Novel Antioxidative Wall Materials for Lactobacillus casei Microencapsulation via the Maillard Reaction between the Soy Protein Isolate and Prebiotic Oligosaccharides

In this study, three kinds of Maillard reaction products (MRPs) have been, for the first time, successfully prepared by conjugating soy protein isolate (SPI) with isomaltooligosaccharide, xylooligosaccharide, or galactooligosaccharide at 80 °C for 30 or 60 min and applied for the construction of Lactobacillus casei (L. casei) microcapsules. The results showed that MRPs exhibited enhanced antioxidative activities compared with their physically mixed counterparts. The digested MRPs displayed excellent resistance to pathogenic bacteria and promoted the growth of L. casei. Moreover, MRP-encapsulated L. casei showed a higher survival rate than free L. casei under tested adverse conditions including heat treatment, storage, and mechanical forces. Under simulated digestion conditions, the viability of L. casei decreased from 8.8 log cfu/mL to 1.6 log cfu/mL, while that of MRP-encapsulated L. casei was maintained at 7.4 log cfu/mL. Thus, MRP-based SPI-oligosaccharide conjugates exhibited great potential for microencapsulation of probiotics.