Utilization of tofu whey concentrate by nanofiltration process aimed at obtaining a functional fermented lactic beverage

• The potential of tofu whey, a by-product, as a source of isoflavones.
• The concentrate by nanofiltration was used to produce a fermented lactic beverage.
• A functional fermented lactic beverage offer an opportunity for the use of tofu whey.

Tofu whey was concentrated using the nanofiltration process up to a volume reduction factor of 4.5. The concentrate was used to produce two fermented lactic beverages: (1) with 10% of concentrated tofu whey + 90% of milk; and (2) with 20% of concentrated tofu whey + 80% of milk. Both beverages were analyzed to determine the total lactic acid bacteria count and the physicochemical, rheological and functional properties during storage (30 days). It was observed that the total lactic acid bacteria count was >8 log CFU mL−1. It was observed that the total solids and protein contents of all beverages remained unchanged, but the use of concentrated tofu whey contributed to the post-acidification process. It can be verified that the viscosity was lower for beverage 2. The apparent viscosity of all samples decreased with an increase in the shear rate, indicating shear thinning and thixotropic properties. The Power Law model was successfully applied to describe the rheological behavior. The total isoflavones content was greater for beverage 2 and remained unchanged during storage, while the oligosaccharides content decreased during storage.