Improved survival of Lactobacillus zeae LB1 in a spray dried alginate-protein matrix

Abstract

The objective of the current research was to investigate the in vitro gastrointestinal digestion and storage properties of probiotic bacteria encapsulated in microparticles containing sodium alginate (AG) and sodium caseinate (NaCas) or soy protein isolate (SPI) through spray drying technology. A probiotic isolate Lactobacillus zeae LB1 was spray dried in AG solution combined with either SPI or NaCas at different ratios. High survival rate (>80%) was obtained for all the encapsulation formula tested. Combination of SPI or NaCas with AG showed a positive effect on both the in vitro gastric resistance and storage stability of L. zeae LB1. Among the formulas tested, microparticles made from a blend of NaCas and AG showed the highest glass transition temperature (Tg), corresponding to the best survival of L. zeae LB1 during storage under the water activity range of 0.11–0.76. The presence of two Tgs in the NaCas-AG particle suggested that phase separation occurred, which proved to have a positive effect on the viability of encapsulated probiotic bacteria during storage and gastric transition. In conclusion, the current study demonstrated that AG combined with NaCas may provide best protection to probiotic bacterial cells during storage, whereas AG combined with SPI proved to have the best gastric resistance property.