• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.1
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• pp.21-25
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• 2002

The contribution of lipid to thermal flayer generation from glucose-protein reaction was accomplished by isolating flavor compounds from casein-glucose (CG)and casein-glucose-coin oil (CGL) which were stored for 2 and 4 weeks at 6$0^{\circ}C$ and then reacted at 16$0^{\circ}C$ for 1hr. The volatiles from the reactant mixtures were isolated by a solvent extraction method with methylene chloride and analyzed by gas chromatography and gas chromatography-mass spectrometry. Pyrazine, methylpyrazine, 2,5-dimethylpyrazine, 2-dimethylpyrazine ,2-ethy-5- methyIpyrazine and 2-acetylpyrrole originated from interaction of thermal degradation of casein and lipid oxidation were identified in the CGL samples. It was also found that 3-methyl-1-butanol, 2-cyclopene-1,4-diode, heptanal, nonanal, and 2-heptanone were derived from lipid source. Two additional fatty acids, heptanoic acid and octanoic acid were also identified in the CGL samples. 5-Hydroxymethyl-2-furfural, the most abundant volatile, was responsible for the formation of sugar degradation product. The results suggested that the presence of lipid in the samples had more effect on the contribution of volatile formation of glucose-protein thermal reaction than the absence of lipid in the samples.

• Preventive Nutrition and Food Science
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• v.22 no.1
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• pp.37-44
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• 2017

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter's L, a, and b values. ${\Delta}E$ was consequently set as the fifth response factor. In the statistical analyses, determination coefficients ($R^2$) for their absorbance, Hunter's L, a, b values, and ${\Delta}E$ were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter's b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, $111^{\circ}C$ reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter's b value was 2.41 h reaction time, $114^{\circ}C$ reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine.

• Journal of Life Science
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• v.18 no.11
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• pp.1570-1577
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• 2008

For useful basic data in developing of Omandungi (Styela plicata) processed products, volatile flavor compounds were analyzed to identify the key reaction flavor compounds induced through heat treatment ($100^{\circ}C$, 10 min) in Omandungi -Doenjang (soybean paste) soups and stew. A total of 128 flavor compounds were identified and composed mainly of esters (16), aromatic compounds (14), N-containing compounds (11), alcohols (34), terpenes (5), carbonyl compounds (23), furans (4), hydrocarbons (13), acids (5) and miscellaneous compounds (3). Three groups including aromatic compounds, alcohols and acids were detected in high amounts in Doenjang. However, the levels of C4-C6 series acids (i.e., pentanoic acid having off-flavor) decreased by cooking ($100^{\circ}C$, 10 min), whereas that of furans (i.e., furfural) as heat induced compounds increased 2 times. Alcohols were detected the major group in Omandungi and followed by hydrocarbons and aromatic compounds in that order. In particular, 3 compounds including decenol, 2,6-dimethylheptanol and octanol were the major alcohols of Omandungi. By cooking, the compounds known heat-induced compound, 2-acetyl-2-thiazoline and benzothiazole, were newly formed in Omandungi-Doenjang stew. The alcohols (i.e., decenol, 2,6-dimethylheptanol), hydrocarbons and aromatic compounds derived from Omandungi were supposed to enhance a seafood-like flavor in Omandungi-Doenjang stew.

• Food Science of Animal Resources
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• v.41 no.2
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• pp.224-236
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• 2021

The objective of this study was to investigate the effects of quality grade (QG) on the physicochemical composition and eating quality attributes of pork belly and shoulder butt. Seventy-two growing-finishing crossbred pigs were slaughtered and their carcasses were graded according to the Korean pork carcass grading system. Based on the grading criteria, the carcasses were classified into: QG 1+ (n=23), QG 1 (n=23) and QG 2 (n=26) groups. At 24 h postmortem, belly and shoulder butt cuts were collected from the QG groups and used for analysis of meat quality, flavor compounds and eating quality attributes. Results showed that the variation in fat content among QG was approximately 2% in the both cut types. The QG showed no effects on all the quality traits: cooking loss, pH and color of the belly or shoulder butt (p>0.05). Thirty-five flavor compounds comprising mainly fatty acids oxidation/degradation-derived products (e.g., aldehydes) and only few Maillard reaction-derived products (e.g., sulfur-and nitrogen-containing compounds) were identified. However, the QG showed a minor effect on the flavor profiles in both the belly and shoulder butt. