• Microbiology and Biotechnology Letters
• /
• v.26 no.1
• /
• pp.50-54
• /
• 1998

Ethyl caproate is one of the important flavor compounds produced during the brewing of rice wine. The rice wine yeast and koji were reported to produce the esterases which synthesize and also hydrolyze ethyl caproate. From the results of monitoring the esterase activities of rice wine yeast and koji, their roles for producing ethyl caproate during brewing were postulated. In case of rice wine yeast, the production of esterase synthesizing ethyl caproate was influenced by the substrate, caproate but that of esterase hydrolyzing ethyl caproate was promoted by ethyl caproate but inhibited by caproate. The production of esterases of koji were not influenced by the substrates for ethyl caproate production but influenced by the growth of koji. The maximum concentration of ethyl caproate produced by rice wine yeast was 0.4 ppm in this research but the production of ethyl caproate by koji was not detected under our experimental conditions. Considering the results of this research, ethyl caproate is not produced by the esterases of koji during brewing but produced by the esterases of rice wine yeast. The growth of rice wine yeast represses that of koji because of the high concentration of ethanol produced by rice wine yeast. The esterases of rice wine yeast may decide the production of ethyl caproate during brewing.

• Applied Biological Chemistry
• /
• v.39 no.1
• /
• pp.16-19
• /
• 1996

The yeast strains isolated for Choungju brewing in the previous report were examined for their microbiological characteristics, together with some comparative tests with Japanese sake yeasts. The isolates KP-16, 21 and 54 were identified as the strains belong to Saccharomyces cerevisae according to the morphological and physiological properties described in Lodder's 'The Yeasts - A texanomic study'. The isolates were grouped into the pink-colored strains by 2,3,5-tripheny tetrazolium chloride over-lay method. The strains KP-16 and 21 were found to be distinguished from the strain KP-54 in aspects of fermentation of sugars, assimilation of carbon sources, and pellicle formation on malt extract broth. ${\alpha}-methyl-D-glucoside$ was not assimilated or fermented by the isolated yeast strains and this is one of the different characters from the Japanese sake yeasts. The isolated strains appeared to have the requirements for biotin and pantothenate, and to have higher tolerance to ethanol than the Japanese sake yeasts. The biotin requirement was not found in the sake yeasts.

• Food Industry
• /
• s.59
• /
• pp.69-74
• /
• 1981

• Korean Journal of Food Science and Technology
• /
• v.34 no.4
• /
• pp.610-616
• /
• 2002

In order to improve a complicated Cheongju manufacturing process, saccharification process with gelatinized rice flour was employed during a Cheongju fermentation. High sugar content without unsaccharified residue appeared to impede the yeast growth and fermentation. To solve this problem, addition of zeolite to the saccharifying solution containing 20% (w/v) sugar and fed-batch system were employed. These adjustments resulted in a increase of yeast viability and 40% time-saving alterations of fermentation. The Cheongju, having 18% (v/v) of ethanol content and fresh and rich flavor, could be made in 12 days. Yeast cells recovered from the fermentation precipitates could be reused up to four times without any adverse effect on cell viability, alcohol production, and flavor of the product. The complicated conventional brewing process of Cheongju can thus be simplified effectively.

• Applied Biological Chemistry
• /
• v.39 no.1
• /
• pp.9-15
• /
• 1996

To improve the quality of Choungju. a kind of rice wine, two different types of koji were prepared and compared : one from wheat bran with Aspergillus usamii mut. shirousami Y-79 and the other from rice with A. oryzae, and yeast strains from cereal wine mashes were newly isolated and applied for the brewing method. Levels of the related enzymes such as glucoamylase, ${\alpha}-amylase$ and acid protease in the wheat bran koji were higher than those in the rice koji, whereas vice versa in the case of acid carboxypeptidase. An amount of $2{\sim}3%$ wheat bran koji to the weight of total rice was adequate for saccharification of the mash and resulted in improved duality of the fermented mash, accompanied by decrease in koji ordor and amino acidity. When the solution of wheat bran koji and the isolated yeast strains were employed, the better Choungju taste was obtained in comparison with those fermented with Japanese sake yeasts, the strain K-7 and 9, due to the lower content of organic acids especially succinic acid. The amino acidity of the fermented mash was able to be controlled to some extent, when the rico types of koji and the isolated strains were employed, by changing the ratio of the two koji types. However, the application of the rice koji with the isolated strains was not desirable for the brewing process because organic acids were produced in excess and ethanol fermentation was retarded.

