Application of High Intensity Ultrasound to Accelerate Crystallization of Anhydrous Milk Fat and Rapeseed Oil Blends

In this study, the impact of high intensity ultrasound (HIU) treatment on anhydrous milk fat and milk fat/rapeseed oil blends with 10-30 w/w% rapeseed oil is examined. Effects of HIU treatment on crystallization kinetics, thermal behavior, microstructure, texture, and oxidation are evaluated. HIU treatment results in an acceleration of the crystallization process, especially for blends with a high rapeseed oil content. HIU treatment reduces the crystal size, however, HIU treatment does not have any significant effects on the melting behavior or hardness. No significant effects of HIU treatment on secondary oxidation products are observed, indicating that lipid oxidation is not facilitated by the HIU treatment. Practical Application: A great potential exists for the use of use of high intensity ultrasound in the food industry to obtain a shorter and more controllable fat crystallization process. Results from this demonstrate how the impact of ultrasound treatment is affected by diluting a hard fat with liquid oil. Such effects are of great importance in, for instance, the dairy industry, where high intensity ultrasound potentially provides an additional processing tool in the production of spreadable blends based on milk fat and rapeseed oil. Ultrasound treatment is introduced in a circulating flow system, a more realistic representation of an industrial setting compared with commonly used probe based bath systems. High intensity ultrasound accelerates the crystallization kinetics of anhydrous milk fat and rapeseed oil blends, resulting in the formation of smaller crystals but no differences in melting properties or hardness. This is obtained in a circulating flow cell, without detection of increased levels of secondary oxidation products.