Effects of drying methods on rennet-induced gelation properties of β-casein-reduced casein micelles

This study investigated the effects of different drying methods on the rennet-induced gel properties of β-casein-reduced casein micelles. The results demonstrated that the storage modulus (G') of gels prepared from dried samples was lower than that of gels from intact casein micelles (CM) and the undried β-casein-reduced casein micelle concentrate (R-CMC). Among β-casein-reduced samples, G' values were ordered R-CMC > freeze-drying (FD) > freeze-spray-drying (FSD) > spray-drying (SD), while rennet coagulation time (RCT) was ordered R-CMC >SD > FD > FSD. Microscopic structure observations aligned with the rheology results. These trends were influenced by particle size; a smaller particle size contributed to a higher G' and a denser gel network, and the sample with the largest particle size exhibited the lowest G' and a looser gel structure. Additionally, colloidal calcium (Ca) played a critical role in RCT; samples containing higher levels of colloidal Ca displayed shorter RCT. In conclusion, the drying method is a key factor governing the gelling properties of β-casein-reduced casein micelles. This study provides a theoretical foundation and technical guidance for their application in cheese products. • Intact micelles exhibited higher Storage modulus than β-casein-reduced ones. • The dried sample has lower rennet gel strength than the undried sample. • Low-temperature drying preserves the gel characteristics of casein micelle rennet gel. • The size of casein micelles affects the gel characteristics of rennet coagulation.