• Preventive Nutrition and Food Science
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• 제4권2호
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• pp.88-91
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• 1999

Aroma components of tea processed from Korean chicory roots were isolated and identified. The model system of amino-carbonyl reaction was carried out to study the formation mechanism of aroma compounds of chicory tea during manufacturing process. The concentration extracts from chicory tea and model system were analyzed and identified by gas chromatography(GC) and GC-mass spectrometry. Twenty-nine compounds, including pyrazines, furans, acids, alcohols, pyrroles and lactones were isolated and identified in chicory tea. The main compounds were pyrazines including methyl pyrazine, 2,5-dimethyl pyrazine, 2, 6-dimethyl pyrazine, 2-ethyl-6-methyl pyrazine, 2-ethyl-3-methyl pyrazine, thrimethyl pyrazine, 3-ethyl-2-5-dimenthyl pyrazine, 5-ethyl-2-3-dimenthyl pyrazine, and 2-acetyl-3-methy pyrazine and pyrroles including acethl pyrrole and formlyl pyrrole ; and furans including furfural , acetyl furan, 5-methyl furan, 5-methyl furfuralm, and furfuryl alcohol. These pyrazine compounds of a roasted and nutty aroma may be important contributors to the flavor of chicory tea. The aroma concentrate of model system also had a roasted and nutty aroma and the main compounds were methyl pyrazine, 2, 5-dimetyl pyrazine, 2, 6-dimethyl pyrazine and trimethyl pyrazine.

• Applied Biological Chemistry
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• 제42권2호
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• pp.111-115
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• 1999

발효방법에 따른 청국장의 휘발성 성분을 비교 조사하기 위해 증자대두에 Bacillus subtilis를 접종시킨 시험구(I), 1차 종균으로서 Lactobacilli(ll) 혹은 Aspergillus oryzae(III)를 접종시켜 소정시간 발효후 Bacillus subtilis를 추가 접종시킨 시험구, 그리고 볏짚을 접종원으로 한 시험구(IV)의 청국장제품을 각각 연속증류추출장치를 사용하여 휘발성 성분을 추출 농축하고 GC와 GC/MS를 이용하여 휘발성 성분을 분석 동정하였다. 그 결과 Bacillus subtilis 단용 발효구(I)와 볏짚을 접종원으로 사용한 시험구(IV)에서 각각 35종과 46종의 휘발성 성분이 검출되었고 Lactobacilli처리구(II)에서는 29종의 휘발성 성분이 검출되었는데 시험구(I), (IV)에 비해 향미성분으로 알려진 2,3,5-trimethyl pyrazine, 2,5-dimethyl pyrazine 등의 함량이 각각 2.2배, 1.5배 증가되었다. 또한 Asp. oryzae처리구(III)에서는 총 36종의 휘발성 성분이 분리 동정되었고 이들 성분 중에서 hexadecanoic acid, 2-methyl pyrazine성분이 많이 검출된 반면 청국장의 불쾌취로 알려진 butyric valeric acid는 검출되지 않았다. 대두 품종별로 제조한 청국장의 휘발성 성분을 비교 검토한 결과 신팔달콩을 원료대두로 사용한 시험구의 청국장이 향미성분은 증가한 반면 불쾌취 성분은 감소되었다.

• 한국식품조리과학회지
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• 제20권3호
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• pp.265-270
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• 2004

To investigate the formation of pyrazines, by-products of chicken were hydrolyzed by protease/peptidase for 4, 8 and 24 hours, after which the hydrolysates were heated with glucose, fructose and xylose, respectively, at l80$^{\circ}C$ for l00min. The formation of pyrazines showed a significant difference by quality and quantity according to the degree of protein hydrolysis. Especially, the formation of 2-methyl pyrazine and 2-ethyl-5-methyl pyrazine was considerably affected by, the degree of protein hydrolysis. Also, 3-ethyl-5-methyl pyrazine, 2-butyl-3-methyl pyrazine, 2-butyl-3,5-dimethyl pyrazine, methyl pyrazine, and 3-ethyl-5-methyl pyrazine were identified only in the hydrolysates for 24 hours.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.112-116
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• 2000

