• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.176-183
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• 2015

To characterize the aroma properties of roasted bulgogi reaction flavor obtained by using a high-temperature reaction apparatus, the volatile flavor and aroma-active compounds were analyzed using simultaneous steam distillation and solvent extraction (SDE)-gas chromatography-mass spectrometry-olfactometry (GC-MS-O). One hundred five volatile compounds were detected in roasted bulgogi reaction flavor using GC-MS. Out of these compounds, furfural was the most abundant volatile compound, followed in order of abundance by 5-methyl furfural, phenylacetaldehyde, and nonanal. Of the volatile compounds identified in roasted bulgogi reaction flavor, 33 aroma-active compounds were detected using GC-O. 2,3-Butanedione and furfural were the most intense aroma-active compounds detected. Other relatively intense odorants included hexanal, octanal, nonanal, undecanal, phenylacetaldehyde, 5-methyl furfural, 2,6-dimethyl pyrazine, and dimethyl trisulfide. These were important aroma-active compounds that contributed to the aroma of roasted bulgogi reaction flavor because of their potency and aroma properties. The concentrations of the aroma-active compounds increased as the reaction temperature increased, whereas those of the sulfide compounds decreased.

• Food Engineering Progress
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• v.14 no.3
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• pp.249-255
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• 2010

Ten commercial activated carbons (ACs) prepared from four different sources (bamboo, wood, peat, and coal) were evaluated for their adsorptive efficiency of six volatile compounds (isoamyl alcohol, hexanal, furfural, ethyl lactate, ethyl octanoate, 2-phenyl ethanol) which were dissolved in a 30% alcoholic model solution. These six volatile compounds are frequently found in alcoholic beverages and possibly contribute to physiological hangover due to their high concentrations. They are also generally regarded as off-flavor compounds at certain levels in alcoholic beverages such as whisky and vodka. Two hundred mL of 30% alcoholic solutions containing these six volatile compounds were treated with 0.2 g of ACs while stirring for 16 hr; the treated solutions were then measured for their adsorptive efficiencies (or removal efficiencies) by gas chromatographic analysis using two different sampling methods (direct liquid injection and headspace-solid phase microextraction). The adsorptive efficiencies of the ACs varied depending on the identity of the volatile compounds and the source material used for making the ACs. Ethyl octanoate, 2-phenyl ethanol, and hexanal were removed at high efficiencies (34-100%), whereas isoamyl alcohol, ethyl lactate, and furfural were removed at low efficiencies (5-13%). AC prepared from bamboo showed a high removal efficiency for isoamyl alcohol, aldehydes (hexanal and furfural), and 2-phenyl ethanol; these major fusel oils have been implicated as congeners responsible for alcohol hangover.

• Journal of the Korean Chemical Society
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• v.21 no.2
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• pp.139-148
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• 1977

The rate of oxime formation of 2-furfural and 5-substituted-2-furfurals such as 5-methyl-2-furfural, 5-isopropyl-2-furfural, 5-tert-butyl-2-furfural, 5-isoamyl-2-furfural and 5-nitro-2-furfural have been measured at 15∼$45^{\circ}C$ in aqueous solution buffered at pH 7. Oxime formation for all the compounds investigated is second-order reaction and their activation energies observed are 5.50, 7.22, 7.03, 7.49, 7.78 and 4.97 kcal/mole, respectively. Hammett equation is obtained for 5-alkyl-2-furfurals and the reaction constants (${\rho}$) calculated at 15, 25, 35 and $45^{\circ}C$ are 2.010, 1.756, 1.541, and 1.311 respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.6
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• pp.565-570
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• 1990

The role of the active oxygens on plasmid DNA damage by carbonyl compounds derived from Maillard reaction was investigated. Plasmid DNA extracted from E. coli Hb1O1 was reacted with carbonyl compounds, such as glyoxal, methyl glyoxal, dihydroxyacetone, diacetyl, glyceraldehyde, glycolaldehyde and furfural with and without the active oxygen scavengers at 37$^{\circ}C$ for 6 hours, and then the degree of damage was determined by using 1 ％ agarose gel electro-phoresis. All of the carbonyl compounds except furfural caused to damage of DNA. Among these, glyoxal, methyl glyoxal and dihydroxyacetone markedly induced the damage of DNA. On the other hand, the DNA damage by the carbonyl compounds was greatly inhibited by catalase, superoxide dismutase and $\alpha$-tocopherol it is considered that the damage of DNA is due to active oxygens, such as singlet oxygen, hydrogen peroxide and superoxide anion generated during the autoxidation of carbonyl compounds.

