Abstract
To improve the survivability of probiotics, Lactobacillus plantarum was microencapsulated using pufferfish skin gelatin (PSG)-based wall materials by spray-drying. This work investigated the protective effect of three different pH-dependent proteins (sodium caseinate (SC), soy protein isolate (SPI), and whey protein isolate (WPI)) combined with PSG on L. plantarum. The experimental results of spray-drying with an inlet temperature of 120 °C and an outlet temperature of 80 °C, storage at 4 °C for 6 months, simulated digestion, and turbidity indicated that PSG/SC had better stability and encapsulation effects and was more suitable to encapsulate L. plantarum than PSG/SPI and PSG/WPI. The optimum preparation conditions for L. plantarum microcapsules were a PSG/SC mass ratio of 2:1, an SC concentration of 20 g/L, and a cell concentration of 10 g/L. The encapsulation efficiency of the obtained microcapsules was 95.0%, and the survival rate was 94.2% in simulated gastric fluid for 2 h and 98.0% in simulated intestinal fluid for 2 h. Amino acid composition analysis exhibited that the imino acid and aspartic acid contents of PSG were 27.98 and 26.16 g/100 g protein, respectively, which was much higher than commercial bovine gelatin. This characteristic was favorable to the high encapsulation efficiency and stability of microcapsules. In vitro release experiments showed that the PSG/SC microcapsules did not disintegrate in simulated gastric fluid for 2 h but could completely release in simulated intestinal fluid for 2 h, which can maintain the high survivability of L. plantarum in simulated digestion. In general, this study demonstrated that microcapsules using PSG/SC as wall materials can effectively improve the survivability of probiotics and have great potential for application in probiotic products.