Utilization of tofu processing wastewater as a source of the bioactive peptide lunasin

Authors: NIETO-VELOZA, ANDREA - University Of Tennessee; ZHONG, QUIXIN - University Of Tennessee; KIM, WON-SEOK - University Of Missouri; D'SOUZAA, DORIS - University Of Tennessee; Krishnan, Hari; DIA, VERMONT - University Of Tennessee

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2021
Publication Date: 5/27/2021
Citation: Nieto-Veloza, A., Zhong, Q., Kim, W., D'Souzaa, D., Krishnan, H.B., Dia, V.P. 2021. Utilization of tofu processing wastewater as a source of the bioactive peptide lunasin. Food Chemistry. 362. Article 130220. https://doi.org/10.1016/j.foodchem.2021.130220.
DOI: https://doi.org/10.1016/j.foodchem.2021.130220

Interpretive Summary: Tofu is a cheese-like product obtained from soybeans. Tofu production involves the grinding of hydrated soybeans to obtain soymilk, which is then coagulated to form the tofu curd. During the process, two waste by-products are obtained in large quantities: okara and tofu whey. Tofu whey is the liquid waste fraction that is being mostly discarded into the sewage or soil, posing an environmental threat. Lunasin, a 5 kDa soy-derived peptide, has gained interest as a dietary supplement for the prevention of several chronic and degenerative diseases. We examined if whey wastewater can serve as alternative source of this bioactive peptide. In this study, we describe a simple and cost-effective method to isolate lunasin from tofu whey wastewater. Our three-step process is competitive with current alternatives in terms of the quantity and purity of the final product, but faster and more sustainable. Our new procedure will enable the US tofu industry to recover a valuable bioactive peptide and at the same time facilitate a better utilization of soybean nutrients for the benefit and well-being of humans.

Technical Abstract: The goal of our study was to design a simple and feasible method to obtain lunasin, a naturally-occurring bioactive peptide, from tofu whey wastewater. A combination of alcoholic precipitation of high-molecular weight proteins from the whey, isoelectric precipitation of lunasin enriched material, and purification via gel filtration chromatography was selected as the best approach using tofu whey prepared at the laboratory scale. This process was applied to tofu whey produced by a local tofu factory and 773 mg of 80% purity lunasin was obtained per kg of dry tofu whey. Significant reduction of nitric oxide, and pro-inflammatory cytokines TNF-a and IL-6 over lipopolysaccharide activated murine macrophages demonstrate its biological activity. Our three-step process is not only simpler and faster than the previously reported methods to obtain lunasin but provides a sustainable approach for the valorization of a waste product, promoting the better utilization of soybean nutrients and active compounds.