• Korean Journal of Agricultural Science
• /
• v.7 no.2
• /
• pp.176-181
• /
• 1980

As a part of experiments aimed to reduce the acidic taste of a soured fruit wine, a selected yeast strain was studied on its morphological and physiological properties as well as its fermentative characteristics of apple wine. The results obtained were as follows. 1. The selected yeast strain was identified as a strain of Schizosaccharomyces pombe. 2. The tolerance of the strain to metabisulfite in apple juice was stronger than that of wine yeast. 3. The growth rate of the strain was more rapid than those of wine yeast and Sake yeast when cultured in apple juice at $25^{\circ}C$, but it was decreased below the levels of others when cultured at $15^{\circ}C$. 4. The levels of ethanol production and acid reduction by the strain were high when the apple wine brewed at $25^{\circ}C$, while these were dropped significantly at $15^{\circ}C$.

• Applied Biological Chemistry
• /
• v.16 no.2
• /
• pp.85-93
• /
• 1973

These experiments were carried out to study influences of the kind of yeasts and of brewing condition on fermentation of Takjoo mash. The results obtained were as follows: 1. Kind of yeasts and the number of yeasts in mash. When the first stage mash was fermented at $20^{\circ}C$ for $1.5{\sim}2.5$ days and at $25^{\circ}C$, $30^{\circ}C$ for $1{\sim}2days$, in the second stage mash that was fermented at high temperature, the number of yeasts was less as compared with the case of fermentation at low temperature, but the living yeasts number of Takjoo yeast strain Dm-1 was more than those of sake yeast, strain No. 7. 2. Kind of yeasts and composition of ripened mash. 1) In the secondstage mash that was fermented at high temperature($30{\sim}35^{\circ}C$), alcohol percentage of ripened mash using the selected Takjoo yeasts (strains: Dm-1, Y-1) was remarkably higher than the case of another yeasts (strains: No.7, No.6, No. 396, No. 1). 2) Acidity of mash had a little differences between strain Dm-1 and strain No. 7. 3) In the second stage mash that was fermented at high temperature ($30{\sim}35^{\circ}C$), the amount of Formol-N using strain Dm-1 was remarkably less than strain No.7. 3. Brewing condition and alcohol percentage of mash. 1) The fit amount of wheat bran Kuk addition per material was 3 percentage and it was adequate to use the mixture of wheat flour Kuk 20 percentage and wheat bran Kuk 1-2 percentage. 2) Though brewing concentration of the first stage mash was duiluted by twice of general brewing concentration, the yeast reproduction was normal. 3) In addition of wheat flour $80{\sim}140g$ per 180ml water, alcohol percentage of the mash increased almost propotionally according to the increase of the amount of wheat flour. 4) It was recognized that three stage brewing was superior in method to two stage brewing at present.

• Microbiology and Biotechnology Letters
• /
• v.34 no.3
• /
• pp.244-249
• /
• 2006

In order to select the best strains to have the feasibility of Cheonghju brewing, 10 wild type yeast strains from 300 different types of Nuruk were investigated on their ethanol resistance, resistance to glucose and flocculation. The amounts of alcohol, organic acids, and volatile compounds, Brix, pH were also examined for the alcoholic beverages made with the 10 selected strains. Almost all strains showed alcohol production activities in the medium containing 18%(v/v) ethanol and 29%(w/v) glucose. The strains 90-2 showed a higher flocculation activity than other strains. Strains 54-3, 90-2 and 91-5 produced more alcohol than control strain (7.42%(w/w)) when fermented with wild type yeast strains. In addition, alcoholic beverages containing low acetic acid also showed low levels of total acidity. GC/MS analysis of the product showed 4 alcohols, 11 esters and 1 acid as volatile compounds. Selected strains were tentatively identified as Phichia sydowiorum (91-5), Zygosaccharomyces cidri (192-2 and 271-4), and as Saccharomyces cerevisiae (18-2, 54-3, 90-2, 91-2, 98-2, 99-5 and 272-7) by BIIOLOG method.

