Characteristics of distillation fractions obtained by various methods for the distillation of solid-state fermented mash by adding dried milk

Abstract

To enhance the flavor of solid-state fermented spirits, the effects of powdered milk on the composition of the distillation fractions obtained by two different distillation methods were evaluated. In the solid-state fermented product, the addition of whole milk powder did not affect alcohol production. However, the addition of milk increased the amino acid content and reducing sugar content, and decreased the formic, acetic, and succinic acid contents. Distillation using a microwave was four times faster than distillation using steam; however, the resulting number of fractions was high, with a wide range of alcohol flow rates. After the addition of whole milk powder, the contents of ethyl acetate and ethyl caproate were 2 times and 16-27 times higher, respectively, in the fraction, and the contents of butyric, valeric, and hexanoic acids among the volatile organic acids increased. In addition, the content of furfural, an odor component, increased 3.45 times from 1,393.73 mg/L to 4,801.93 mg/L. The microwave distillation method resulted in a 1.46-fold higher ethyl caproate content in the distillate compared with that obtained by steam distillation. However, as the temperature of the solid-state fermented mash was raised to over 300°C, the content of furfural increased by 3.29 times. These results support the use of milk powder in distilled spirits and may guide the development of optimized methods.