Composition of proteins in fresh whey as waste in tofu processing

Abstract

Tofu whey is a pale-yellowish liquid with specific aroma/taste which remains as the byproduct/waste after tofu squeezing and represents an environmental problem for direct disposal. Understanding the fresh tofu whey protein composition and the activity of bioactive peptides could be useful for the application of tofu whey as a functional food additive. Tofu whey was obtained during the tofu production from six soybean genotypes by hydrothermal processing in combination with chymosin-pepsin rennet. Basic 7S globulin (14.28–19.13%), γ-conglycinin (7.73–9.31%) and β-conglycinin (10.59–12.90%) were registered of the total extracted proteins. Glycinin was present with a dominant share of acidic (24.64–27.55%) versus basic polypeptides (12.18–14.61%) in the total extracted proteins. High content of total protein (22.67–28.00%), balanced content (9.76–13.33% of the total extracted proteins) and residual activity (1.95–3.76%) of trypsin inhibitors and low lectins content (5.04–5.48% of the total extracted proteins) indicate good nutritional value of the tofu whey samples. Tofu whey can be potentially useful for application as a cheap, nutritional and functional food additive and can enable sustainable production through the recycling of waste.