• Journal of Korea Foresty Energy
• /
• v.24 no.1
• /
• pp.39-46
• /
• 2005

In this study, the possibility of sugar conversion of poplar wood(Populus $alba{\times}rglandulosa$) and their degradation features of major wood components were characterized using flow type supercritical water treatment system. The finely ground poplar wood meals were treated for 2min. under subcritical condition$(23MPa,\;275^{\circ}C\;and\;325^{\circ}C)$ and supercritical condition $(23MPa,\;375^{\circ}C\;and\;415^{\circ}C)$. respectively. The degradation products of poplar wood meals appeared brownish colors, including undegraded solids. Increasing the temperature of the system, the degradation rate of poplar wood meals was accelerated and reached up to $94\%\;at\;375^{\circ}C$. The total amount of reducing sugars in degradation products determined by DNS method were gradually lowered when the temperature condition became severe. This indicated that the reducing sugars formed were further degraded to kan derivatives by certain side reaction such as pyrolysis under higher temperature. In order to characterize degradation features of lignin, the degradation products were extracted with ethylacetate and the organic phases were subjected to GC-MS analysis. Main lignin degradation products were identified to vanillin, guaiacol, syrinaldehyde, 4-prophenyl syringol and dihydrosinapyl alcohol, which could be formed by the cleavage of ether linkages in lignin polymers by high temperature condition.

• Korean Journal of Food Science and Technology
• /
• v.50 no.2
• /
• pp.123-131
• /
• 2018

The objective of this study was to evaluate the effect of roasting degree of barley on aroma characteristics of boricha (barley tea) using solvent-assisted flavor evaporation-gas chromatography-mass spectrometry and gas chromatography-olfactometry. Fifteen volatile compounds including pyrazine, ethylpyrazine, butyrolactone, and guaiacol were considered important volatile compounds, which are generated by roasting barley, because concentrations of those volatiles were significantly increased (p<0.05) as roasting degree of barley was darker. Guaiacol (smoky), furfuryl alcohol (burnt sugar), and furfural (caramel) were detected as aroma-active compounds of boricha with high intensity. Aroma intensity of aroma-active compounds in boricha increased with increase in roasting degree of barley. However, one unknown compound with burnt smell was detected as off-flavor in dark roasted barley. Therefore, it is implied that medium roasting of barley is desirable during boricha manufacturing. Furthermore, boricha manufactured with steamed barley contained more abundant volatile flavor compounds, which may lead to better aroma quality of boricha.

• Applied Biological Chemistry
• /
• v.44 no.4
• /
• pp.262-268
• /
• 2001

Two commercial wood vinegar liquors prepared from Cryptomeria japonica and Quercus sp., which are used as a mineral fertilizer in Korea, were extracted using dichloromethane as a solvent, respectively. The extracts were separated into acidic, phenolic, neutral and basic fraction by acid or alkali treatment, and the compositions of each fraction were analyzed by means of GC and GC-MS. A total of 103 compounds including 26 acids, 32 phenols and 45 neutral compounds were identified. The major components were acetic, propionic and n-butyric acid, representing of $41{\sim}58%$ of the acidic fraction, guaiacol, 4-methylguaiacol and phenol, repersenting of $53.2{\sim}63.9%$ of the phenolic fraction, and furfural, 3-methyl-2-cyclopenten-2-one, 2,3-dimethyl-2-cyclopenten-1-one and 5-methyl-2-furfural in the neutral fraction. In addition to these compounds, phenolic fraction in dichloromathane extract from wood vinegar liquor of C. japonica included large amounts of vanillin, acetovanillone and tentatively identified ethylvanillyl ether while that of Quercus sp. included some amounts of syringol and 4-methylsyringol.

