The melting properties of milk fat fractions obtained by double fractionation using a commercial process

Summary

Solid fractions obtained by a commercial process from anhydrous milk fat were refractionated and the softening point (SP), iodine value (IV), and melting thermograms determined. The content of high melting fats and liquid fat content at the SP were calculated for each fraction from its thermogram. Refractionation at 28 °C did not alter the properties of the resultant solid fat. The small amount of liquid fat obtained by refractionation resembled intact milk fat in the properties measured. Refractionation at 31–32 °C yielded a solid fat having a higher SP, lower IV, and increased high melting fat content. Triple refractionation resulted in a solid fraction having a restricted melting range and capable of crystallizing in an unstable polymorphic form upon quick cooling. Tempering the refractionated solid fats at the melting gap temperature of 20–22 °C resulted in elimination of phases melting below −10 °C and enhancement of the melting gap. The content of high melting fat was correlated with the SP. The SP occurred when 95 % of the fat (S.D.±2·7 %) had melted.