Solvent effects on the crystallization behavior of milk fat fractions

The high-and medium-melting fractions of milk fat (HMF and MMF, respectivel y) were crystallized in the presence of various solvents, including the low -melting fraction of milk fat (LMF), canola oil (CO), hexane, and ethyl ace tate. Choice of solvent was shown to have a strong influence on phase behav ior and crystallization kinetics. Dilution and solubilization effects were observed for all the blends. More solids were formed in the HMF and MMF ble nds with LMF than with CO, and complexes were formed between the milk fat f ractions possibly because of molecular complementarity. Solids were slightl y higher for the more polar ethyl acetate than for hexane. Crystallization proceeded more rapidly in the presence of LMF and ethyl acetate than in the presence of CO and hexane, respectively. According to the Hildebrand equat ion, HMF and MMF were ideally soluble in LMF and CO. X-ray diffraction spec troscopy (XRD) revealed the existence of liquid-state structure in mixtures of HMF/CO, HMF/LMF, MMF/CO, and MMF/LMF. The observed liquid-state structu re was reminiscent of liquid crystals; No differences were observed in the structure of the liquid phase between LMF- and CO-containing mixtures.