Fermentation Rates of Grape Juice. II Effect of Initial °Brix, pH, and Fermentation Temperature

Yeast cell growth rate and grape juice fermentation rate were shown to be dependent on initial Brix and pH as well as on fermentation temperature. Variation between pH 3.5 and 4.0 caused small but significant fermentation rate changes. Changes are large at pH 3.0 compared with the other two pHs. Optimum fermentation rates for grape juice occur between 15 and 20° initial Brix, and so does optimum yeast growth rate with these media. Temperature interactions with pH were demonstrated on rate of fermentation and yeast growth rates. The lower the pH with increasing temperature the greater the effects found on rate of fermentation and rate of yeast growth.