This paper presents anisotropic ethcing characteristics of single-crystal silicon in tetramethylammonium hydroxide(TMAH):isopropyl alcohol(IPA) solutions containing pyrazine. With the addition of IPA to TMAH solutions, etching characteristics are exhibited that indicate an improvement in flatness on the etching front and a reduction in undercutting, but the etch rate on (100) silicon is decreased. The (100) silicon etch rate is improved by the addition of pyrazine. An etch rate on (100) silicon of $0.8\;{\mu}m/min$, which is faster by 13 % than a 20 wt.% solution of pure TMAH, is obtained using 20 wt.% TMAH:0.5 g/100 ml pyrazine solutions, but the etch rate on (100) silicon is decreased if more pyrazine is added. With the addition of pyrazine to a 25 wt.% TMAH solution, variations in flatness on the etching front were not observed and the undercutting ratio was reduced by 30 ~ 50 %.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.23-26
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• 1997

This work presents the TMAH/IPA anisotropic etching characteristics with addition of Pyrazine. (100) Si etching rate of 0.747 ${\mu}{\textrm}{m}$/min at 8$0^{\circ}C$ was obtained using TMAH 25 wt.% / IPA 17 vol.% / pyrazine 0.1 g. The etching rate of (100) Si is increased about 52% compare to pure TMAH 25 wt.%. But etching rate of (100) Si is decreased with increasing Pyrazine additive. Activation energy of TMAH/IPA/pyrazine is much lower than TMAH and TMAH/IPA solutions. Addition of Pyrazine does not effect on surface flatness and decreases undercutting ratio about 20 %. Therefore, TMAH/IPA/pyrazine is an attractive anisotropic etchant because of alkaline-ion free.

• 한국식품저장유통학회지
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• 제13권2호
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• pp.269-272
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• 2006

황기가 청국장 향기성분에 미치는 영향을 조사하기 위해 청국장과 황기청국장을 제조하여 향기성분을 SDE, headspace, SPME 추출한 후 GC/MS로 정성하였다. 추출방법별 정성된 화합물의 수는 총 30개로 SDE 23개, headspace 6개, SPME 7개로 나타났다. 추출물을 관능기별로 구분하면 ketone류 6개, alcohol류 8개, heterocylic 화합물 3개, aldehyde류 3개, hydrocarbone류 6개, 기타 화합물 5개로 분류할 수 있다. 청국장의 주요향기성분으로 SDE 추출물은 3-hydroxy-2-butane, 2-furanmethanol, 2-methoxy-4-vinylphenol과 4-vinylphenol이었으며 headspace 추출물은 2,3-butanedione, 3-hydroxy-2-butane, ethanol, 2,6-dimethyl pyrazine과 acetic acid, SPME 추출물은 acetone, ethanol, 2,5-dimethyl pazine, tetrameyl pyrazine과 acetic acid이었다. 청국장의 특징적인 향기성분인 2,5-dimethyl pyrazine과 2,6-dimethyl pyrazine, tetramethyl pyrazine 함량은 청국장이 황기청국장에 비해 높게 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.397-400
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• 1997

This paper presentes the characteristics of Si anisotropic etching and electrochemical etch-stop in aqueous TMAH/IPA/pyrazine solution. (100) Si etching rate of 0.747 $\mu\textrm{m}$/min which faster 86% than TMAH 25 wt.%/IPA 17 vol.% solution was obtained using best etching condition at TMAH 25 wt.%/IPA 17 vol.%/pyrazine 0.1 g and the etching rate of (100) Si was decreased with more additive quantity of pyrazine. I-V curve of p-type Si in TMAH/IPA/pyrazine was obtained. OCP(Open Circuit Potential) and PP(Passivation Potential) were -2 V and -0.9 V, respectively. Si diaphragms were obtained by electrochemical etch-stop in aqueous TMAH/IPA/pyrazine solution.

