Size-controllable core/shell whey protein microgels with narrow particle size distribution fabricated by a facile method

Biopolymer-based microgels are increasingly being viewed as promising building blocks for diverse applications, including drug delivery, novel food ingredients, sensing, and cell biology. The formation of microgels with a narrow size distribution is of key importance because the functional properties of these microgels largely rely on their sizes. This study describes the use of protein-polysaccharide segregative phase separation as a facile method to fabricate whey protein-based microgels by heating mixtures of whey protein and anionic polysaccharides. The spherical microgels had a narrow size distribution and their size could be precisely controlled to 1, 3, and 6 μm. The scanning electron microscopic images revealed a core-shell morphology of the individual microgel with an internal structure of densely cross-linked protein network and an outer "hairy" layer of polysaccharide, resembling the hair-like structures of the casein micelles. Compared to the whey protein, the core/shell microgels could produce emulsions that were stable without flocculation and creaming during a 28-day storage test. Considering the size-controllable protein-based microgels can be fabricated in a convenient method without using toxic reagents or high energy input, these microgels will have broad applications in the food, pharmaceutical, and personal care industries.