Development of the original whey‐based vinegar using rapeseed meal or wheat bran as a raw material for koji

Abstract

Here, a novel whey-based vinegar, called lacto-vinegar, was developed. Rapeseed meal (RM) or wheat bran (WB) was used as a raw material for making koji. Whey solution was first saccharified with the RM/WB-koji and then transformed into an alcoholic beverage via fermentation with Zymomonas mobilis. The alcoholic product was further brewed into vinegar with Acetobacter pasteurianus. The resulting lacto-vinegar contained about 4% (vol/vol) acetic acid. Several analyses revealed that lacto-vinegar made using RM-koji was superior to that made using WB-koji in terms of amino acid composition, antihypertensive activity, and antioxidant capacity, indicating that RM is more beneficial than WB as a raw material for making koji in lacto-vinegar production. In addition, the lacto-vinegar had higher nutritional and functional values than those of conventional vinegar available on the market. Thus, the novel lacto-vinegar brewing method developed in this study would expand the possibilities of whey utilization. Novelty impact statement The utilization of whey by developing a new method of vinegar production was presented. A novel whey-based vinegar (lacto-vinegar) fermented using rapeseed meal (RM) as a raw material for koji had much higher amino acid content, antihypertensive effect, and antioxidant capacity than the commercial vinegar. The koji production by fermenting RM with Aspergillus oryzae resulted in the formation of sinapic acid derivatives with unknown structures as antioxidants.