• 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.

• Journal of the Korean Wood Science and Technology
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• v.50 no.6
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• pp.475-489
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• 2022

The objective of this study was to understand the conversion characteristics of glucose and xylose using the major monosaccharide standards for lignocellulosic biomass. The acid-catalyzed organosolv pretreatment conducted using ethanol was significantly different from the acid-catalyzed process conducted in an aqueous medium. 5-hydroxymethylfurfural (5-HMF), levulinic acid and furfural were produced from glucose conversion. The maximum yield of 5-HMF was 5.5%, at 200℃, when 0.5% sulfuric acid was used. The maximum yield of levulinic acid was 21.5%, at 220℃, when 1.0% sulfuric acid was used. Furfural was produced from xylose conversion and under 0.5% sulfuric acid, furfural reached the maximum yield 48.5% at 210℃. Ethyl levulinate and methyl levulinate were also formed from the glucose standard following the esterification reaction conducted under conditions of the combined conversion method, which proceeded under both ethanol-rich and water-rich conditions.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.61-65
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• 2018

In this study, the conversion of glucosamine, which is a major monomer in chitin/chitosan of crustacean shell, using solid acid catalyst was performed to obtain chemical intermediates such as levulinic acid and 5-hydroxymethyl furfural (5-HMF). The conversion reaction was optimized with four reaction factors of selection of ionic resin catalyst, reaction temperature, catalyst amount, and reaction time. As an optimized result, the highest levulinic acid yield was achieved approximately 36.86% under the determined conditions (Amberlyst 15 as a solid-acid catalyst, $180^{\circ}C$, 5% catalyst amount and 60 min). On the other hand, 5-HMF yield was found to be 0.91% at the condition.

• Food Science and Preservation
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• v.12 no.3
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• pp.195-198
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• 2005

Among organic acids, Prunus mume extract(PME) was mostly consisted of $0.47\;mg\%$ citric, $0.43\;mg\%$ malic and $0.25\;mg\%$ oxalic acid Volatile compounds in PME were identified by GC/MSD, showing that acetic acid($8.3\%$) and p-coumaric acid($13.1\%$) as well as 5-hydroxymethyl furfural($32.3\%$), furfural($8.3\%$), and 3-methyl-2,3-furandione($2.3\%$) were major compounds which are known as antimicrobial substances.

• Journal of the Korean Wood Science and Technology
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• v.44 no.3
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• pp.389-397
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• 2016

In this study, ethanol was produced from a biomass hydrolysate that had been treated by electrodialysis (ED) and Amberlite XAD resin to remove fermentation inhibitors. Most of the acetic acid (95.6%) was removed during the ED process. Non-ionizable compounds such as total phenolic compounds, 5-hydroxymethyl furfural, and furfural were effectively removed by the XAD resin treatment. Ethanol production was improved when the ED-treated hydrolysate was treated with XAD-4 resin for a short reaction time. The highest ethanol production from ED-treated hydrolysate was $6.16g/{\ell}$ (after 72 h of fermentation) when the treatment with XAD-4 resin was for 5 min. Among the lignin-derived fermentation inhibitors tested, syringaldehyde in low concentrations (1 and 2 mM) in the hydrolysate increased ethanol production, whereas a high concentration (5 mM) inhibited the ethanol production process. A synthetic medium containing syringaldehyde and ferulic acid was prepared to investigate the synergistic effect of inhibitors on ethanol fermentation. Ethanol production decreased in the mixture of 1 mM syringaldehyde and 1 mM ferulic acid, implying that the effect of ferulic acid on ethanol fermentation is comparable to that of syringaldehyde.

• Korean Journal of Pharmacognosy
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• v.42 no.2
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• pp.117-126
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• 2011

Twenty-two compounds were isolated from the 70% ethanolic extract of Rehmanniae Radix Preparata (Scrophulariaceae) and their structures were identified as three triterpenoids [oleanolic acid (1), pomonic acid (2) and ursolic acid (5)], an iridoid, catalpol (13), four furan derivatives [5-hydroxymethyl-2-furaldehyde acetate (3), 5-hydroxymethyl-2-furfural (6), 5-hydroxymethyl-2-furancarboxylic acid (7), and 5-(${\alpha}$-D-galactopyranosyloxymethyl)-2-furancarboxaldehyde (15)], three phenethyl alcohol glycosides [darendoside B (14), phenethyl alcohol 2-O-${\beta}$-D-xylopyranosyl(1${\rightarrow}$6)-${\beta}$-D-glucopyranoside (17), and salidroside (19)], four sugar derivatives [L-arabinose (11), raffinose (20), stachyose (21), and mannitol (22)], and seven others [2,5-dihydroxyacetophenone (4), succinic acid (8), daucosterol (9), ${\beta}$-sitosterol (10), adenosine (16), uridine (18) jio-cerebroside (12)]. The chemical structures of these compounds were identified on the basis of spectroscopic methods and comparison with literature values. This is the first report of the triterpenoids oleanolic acid (1), pomonic acid (2), and ursolic acid (5) from the genus Rehmannia, as well as the first report of compounds 5-hydroxymethyl-2-furaldehyde acetate (3), 2,5-dihydroxyacetophenone (4), daucosterol (9), darendoside B (14), 5-(${\alpha}$-D-galactopyranosyloxymethyl)-2-furancarboxaldehyde (15), adenosine (16), phenethyl alcohol 2-O-${\beta}$-D-xylopyranosyl(1${\rightarrow}$6)-${\beta}$-D-glucopyranoside (17), and salidroside (19) from the Rehmanniae Radix Preparata.

