Evaluation of a potentially probiotic non-dairy beverage developed with honey and kefir grains: Fermentation kinetics...

The aim of this work was to study the fermentation process of honey with kefir grains through a comprehensive understanding of its rheological properties, probiotic cell viability, instrumental color parameters and kinetic aspects in a batch bioreactor and during storage. The results showed that kefir grains were well adapted to bioreactor conditions, reaching high levels of cell viability (over 10⁶ CFU mL^-1 for total yeast and bacteria), phenolic compounds content (190 GAE/100 g) and acidification after 24 h of fermentation at 30 ℃. Colorimetric analysis showed that lightness (L*) and redness (a*) remained constant, while yellowness intensities (b*) decreased during fermentation time. After 35 days of storage, honey kefir beverage maintained its chemical characteristics and microbial viability as required to be classified as a probiotic product. The Ostwald-de-Waele (R²≥ 0.98) and Herschel-Bulkley (R²≥ 0.99) models can be used to predict the behavior of honey kefir beverage. The parameters analyzed in this study should be taken into account for industrial production of this novel non-dairy beverage.