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 (T g ), 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 T g s 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.

中文翻译：

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提高玉米乳杆菌 LB1 在喷雾干燥的藻酸盐-蛋白质基质中的存活率

摘要 本研究的目的是通过喷雾干燥技术研究包裹在含有海藻酸钠 (AG) 和酪蛋白酸钠 (NaCas) 或大豆分离蛋白 (SPI) 的微粒中的益生菌的体外胃肠消化和储存特性。将益生菌分离株玉米乳杆菌 LB1 在 AG 溶液中喷雾干燥，并结合不同比例的 SPI 或 NaCas。所有测试的封装配方都获得了高存活率 (>80%)。SPI 或 NaCas 与 AG 的组合显示出对 L. zeae LB1 的体外胃抗性和储存稳定性的积极影响。在测试的配方中，由 NaCas 和 AG 的混合物制成的微粒显示出最高的玻璃化转变温度 (T g )，对应于 L 的最佳存活率。玉米 LB1 在水活度范围 0.11-0.76 下储存期间。NaCas-AG 颗粒中两个 T gs 的存在表明发生了相分离，这证明对封装的益生菌在储存和胃转变过程中的生存能力具有积极影响。总之，目前的研究表明，AG 与 NaCas 结合可以在储存过程中为益生菌细胞提供最好的保护，而 AG 与 SPI 结合被证明具有最佳的胃耐受性。