Optimization of Acetic Acid Fermentation of Hardy Kiwi Vinegar using Low-pH Tolerant Acetobacter pasteurianus AFY-4

Acetobacter pasteurianus AFY-4 was isolated from fermented vinegar in Hongcheon-gun, Gangwon-do. The A. pasteurianus AFY-4 strain had a higher tolerance to low-pH. Optimization of acetic acid fermentation of hardy kiwi (Actinidia arguta) was conducted using the A. pasteurianus AFY-4 strain based on the response surface methodology (RSM). The optimization of acetic acid fermentation for producing hardy kiwi vinegar was determined by five levels of initial ethanol, initial acetic acid, and acetic acid bacteria (AAB) inoculum volume, using the central composite design. The acetic acid yield and residual ethanol for acetic acid fermentation of hardy kiwi optimized by the RSM were significantly different. The optimal conditions for acetic acid fermentation of hardy kiwi vinegar were 8.95% of the initial ethanol, 1.86% of the initial acetic acid, and 25.02% of the AAB inoculum volume.