• Journal of Microbiology and Biotechnology
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• v.32 no.6
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• pp.761-767
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• 2022

EHT1 and EEB1 are the key Saccharomyces cerevisiae genes involved in the synthesis of ethyl esters during wine fermentation. We constructed single (Δeht1, Δeeb1) and double (Δeht1Δeeb1) heterogenous mutant strains of the industrial diploid wine yeast EC1118 by disrupting one allele of EHT1 and/or EEB1. In addition, the aromatic profile of wine produced during fermentation of simulated grape juice by these mutant strains was also analyzed. The expression levels of EHT1 and/or EEB1 in the relevant mutants were less than 50% of the wild-type strain when grown in YPD medium and simulated grape juice medium. Compared to the wild-type strain, all mutants produced lower amounts of ethyl esters in the fermented grape juice and also resulted in distinct ethyl ester profiles. ATF2, a gene involved in acetate ester synthesis, was expressed at higher levels in the EEB1 downregulation mutants compared to the wild-type and Δeht1 strains during fermentation, which was consistent with the content of acetate esters. In addition, the production of higher alcohols was also markedly affected by the decrease in EEB1 levels. Compared to EHT1, EEB1 downregulation had a greater impact on the production of acetate esters and higher alcohols, suggesting that controlling EEB1 expression could be an effective means to regulate the content of these aromatic metabolites in wine. Taken together, the synthesis of ethyl esters can be decreased by deleting one allele of EHT1 and EEB1 in the diploid EC1118 strain, which may modify the ester profile of wine more subtly compared to the complete deletion of target genes.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1035-1042
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• 2000

Volatile compounds of kochujang prepared with meju and koji were analyzed by using a purge and trap method during fermentation and identified with GC-MSD. Thirteen alcohols, seventeen esters, seven acids, six aldehydes and nine others were identified. Twenty four volatile flavor detected immediately after making kochujang including 7 alcohols and 9 esters. Six volatile flavor compounds including 1 alcohol and 3 esters were more found after 30 day of fermentation and increased to forty nine of volatile compounds after 150 days. Six alcohols such as ethanol, 3-methyl-butanol, 2-methyl-1-propanol, 1-butanol and nine esters such as ethyl acetate, ethyl butyrate, ethyl caproate, ethyl carpylate and seven others were commonly found through the fermentation period. Peak area (%) of 1-butanol was the highest one among the volatile flavor compounds after 30 day of fermentation and ethanol showed the highest peak area after 60-90 day and 150 day of fermentation, and 3-methyl-1-butanol showed the highest peak area after 120 day of fermentation, 2-Methyl-1-propanol, ethyl butyrate, ethyl acetate, acetaldehyde, ethoxyethene, ethenone, methylbenzene were detected in the kochujang during the fermentation.

• Preventive Nutrition and Food Science
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• v.13 no.1
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• pp.12-17
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• 2008

Douchi, a popular seasoning agent in Chinese dishes prepared by the Aspergillus oryzae fermentation of black beans, was subjected to supercritical fluid extraction (SFE) and gas chromatography-mass spectrometry analysis for its volatile components. A total of 73 components were identified in two commercial brands, which were positively confirmed and quantified. Among the common components in the two brands were 18 acids, 12 alcohols, 11 aldehydes, 9 esters, 1 furan, 11 other oxygen-containing compounds, 4 pyrazines, 2 pyridines and 5 miscellaneous compounds. The most abundant components found were acetic acid, benzoic acid, 2,6-dimethylpyrazine, 2-piperidinone, 3-methylbutanoic acid, maltol, 4-ethylphenol, 2-methylpropanoic acid, butanoic acid, 2-pyrrolidinone, all fatty acids and some esters.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.794-800
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• 1999

This study was carried out to obtain the basic information for improving the flavor quality of yakju. Three kinds of yakju were prepared with different yeast strains to investigate the effects of those strains on flavor components. A total of 23 strains were isolated from fruits such as apple, pear, persimmon and citron and two strains were excellent in producing ethanol and flavors. They were identified as Saccharomyces cerevisiae S 2 and Saccharomyces cerevisiae S 6 from morphological cultural test and physiological quality. Yakju A, B and C were prepared with S 2, S 6 and Saccharomyces cerevisiae IFO 1950, respectively. Flavor components of yakju were analyzed by gas chromatography and mass spectr ometry. A total of 57 peaks were detected and 13 compound were identified. They were 4 alcohol, 2 esters, 7 acids and miscellaneous compounds.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.366-372
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• 2001

