Flavor characteristics of rice-grape wine with starch-hydrolyzing enzymes

A brewing process for rice-grape wine, in which rice powder and grapes are concurrently fermented, was developed. Rice powder was mixed with α-glucosidase, glucose isomerase, and yeast, and then incubated for 2 days at 25°C. Then a mixture of 'Muscat Baily A' and 'Campbe Early' grape must was added to the fermented mixture of rice and maintained at 4°C to allow for complete ethanol fermentation. The rice-grape wine contained 11.6% ethanol, compared to 9.6% ethanol for grape wine. The aroma profile revealed that 2-methyl-1-propanol, 2-methyl propyl acetate, and phenethyl acetate were in greater abundance in the rice-grape wine, whereas ethyl hexanoate, diethyl succinate, and ethyl decanoate were more abundant in the grape wine. The esters formed from fatty acids and ethanol increased during 2 years of storage for both wines. An electronic nose analysis revealed no significant difference in the aromas of the rice-grape and grape wine samples.