• Applied Biological Chemistry
• /
• v.45 no.2
• /
• pp.59-65
• /
• 2002

Different amounts of the Opuntia ficus-indica var. saboten fruit were soaked in different alcohol concentrations of a Korean rice wine distillate for 4 months. Changes in pH, brix degree, contents of reducing sugar and polyphenol compound, alcohol concentration, turbidity, and color were analyzed during the soaking period. Quality of the final product was determined through the analysis of the volatile flavor compounds and sensory evaluation. During the soaking periods, pH, alcohol concentration, and contents of polyphenol compound decreased, whereas the content of reducing sugar increased. These changes were affected more by the content of the fruit than the alcohol concentration of the soaking media. Turbidity of the wine increased with higher fruit contents, while the increase of alcohol concentration resulted in the turbidity decrease. As the soaking period increased, lightness and yellowness increased but redness decreased. Acetaldehyde, acetyl acetone, ethyl alcohol, guaiacol, thymol, and acetic acid phenyl ester were detected in all liquors. Significant differences in all sensory attributes test were shown by six experimental groups (p<0.05), and the best overall acceptability was obtained from the liquor made of 67% fruits and 30% alcohol concentration.

• Korean Journal of Food Science and Technology
• /
• v.43 no.3
• /
• pp.348-360
• /
• 2011

To verify the volatile compounds contributing to coffee off-flavor, medium roasted Colombian, Sumatra, Ethiopian and light and dark roasted Colombian bean coffees were sequentially and studiously over extracted. Eight espresso samples and eight filter-dripped samples were analyzed by gas chromatography/mass spectrometry with the solidphase microextraction method and evaluated by sensory tests. In total, 67 compounds were detected, and desirable aroma decreased sharply, while off-flavors increased rapidly after 30 mL of espresso and 200 mL of drip coffee. Percent peak area of 4-ethylguaiacol revealed a linear increase during extraction and was highly correlated with increasing off-flavor, suggesting that it could be an indicator of over extraction. Considering the odor activity value, guaiacol and 4- vinylguaiacol were also contributory compounds to off-flavors.

• Journal of Life Science
• /
• v.25 no.6
• /
• pp.673-679
• /
• 2015

The culture conditions needed to maximize the production of laccase from Pholiota highlandensis mycelia were investigated. Among the tested media for laccase production, Coriolus versicolor medium (CVM; 2% dextrose, 0.4% peptone, 0.6% yeast extract, 0.046% KH₂PO₄, 0.1% K₂HPO₄, 0.05% MgSO₄·7H₂O) showed the highest activity for the enzyme. Then, to optimize culture conditions for laccase activity, the influences of various carbon, nitrogen, phosphorus, and inorganic salt sources in CVM were investigated. The optimum culture medium was 2% fructose, 0.4% peptone with 0.6% yeast extract, 0.05% NaH₂PO₄, and 0.05% MgSO₄·7H₂O as carbon, nitrogen, phosphorus, and inorganic salt sources, respectively. Several aromatic compounds in the medium enhanced laccase activity to varying degrees. Guaiacol induced maximum laccase production, yielding 114.1 U/ml laccase activity after cultivation for 11 days at 25℃. The optimum pH and temperature for laccase production were 8.0 and 35℃, respectively. Native polyacrylamide-gel electrophoresis (PAGE) followed by laccase-activity staining with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the substrate was performed to identify the presence of laccase under the optimum conditions studied. Zymogram analysis of the supernatant culture showed an enzymatic band with a molecular mass of about 90 kDa.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.31 no.2
• /
• pp.251-256
• /
• 2002

Fresh bamboo (Phyllostachys bambuoides sieb. et zucc.) was charred at the mechanical steel kiln and traditional earth kiln with subsequent condensation of its smoke to 10$0^{\circ}C$. It was settled down for 12 months to remove tar components and then the middle layer of the liquid was collected as a bamboo smoke distillates to analyze its chemical composition and physicochemical characteristics for use as food additives or processing aids. The gravity, transmittance, reflectivity, and viscosity were 1.008, 89.05%, 1.36%, and 12.48 cp in the bamboo smoke distillates processed by mechanical steel kiln (MBSD) and 1.012, 98.33%, 1.34% and 9.05 cp in the bamboo smoke distillates by traditional earth kiln (TBSD), respectively. The color of TSBD was brighter than that of MBSD. The pH and titratable acidity, tar and remains were 3.55 and 2.830%, 2.803% and 0.671%, respectively, in the MBSD and 2.93 and 3.470%, 0.051% and 0.004%, respectively, in the TBSD. The major phenolic compounds of bamboo smoke distillates (BSD) were phenol, Ο-cresol, p-cresol, and guaiacol and the major organic acids were acetic acid, propionic acid, iso-butyric acid, and n-butyric acid, and major alcohols were methanol, furfuryl alcohol, and maltol. The contents of phenolic compound and alcohol were more in MBSD than in TBSD whereas the content of organic acid was more in TBSD than in MBSD. Therefore, toxic compounds for the human body, such as methanol from BSD should be removed for use as a food ingredient in the future.

