• 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.

• 한국연초학회지
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• 제10권2호
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• pp.131-136
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• 1988

The mutagenicity of pyrolyzates (at 30$0^{\circ}C$, $600^{\circ}C$ and 75$0^{\circ}C$) prepared from three kinds of Maillard reaction Products, KG-19, KG-24 and KG-32, and that of the tar of cigarettes added these products were determined by using Salmonella typhimurium TA 98. The pyrolyzates of Maillard reaction products showed linear increases of revertant colonies according to the increase of pyrolysis temperature and dose of pyrolyzates, respectively. However, there was no difference in revertant colonies between the tar of cigarettes containing these products and those containing imported Maillard reaction products, or not containing any reaction product. It seems due to a little amount of these products added to the cigarettes.

• 한국수산과학회지
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• 제19권3호
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• pp.212-218
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• 1986

In order to isolate antioxigenic substrates, the browning reaction products of xylose and various amino acids were analysed by TLC and dialysis. Rf values of browning reaction products of xylose and hydrophobic amino acids separated on silica gel TLC plate were shown in the range of 0.38 to 0.56 and that of basic amino acids was around 0.2. Browning reaction products made from xylose and Trp were separated on TLC into four bands with Rf values of 0.25, 0.55, 0.81 and 0.91 respectively. Among these the bands with Rf values of 0.25 and 0.55 appeared having strong antioxidant activity. The band of Rf 0.55 which showed the highest activity was positive to Prochazka reagent and had an absorption maximum at 275 nm. In dialysis of the xylose-Trp browning reaction products, the undialysed fraction (inner solution) was repsponsible to the antioxidant activity, which was separated into two bands with Rf values of 0.25 and 0.55 on TLC. The inner fractions of the browning products of xylose and His or Arg were also apparent in antioxdant activity.

• 한국수산과학회지
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• 제19권1호
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• pp.1-9
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• 1986

In order to isolate and clarify the antioxygenic substances from the browning reaction products, the antioxidant activity of various amino acids and their browning reaction products were measured when they were reacted with xylose. Among nonpolar amino acids Met and Trp appeared to have stronger antioxidant effect than others. Most of polar and basic amino acids, however, did not have antioxidant activity. Ser and Cys showed a rather slight prooxidant effect. The browning reaction products of Trp and His had a higher level of antioxidant activity than that they were reacted as free amino acids. But the browning product of Met did not show the antioxidant activity. When all amino acids were divided on their polar characteristics, the higher optical density of the browning reaction products showed, the stronger antioxidant activity revealed.

• 생약학회지
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• 제31권2호
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• pp.240-244
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• 2000

Antimutagenicity profiles of the enzymatic browning reaction products(EBRP) were investigated. The rec-assay with Bacillus subtilis strains $H17(rec^+)$ and $M45(rec^-)$ was carried out using their spores. The biological activities were evaluated for seven different enzymatic browning reaction products, which resulted from the reactions of seven polyphenols with polyphenol oxidase isolated from Ginkgo biloba leaves. In the spore $rec^-$ assay, most of the polyphenolic compounds tested were positive, whereas their enzymatic browning reaction products were tested negative. The mutagenicity of enzymic browning mixtures of the polyphenols and the enzymes obtained from Ginkgo biloba leaves showed negative results in the mutagenicity test using Bacillus subtilis strains $H17(rec^+)$ and $M45(rec^-)$. In the case where polyphenol oxidase inhibitors were added in the enzymatic reaction mixtures with polyphenols, the polyphenols showed mutagenic effect in the spore $rec^-$ assay. This suggests that the activity of polyphenol oxidase is decreased.

• 미생물학회지
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• 제25권4호
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• pp.304-308
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• 1987

The mode of transglycosylation reaction observed during the action of low-molecular-weight 1,4-$\beta$-D-glucan glucanohydrolase (EC 3.2.1.4) purified from Trichoderma koningii ATCC 26113 was investigated using $^{1}H-NMR $spectroscopy. The H-1 proton resonances were analysed. After reaction of the enzyme with cellotriose, the reaction products were separated by high performance liquid chromatography. H-1 resonances of the products were consisted with those of cellobiose, cellotriose and cellotitraose, respectively. Therefore it was proved that all the reaction products formed by the action of the enzyme on cellooligosaccharides, including transglycosylation products, possess only H-NMR -1,4-glycosidic linkage(s).

