Utilization of rice pasta by-products as the substrate for vinegar fermentation.

The aim of this study was to utilize four rice pasta by-products (RPB), including white rice pasta, black jasmine rice pasta, red jasmine rice pasta and brown rice pasta, to ferment into four vinegars. The dynamic variations during fermentation and their quality were evaluated. During alcoholic fermentation, the saccharified substrates were fermented with Saccharomyces cerevisiae for 12 days, resulting in an alcohol yield of approximately 10% (v/v) after 4 days of fermentation. Further, acetic acid fermentation using Acetobacter aceti at ambient temperature for 20 days led to the production of RPB vinegars with 4.00-4.54% (w/v) of titratable acidity (expressed as acetic acid) (p > 0.05). Significant differences were found among four RPB vinegars in terms of color values (L*, a*, b* and hue angle) (p ≤ 0.05). All RPB vinegars exhibited good sensory acceptance, with the overall acceptability score ranging of 6.0-7.0 (p ≤ 0.05). Total phenolic contents, DPPH radical scavenging activities and xanthine oxidase inhibitory activities of four RPB vinegars varied within the range of 139.78 to 166.34 µg GAE/mL, 41.80 to 50.13% and 82.47 to 87.30% (p ≤ 0.05), respectively, demonstrating their competent functional properties. Overall results suggested that vinegar can be effectively produced from RPBs by fermentation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-024-06030-z.