• Journal of Life Science
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• v.20 no.3
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• pp.321-325
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• 2010

Among endogenous oral microflora, Streptococcus mutans plays a critical role in dental plaque formation, which mainly contributes to the development of caries and periodontal disease. Phytochemicals are plant-derived chemical compounds that have been studied as beneficial nutrients to human health. The purpose of this study was to determine the effects of phytochemicals against S. mutans. Among them, oleanolic acid (OA) and 5-(hydroxymethyl)-2-furfural (HF) from Thomson seedless raisins were tested for anti-microbial effects against various clinically important bacteria. OA inhibited the growth of Gram-positive bacteria, but not Gram-negative bacteria. However, HF did not display any antibacterial effect against any of the strains tested. OA also exhibited inhibitory effects in surface adherence and biofilm formation of S. mutans. The results suggest that OA can be utilized as a potential anti-plaque and anti-caries agent by controlling the physiological characteristics of S. mutans on teeth.

• Korean Journal of Pharmacognosy
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• v.36 no.3 s.142
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• pp.235-239
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• 2005

Changes in chemical composition of the ethanolic extract of roasted Asparagi Tuber were investigated by HPLC. One dramatically increased peak $(t_R\;14.85 min)$ was isolated by silica gel column chromatograph and identified as 5-hydroxymethyl furfural (HMF) by comparing its $1^H-NMR$ data with that of a commercial standard. HMF content reached its maximum level at $190^{\circ}C$ for 60 minutes. Under these conditions, HMF contents in the roasted Asparagi Tuber was increased about thirteen times (9.26mg/g) over the not-roasted control (0.71 mg/g). No significant differences were found in macrophage-activating, prolyl endopeptidase-inhibiting, antioxidative (DPPH), anti-coagulating (activated partial thromboplastin times), and ACE-inhibiting activities between roasted and not-roasted Asparagi Tuber.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.3
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• pp.371-380
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• 2023

This study aimed to present data for the industrialization of Omija added onion fermented beverage (OOFB) development by analyzing the volatile flavor components. A total of 55 compounds, including 4 terpene derivatives, 9 esters, 5 aromatic compounds, 6 alcohols, 7 ketones, 3 aldehydes, 11 acids, 1 sulfur-containing compound, 8 furans and 1 other, were identified in OOFB. The content of fragrance components was high with 37.8% of acids and 29.0% of furans. 2,5-dimethyl thiophene, a sulfur compound, is a compound produced during the acetic acid fermentation of onion, and is thought to affect the onion flavor of OOFB.

• Journal of Microbiology and Biotechnology
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• v.24 no.5
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• pp.667-674
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• 2014

Twenty-five Saccharomyces cerevisiae strains were screened for the highest sugar tolerance, ethanol-tolerance, ethanol production, and inhibitor resistance, and S. cerevisiae KL5 was selected as the best strain. Inhibitor cocktail (100%) was composed of 75 mM formic acid, 75 mM acetic acid, 30 mM furfural, 30 mM hydroxymethyl furfural (HMF), and 2.7 mM vanillin. The cells of strain KL5 were treated with ${\gamma}$-irradiation, and among the survivals, KL5-G2 with improved inhibitor resistance and the highest ethanol yield in the presence of inhibitor cocktail was selected. The KL5-G2 strain was adapted to inhibitor cocktail by sequential transfer of cultures to a minimal YNB medium containing increasing concentrations of inhibitor cocktail. After 10 times of adaptation, most of the isolated colonies could grow in YNB with 80% inhibitor cocktail, whereas the parental KL5 strain could not grow at all. Among the various adapted strains, the best strain (KL5-G2-A9) producing the highest ethanol yield in the presence of inhibitor cocktail was selected. In a complex YP medium containing 60% inhibitor cocktail and 5% glucose, the theoretical yield and productivity (at 48 h) of KL5-G2-A9 were 81.3% and 0.304 g/l/h, respectively, whereas those of KL5 were 20.8% and 0.072 g/l/h, respectively. KL5-G2-A9 reduced the concentrations of HMF, furfural, and vanillin in the medium in much faster rates than KL5.