Saccharomyces cerevisiae and kefir production using waste pomegranate juice, molasses, and whey

The growth of Saccharomyces cerevisiae (baker’s yeast) and kefir was studied in substrates containing pomegranate juice, molasses, and cheese whey, at various conditions such as fermentation temperature, air supply, initial sugar concentration, and substrate composition. The results showed that, in the case of kefir, the highest production yield of biomass (0.24 g/g of utilised sugar) and productivity (6.5 g/l/day) was obtained in 40/60 and 20/80% of pomegranate/cheese whey. S. cerevisiae grew easily on all substrates with higher cell mass yields (0.34 g/g) and productivities (13.1 g/l/day) compared to kefir, with the best results obtained at the ratio of 40/60 and 20/80% of pomegranate/molasses. These results are promising regarding the exploitation of non-conventional substrates, such as the juice from discarded pomegranate fruits of a currently significantly increasing market, for microbial biomass production.