• Journal of Microbiology and Biotechnology
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• 제22권3호
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• pp.400-406
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• 2012

To improve the hydrogen yield from biological fermentation of organic wastewater, a co-culture system of dark- and photo-fermentation bacteria was investigated. In a pure-culture system of the dark-fermentation bacterium Clostridium butyricum, a pH of 6.25 was found to be optimal, resulting in a hydrogen production rate of 18.7 ml-$H_2/l/h$. On the other hand, the photosynthetic bacterium Rhodobacter sphaeroides could produce the most hydrogen at 1.81mol-$H_2/mol$-glucose at pH 7.0. The maximum specific growth rate of R. sphaeroides was determined to be 2.93 $h^{-1}$ when acetic acid was used as the carbon source, a result that was significantly higher than that obtained using either glucose or a mixture of volatile fatty acids (VFAs). Acetic acid best supported R. sphaeroides cell growth but not hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag phase. There were distinguishable inflection points in a plot of accumulated hydrogen over time, resulting from the dynamic production or consumption of VFAs by the interaction between the dark- and photo-fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was 15.9 ml-$H_2/l/h$, which was achievable in a sustainable manner.

• Journal of Microbiology and Biotechnology
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• 제22권5호
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• pp.668-673
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• 2012

Biohydrogen production from organic wastewater by anaerobically activated sludge fermentation has already been extensively investigated, and it is known that hydrogen can be produced by glucose fermentation through three metabolic pathways, including the oxidative decarboxylation of pyruvic acid to acetyl-CoA, oxidation of NADH to $NAD^+$, and acetogenesis by hydrogen-producing acetogens. However, the exact or dominant pathways of hydrogen production in the anaerobically activated sludge fermentation process have not yet been identified. Thus, a continuous stirred-tank reactor (CSTR) was introduced and a specifically acclimated acidogenic fermentative microflora obtained under certain operation conditions. The hydrogen production activity and potential hydrogen-producing pathways in the acidogenic fermentative microflora were then investigated using batch cultures in Erlenmeyer flasks with a working volume of 500 ml. Based on an initial glucose concentration of 10 g/l, pH 6.0, and a biomass of 1.01 g/l of a mixed liquid volatile suspended solid (MLVSS), 247.7 ml of hydrogen was obtained after a 68 h cultivation period at $35{\pm}1^{\circ}C$. Further tests indicated that 69% of the hydrogen was produced from the oxidative decarboxylation of pyruvic acid, whereas the remaining 31% was from the oxidation of NADH to $NAD^+$. There were no hydrogen-producing acetogens or they were unable to work effectively in the anaerobically activated sludge with a hydraulic retention time (HRT) of less than 8 h.

• 농업과학연구
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• 제46권1호
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• pp.125-135
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• 2019

Late-maturing Dark Horse, and early-maturing High Speed oat varieties were seeded on March 3, 2016 and harvested on three periods: May 31, June 10, and June 20 coded as early, mid, and late-harvest, respectively. Dried and ground samples were subjected to chemical analysis to determine nutritional values such as crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), organic matter (OM), and total digestible nutrient (TDN). Effective degradability (ED) of nutrients and fermentation characteristics including volatile fatty acid (VFA) composition, pH, gas production, and ammonia-N concentration were evaluated through an in vitro digestion method. Varieties of oat hays showed significant difference in terms of nutritional value, ED, and fermentation characteristics. Dark Horse showed higher CP and OM, and lower EE contents than High Speed. Dark Horse also showed higher EDDM (dry matter), NDF, ADF, and OM than High Speed, and although High Speed showed higher pH and ammonia-N, it had lower gas and total VFA production than Dark Horse. However, in terms of harvest period, significant difference was only observed in Dark Horse where early-harvest increased the CP, and late-harvest increased the NDF and OM contents. In addition, early-harvest of Dark Horse increased the EDDM and EDNDF of the forage. Therefore, early-harvest of late-maturing Dark Horse would give better nutrient efficiency than High Speed. Allowing Dark Horse to advance in maturity would decrease its nutrient productivity and efficiency.

• 한국축산식품학회지
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• 제44권2호
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• pp.443-463
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• 2024

This study investigated the impact of activated carbon, palm activated carbon, and zeolite on horse oil (HO) extracted from horse neck fat using supercritical fluid extraction with deodorant-untreated HO (CON) as a comparison. The yield and lipid oxidation of deodorant untreated HO (CON) were not significantly affected by the three deodorants. However, deodorant-treated HOs exhibited significantly elevated levels of α-linolenic acid (C18:3n3) and eicosenoic acid (C20:1n9) compared to CON (p<0.05), while other fatty acids remained consistent. Zeolite-purified HO demonstrated significantly lower levels of volatile organic compounds (VOCs) than other treatments (p<0.05). Remarkably, zeolite decreased the concentration of pentane, 2,3-dimethyl (gasoline odor), by over 90%, from 177.17 A.U. ×10⁶ in CON to 15.91 A.U. ×10⁶. Zeolite also effectively eliminates sec-butylamine (ammonia and fishy odor) as compared to other deodorant-treated HOs (p<0.05). Additionally, zeolite reduced VOCs associated with the fruity citrus flavor, such as nonanal, octanal, and D-limonene in HO (p<0.05). This study suggests that integrating zeolite in supercritical fluid extraction enhances HO purification by effectively eliminating undesirable VOCs, presenting a valuable approach for producing high-quality HO production in the cosmetic and functional food industries.