• Journal of Life Science
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• v.20 no.1
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• pp.113-118
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• 2010

The study was conducted to identify volatile flavor compounds in concentrated onion extracts ($Oniwell^{TM}$) during storage at $30^{\circ}C$ for 150 days. A total of 23 compounds was detected in samples by solid phase microextraction (SPME)/GC/MSD, consisting mainly of 9 sulfur-containing compounds, 5 carbonyl compounds, 4 furans, 2 aromatic compounds and 3 miscellaneous compounds. The sulfur-containing compounds were major compounds with ranges of 75.8~67.3% of total volatiles. In particular, dimethyl trisulfide, with a cooked cabbage-like odor, was 50.1~42.1% of the total amount of sulfur-containing compounds. Two compounds, dimethyl disulfide (fresh garlic/green onion-like) and methylpropyl disulfide (garlic salt-like), were significantly increased with longer storage periods (p<0.05). Four furans (furfural, 2-acetylfurn, 5-methyl-2-furfural, furfurylalcohol), known as thermally generated flavors, ranged from 14.2~12.9% of total volatiles, and the amounts of 4 aldehydes (2-, 3-methylbutanal, benzaldehyde, phenylactaldehyde) derived from lipid oxidation during heat treatment were followed in that order. Accordingly, it was estimated that these 3 groups including sulfur-containing compounds, furans and aldehydes played key roles in flavors in concentrated onion extracts ($Oniwell^{TM}$) during storage.

• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2165-2172
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• 2017

Lignocellulose is now a promising raw material for biofuel production. However, the lignin complex and crystalline cellulose require pretreatment steps for breakdown of the crystalline structure of cellulose for the generation of fermentable sugars. Moreover, several fermentation inhibitors are generated with sugar compounds, majorly furfural. The mitigation of these inhibitors is required for the further fermentation steps to proceed. Amino acids were investigated on furfural-induced growth inhibition in E. coli producing isobutanol. Glycine and serine were the most effective compounds against furfural. In minimal media, glycine conferred tolerance against furfural. From the $IC_{50}$ value for inhibitors in the production media, only glycine could alleviate growth arrest for furfural, where 6 mM glycine addition led to a slight increase in growth rate and isobutanol production from 2.6 to 2.8 g/l under furfural stress. Overexpression of glycine pathway genes did not lead to alleviation. However, addition of glycine to engineered strains blocked the growth arrest and increased the isobutanol production about 2.3-fold.

• Preventive Nutrition and Food Science
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• v.13 no.1
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• pp.54-59
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• 2008

This study was conducted to investigate the effect of pH on the formation of furfural compounds from glucose and fructose reacting with amino acid enantiomers in the Maillard reaction. Hydroxymethylfurfural (HMF) content was highest at pH 4.0, and decreased with increasing pH. HMF was significantly higher in glucose-based systems than fructose-based systems. Furfuryl alcohol (FFA) and 5-methyl-2-furaldehyde (MF) were not increased with increasing pH, and only small amounts were formed. In addition, 2-furaldehyde (F) was found to increase in the systems, as pH increased. However, the content was small and variable. 2,5-Dimethyl-4-hydroxy-3(2H)-furanone (DMHF) was only found in Glc/D-Asn, Glc/L-Lys and Fru/D-Lys system, but the content was not increased with increasing pH. 2-acetylfuran (AF) was higher in Glc (or Fru)/L-Lys and Glc (or Fru)/D-Lys systems at pH 7.0. However, at pH 4.0, the content of AF was higher in the Glc (or Fru)/Gly and Glc (or Fru)/L-Asn systems. Therefore, this study aimed to observe the effect of pH, sugars and amino acid enantiomers on the production of furfural and related compounds by the Maillard reaction. A clear tendency was observed for some classes of compounds to be more easily formed at higher or lower pH. HMF was more readily formed at lower pH, while FFA, F, DMHF and MF were inhibited by acidic conditions. Particularly, compounds like FFA, F and MF were not affected by pH changes. In addition, DMHF and MF were only formed in L-Lys and D-Lys system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.1
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• pp.116-122
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• 2012

