• Journal of Microbiology and Biotechnology
• /
• v.17 no.2
• /
• pp.297-304
• /
• 2007

The effect of yeast propagated at different aeration conditions on yeast physiology, fermentation ability, and beer quality was investigated using three strains of Saccharomyces cerevisiae. It was shown that yeast cells grown under continuous aeration conditions during propagation were almost two times higher as compared with discontinuous aeration conditions. The maximum of cell growth of all samples reached between 36 hand 48 h. The concentration of trehalose was increased under continuous aerated yeasts, whereas glycogen was decreased. It was also observed that the concentration of glycogen and trehalose in yeast cells had no direct effect on subsequent fermentation ability. The effect of yeast propagated under different aeration conditions on subsequent fermentation ability was different from yeast strains, in which the influence will be most pronounced at the first fermentation. Later, the yeasts might regain its original characteristics in the following fermentations. Generally, continuously propagated yeast had a positive effect on beer quality in subsequent fermentation. Hence, the concentration of aroma compounds obtained with yeast propagated under 6 1/h for 48 h aeration was lower than those grown under other aeration conditions in the bottom yeasts; in particular, the amounts of phenylethyl alcohol, ester, and fatty acids were decreased.

• Food Science and Biotechnology
• /
• v.17 no.4
• /
• pp.739-744
• /
• 2008

The method of yeast propagation has an influence on yeast physiology, fermentation ability, flocculation rate, and taste stability of beer. In order to find optimal conditions for propagation, several parameters were investigated in combinations. The bottom brewing yeast grown at $10^{\circ}C$ indicated that a higher flocculation capacity during the $1^{st}$ fermentation. However, the taste stability and the aroma profile were not affected by parameters of propagation investigated. The beer quality was rather affected by storage duration. In addition, a correlation between tasting and chemiluminescence was found at the beer, which was produced using bottom brewing yeast. The propagation at $10-25^{\circ}C$ with addition of zinc ion indicated the best condition to improve fermentation ability, flocculation rate, and filterability for bottom brewing yeast, whereas the propagation at $30^{\circ}C$ with addition of zinc ion showed the best condition to increase fermentation ability for top brewing yeasts.

• Food Science and Preservation
• /
• v.7 no.2
• /
• pp.228-232
• /
• 2000

To utilize abundant potatoes effectively, it was studied on alcohol fermentation strains which were isolated and identified. Fifteen yeast strains with high alcohol fermentation ability were isolated from rotted potatoes. Among them, two isolated strains, 5-3A and 10-4B showing the highest alcohol fermentation ability were identified as Zygosaccharomyces fermentati based on the morphological and physiological characteristics. Their optimum conditions for the alcohol fermentation in 25% glucose were pH 3.0, 30$^{\circ}C$ and 150 rpm of shaking speed, respectively.

• Journal of the East Asian Society of Dietary Life
• /
• v.7 no.4
• /
• pp.538-544
• /
• 1997

To utilize abundant poor persimmon fruits effectively, It was studied on alcohol fermentation strains which were isolated and indentified from poor persimmon fruits. The strains which had exellent alcohol production ability were analysized morphogical, cultural characteristics and identified Saccharomyces cerevisiae YJK 20, Sacachromyces kluveri DJ 97. Alcohol production ability between the isolated strains and industrial alcohol yeasts was compared in the YPD medium, persimmon extract medium. Isolated strains had high alcohol production ability in both of two medium, respectively. So it was expected that the strains. YKJ 20 and DJ 97 had good alcohol fermentation ability of persimmon fruits.

• Korean journal of food and cookery science
• /
• v.32 no.4
• /
• pp.466-475
• /
• 2016

Purpose: This study investigated the quality characteristics and antioxidant effects of Yakju added with rose, camellia, or cockscomb flower during fermentation. Methods: The quality characteristics and antioxidant effects were estimated including pH, amino acidity, total acid, ethanol content, color value, sensory test, electric donating ability, nitrite-scavenging ability, and ferrous ion chelating effect. Results: The pH values of Yakjus added with rose, camellia, or cockscomb flower were decreased after 2 days of fermentation and then increased after 4 days of fermentation, with final pH ranging from 4.15 to 4.27. Total acid content and amino acidity were increased during fermentation. The ethanol content in Yakjus fermented with rose, camellia, or cockscomb flower was rapidly increased after 2 days of fermentation, reaching the maximum content of 19.1% after 8 days of fermentation. In color evaluation, the L values of Yakjus added with rose, camellia, or cockscomb flower did not changes during fermentation, whereas values of a and b were increased. Total phenolic compound contents in Yakjus added with rose, camellia, or cockscomb flower were 0.67, 0.59, and 0.52 mg/mL, respectively. Total flavonoid contents in Yakjus added with rose, camellia, or cockscomb flower were 0.20, 0.09, and 0.26 mg/mL, respectively. In sensory test, the overall acceptability of Yakjus added with cockscomb flower was higher than that of Yakju added with rose or camellia flower. However, the difference was not statistically significant (p<0.05). Electron donating ability and nitrite-scavenging abilities were the highest in Yakjus added with rose flower, whereas ferrous ion chelating effect was the highest in Yakjus added with cockscomb flower. Conclusion: These results indicated that Yakjus added with rose, camellia, or cockscomb flower might have valuable functional properties due to their antioxidant effects.

