This study was conducted to investigate the characteristics of Yakju fermented using different 7 commercial yeasts; La parisienne (black), La parisienne (red), Fermivin, RC212, K1-V1116, D47, and EC1118. After completion of fermentation, the total acid content in Yakju ranged from 0.26 to 0.40%; the lowest and highest values corresponded to fermentation using La parisienne (red) and EC1118, respectively. The amino acidity of the different Yakju samples varied significantly in the range of 2.49 to 5.50. The Yakju fermented with K1-V1116, La parisienne (black), La parisienne (red) showed high amino acidity levels of 5.59, 5.55 and 5.34, respectively, but that fermented with Fermivin showed a low level of 2.49. EC1118 seemed to be most suitable for producing the dry type of alcoholic beverage because of the low reducing sugar content (0.19%) and soluble solid (7.2 °Brix). The main organic acids in Yakju were succinic acid, lactic acid, citric acid, malic acid and acetic acid. Further, the succinic acid content in Yakju fermented with La parisienne (black), La parisienne (red) was high (about 1,080 mg/L). The main volatile compounds were acetaldehyde, acetic acid and iso-amyl alcohol, and the acetaldehyde and acetic acid contents of the different Yakju samples varied substantially.

This study aimed to control sugar consumption during makgeolli fermnetation using high temperature treatments after 3 days of fermentation at normal temprature. makgeolli fermentation was performed at 25°C for the initial 3 days and at 34, 37, 40, and 43°C, respectively, for the next 4 days. When fermented at 25°C (control), the alcohol content increased up to 16.5%; however the alcohol content of makgeolli treated at elevated temperatures reduced by 13.8 %. In the control group, typical saccharification and fermentation proceeded simultaneously, and the reducing sugar content remained low due to sugar consumption by active yeast. However, at high fermentation temperatures, the nuruk enzymes functioned normally and saccharification proceeded well; however the conversion of fermentable sugars to alcohol was inhibited, possibly due to a decrease in yeasts activity. The viable cell count of yeasts was 4-6 log CFU/mL regardless of the fermentation temperature. These results indicate the possibility of producing sweet live-yeast makgeolli without the addition of artificial sweeteners through a temperature-controlled makgeolli fermentation.