Optimization of glutinous rice wine brewing conditions by using Taguchi method and semiempirical equation

Abstract

AbstractGlutinous rice wine brewing from uncooked material was studied using the Taguchi L9 orthogonal array. Using uncooked rice skips rice soaking and steaming procedures, required low energy, and provides high ethanol yield. The influences of brewing on the ethanol yield were investigated. The results indicated that the degree of importance of these factors was as follows: fermentation temperature (Tf) > amount of inoculum (Xo) > fermentation duration (tf) > gelatinization temperature (Tg). The optimal conditions were as follows: gelatinization temperature of 85°C, fermentation temperature of 25°C, fermentation duration of 16 days, and amount of inoculum by weight of 0.5%. The ethanol yield was 48% by volume and was in agreement with that predicted by the Taguchi method. Ethanol yield data were fitted with a polynomial equation and semiempirical equation as a function of Tf, Xo, tf, and Tg. The result of these equations confirms the optimal conditions obtained from Taguchi L9 orthogonal array experiment. Results from the semiempirical reaction kinetic model suggested that ethanol yield plateaued after a certain number of fermentation days.Practical applicationsSimilar strategy can be applied to other wine brewing processes to obtain a rational kinetic model and optimal condition within few tests.