Volatile flavor compounds derived from four black garlic extracts purchased in a local market were analyzed for the purpose of quality assessment. A total of 68 compounds was detected in samples using solid phase microextraction (SPME)/GC/MSD, and they were mainly sulfur-containing compounds, including three unknown compounds (21), aldehydes (10), furans (7), alcohols (6), aromatic compounds (7), ketones (4), acids (4), nitrogen-containing compounds (3), esters (2), and miscellaneous compounds (4). 2,6-Dimethyl-4-heptanone having a fruity-sweet odor was the most abundant in all of the samples. Six sulfur-containing compounds including allyl sulfide, 4-methyl-1,2,4-thiazole, 1,3,5-trithiane, unknown I (RI 1564), unknown II (RI 1565), and unknown III (RI 1613) were detected in all of the samples and appeared to contribute to the garlic-like odor. Particularly, three aldehydes (3-methylbutanal, benzaldehyde, phenylacetaldehyde), four furans (furfural, 2-acetylfuran, 5-methyl-2-furfural, furfural alcohol), and others (2,6-dimethylpyrazine, acetic acid) formed through a Maillard reaction during garlic aging were detected in all of the samples, and they contributed to the characteristic burnt, sweet, and sour flavors of black garlic extracts.

• Korean Journal of Food Science and Technology
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• v.14 no.3
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• pp.265-270
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• 1982

An attempt was made to investigate the antioxidant activity of maltol, kojic acid, levulinic acid, furfural, 5-hydroxymethyl furfural (5-HMF), and pyrazine which had been known to be important intermediates of Maillard browning reactions. The activity of these compounds was determined by comparing induction periods of soybean oil substrates containing each compound at a 0.01M level with that of a control. The induction period was arbitrarily taken as the time in hours for a substrate to reach a peroxide value of 60meq/kg oil. The substrates and control were stored at $45.0{\pm}1.0^{\circ}C$ for 30 days. The induction periods of the control, kojic acid, furfural, 5-HMF, maltol, levulinic acid, and pyrazine were respectively 468, 592, 510, 498, 486, 450, and 402 hours. Kojic acid demonstrated considerable antioxidant activity, whereas furfural, 5-HMF, and maltol showed weak activivity. Pyrazine and levulinic acid showed pro-oxidant activity. Although the prooxidant activity of pyrazine seemed definite, that of levulinic acid appeared very weak.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.561-569
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• 2023

Furfural is a platform chemical that is produced from xylose, one of the hemicellulose components of lignocellulosic biomass. Furfural can be used as an important feedstock for phenolic compounds or biofuels. In this study, we compared and optimized the conditions for producing furfural from xylose in a batch system using two types of catalysts: sulfuric acid, which is commonly used in the furfural production process, and formic acid, which is an environmentally friendly catalyst. We investigated the effects of xylose initial concentration (10 g/L~100 g/L), reaction temperature (140~200 ℃), sulfuric acid catalyst (1~3 wt%), formic acid catalyst (5~10 wt%), and reaction time on the furfural yield. The optimal conditions according to the type of catalyst were as follows. For sulfuric acid catalyst, 3 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 10min of reaction time resulted in a maximum furfural yield of 59.0%. For formic acid catalyst, 5 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 150 min of reaction time resulted in a furfural yield of 65.3%.