BIOVALORIZATION OF SOY (TOFU) WHEY INTO FERMENTED BEVERAGES THROUGH YEAST FERMENTATION

Abstract

Soy whey is a by-product generated from tofu production and is commonly discarded as wastewater by tofu producers. Soy whey supplemented with only sucrose and malic acid has been successfully biotransformed into soy alcoholic beverage with six of the nine yeasts examined. Due to the low YAN content in soy whey, amino acids were then added to the soy whey. Amino acids aided in enhancing the overall fermentation process by speeding up the sugar utilization and increasing aroma compound production. However, it was found that isoleucine had an “inhibitory” effect on T. delbrueckii Biodiva during the early stages of the fermentation; initial yeast growth and sucrose hydrolysis were retarded in the presence of isoleucine. Invertase activity assay revealed that isoleucine had a mild inhibitory effect on the invertase activity, but more study will need to be carried out to understand the pathways affecting yeast growth and sucrose hydrolysis by isoleucine.