• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.4271-4274
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• 2012

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.1939-1945
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• 2009

Kinetic investigations on the oxidation of pyrazine and four 2-substituted pyrazines viz., 2-methylpyrazine, 2-ethylpyrazine, 2-methoxypyrazine and 2-aminopyrazine by bromamine-B (BAB) to the respective N-oxides have been studied in HCl$O_4$ medium at 303 K. The reactions show identical kinetics being first-order each in $[BAB]_o\;and\;[pyrazine]_o$, and a fractional- order dependence on $[H^+]$. Effect of ionic strength of the medium and addition of benzenesulfonamide or halide ions showed no significant effect on the reaction rate. The dielectric effect is positive. The solvent isotope effect was studied using $D_2$O. The reaction has been studied at different temperatures and activation parameters for the composite reaction have been evaluated from the Arrhenius plots. The reaction showed 1:1 stoichiometry and the oxidation products of pyrazines were characterized as their respective N-oxides. Under comparable experimental conditions, the oxidation rate of pyrazines increased in the order: 2-aminopyrazine > 2-methoxypyrazine > 2-ethylpyrazine > 2-methylpyrazine > pyrazine. The rates correlate with the Hammett $\sigma$ relationship and the reaction constant $\rho$ was found to be -0.8, indicating that electron donating centres enhance the rate of reaction. An isokinetic temperature of $\beta$ = 333 K, indicated that the reaction was enthalpy controlled. A mechanism consistent with the experimental results has been proposed in which the rate determining step is the formation of an intermediate complex between the substrate and the diprotonated species of the oxidant. The related rate law in consistent with observed results has been deduced.

• Preventive Nutrition and Food Science
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• 제2권4호
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• pp.360-367
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• 1997

The chemistry background of the Maillard reaction focused on pyrazines and factors affecting the reaction products were reviewed. The Maillard reaction, also called a non-enzymatic browning reaction, is quite complex and generates numerous reaction products. In processed foods, it is generally accepted as a key reaction to produce flavor components. Specially, pyrazines possess an important impact character on the roasted foods with other heterocyclic compounds. The Maillard reaction is initiated by condensation between reducing sugar and amino group, and N-glycosylamines are produced via Schiff base with dehydration of water. After the rearrangement of the N-glycosylamines, they follow transformation into deoxyhexosones which are reactive intermediates. Degradation and fragmentation are facilitated by rearranged compounds. By condensation, pyrazine, one of the final Maillard products, is generated as a relatively stable form to provide specific aromas. During the processes of the reaction, chemical or physical environmental parameters affect the formation of the products.

• 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.

• Food Science and Biotechnology
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• 제18권3호
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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.

• 한국식품과학회지
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• 제32권3호
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• pp.654-658
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• 2000

Coca bean을 마이크로파로 roasting하고 그 향기성분의 변화를 methyl pyrazine류를 중심으로 살펴보고 이를 상법으로 roasting한 경우와 비교해 보았다. 전자렌지를 개조하여 마이크로파 roasting system을 설계하여 실험에 사용하였고 열전쌍을 이용한 온도측정법으로 cocoa bean의 품온을 측정하였다. 마이크로파 roasting은 roasting 시간을 30분으로 고정하고 온도를 110, 120, 130, 140 및 $150^{\circ}C$로 변화시킨 경우와 roasting 온도를 $130^{\circ}C$로 고정하고 roasting 시간을 5, 10, 20 및 30분으로 변화시킨 경우로 구분하여 행하였다. 상법 roasting은 $120^{\circ}C$에서 15분간 실시하였다. Methyl pyrazine 류의 함량과 함량비는 마이크로파 roasting 온도 및 rosting 시간에 영향을 받았으며 적정한 methyl pyrazine류의 비는 $140^{\circ}C$ 30분 roasting에서 얻을 수 있었다.

• 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.

