Polymorphic Transformation in Mixtures of High- and Low-Melting Fractions of Milk Fat

• Published in: Journal of agricultural and food chemistry 2006-08, Vol.54 (16), p.6030-6033
• Main Authors: Cisneros, Andrea, Mazzanti, Gianfranco, Campos, Rodrigo, Marangoni, Alejandro G
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Chemical Phenomena; Chemistry, Physical; Crystallization; Fats - chemistry; food chemistry; Food industries; Fundamental and applied biological sciences. Psychology; high-melting fraction; low-melting fraction; Milk - chemistry; Milk and cheese industries. Ice creams; milk fat; mixtures; reaction kinetics; synchrotron X-ray diffraction; Synchrotrons; X-Ray Diffraction
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0600814

The kinetics of crystallization of high-melting fraction (HMF) and a mixture of 40% HMF and 60% low-melting fraction (LMF) of milk fat were studied at 5 °C by time-resolved in-situ synchrotron X-ray diffraction. HMF crystallized in the α polymorph, had a longer lifetime than the ones previously reported in pure milk fat, and was almost completely solid. The HMF/LMF mixture crystallized initially in the α form and transformed into the β‘ polymorph, with a solid fat content much lower than that of HMF. The polymorphic change was therefore attributed to a delayed sudden formation of β‘ mixed crystals from the uncrystallized melt. These findings are important for the food industry and as fundamental knowledge to improve our understanding of the origin of the macroscopic physical properties of solid milk fat fractions used in many manufacturing processes. Keywords: Milk fat crystallization; lipid polymorphism; lipid phase transitions; synchrotron X-ray diffraction