• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.881-888
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• 2010

solvent-tolerant bacterium strain, MH6, was isolated by hydrophilic organic solvent DMSO enrichment in the medium and identified as Serratia marcescens. The extracellular protease with novel organic-solvent-stable properties from strain MH6 was purified and characterized. The molecular mass of the purified protease was estimated to be 52 kDa on SDS-PAGE. The open reading frame (ORF) of the MH6 protease encoded 504 amino acids with 471 amino acid residues in the mature protease. Based on the inhibitory effects of EDTA and 1,10-phenathroline, the MH6 protease was characterized as a metalloproteinase. The enzyme activity was increased in the presence of $Ni^{2+}$, $Mg^{2+}$, and $Ca^{2+}$. The protease could also be activated by the nonionic surfactants Tween 80 (1.0%) and Triton X-100 (1.0%). The protease showed remarkable solvent stability in the presence of 50% (v/v) solutions of long-chain alkanes and long-chain alcohols. It was also fairly stable in the presence of 25% solutions of hydrophilic organic solvents. Owing to its high stability in solvents and surfactants, the MH6 protease is an ideal candidate for applications in organic catalysis and other related fields.

• The Korean Journal of Food And Nutrition
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• v.13 no.5
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• pp.453-459
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• 2000

In order to promote the utilization of Rubus coreanum as functional food, and its physicochemical properties and volatile flavor were examined. The contents of chemical compounds showed 5.39% of moisture, 17.3% of total sugars, 8.6% of reducing sugars, 4.5% of crude ash, 3.9% of crude fiber, 10.6% of crude protein and 1.7% of crude fat and that of free sugars was 1.52% of sucrose, 3.98% of fructose, 1.24% of glucose. Among organic acid was 10.2% of citric acid, 6.29% of oxalic acid and 1.94% of malic acid. The highest component of free amino acids was 1,260.3mg of aspartic acid, 1,054.3mg of glutamic acid, respectively. And that of minerals was 38,789ppm of K. A total of 52 volatile flavor components (11 alcohols, 13 acids, 20 carbonyls, 5 hydrocabons, 3 esters) were identified in the Rubus coreanum, respectively. The major volatile flavor components of Rubus coreanum were 3.78% of linalool in alcohols, 14.40% of caproic acid in acids, 2.99% of 2-hydroxy-4-methoxyacetophenone in carbonyls, 1.59% of aromadendrene in hydrocabons and 0.43% of methyl palmitate in esters.

• The Korean Journal of Food And Nutrition
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• v.32 no.5
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• pp.434-441
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• 2019

In this study, we analyzed the nutritional composition properties of soybeans and the organic acids, amino acids and volatile flavor compounds of fermented soybean products. We used five soybean cultivars including Pyeongwon, Jinpung, Saedanbaek, Saeolkong and Cheonga for this experiment. Physicochemical analysis of soybeans, showed that the cured protein and fat contents were 35.12~45.12 and 14.26~20.14%, respectively. The rank order of major organic acids was lactic acid > acetic acid > fumaric acid, with Saedanbaek being the highest. Total amino acid content of the samples was 358.12~657.28 mg/100 g, and glutamic acid, alanine, cysteine, valine, leucine, histidine and arginine were the major amino acids. We identified a total of 34 volatile aroma-compounds, including 7 alcohols, 7 acids, 7 ketones, 5 phenols, 2 esters, 1 furan, 4 pyrazines, and 1 miscellaneous compounds. As a result of this, could be applied to determine the suitability of cultivars and the quality for the process of the fermented soybean products.

• Mycobiology
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• v.42 no.4
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• pp.353-360
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• 2014

Makgeolli is a traditional Korean alcoholic beverage. The flavor of makgeolli is primarily determined by metabolic products such as free sugars, amino acids, organic acids, and aromatic compounds, which are produced during the fermentation of raw materials by molds and yeasts present in nuruk, a Korean fermentation starter. In this study, makgeolli was brewed using the wild yeast strain Saccharomyces cerevisiae Y98-5, and temporal changes in the metabolites during fermentation were analyzed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. The resultant data were analyzed by partial least squares-discriminant analysis (PLS-DA). Various metabolites, including amino acids, organic acids, sugar alcohols, small peptides, and nucleosides, were obviously altered by increasing the fermentation period. Changes in these metabolites allowed us to distinguish among makgeolli samples with different fermentation periods (1, 2, 3, 6, 7, and 8 days) on a PLS-DA score plot. In the makgeolli brewed in this study, the amounts of tyrosine ($463.13{\mu}g/mL$) and leucine ($362.77{\mu}g/mL$) were high. Therefore, our results indicate that monitoring the changes in metabolites during makgeolli fermentation might be important for brewing makgeolli with good nutritional quality.

• Food Science and Preservation
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• v.6 no.2
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• pp.233-238
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• 1999

This study was determined changes of components of sweet and astringent persimmon vinegars by two stages fermentation. Free sugars of persimmon juices before alcohol fermentation were mainly composed of glucose, fructose and sucrose. The content of glucose, fructose and sucrose of sweet persimmon juice was 6.60, 6.12 and 1.74%, respectively, and those of astringent persimmon was 5.63, 5.21, 0.62%, respectively. The contents of free sugar decreased continuously during fermentation. Major organic acids of persimmon juices were acetic, galacturonic, malic, citric and ascorbic acid. Alcohols of persimmon juices was detected methanol, ethanol, iso-propylalcohol, n-propylalcohol and iso-butylalcohol at the initial fermentation. The contents of alcohols increased continuously up to 4days of fermentation but their contents except ethanol decreased slightly at 5th day of fermentation. Contents of free amino acid were higher in sweet persimmon than those in astringent persimmon. Volatile components increased during acetic acid fermentation.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.827-838
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• 1997

