Enhanced antioxidant capacity of brown rice vinegar supplemented with soy residue

Abstract

Background and objectivesThis study aimed to prepare and use soy residue as a supplement to enhance the antioxidant activities of grain vinegar, which has relatively lower antioxidant activities than fruit vinegar. Brown rice vinegar (BRV) was supplemented with 30% soy residue (BROV3) and 50% soy residue (BROV5).FindingsAfter 3 days of alcohol fermentation, the BROVs had lower sugar contents (6.43–9.4 °Brix), alcohol contents (4.47%–7.5%), and pH (3.65–3.66) while higher acidity (0.75%) than BRV (12.47 °Brix, alcohol content 11%, pH 3.72, acidity 0.66%). During 10 days of acetic fermentation, the BROVs showed higher pH (3.23–3.38) and lower acidity (4.05%–4.35%) than BRV (pH 2.88, acidity 4.86%). As the soy residue content was increased, the contents of essential amino acids increased from 22.03 mg/L (BRV) to 515.27 mg/L (BROV5), but those of desirable volatile compounds decreased, and those of undesirable compounds increased. The polyphenolics, flavonoids, and isoflavone contents and DPPH and ABTS+ radical‐scavenging activities of the BROVs increased with increasing soy residue content.ConclusionsAlthough soy residue addition decreased certain desirable volatile compounds and increased certain undesirable ones, it improved the antioxidant activity and overall quality of brown rice vinegar.Significance and NoveltyThe potential of soy residue for enhancing vinegar functionality was confirmed.This article is protected by copyright. All rights reserved.