Comprehensive utilisation of electro-activated whey-based media in cell growth, metabolite production and aroma compounds synthesis using a starter culture originated from kefir grains

Abstract

Electro-activated whey (EA-whey), electro-activated whey permeate (EA-WP) and electro-activated lactose (EA-lactose) were explored as carbon sources to produce valuable metabolites including organic acids, exopolysaccharides, and volatile flavour compounds using kefir grains as a starter culture. The results showed that the EA-substrates achieved a higher biomass growth in a reduced fermentation time than their non-EA counterparts. The highest cell growth (6.04 g L−1) was obtained for EA-whey, which was even 1.7-fold higher than a standard nutrition broth. Furthermore, EA-whey produced a maximum of 8.46, 3.97, 0.60, and 1.02 g L−1 of lactic, acetic, citric, and propionic acid, respectively. Likewise, EA-whey achieved the highest kefiran production of 2.99 g L−1. Nevertheless, production of numerous aromatic volatile compounds during fermentation of EA-whey may improve organoleptic characteristic of the fermented products. Thus, the EA-substrates, especially EA-whey, could be potential feedstock to develop bioprocesses for producing valuable metabolites using kefir grains as a suitable starter.