Acetic acid is the primary organic acid in rice vinegar, produced via aerobic fermentation of ethanol derived from rice starches by Acetobacter species. In culinary applications, it imparts sharp sourness, enhances flavors, acts as a preservative by lowering pH to inhibit microbial growth, and tenderizes proteins. Chemically, it is a weak carboxylic acid with pKa 4.76, fully miscible in water and ethanol, and participates in esterification reactions. Rice vinegar typically contains 4-5% acetic acid, distinguishing it from stronger distilled vinegars. It contributes to umami balance in Asian cuisines and is valued for its mild aroma profile compared to other vinegars.