In vitro viability of L. Casei B-442 and fructooligosaccharides integrity in Amazonian sapota-do-solimões functional juice

Sapota-do-solimões (Quararibea cordata) juice was fermented by Lacticaseibacillus casei B-442 to produce a probiotic and a synbiotic juice. The synbiotic juice was obtained by adding fructooligosaccharides (FOS, 7%, w/v). After the fermentation (37 °C by 15 h) the L. casei viability was above 11 log CFU/mL in both juices. The microbial survival rate after 30 days of cold storage (4 °C) was higher in probiotic juice (97%) than in prebiotic juice (82%). The effect of fermentation and the food matrix on L. casei viability was assessed by the simulated digestion at the beginning and the end of cold storage (4 °C for 30 days). After the simulated digestion, the probiotic counts were above 8 log CFU/mL in synbiotic juice and above 4 log CFU/mL in probiotic juice. The main L. casei metabolites produced in the sapota-dos-solimões juice were lactic acid and acetic acid. Isobutyric, and propionic acids presented higher production in synbiotic juice compared to the probiotic juice. No FOS hydrolysis was observed during the storage or the simulated digestion. L. casei did not consume FOS as carbon source. Thus, sapota-do-solimões juice is an exotic suitable non-dairy-based matrix for functional beverages.