• Korean Journal of Food Science and Technology
• /
• v.37 no.2
• /
• pp.199-205
• /
• 2005

Physicochemical quality characteristics of seed mashes were investigated for development of new creative breadmaking in bakery. Aridity of seed mashes fermented with Koji, lactic acid bacteria, and baker's yeast was slightly lower than those fermented with Koji and yeast. ${\alpha}-Amylase$, saccharifying amylase, and acidic protease activities of seed mash composed of water (560 mL) and Koji (400 g) were 0.26 SKB, 36 SP, and 645 HUT/g, respectively. Reducing sugar content of seed mash made with Koji increased up to 13.04% after 36 hr fermentation, then decreased drastically thereafter, whereas that of seed mashes made with Koji, yeast, and lactic acid bacteria increased up to 6.5% at 6 hr, decreased to 1 to 2.5% at 12 hr, and remained less than 0.7% after 18 hr fermentation. Total organic acid contents were 10.4-12.25mg/mL. Flavor compounds including ethyl acetate, ethyl caprylate, isoamyl acetate, and p-vinyl guaiacol were detected in seed mash fermented with Koji, yeast, and L. brevis. These results show use of seed mash fermented with Koji, S. cerevisiae, and lactic acid bacteria enhances bread flavor.

• Korean Journal of Food Science and Technology
• /
• v.32 no.5
• /
• pp.1015-1021
• /
• 2000

Volatile flavor components (VFCs) in cooked black rices (Suwon-415 and Chindo) were studied. The major reactions during cooking, which result in aroma volatiles, are the Maillard reaction between amino acids and reducing sugars, and thermal degradation of lipid. Black rices washed with water were soaked in 1.5 folds water and heated at $110^{\circ}C$ in oil bath for 30min. VFCs in cooked black rices were extracted for three hours by SDE and were analyzed by GC and GC/MS. A total of 91, 82 volatiles were identified in Suwon-415 and Chindo black rice, respectively. Suwon-415 was composed of 26 alcohols, 10 aldehydes, 5 acids, 11 esters, 15 ketones, 9 hydrocarbons, 3 furans, 3 nitrogen containing compounds and 9 sulfur containing compounds. Chindo was composed of 28 alcohols, 9 aldehydes, 4 acids, 12 esters, 14 ketones, 5 hydrocarbons, 3 furans, 3 nitrogen containing compounds and 4 sulfur containing compounds.

• Journal of the Korean Wood Science and Technology
• /
• v.30 no.4
• /
• pp.87-95
• /
• 2002

Three different species of green and air-dried Korean bamboos were carbonized by using three different types of kilns designated as special (800~1000℃), improved (600~700℃) and simple kiln (400~500℃), and the bamboo vinegars obtained from the carbonization processes were characterized. In the case of the special kiln, most of the bamboo vinegars obtained at the first recovery stage showed high values of specific gravity and also in content of organic acid and water-soluble tar. The bamboo vinegars obtained from the improved kiln showed various physical properties depending on their species. In the case of simple kiln, the bamboo vinegars obtained from air-dried bamboos and at temperatures below 80℃, showed a higher specific gravity and more water-soluble tar as well as total organic components than those obtained at 80~150℃. A good linear relationship (correlation coefficient of ca. 0.90) was obtained between the specific gravities and the sum of organic acids and water-soluble tars. Therefore, this correlation coefficient might be a good index to determine the quality of bamboo vinegars. The major chemical constituents of the bamboo vinegars were acetic acid and considerable amounts of phenols: guaiacol, ethyl guaiacol, syringol, and methyl syringol.