• 동아시아식생활학회:학술대회논문집
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• 동아시아식생활학회 2004년도 참깨과학 국제학술대회 발표 논문집
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• pp.107-129
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• 2004

참기름은 특유의 풍미와 건강 기능적 특성으로 한국에서 널리 이용되고 있으며, 제조방법에 따라 휘발성 향기성분과 항산화성이 달라지기 때문에 이에 대한 연구가 많이 행해져 왔다. 이에 한국, 일본, 중국 참기름의 품질특성과 기호특성을 알아보기 위해 시판 한국, 일본, 중국 참기름을 대상으로 이화학적 특성, 휘발성 향기성분, 항산화성, 이들간의 상관성 및 관능평가를 조사하였다. 지방산 조성은 올레산, 리놀산이 거의 80%이상이고, P/S 비는 4.99${\sim}$5.73 이었으며, 토코페롤은 ${\gamma}$체가 대부분으로 23.14${\sim}$34.85 mg/100g 범위이었다. 리그난 함량에 있어서는 세사민(322.91${\sim}$689.39ppm), 세사몰린(62.19${\sim}$289.82ppm)이 대부분이었고, 세사몰은 8.52${\sim}$51.21ppm 로 제조국간의차이가 뚜렷하여 한국>중국>일본의 순으로 많았다. 산화안정성의 지표가 되는 유도기간은 한국>중국>일본 순이었고, Lovibond 색가에서는 제품간의 차이는 있지만 대체로 한국${\geq}$중국>일본제품의 순서로 red 값과 yellow 값이 큼을 알 수 있었다. 향기성분의 주요 구성은 pyrazines>phenols>aldehydes> furans 이었고, 이외에 pyrroles, thiazoles, indoles 을 소량 포함하고 있었다. 향기성분 총량은 한국>중국>일본 제품의 순서로 많았고, 한국제품에 pyrazines 이 총향기성분 함량의 35%으로 월등히 많았으며, 중국 참기름의 경우는 phenols이 많았다. good flavor(pyrazines, pyroles, thiazoles, furans)/off flavor(phenols, aldehydes, Indoles)은 대체로 한국>일본${\fallingdotseq}$중국이었다. 또한, Pyrazines, sesamol, b 값(yellowness), 유도기간 간에는 양의 상관이 있음을 알았다. 한국, 일본, 중국 참기름에 대한 기호특성을 조사한 결과에서는 한국인들은 고소한 향의 강도, 고소한 향의 기호도, 전체적인 맛에서 한국참기름>일본참기름>중국참기름의 순서로 일본인들은 전체적인 맛에서는 한국인들과 비슷한 기호성을 보였으나, 고소한 향의 기호도에서는 한국참기름과 일본참기름을 동일하게 평가한 반면, 중국인들은 고소한 향의 강도, 고소한 향의 기호도, 전체적인 맛에서 뚜렷하게 일본참기름을 우수하게 평가하였다.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1495-1499
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• 2009

The volatiles formed from the reactions of L-ascorbic acid with L-alanine at 5 different pH (5, 6, 7, 8, or 9) and $140{\pm}2^{\circ}C$ for 2 hr was performed using solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis were identified to be 25 different kinds. The reaction between L-ascorbic acid and L-alanine led mainly to the formation of pyrazines. Many of these were alkylpyrazines, such as 3-ethyl-2,5-dimethylpyrazine, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, 3,5-diethyl-2-methylpyrazine, methylpyrazine, 2-ethyl-6-methylpyrazine, and 2,3-diethyl-5-methylpyrazine, other compounds identified were furans, phenols, benzoquinones, 2,4,6-trimethylpyridine, and 2-methylbenzoxazole. The studies showed that furans, such as furfural and benzofuran were formed mainly at acidic pH. In contrast, higher pH values could promote the production of pyrazines.

• Fibers and Polymers
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• 제1권2호
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• pp.71-75
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• 2000

Intermolecular cyclization of 2-alkylamino-3-chloro-5,6-dicyanopyrazine 2 in the presence of tributylamine in N,N-dimethylformamide (DMF) gave 5,10-disubstituted-2,3,7,8-tetracyano -5,10-dihydrodipyrazino〔2,3-b:2',3'-e]pyrazines 3, which showed strong mesomorphic property and were anticipated as new chromophoric system for functional dye materials. Absorption spectra, fluorescent properties and other physical properties were correlated with their chemical structures. Vanadyl oligomeric porphyrazine with long alkyl groups synthesized from 3 had satisfactory solubility in tetrahydrofuran (THF), diethyl ether and dimethylsulfoxide (DMSO). The syntheses and characterization of vanadyl polymeric porphyrazines derived from 3 with long alkyl groups are reported.