CHEMICAL AND THERMAL-CHARACTERISTICS OF MILK-FAT FRACTIONS-ISOLATED BY A MELT CRYSTALLIZATION

Anhydrous milk fat (AMF) was fractionated by a two-stage dry fractiona tion process to produce three fractions: high melting (HMF), middle me lting (MMF), and low melting (LMF). The HMF (m.p. 42 degrees C) exhibi ted a broad melting range similar to a plastic fat. The MMF (m.p. 33 d egrees C) resembled the original AMF (m.p. 31 degrees C), but with sli ghtly higher solid fat content. The LMF (m.p. 16 degrees C) was liquid at ambient temperature. Differences in the thermal properties of thes e fractions were attributed to the triacylglycerols (TAG) and their fa tty acid composition. Saturated TAG with carbon numbers of 36-54 were concentrated in the HMF; whereas unsaturated TAG of carbon number 36-5 4 predominated in the LMF. Likewise, the long-chain saturated fatty ac ids were significantly higher and the long-chain unsaturated fatty aci ds were significantly lower in the HMF fraction. Binary blends of milk -fat fractions with a range of melting profiles were produced by mixin g HMF with AMF, MMF, or LMF. Laboratory-prepared fractions were simila r to commercially available fractions.