Consortium of selected yeasts to produce healthy soy fermented beverage: Evaluation of microbial evolution, analytical, sensorial, and functional features

Currently, an increasing number of intolerant and vegan consumers are driving the market towards plant-based milk alternatives. Here, selected probiotic yeasts, belonging to the Candida zeylanoides, Kluyveromyces lactis and Debaryomyces hansenii species, previously characterized for their aptitude to ferment animal milk, were tested in soy milk. Trials at different fermentation times with the developed yeast consortium (Yc) coinoculated with a lactic bacterium commercial strain were carried out. Yc showed good fermentation performance, conferring distinctive analytical and aromatic properties to the resulted soy fermented beverage, a product similar to an industrial kefir. Analytical determinations did not show significant variations between the end of fermentation and cold storage (4 weeks at 4 °C), indicating full stability. Phenol amounts and antioxidant activity were significantly increased in soy fermented beverage fermented by Yc. All yeasts remained viable until the end of storage with a final concentration of approximately 8 Log CFU/ml, a value suitable for a probiotic commercial claim. Overall, the results suggest that Yc is a promising multistarter candidate for functional soy products.