• Natural Product Sciences
• /
• v.17 no.4
• /
• pp.363-366
• /
• 2011

Guibi-tang is a traditional medicine used for the treatment of colds. We investigated the levels of several compounds in Guibi-tang before and after fermentation with Lactobacillus and tested their ability to inhibit angiotensin-converting enzyme. Six known compounds (decursin, decursinol angelate, nodakenin, liquiritin, formononetin, and 6-gingerol) and 2 unidentified compounds were detected in Guibi-tang (GB) and fermented Guibi-tang (FGB) by an established HPLC-DAD method. The levels of the 6 known compounds were decreased after fermentation. FGB showed more potent inhibition of angiotensin-converting enzyme activity than GB. In conclusion, fermentation with Lactobacillus affects the content of several compounds in GB and improves its angiotensin-converting enzyme inhibitory activity.

• Food Science and Biotechnology
• /
• v.15 no.4
• /
• pp.582-588
• /
• 2006

The antioxidant and antimicrobial activity of the fermentation extract (PFE) and the 50 and 80% ethanol extracts (PE 50, PE 80) of Pinus densiflora pine needles were evaluated. Electron donating ability, superoxide dismutase (SOD) ability, and antimicrobial activity were observed in PFE; those abilities differed in PE 80 and PE 50, depending on the ethanol concentration used for the extraction. PFE had the highest electron donating ability with a value of 92.20%, while PE 80 and PE 50 had values of 74.66 and 53.47%, respectively. For SOD activity, PE 80 exhibited a slightly higher value of 31.11% compared to that of PFE and PE 50, which were 29.65 and 25.43%, respectively. PFE, PE 50, and PE 80 were all found to inhibit bacteria, and the effectiveness of this inhibition was strongly related to the type of extracts used. PFE showed good antimicrobial effects for all of the tested Gram-positive strains and for most of the tested Gram-negative strains. These results suggest that PFE has superior functionality compared to the ethanol extracts (PE 80, PE 50), in terms of antioxidant and antimicrobial activity. On the basis of these results, pine needle fermentation extracts can be used for industrial applications as a functional material.

• Journal of Microbiology and Biotechnology
• /
• v.4 no.3
• /
• pp.215-221
• /
• 1994

Two strains of yeast (RA-74-2 and RA-912) showing superior fermenting ability at a high temperature were isolated from soils and wastewaters by an enrichment culture method. Based on the morphological and physiological charateristics, the two strains were identified as Saccharomyces cerevisiae and Kluyveromyces marxianus, respectively. RA-74-2 was able to grow upto $43^{\circ}C$ and sustain similar fermenting ability in the temperatures range from 30 to $40^{\circ}C$. In addition, the sugar- and ethanol-tolerance of RA-74-2 were 30% (w/v) glucose and 10% (v/v) ethanol, which appeared to be higher than those of nine other industrial yeast strains currently being used in the alcohol factories. The thermotolerant ethanol fermenting yeast RA-912 showed identical growth in the temperatures range from 35 to $45^{\circ}C$ and was resistant to various heavy metals. The quality and quantity of byproducts of the isolated yeast strains in fermentation broth after fermentation at $40^{\circ}C$ and $45^{\circ}C$ were similiar with those obtained at $30^{\circ}C$. These results show that RA-74-2 can be adopted for the ethanol fermentation process where the expenses for cooling system is significant, and suggest that RA-912 may be applied in either SSF(simultaneous saccharification and fermentation) or Flash-fermentation process and RA-912 may be used as a gene donor for the development of thermotolerant ethanol-fermenting yeasts.

• Journal of the East Asian Society of Dietary Life
• /
• v.4 no.3
• /
• pp.75-86
• /
• 1994

The study was conducted to research the desirable method for fermentation of acidic apple beverage in the farmhouse. Step by step fermentation(SSF), complex fermentation after crushing of the fruit(CCF), complex fermentation after slicing of the fruit(SCF) and natural fermentation added yeast only after slicing of the fruit(SYNF) were compared. The brief fermentor for using stationary complex fermentation in the farmhouse was made in this experiment. The ability of acid production, flavor, taste and color were measured by sensory evaluation and mechanical methods. The quality of vinegar by SYNF and SCF were estimated by color, flavor, content, composition of sugar, and organic acids, and which was a suitable fermentation method for the farmhouse. The strains of acetobacter, SYNF-1 and 2 were isolated from the SYNF vinegar, and if has been shown that the SYNF-1 was a main strain in this study.

• Journal of the East Asian Society of Dietary Life
• /
• v.4 no.3
• /
• pp.135-146
• /
• 1994

The study was conducted to research the desirable method for fermentation of acidic beverage in the farmhouse using peach dropped at harvesting periods. Step by step fermentation(SSF), complex fermentation after crushing of the fruit(CCF), complex fermentation after slicing of the fruit(SCF) and natural fermenation added yeast only after slicing of the fruit(SYNF) were compared. The brief stationary fermentor for complex fermentation in the farmhouse was made in this experiment. The ability of acid production, flavor, taste and color were measured by sensory evaluation and mechanical methods. The quality of vinegar by SYNF was the most desirable, estimated by the color, the flavor, the content and composition of sugar, and of organic acids, and which was a suitable fermentation method for the farmhouse. The strains of acetobacter SYNF-1, 2 and 3 were isolated from the SYNF vinegar, and the SYNF-1 was a main strain.