Preparation of Ca-alginate-whey protein isolate microcapsules for protection and delivery of L. bulgaricus and L. paracasei

To promote the application of probiotics that are beneficial to hosts, calcium-alginate (Ca-Alg) coated whey protein isolate microcapsules were prepared for protection and delivery of L. bulgaricus and L. paracasei. The internal layer was formed with transglutaminase-induced gelation of whey protein isolate (WPI). Sodium alginate (SA) was applied to form outer layer with external Ca2+ gelation method. The microcapsules loaded with probiotics were characterized by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC). The results showed that the co-encapsulation efficiency was 90.54% and 84.46% of WPI micro-beads and Ca-Alg-coated microcapsules, respectively. The trehalose was added as cryoprotectant to improve the survival rate of probiotics in freeze-dried Ca-Alg-coated microcapsules from 3% to 41.26%. Ca-Alg-coated microcapsules have regular morphology and intensified structure. The protection of Ca-Alg-coated microcapsule for probiotics was improved under simulated gastrointestinal and thermal conditions. Ca-Alg-WPI microcapsules showed a useful way for protection and delivery of L. bulgaricus and L. paracasei.