Effect of electro-activated sweet whey on growth of Bifidobacterium, Lactobacillus, and Streptococcus strains under model growth conditions.

Recently, we demonstrated the efficacy of electro-activation to improve the functionalities of whey that can be used as a prebiotic and antioxidant agent through lactulose and Maillard reaction products formation. The aim of the present study was to evaluate the effect of electro-activated sweet whey (EA-whey) on growth of probiotics of Bifidobacterium, Lactobacillus, and Streptococcus strains in pure cultures and to compare EA-whey with non-electro-activated whey, lactulose, lactose, sucrose, glucose and galactose at different concentrations (1.25, 2.5 and 5%). The bacterial growth was monitored through maximum optical density (ODmax) and maximum growth rate (µmax) measurements. Moreover, the effects of EA-whey on the growth of L. johnsonii La-1 in the presence of oxygen was assessed. FTIR spectroscopy analyses of the bacterial membrane structure were monitored as a function of EA-whey concentration. The results showed that EA-whey enhanced the growth of all the test bacteria. They clearly demonstrated a promoting bifidogenic effect of EA-whey compared to lactulose. The growth of L. johnsonii La-1 was greatly enhanced under aerobic conditions by the supplementation of the growth medium with EA-whey. This growth promoting effect could be related to the ability of EA-whey to prevent the accumulation of hydrogen peroxide, its high antioxidant capacity and lactulose content. Moreover, FTIR spectra showed that EA-whey acts as an antioxidant in regards to cell membrane lipids oxidation by oxygen species and limited their adverse effect on probiotic bacteria during their growth. Thus, EA-whey, a potential prebiotic and antioxidant, could be used as active ingredient in manufacturing functional fermented dairy products.