Development of a new method for the production of kefiran and kefir grains

Abstract

Consumption of probiotic and functional foods have been a constant trend over the last years. One product that belongs to this category is kefir, a fermented milk that have been related with multiple health benefits kefir produced using as inoculum a symbiotic microbial community composed primarily of lactic acid bacteria and yeast embedded on a matrix of a polysaccharide named kefiran. This matrix is the responsible of most of the health benefits associated with kefir consumption and have also gained recent interest do to its numerous possible commercial applications. Factors like grain instability and slow growth difficult their use on kefir industrial production, for which artificially designed starter cultures are commonly used to mimic the organoleptic characteristics of kefir. The resulting beverages, however, fail in providing many of the positive effects associated with kefiran because its producing microorganism is either not capable of grown on such synthetic cultures or cannot achieve normal biomass production under conditions different from that existing on kefir grain symbiotic community. This work was focused on the development and application of a novel method based on technology used on wastewater treatment for the production of kefir grains and kefiran (inferred from biomass production) by using whey, the most significant wastewater resulting from the food industry, as a fermentation media. Results obtained using the novel method showed to be significantly higher than those obtained by the traditional method and whey pH of 6.6 resulted to be the optimum conditions for biomass production. The results obtained from the addition of substrates resulted all on higher significance difference when compared to the control (whey alone on the bioreactor). Addition of 10g/L of lactose resulted to be more efficient than addition of 50g/L of lactose. Also, addition of 5g/L of yeast extract resulted on a biomass production significantly higher than the addition of 10g/L of lactose but significantly lower than what the addition of 50g/L. However, such significant difference can be regarded as irrelevant when taking into account that yeast extract concentration was ten times lower than that of lactose. Highest biomass production was obtained by the addition of the combination of 10g/L of lactose and 5g/L of yeast extract, which resulted on a mean biomass production of 1417.7% after 10 days (141.7% daily). These results were more than two times higher than the maximum biomass production found on the literature (582% in 22 days; Schoevers and Britz, 2003) in less than half the time. Results obtained by using the newly developed bioreactor represent the opening of a whole new field of possibilities regarding investigations with kefir grains. Application of novel technologies such as those presented on the bioreactors used for the treatment of wastewaters may be a new option for investigations regarding the mechanisms of synthesis of kefir granules, for the optimization of kefir grain and kefiran production, and for the possible use of kefir grains for the treatment of wastewaters with or without the simultaneous production of highly valuable compounds such as lactic acid, among others.