Utilization of tofu whey pre-treated by electromembrane process as a growth medium for Lactobacillus plantarum LB17

Lactobacillus plantarum is a probiotic microorganism which can use oligosaccharides like stachyose and raffinose during fermentations. Tofu whey (TW), a by-product of tofu production, is a good source of carbohydrates, mainly sucrose, raffinose and stachyose, as well as protein and magnesium (from the coagulant agent). In this context, the objectives of this study were to study the efficiency of electromembrane processes on salt (conventional electrodialysis) and protein (bipolar membrane electroacidification) recovery from the TW and to evaluate the potential of a partially demineralized pre-treated TW as a growth medium for L. plantarum. It appeared that skimming and demineralization of the TW allowed the recovery of almost 45% and 54% of the initial proteins and minerals contents respectively. However, the electroacidification process was inefficient for the precipitation of residual proteins in the TW. The demineralization level of the TW did not have a significant effect on the viable counts obtained for L. plantarum in demineralized skimmed tofu whey (DSTW)-based media. During fermentations, more than 60% of the initial contents of stachyose, raffinose and sucrose in TW were metabolized by the bacteria. These results suggest that the DSTW could be used as a potential low cost growth medium for lactobacilli and that the coagulant agent and protein recovered could be reused in tofu process to increase yield.