Characterization of Novel Dairy Leuconostoc mesenteroides S-L8 Strain for Opuntia ficus-indica Fruit Juice and Peels Fermentation

Lactic acid fermentation of vegetable foods and byproducts constitutes a featured technology for their preservation and valorization, promoting their functional and health benefits. This study explores the probiotic and technological properties of a lactic acid bacterium strain isolated from cow milk, selected for its ability to ferment the juice and byproducts of Opuntia ficus-indica fruits. This strain was identified by genotypic characterization as Leuconostoc mesenteroides S-L8. The evaluation of its gastrointestinal environment tolerance, cell surface properties, antimicrobial activity, and safety profile showed the probiotic potential of L. mesenteroides S-L8. This strain was able to grow in and acidify both cactus pear juice and peel extract, reaching cell counts near 8 log CFU/mL, pH values <4 (ΔpH = 2), and lactic acid contents between 6.5 and 7.2 mg/mL at 24 h of growth. The cactus pear juice and peel extract fermented with strain S-L8 preserves the phenolic compound content and showed improved antioxidant capacities (increment between 63 and 75% in ABTS radical scavenging activity) of unfermented products. The results obtained showed the potential of L. mesenteroides S-L8 for their use as a starter for the fermentation of O. ficus-indica fruit juice and byproducts, contributing to the sustainable exploitation of this fruit through the production of functional fermented products and valuables metabolites.