• Korean Journal of Microbiology
• /
• v.52 no.2
• /
• pp.220-225
• /
• 2016

To improve antioxidant glutathione (GSH) content and saccharification ability in sake yeasts of Saccharomyces cerevisiae, the ${\gamma}$-glutamylcysteine synthetase gene (GSH1) from S. cerevisiae, glucoamylase gene (GAM1) and ${\alpha}$-amylase gene (AMY) from Debaryomyces occidentalis were co-expressed in sake yeasts for manufacturing a refreshing alcoholic beverage abundant in GSH from rice starch. The extracellular GSH content of the recombinant sake yeasts increased 1.5-fold relative to the parental wide-type strain. The saccharification ability by glucoamylase of the new yeast strain expressing both GAM1 and AMY genes was 2-fold higher than that of the yeast strain expressing only GAM1 gene when grown in the culture medium containing 2% (w/v) rice starch. It generated 11% (v/v) ethanol from 20% (w/v) rice starch and consumed up to 90% of the starch content after 7 days of fermentation.

• Journal of the Korean Society of Food Culture
• /
• v.4 no.3
• /
• pp.293-300
• /
• 1989

오늘날의 청주(淸酒)는 SAKE라는 이름으로 일본(日本)을 대표(代表)하는 술로 여겨지고 있으나 사실 일본식(日本式) 청주(淸酒)의 제법(製法)도 결국(結局)은 우리나라에 그 근원을 두고 있다. 오늘날의 청주(淸酒)는 우리의 술 빚는 법이 일본(日本)으로 전래된 후, 일본(日本)에서 잘 다듬어져 다시 우리나라에 상륙(上陸)한 것으로 現在의 청주(淸酒)의 근본도 그 뿌리는 백제를 비롯한 우리나라에 있음은 주지할 만한 사실이다. 그러나 우리 고유의 술빚는 법이 체계적으로 정리되지 못하고 사라져 버린데에는 우리의 전통사상의 일부인 과학, 기술 노동을 천시하는 풍조와 술빚는 일을 특히 여성의 전유물로 여겨 양조법의 정립이 이루어지지 못한 것도 큰 이유라 하겠다. 자가용(自家用)으로만 사용되던 주조(酒造)에서 탈피하여 공업적(工業的)인 규모의 청주생산은 1883년 1월 후꾸다라는 일본인이 부산에 세운 공장을 시초로, 1917년 현 백화양조의 전신이라 할 수 있는 조선주조주식회사 설립으로 본격화되었다. 우리의 전통청주(약주)는 곡류와 누룩을 이용하여 빚는데, 누룩은 밀기울을 잘 다져서 장기간에 걸쳐 제조하며, 누룩에는 당화효소를 분비하는 곰팡이류와 알콜발효를 할 수 있는 효모류가 함께 부착되어 있다. 따라서 호화시킨 곡류와 누룩을 함께 넣어서 술을 빚게되면 당화와 발효가 동시에 일어나게 된다. 일본식 청주도 Koji라 불리는 국(麴)을 제조하는 것을 달리할 뿐 우리 전통청주와 제법의 맥락은 같다. Koji는 찐쌀에 곰팡이류를 인위적으로 접종하여 배양한 것으로, 결국 당과용 효소를 얻는다는 것은 누룩과 같은 원리이나 곰팡이균을 분리하여 접종하는 것이 다르다. 한국의 청주판매 현황을 보면 80년대 초반 급격한 감소추세를 보였으나, 업계가 적극적인 판촉활동을 벌임과 동시에 새로운 TYPE의 냉청주(冷淸酒)를 개발하여 여름철이 비수기였던 시장 상황을 완전히 깨뜨려 사계절의 주류로 만드므로서 뚜렷한 회복, 증가추세로 바꾸었다. 앞으로 좀더 잘 다듬어지고 현대 이미지에 맞는 청주가 지속적으로 등장하여야 하며, 결국 이러한 민족고유의 맛이 가미된 청주 TYPE의 주류가 우리나라를 대표하는 국주로까지 발전할 수 있으리라 확신한다.