Optimal substrates and reaction conditions were studied to develop boiled or roasted meat flavor by Maillard reaction under a model system. Sugars for the reactions were xylose, ribose, glucose, lactose, maltose, and sucrose. Amino acids were cystine, cysteine, methionine, lysine, and glycine as the reaction substrates. The reacted solutions were measured their absorbances at 278 nm and 420 nm and were evaluated their sensory properties. Except cysteine, the pentose mixtures with all of the four amino acids showed a faster reaction rate than those mixtures with hexose or disaccharides. pH was decreased rapidly until 8 hours and then changed a little thereafter. Sensory evaluation showed that cystine-lactose or cystine-xylose from single substrate and cystine-lactose-maltose, and cystine-lactose-xylose from mixed substrates reacted at $100^{\circ}C$ for 16 or 20 hours were found to be close to boiled or roasted meat flavor. The volatile compounds from the four selected sugar-amino acid solutions by GC/MS were 8 hydrocarbons, 10 aldehydes, 6 ketones, 7 alcohols, 2 aromatics (benzene), 1 ester, 4 furans, 1 base and 5 sulfur compounds.

• Preventive Nutrition and Food Science
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• v.3 no.1
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• pp.15-21
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• 1998

Volatile flavor compounds in hydrolyzed blue mussel(HBM) produced by OptimaseTM APL-440, with untreated blue mussel(UBM) were compared. A total of 100 volatile compounds were detected in both HBM and YBM , consisting mainly of 25 aldehydes, 16 ketones, 17 alcohols, 8 nitrogen-containing compounds, 11 aromatic compounds, 8 terpenes, and 15 miscellaneous compounds. Levels of aromiatic compounds decreased after hydrolysis, whereas levels of 7 nitrogen-containing compounds increased. The compounds , 3-methylbutanal, (z)-4-heptenal, and (E,Z)-2-, 6-nonadienal , had the highest odor values in both samples. Total free amino acids in HBM were 21.89%(w/w) and increased by 3,4 times higher than UBM. glutamic acid and aspartic acid, having sour tastes, were the major taste-active compounds in HBM.

• Food Science and Preservation
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• v.18 no.4
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• pp.552-558
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• 2011

Hypsizigus marmoreus is a wild mushroom commonly consumed in South Korea due to its beneficial effects on health. In the present study, the general chemical and inorganic-element composition, the total amino acid contents, and the volatile-flavor compounds of H. marmoreus were investigated for food uses. The proximate compositions consisted of 60.1% carbohydrate, 32.0% crude protein, 8.98% moisture, 5.0% ash, and 2.0% crude lipid. The minerals in H. marmoreus were found to be as follows; potassium (429.5 mg), phosphorus (101.9 mg), sodium (20.3 mg), magnesium (54.86 mg), calcium (2.7 mg), zinc (0.8 mg), iron (0.7 mg), manganese (0.2 mg), and copper (0.1 mg), based on 100 g of mushroom dry weight. Seventeen kinds of total amino acids were found in H. marmoreus, with the glutamine acid content being the highest (2,340 mg/100 g), followed by the asparagine, serine, arginine, and leucine contents. The volatile-flavor components of H. marmoreus were collected via simultaneous steam distillation extraction (SDE), and were analyzed via gas chromatography-massspectrophotometry (GC-MS). A total of 17 volatile-flavor compounds were identified, including eight aldehydes, seven alcohols, one acids, and one other compounds. The most abundant compound was 2,3,6-trimethy1 pyridine, which accounted for more than 40% of the total volatiles; other important compounds were 1-octen-3-o1, buty1hydroxytoluene (BHT), isoocty1 phthalate, 3-octanal, 1-undecanol, and 2-amylfuran. These results provide preliminary data for the development of H. marmoreus as an edible food material.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.283-291
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• 2017

Rice that the half of population in the world eats as a staple food is mostly produced and consumed in Asia. However, its consumption is nowadays decreasing mainly due to diet diversity. Accordingly, some attempts are in demand to enhance the utilization of rice. In this study, profiling of volatile and non-volatile flavor components in rice pastes obtained by ${\alpha}$-amylase was performed and compared according to nine different rice cultivars domestically cultivated in Korea using gas chromatography-mass spectrometry combined by solid phase microextraction and gas chromatography-time of flight-mass spectrometry after a derivatization, respectively. In total, 46 volatile compounds identified included 6 alcohols, 6 aldehydes, 4 esters, 4 furan derivatives, 4 ketones, 1 acid, 1 sulfur-containing compound, 7 hydrocarbons, 5 aromatics and 8 terpenes. The non-volatile flavor components found were composed of 12 amino acids, 6 sugars and 4 sugar alcohols. In principal component analysis, rice paste samples could be discriminated according to cultivars on the score plots of volatile and non-volatile flavor compounds. In particular, some volatile compounds such as pentanal and 4,7-dimethylundecane could contribute to distinguish Senong 17 white and Senong 17 brown, whereas ethanol, 6-methylhep-5-en-2-one, and tridecane could be highly related to the discrimination of Iipum from other cultivars. Among non-volatile compounds, some amino acids such as glycine, serine and ${\gamma}$-aminobutyric acid and some sugars such as sucrose and fructose were mainly responsible for the discrimination of Danmi from the other cultivars. On the other hand, galactose, arabitol and mannose were more closely related to Senong 17 white than Senong 17 brown.

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