Casein Microparticles from Blend Films Forming Casein/α-Tocopherol Emulsion Droplets in Solution

Microparticles continue to receive widespread attention from food professionals because of their potential use as carriers of bioactive substances. This study demonstrates a novel method to prepare casein microparticles, which co-assemble with α-tocopherol (αT) into emulsion droplets. When the particles were extracted from the pectin matrix via enzymatic degradation, they remained stable in a buffer solution for at least 3 weeks. Optical microscopy showed that the size distribution of the microparticles is between 5 μm and 50 μm, which is in accordance with previous observations in blend films. High-performance liquid chromatography revealed that the amounts of α_S1- and κ-casein in the microparticles are significantly higher than those in native casein micelles. Confocal Raman microscopy showed that in the presence of α-tocopherol, the microparticles assemble into emulsion droplets, with phenol in the core and casein in the shell. Herein, we demonstrate a new method to form casein-based emulsion droplets for potential use as carriers of bioactive substances.