Vinegar production from Thai rice varieties with emphasis on the biological properties of Sangyod rice vinegar

Vinegar is rich in bioactive compounds and is recognized for its potential health benefits, including metabolic regulation and weight management. This study aimed to develop vinegar from three organic Thai rice varieties and further evaluate the bioactive compounds and associated biological properties. Vinegars were produced from Sangyod and Hom Nil pigmented rice varieties, as well as white Jasmine rice. During a 14-day alcoholic fermentation, all rice wines achieved ethanol concentrations exceeding 10% (v/v) within 5 days. Subsequently, high titratable acidity (expressed as acetic acid) were obtained in Jasmine (5.47% w/v) and Sangyod (5.40% w/v) rice vinegars after 14 days of acetic acid fermentation, along with low levels of turbidity (9.84 and 9.38 NTU, respectively). Sensory evaluation indicated that Sangyod rice vinegar (6.80) had a slightly higher overall acceptability score compared to Jasmine rice vinegar (6.23) (p > 0.05). Based on these results, Sangyod rice vinegar was selected for further investigation. It demonstrated notable antioxidant activity, with 46.23% DPPH inhibition, likely attributable to its phenolic content (154.76 mg GAE/mL) and vitamin E (0.21 mg/100 g). In addition, it exhibited significant in vitro inhibitory effects on α-glucosidase (IC50 of 14.08 mg/mL) and lipase (IC50 of 9.08 mg/mL), although anti-inflammatory and α-amylase inhibitory activities were not detected. These findings suggest that Sangyod rice vinegar has potential as a functional food with antioxidant, antiglycemic, and anti-lipase properties, offering various health benefits.