Physicochemical and microbiological characterization of a novel functional beverage from water kefir grains and yacon roots

Abstract

The development of functional fermented beverages that combine complementary ingredients is a promising approach to enhance nutritional and health benefits. This study formulated and characterized a novel beverage from yacon (Smallanthus sonchifolius) using water kefir grains. Yacon was chosen for its high content of fructooligosaccharides (60% dry weight) and antioxidant capacity (58% DPPH inhibition). Water kefir provided a probiotic culture rich in lactic acid bacteria and yeasts. Fermentation was conducted under controlled conditions, followed by evaluation of physicochemical, microbiological, and sensory properties. The final product exhibited moderate antioxidant activity (38% DPPH inhibition), phenolic content around 40 mg GAE/L, and organic acids including lactic, acetic, and butyric acids, resulting in a pH of about 3.6. Its volatile profile indicated complex metabolic activity consistent with fermentation. Ethanol concentration remained low (0.3%). Microbial analysis revealed beneficial fermentative organisms, with counts of 7.44 log CFU/mL lactic acid bacteria, 8.00 log CFU/mL acetic acid bacteria, and 7.81 log CFU/mL yeasts. Sensory evaluation with 141 untrained panellists indicated approximately half were willing to purchase the beverage. These results suggest that the combined use of water kefir and yacon produces a novel, health-promoting fermented beverage with potential benefits for consumers interested in digestive health.