• 대한화학회지
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• 제46권3호
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• pp.301-305
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• 2002

• 약학회지
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• 제40권6호
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• pp.727-733
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• 1996

2-(Allylthio)pyrazine is effective in selectively suppressing constitutive and inducible expression of cytochrome P450 2E1. The effect of 2-(allylthio)pyrazine against potentiat ed chemical injury was studied in rats. Vitamin-A pretreatment of rats substantially increased carbon tetrachloride hepatotoxicity, as supported by an ~4-fold increase in serum alanine aminotransferase (ALT) activity. Concomitant pretreatment of rats with 2-(allylthio)pyrazine at the daily dose of 200mg/kg resulted in a 76% decrease in vitamin-A-potentiated hepatotoxicity, which supported the possibility that 2-(allylthio)pyrazine protects the liver against chemical-induced hepatic injury by the mechanism associated with Kupffer cell inactivation. Pyridine pretreatment caused substantial enhancement in carbon tetrachloride hepatotoxicity. 2-(Allylthio)pyrazine treatment of rats reduced the pyridine-potentiated toxicity in a dose-dependent manner. Animals treated with both pyridine and 2-(allylthio)pyrazine prior to intoxicating dose of CCl$_4$ resulted in 85% and 47% decreases in pyridine-increased triglycerides and cholesterol levels in the liver. The protective effect of 2-(allylthio)pyrazine on the DNA strand breakage induced by benzenetriol was assessed by measuring the conversion of supercoiled ${\Phi}x$-174 DNA to the open relaxed form. 2-(Allylthio)pyrazine blocked the benzenetriol-induced conversion of supercoiled DNA to open circular form in a dose-dependent manner. The presence of 2-(allylthio)pyrazine at the doses from I to 10mM in the incubation mixture containing 5 ${\mu}$M benzenetriol completely protected benzenetriol-induced DNA strand breakage with the EC50 for the 2-(allylthio)pyrazine blocking being noted as ~220 ${\mu}$M, whereas allyl disulfide exerted protecting effect at relatively high concentrations (i.e. ~850 ${\mu}$M), suggesting that 2-(allylthio)pyrazine effectively scavenges the reactive oxygen species. These results provide evidence that 2-(allylthio)pyrazine blocks vitamin A- or pyridine-potentiated CCl$_4$ hepatotoxicity and that the agent is active in protecting DNA by scavenging the reactive oxygen species.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.147-151
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• 2000

This paper presents the electrochemical etch-stop characteristics of single-crystal silicon in a tetramethyl ammonium hyciroxide(TMAH):isopropyl alcohol(IPA):pyrazine solution. Addition of pyrazine to a TMAH:IPA etchant increases the etch-rate of (100) silicon, thus the elapsed time for etch-stop was shortened. The current-voltage(I-V) characteristics of n- and p-type silicon in a TMAH:IPA:pyrazine solution were obtained, respectively. Open circuit potential(OCP) and passivation potential(PP) of n- and p-type silicon, respectively, were obtained and applied potential was selected between n- and p-type silicon PP. The electrochemical etch-stop is applied to the fabrication of 801 microdiaphragms having $20\;{\mu}m$ thickness on a 5-inch silicon wafer. The averge thicknesses of 801 microdiaphragms fabricated on the one wafer were $20.03\;{\mu}m$ and standard deviation was ${\pm}0.26{\mu}m$. The silicon surface of the etch-stopped microdiaphragm was extremely flat without noticeable taper or other nonuniformities. The benefits of the electrochemical etch-stop in a TMAH:IPA:pyrazine solution become apparent when reproducibility in the microdiaphragm thickness for mass production is considered. These results indicate that the electrochemical etch-stop in a TMAH:IPA:pyrazine solution provides a powerful and versatile alternative process for fabricating high-yield silicon microdiaphragms.