• 한국식품저장유통학회지
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• 제30권1호
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• pp.52-64
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• 2023

100 different yeast colonies were isolated from spontaneously fermented kiwis, persimmons, apples, pears, watermelons, grapes, grape fruits, peachs, and plums, and selected yeast strains were used to produce kiwi-persimmon mixed wine (KPMW). Among the isolates, five representative strains exhibited tolerance to sucrose, alcohol, pH, and potassium metabisulfite when compared with the control yeast strain (Saccharomyces cerevisiae KCCM 12615). All five yeast strains (Y4, Y10, Y28, Y78, and Y81) exhibited 99% 26S rDNA sequence similarity to S. cerevisiae. The pH, acidity, Brix, reducing sugar, alcohol, and organic acid contents were consistent in KPMW prepared from the S. cerevisiae KCCM 12615 and Y28 strains. KPMW made from the Y4, Y10, and Y28 strains exhibited lower quantities of free sugars than those of the KPMW made from the other yeast strains. The level of ethyl esters in KPMW prepared from the Y28 was higher than that in the other KPMWs. All strains, except for Y28, produced lower concentrations of sulfur and ketone compounds. Furthermore, the KPMW produced by the Y28 strains had total phenolic contents with 1.1 g/L, with DPPH and ABTS radical scavenging activities of 57.06% and 55.62%, respectively, and a FRAP assay value of 0.72. Our results suggest that Y28 is a promising yeast strain for producing high-quality wines.

• 한국식품영양과학회지
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• 제38권11호
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• pp.1564-1570
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• 2009

김치와 각각의 부재료들의 향기 성분을 비교하기 위하여 GC/MS로 정성 분석한 결과, 김치의 향기 성분은 sulfide 계열의 황 화합물과 유기산, 알코올류 등으로 나타났고, 김치의 냄새를 구성하는 물질들은 김치의 냄새를 각각의 부재료에서 검출된 향기 성분들로부터 유래한 것으로 확인되었다. 김치 특유의 이취를 저감시키기 위하여 김치의 부재료인 마늘, 생강, 양파 및 파를 각각 5 mm의 길이와 0.3 mm의 두께로 세절하고 100$^{\circ}C$ 에서 2분간 데친 후, 정수된 물 4$^{\circ}C$ 에서 12시간 동안 침지처리 하였다. 부재료 침지처리가 김치의 군덕내(moldy odor)와 신내(sour odor)에 미치는 영향을 관능검사로 평가한 결과, 세절침지처리김치에서 일반김치에 비하여 신내와 군덕내가 크게 감소한 것으로 나타났다. 또한 부재료의 침지처리가 숙성 중 김치에서 pH, 산도, 유산균수에 영향을 미치는 것으로 나타났다.

• 한국식품영양학회지
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• 제29권4호
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• pp.538-546
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• 2016

This study was carried out to evaluate the quality characteristics of Korean domestic commercial white wines. Four sample wines were analyzed in terms of their pH, total acidity, volatile acidity, alcohol content, soluble solid, free $SO_2$, total $SO_2$, color, free sugar content, organic acid, volatile compounds, total polyphenol content, DPPH radical scavenging activity and sensory characteristics. The pH of wines ranged from 3.06 to 3.76 and their total acidity from 0.43 to 0.83% (v/v). The alcohol content of samples ranged from 9.4 to 12.8% (v/v) and their soluble solid contents from 9.9 to $12.3^{\circ}Brix$. The free $SO_2$ and total $SO_2$ contents of the W1 wine were lower than those of the other wines, while the color intensity, a (redness) and b (yellowness) of W1 wine were higher than the values of the other wines. The malic acid contents of the four wines indicated that complete malolactic fermentation (MLF) occurred in W1, incomplete MLF in W3, and was absent in W2 and W4. Aroma analysis resulted in identification of 10 alcohols, 11 esters, 2 ketones and 6 miscellaneous compounds. 2,3-Epoxybutane and 1-(ethenyloxy)-pentane levels in were significantly higher W1 than the other wines, while several types of ester predominated in W2, W3 and W4. W1 had the lowest sensory score among the four wines. Therefore, the quality characteristics of domestic white wines are considered to be acceptable.

