium-chain (C10 to C12) fatty acids and lower concentrations of long-chain (C14 to C18) fatty acids. Melting behavior of the various fractions, studied by differential scanning calorimetry, reflected the alterations in triglyceride composition. Fractions with unique melting behavior (i. e., a single narrow melting zone and a melting peak maximum of 8°C) were isolated. Fractions obtained at (40°C) 17.2 and 20.7MPa had lower cholesterol (1.07 and 1.76 mg/g), determined by enzymatic assay, compared with those obtained at 10.3 and 13.8MPa (2.96 and 2.78 mg/g). Supercritical CO2 extraction may be a potential process for modifying butter oil into fractions with altered physical and chemical properties.