Chemical and thermal characteristics of milk-fat fractions isolated by a melt crystallization

Anhydrous milk fat (AMF) was fractionated by a two-stage dry fractionation process to produce three fractions: high melting (HMF), middle melting (MMF), and low melting (LMF). The HMF (m.p. 42 degrees C) exhibited a broad melting range similar to a plastic fat. The MMF (m.p. 33 degrees C) resembled the original AMF (m.p. 31 degrees C), but with slightly higher solid fat content. The LMF (m.p. 16 degrees C) was liquid at ambient temperature. Differences in the thermal properties of these fractions were attributed to the triacylglycerols (TAG) and their fatty acid composition. Saturated TAG with carbon numbers of 36-54 were concentrated in the HMF; whereas unsaturated TAG of carbon number 36-54 predominated in the LMF. Likewise, the long-chain saturated fatty acids were significantly higher and the long-chain unsaturated fatty acids were significantly lower in the HMF fraction. Binary blends of milk-fat fractions with a range of melting profiles were produced by mixing HMF with AMF, MMF, or LMF. Laboratory-prepared fractions were similar to commercially available fractions.