Interactions of Milk Fat and Milk Fat Fractions with Confectionery Fats

¹ Pillsbury Co., 330 University Ave. SE, Minneapolis, MN 55414
² Department of Food Science, University of Wisconsin, 1605 Linden Drive, Madison, WI 53706

The objectives of this study were to provide a better understanding of the effects of triacylglycerol (TAG) and non-TAG compononents (minor lipids) of milk fat on phase and crystallization behavior of binary mixtures palm kernel oil (PKO) and the physical properties of corresponding compound coatings. Binary mixtures of a fractionatedd PKO with the different milk fats were examined for melting profiles, crystallization kinetics, and crystalline microstructures, and polymorphic changes during storage. Compound coatings were made with equivalent binary fat mixtures and measured for hardness and bloom formation. Milk fat and milk fat fractions affected crystallization rates of fractionated PKO, depending on the melting point of the fat. High-melting components resulted in more rapid crystallization, whereas the original milk fat and low-melting components inhibited crystallization. The crystal structure (e.g., number, size, shape) of the PKO crystals was influenced significantly by the addition of milk fat fractions and was influenced by the presence or absence of the minor lipids in milk fat. Milk fat and milk fat fractions had a softening effect on fractionated PKO, which was apparent in the binary mixtures as well as the compound coatings. In general, as the solide fat content (at 25°C) of the binary mixtures increased, the hardness of the respective coatings increased. This also was related to an increased rate of bloom formation during storage.

Key Words: milk fat • palm kernel oil • confectionary coatings • crystallization

Submitted on September 2, 1999
Accepted on June 8, 2000