• Bulletin of the Korean Chemical Society
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• 제18권3호
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• pp.287-291
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• 1997

The photochemical reaction of aqueous dichloromethane in the absence (saturated with argon) and the presence of O2 (saturated with air or oxygen) has been investigated using 184.9 nm UV light. The irradiation of the solution causes the formation of 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and chloride ion. The initial quantum yield of the products in the absence of oxygen was determined to be 8.6 × 10-3, 7.3 × 10-3, 4.4 × 10-3 and 2.3 × 10-2, respectively. In addition to these main products, small amounts of 1,2,3-trichloropropane, 1,1,2,2,3-pentachloropropane, 1,1,2,3,3-pentachloropropane, 1,3-dichloropropane and 1,1,2,2,3,3-hexachloropropane were detected. In the presence of oxygen, hydrogen peroxide was also detected along with the products listed above. With increasing the concentration of oxygen, while formation of the chlorinated organic products diminished, formation of chloride ion increased. Probable reaction mechanisms for the photochemical reaction were presented on the basis of products analysis.

• 대한환경공학회지
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• 제29권9호
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• pp.989-996
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• 2007

본 연구에서는 망간산화물 존재 하에서의 1-naphthol(1-NP)의 산화-결합반응을 통한 변환반응과 반응산물을 조사하였다. 변환 반응에 의해 생성된 반응산물을 대상으로 한 용매 추출과 HPLC, GC/MS, LC/MS 및 UV-Vis. 흡광특성 분석 등을 통해 반응산물의 분자 구조특성을 규명하였다. 반응 상등액에서 검출된 반응산물은 모두 1-NP에 비하여 높은 극성을 보였다. 주요 반응산물로는 1,4-naphthoquinon(1,4-NPQ)와 dimer, trimer 등의 소 중합체(oligomers)를 포함하며 특히, 용매추출$(CH_2Cl_2)$ 후 수용액에 잔류하는 친수성 형태의 반응산물은 다양한 분자량의(m/z=$400\sim2000$) 중합체로서 토양 휴믹물질(풀빅산)과 유사한 형태의 UV-Vis 흡광특성을 보였다. 또한, 비 반응성 생성물인 1,4-NPQ는 1-NP 존재 하에서 망간산화물에 의한 교차-결합(cross-coupling)을 통해 중합체로 변환될 수 있음을 확인하였다. 본 실험조건(20.5 mg/L, 1-NP, 2.5 g/L $MnO_2$, pH 5)에서 산화-결합 반응에 의한 중합체 형성으로 제거되는 1-NP의 양(mg/L)은 초기농도 대비 약 83%에 해당하며, 이들 중 약 30% 정도는 침전층에서 중류수와 메탄올$(CH_3OH)$에 의해 추출되지 않는 안정화된 형태의 불용성 중합체 생성물로 존재하였다. 이상의 결과는 망간산화물에 의한 산화-결합반응이 naphthol 오염토양의 처리에 있어서 소 중합체와 중합체 침전물로의 변환을 통한 오염 저감 및 제거 효과를 나타냄을 제시한다.

• 복식
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• 제65권5호
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• pp.74-87
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• 2015

It is common for popular products to sell out, and be out of stock. The purpose of this study is to examine the responses of consumers who have experiences of shopping online, and finding their desired products unavailable from being sold out. In order to carry out the study, in-depth interviews were conducted with ten recruits who were recruited from the Internet community, Soul Dresser, which is part of the Korean web portal, Daum. First, the cognitive reaction of the interviewees showed both positive and negative responses when they found out that their desired product was sold out. However, in the case of emotional reaction, all of them showed negative reactions. Observations showed that consumers researched and found similar products including price when they realized that their desired products were not going to be re-stocked. And in cases of similar products not being available, the consumers looked to buy other types of products such as bags, shoes, and other accessories.

• Journal of Photoscience
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• 제2권2호
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• pp.77-81
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• 1995

Photoreactions of pseudosaccharin ethers have been investigated. Pseudosaccharin 3-allyl ether undergoes a facile photoreaction via reaction pathways involving homolysis of bond between pseudosaccharyl oxygen and 3-allyl carbon, and excited nucleophilic substitution of allyloxy group by solvent which are not quenched by oxygen present in the reaction. Product yield demonstrates that the homolysis pathway predominates over the nucleophilic substitution in ca. 7:1 ratio. In contrast, pseudosaccharin alkyl ethers follow different reaction routes to produce two products, solvent-substituted pseudosaccharin alkyl ethers and reduction products, 3-alkoxy-1, 2-benzisothiazoles. The formations of reduction products, 3-alkoxy-1, 2-benzisothiazoles are completely quenched by oxygen.