Isolation and Characterization of Shochu Yeasts with Superior Brewing Ability from Shochu Mashes

Abstract

Seven yeasts with superior ability in terms of alcohol fermentation and aromatic ingredient generation were isolated from 272 wild yeasts obtained from shochu mashes of shochu breweries. These seven yeasts were examined for their fermentation ability with rice and sweet potato using small scale of fermentation tests. Moreover, their thermotolerance was evaluated by growth tests and fermentation tests with barley koji. Among the isolated seven yeasts, the shochu yeast "MF062" was superior in the characteristics of fast fermentation, high alcohol production, aromatic ingredient generation and thermotolerance. It was named the "Heisei Miyazaki Yeast". From the results of analyses of physiological and genetic characteristics of MF062, it was shown to be a Saccharomyces cerevisiae, but it showed different characteristics from the industrial yeasts used in shochu production. Using a sweet potato shochu brewing test, with 60 kg of raw materials and yeast MF062, it was confirmed that a high alcohol production yield and a high quality shochu could be obtained.

Characteristics of aromatic compound production using newshochuyeast MF062 isolated fromshochumash

“…However, MF062 showed almost the same content of ethanol compared with the other yeasts. The ethanol content obtained with MF062 in the fermentation tests with barley koji was higher than that obtained with the other yeasts . This result may be dependent on some components contained in barley koji .…”

“…The concentration of ethanol and the aromatic compounds of the matured mashes were measured on day 10. Fermentation tests with barley koji were carried out for 9 days, where 60 mL of water and 50 g of barley koji were mixed with 100 μL of pre‐cultured yeast and incubated for 9 days at each temperature in the manner previously described .…”

“…An excellent shochu yeast, Heisei Miyazaki yeast (MF062) was successfully isolated. MF062 was selected from 272 isolates from shochu breweries in Miyazaki Prefecture for its high fermentation ability and thermotolerance, as well as desirable flavour‐producing characteristics on the basis of growth, fermentation, and small‐scale shochu production tests . MF062 is used for commercial shochu production in seven shochu breweries.…”

Isolation and characterization of yeast for the production of rice wine with low fusel alcohol content

“…In fact, various methods, such as low-temperature fermentation technology [ 16 ], nitrogen compensation during fermentation [ 17 ], and FA removal by nanofiltration after distillation [ 15 ], have been employed in rice wine production or the laboratory to reduce the FA content and control it to within a suitable range in the final products. However, these strategies only partially solve the problem and increase production costs.…”