Physical, chemical and stability properties of buffalo butter oil fractions obtained by multi-step dry fractionation

Chemical, physical and stability properties of buffalo butter oil fractions, obtained by stepwise crystallization at several temperatures between 15 and 40 °C, were investigated. Saponification, iodine, Reichert-Meissl, Polenske and Krishner values of low-melting fractions (LMF) were significantly higher (P<0.05) than high-melting fractions (HMF) or the original butter oil. Cholesterol, fat-soluble vitamins (A, D and E) and lactones tended to concentrate more in LMF than middle-melting fractions (MMF) and HMF. Refractive index and specific gravity of MMF lie between those of LMF and HMF. LMF showed the lowest stability toward thermal oxidation (5.6 h) when compared to MMF (7.7-11.2 h) and HMF (11.1-16.0 h). Rate of hydrolysis of LMF was the highest (7.8 ml of 4 g/l NaOH) among all the obtained fractions, while HMF was the lowest (4.9-1.6 ml of 4 g/l NaOH). Differences in chemical and physical properties of the fractions were attributed to differences in fatty acid composition.