Volatile flavor components in the mash of Takjus prepared by using Aspergillus oryzae nuruk were identified by using Gas Chromatography and Gas Chromatography-Mass Spectrometry. Twenty-four esters, 21 alcohols, 10 acids, 9 aldehydes and 4 others were found in the mash of Takju. Thirty six components including 13 esters and 12 alcohols were detected in the beginning of fermentation. Twenty nine components were more detected after second day of fermentation and 68 components were detected after 12 days of fermentation. Thirty five flavor components including 12 alcohols such as ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol and benzeneethanol, 13 esters such as ethyl acetate, ethyl caprylate, ethyl butyrate and isoamyl acetate, 4 aldehydes and 6 acids were usually detected in the fermentation process. Ethanol was predominantly found in the range of $79.86{\sim}89.54%$ as a major component by using relative peak area. 3-Methyl-1-butanol, ethyl caprylate and benzeneethanol were some of the major volatile components through the fermentation respectively. Peak area of 2-methyl-1-propanol, 1-hexanol, 1-dodecanol, ethyl acetate, monoethyl butanoate, acetic acid and isobutylaldehyde among the same group were higher than other components depending upon fermentation time.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.691-698
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• 2000

Volatile flavor components in the mash of takjus prepared by using Rhizopus japonicus nuruk were identified by using GC and GC-MS. Twenty-four esters, 19 alcohols, 9 acids, 10 aldehydes and 4 others were found in the mash of takju. Thirty nine components including 14 esters and 12 alcohols were detected in the beginning of fermentation. Seventeen components were more detected after second day of fermentation and 66 components were detected after 12 days of fermentation. Thirty eight flavor components including 12 alcohols such as ethanol, 2-methyl-1-propanol and 3-methyl-1-butanol, 14 esters such as ethylacetate, ethylcaprylate and isoamylacetate, 6 aldehydes and 5 acids were usually detected in the fermentation process. Ethanol was predominantly found in the range of 76.2149-92.1155% as a major component by using relative peak area. 3-Methyl-1-butanol, 2-methyl-1-propanol, ethyl caprylate, 2,3-butanediol and benzeneethanol were some of the major volatile components through the fermentation. Peak area of ethylacetate, diethyl succinate, octanoic acid, acetic acid and isobutylaldehyde among the same group were higher than other component depending upon fermentation time.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.944-950
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• 2005

Volatile flavor components of Takjus mash prepared using Aspergillus kawachii nuruk were identified by GC and GC/MS. Twenty-two esters, 20 alcohols, 10 acids, 8 aldehydes, and 3 others were found in Takju mash. Thirty two components including 13 esters and 13 alcohols were detected at beginning of fermentation. Thirteen more components were detected after second day of fermentation, and 63 additional components after 12 days of fermentation. Twenty nine flavor components including 12 alcohols such as ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol, and benzeneethanol, 12 esters such as ethyl acetate, ethyl caprylate, and ethyl butyrate 3 aldehydes, and 2 acids were detected during fermentation. Major volatile components detected during fermentation included 3-methyl-1-butanol, ethyl caprylate, and benzeneethanol. Peak areas of 2-methyl-1-propanol, 1-hexanol, 2, 3-butanediol (D.L), 1-dodecanol, 2-phenylethyl acetate, ethyl acetate, and monoethyl butanoate were higher than those of other components depending upon fermentation period.

• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.491-499
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• 1999

A great variety of the volatile metabolic by-products was formed in yeast cell during alcohol fermentation. The seibel grape (Vitis labrasca) which was grown in the Southern Korea used for wines. The objective of this research was to identify the volatile flavor compounds during alcohol fermentation and aging at 12$^{\circ}C$. saccharomyces cerevisiae and Schizosaccharomyces pombe were inoculated and fermented in seibel grape must. The volatile flavor compounds of logarithmic, stationary and death phases were extracted, concentrated and identified by gas chromatography/mass spectrometer (GC/MS). The volatile flavor compounds were determined by a Hewlett-Packard 5890 II Plus GC which was equipped with Supelcowax 10 fused silica capillary column (60m$\times$0.32mm$\times$0.25${\mu}{\textrm}{m}$ film thickness) wall coated with polyethyleneglycerol. The scan detection method allowed the comparison of the spectrum from the chromatogram of volatile flavor compounds to those in data Wileynbs base library. Among the volatile compounds collected by ether-hexane extraction method, the evolution of 20 main compounds, such as 9 esters (ethyl butyrate, isoamyl acetate, ethyl caproate, n-hexyl acetate, ethl caprylate, ethyl caprate, diethy succinate, ethyl hexadecanoate, 2-pheneethyl acetate), 4 alcohols (3-methyl-1-butanol, 1-hexanol, 1-heptanol, benzoethanol), 4 ketones and acids (2-octanone, caproic acid, caprylic acid, capric acid), 2 furan and phenol (2,6-bis(1,1-dimethyl ethyl)phenol, 2,3-dihydrobenzofuran) were observed during alcohol fermentation and aging. The production of the esters during alcohol fermentation with S. cerevisiae was higher than those of Sch. pombe. The sensory scores of the aged wine samples in aroma, taste and overall acceptability were not significantly different(p<0.05).

• Food Science and Biotechnology
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• v.18 no.3
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• pp.700-705
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• 2009

In this study, the volatile compounds in 9 commercial fermented soybean pastes were extracted and analyzed by headspace-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS), respectively. A total of 63 volatile components, including 21 esters, 7 alcohols, 7 acids, 8 pyrazines, 5 volatile phenols, 3 ketones, 6 aldehydes, and 6 miscellaneous compounds, were identified. Esters, acids, and pyrazines were the largest groups among the quantified volatiles. About 50% of the total quantified volatile material was contributed by 5 compounds in 9 soybean paste samples; ethyl hexadecanoate, acetic acid, butanoic acid, 2/3-methyl butanoic acid, and tetramethyl-pyrazine. Three samples (CJW, SIN, and HAE) made by Aspergillus oryzae inoculation showed similar volatile patterns as shown in principal component analyses to GC-MS data sets, which showed higher levels in ethyl esters and 2-methoxy-4-vinylphenol. Traditional fermented soybean pastes showed overall higher levels in pyrazines and acids contents.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1144-1150
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• 1997

Volatile flavor components of soybean koji kochujang made from a glutinuous rice by improved method were analyzed by using a purge and trap method during fermentation, and identified with GC-MSD. Fifty-six volatile flavor components including 16 alcohols, 15 esters, 7 acids, 4 aldehydes, 5 alkanes, 3 ketones, 1 benzene, 1 alkene, 2 phenol and 2 others were found in improved kochujang. The number of volatile flavor components detected immediately after making kochujang were 32 and increased to 46 components after 30 day of fermentation. The most number 55 of volatile flavor components were found after 90 day of fermentation. Thirty-one kinds of volatile flavor components were commonly found through the fermentation period 9 alcohols such as 2-methyl-1-propanol, ethanol, 3-methyl-1-butanol, 8 esters such as methyl acetate, ethyl acetate, 2-methylpropyl acetate, 3 aldehydes such as butanal, acetaldehyde, furfural and 11 othesrs. Although the various types of peak areas (%) of volatile flavor components were shown in kochujang during the fermentation days, ethanol. ethyl acetate, ethyl butanoate, 2-methylpropyl acetate, 2-methyl-1-propanol and 3-methyl-1-butanol were mainly detected during fermentation. Those might be the major volatile flavor components in kochujang made by improved method. Peak area of ethanol was the highest one among the volatile flavor components at immediately after mashing and 90 day while ethyl acetate showed the highest Peak area after $30{\sim}60$ day of fermentation and 3-methyl-1-butanol showed the highest peak area after $120{\sim}150$ day of fermentation.