Growth, survival, and metabolic activities of probiotic Lactobacillus spp. in fermented coffee brews supplemented with glucose and inactivated yeast derivatives

Abstract

Amidst rising interest in non-dairy probiotic foods, and growing global coffee consumption patterns, it would be opportune to ferment coffee brews with probiotics, yet it remains unexplored. In this study, we aimed to develop a fermented coffee beverage rich in live probiotics, by supplementing nutrient-deficient coffee brews with glucose and inactivated yeast derivatives. This was followed by fermentation with single probiotic bacteria cultures (Lactobacillus rhamnosus GG, L. paracasei Lpc-37, L. plantarum 299v, and L. acidophilus NCFM), and subsequent storage at 4 and 25 °C. We demonstrated that nutrient supplementation was essential in supporting probiotic growth and survival in coffee brews, as viabilities above 7 Log CFU/mL could not be sustained longer than 2 weeks in non-supplemented coffees. In contrast, viabilities above 7 Log CFU/mL were maintained for 10 weeks by L. rhamnosus GG and L. paracasei Lpc-37 in supplemented coffees stored under refrigeration. Probiotic metabolic activities led to consumption of glucose, glutamic acid, and alanine, with simultaneous formation of lactic acid, 3-methylbutanoic acid, and diacetyl. Nevertheless, endogenous coffee volatiles, bioactive components, and antioxidant capacities were retained. Overall, we illustrate the potential functionalities of probiotic fermented coffee brews, arising from high probiotic live counts and retention of major coffee bioactive components.

Keywords: Biotransformation; Functional beverage; Growth factors; Lactic acid bacteria; Non-dairy foods; Viability.