Effect of isomaltose oligosaccharide on the freeze-drying process and shelf-life of Pediococcus pentosaceus

Improvement in the survival of the edible probiotic Pediococcus pentosaceus during the preparation and storage is important. In this study, the protective effects of isomaltose oligosaccharide in a protective agent (sodium glutamate, skimmed milk, and trehalose) on P. pentosaceus during vacuum freeze-drying and low-temperature storage were evaluated. Cell damage, and texture were evaluated using fluorescence analyses, and scanning electron microscopy, respectively, and a water activity assay was performed storage after 1 month of storage (−80, −20, 4, 25 °C). The viability of P. pentosaceus agents (24444, QK-1, MQ-1, and RQ-1) were evaluated for 9 months storage. The results showed that IMO increased 11.02% survival rate of P. pentosaceus QK-1 during the freeze-drying process, which was better than that of 24444, MQ-1, and RQ-1; the texture of the protective agent was thin, with a compact and granular cross-section. Decreased water activity (18.71–34.26%) and cell damage (8.32–10.53%), also enhanced survival rate (5.98–12.85%) were observed in the IMO-containing groups in storage. The survival rates of P. pentosaceus (QK-1, MQ-1, RQ-1) direct-injection agents (9 months) exceeded 90% under gastrointestinal satiety-mimicking conditions in vitro. Our data indicate that IMO has a good protective effect on the freeze-drying and storage processes of P. pentosaceus.