Effect of Co-Fermentation of Saccharomyces boulardii CNCM-I745 with Four Different Probiotic Lactobacilli in Coffee Brews on Cell Viabilities and Metabolic Activities

Abstract

Amid trends in non-dairy probiotic foods and functional coffees, it is timely to develop a high-count probiotic, fermented coffee beverage. Here, we aimed to enhance the viabilities of different probiotic lactobacilli strains in coffee brews by co-culturing with the probiotic yeast, Saccharomyces boulardii CNCM-I745. The growth, survival, and metabolic activities of Lactiplantibacillus plantarum 299v, Lactobacillus acidophilus NCFM, Limosilactobacillus fermentum PCC, and Lactobacillus gasseri LAC-343 were monitored when cultured individually or co-cultured in coffee brews with S. boulardii CNCM-I745. In co-cultures, all four probiotic lactobacilli maintained viable populations above 5.5 Log CFU/mL for at least 6 months at 4 and 25 °C. In contrast, singly cultured lactobacilli populations generally could not be detected beyond 3 months of storage at either temperature. In co-cultures, vigorous nutrient uptake (glucose, glutamate, and alanine) by the yeast limited lactic acid accumulation by the lactobacilli. Co-culturing also led to accumulations in yeast-derived metabolites (ethanol, 2/3-methylbutanol, 2,3-dimethoxystyrene, and decanoic acid), and lactobacilli-derived metabolites (4-ethylphenol), but the coffee bioactive components (caffeine, trigonelline, and 5-O-caffeoylquinic acid) and antioxidant capacities were maintained. Overall, S. boulardii CNCM-I745 is effective in enhancing the viabilities of probiotic lactobacilli from different species, which may be useful in developing shelf-stable probiotic foods.