Polymorphism in Milk Fat Shown by X-ray Diffraction and Infrared Spectroscopy

Abstract

The occurrence of three polymorphic modifications, alpha, beta-prime, and beta was studied by X-ray diffraction and infrared spectroscopic methods. Excellent agreement between the two methods was obtained. Slow cooling of milk fat resulted in formation of the beta-prime and beta modifications. Rapid cooling of milk fat resulted in formation of the alpha form which, upon holding of the sample at 5 C, underwent transformation to the beta-prime and beta forms. The high melting fraction (HMF) of milk fat obtained by crystallization from acetone existed in the beta form. Slow cooling of the melted HMF produced the beta-prime form, rapid cooling the alpha form. X-ray diffraction patterns obtained with milk fat solidified at room temperature were diffuse. Resolution was greatly improved by removal of the liquid portion of the fat by pressure filtration. © 1968, American Dairy Science Association. All rights reserved.