• 한국식품저장유통학회지
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• 제19권1호
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• pp.159-166
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• 2012

첨가하는 감의 가공형태에 따른 감 막걸리의 품질특성을 조사하기 위해 여러 가지 가공형태인 곶감, 감말랭이, 감분말, 감껍질분말, 감페이스트를 시험에 사용하였다. 막걸리 제조에 사용된 감의 수분함량, 총폴리페놀 및 가용성고형물 함량은 가공형태별 큰 차이를 보였으며, 이러한 요소들이 감막걸리의 총폴리페놀 및 알코올 농도에 영향을 미치는 것으로 나타났다. 감막걸리의 pH와 총산은 각각 3.7~4.1 및 0.2~0.3% (w/v) 정도의 분포를 보여, 시판되고 있는 막걸리와 비슷하였다. 아미노산도는 발효 3일째보다 5일째 급격히 상승하였는데, 감분말, 감껍질분말 및 감페이스테에서 비교적 높은 값을 보였다. 감막걸리의 휘발산 함량은 전반적으로 80~100 ppm 정도였으며, 감페이스트 처리에서 가장 높은 함량을 보였다. 감막걸리의 주된 유기산은 oxalic, citric, tartaric, malic, succinic, lactic, acetic acid 이었으며, 이들 유기산중 lactic acid의 함량이 가장 높았다. 감분말 및 감페이스트 첨가 감막걸리의 황색도 값이 높았으며, 색에 대한 기호성도 우수하였다. 맛과 전체적인 기호성(선택 비율)에 있어서, 감말랭이 첨가 막걸리가 가장 우수하였다.

• 한국식품영양학회지
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• 제19권4호
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• pp.466-472
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• 2006

붉은 대게 가공공정 중에 얻어지는 자숙액 및 내장의 천연 게향 소재로서의 가능성을 검토하고자 정미성분을 포함한 신품학적인 특성을 분석 비교한 결과는 다음과 같다. 붉은 대게 자숙액을 $40\;^{\circ}Brix$까지 농축시키면서 관능 검사 및 냄새 특성 강도를 수행한 결과 $30\;^{\circ}Brix$가 가장 양호하였다. 그리고 붉은 대게 농축 자숙액$(30^{\circ}Brix)$과 내장의 불휘발성 유기산에서는 lactic acid가 가장 많았고 다음으로 succinic acid이었다. 핵산 관련 물질은 IMP, Hx 및 GMP가 내장에서 대부분이었고, AMP, HxR, IMP 및 GMP 등이 자숙액에서 대부분을 차지하였다. 내장의 유리 아미노산 총량은 농축 자숙액에 비해 5.6배나 많았다. 조성면에서는 methionine, lysine, arginine, valine, histidine, alanine, hydroxy proline 및 glycine 등 8종이 자숙액 전체 아미노산의 72%를 차지하였고, 내장에서는 methyl histidine, leucine, alanine, glutamic acid, glycine, valine, threonine, taurine, isoleucine 및 serine 등 10종이 전체의 74%를 차지하였다. 결론적으로 천연 게향 제조를 위한 소재로서는 $30\;^{\circ}Brix$ 농도의 붉은 대게 농축 자숙액에 0.5%(w/w)의 붉은 대게 내장을 첨가하는 것이 적합하였다

• 분석과학
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• 제23권4호
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• pp.423-428
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• 2010

젤펜잉크 중 휘발성 성분을 스크리닝하여 개체특성자료를 확보하고자 3개국에서 생산된 16종의 흑색 젤펜잉크 카트리지를 시료로 분석하였다. 검출된 성분은 총 20종으로 isopropylalcohol, 2-methyl-2-propanol, 2-butanone, hydrazinecarbothioamide, benzeneacetic acid (ethyl ester), benzeneacetic acid, dimethoxymethy-silane, 2,2-dimethoxybutane, tetrahydro-2-methyl-furan, 1,2-ethanediol, silicic acid (tetramethyl ester), 1,2-propanediol, propyleneglycol, 3-ethyl-3-hexanol, 1,1-dipropoxy-propane, 2-butoxy-ethanol, 2,2'-oxybisethanol, 1-butyl-benzene, 2-pyrrolidinone, 2-(2-butoxyethoxy)-ethanol이었다. 그중 2,2-dimethoxybutane은 3.02~47%의 비율범위로 16종 젤펜 모든 시료에서 검출되었으며 tetrahydro-2-methyl-furan의 경우 1.19~52.19%로 GP1을 제외한 15종의 시료에서 검출되었다. 특히 일본산 제품 5종에서는 1,2-ethanediol가 52.83~95.84%의 범위, 한국산 동아제품 3종에서는 76.17~93.51%의 범위로 1,2-propanediol가 높은 함유율로 나타나 생산국에 따른 특성과 제조사별 특정성분의 함유분포를 알 수 있어서 잉크 휘발성 성분으로 개체특성을 확인하였다.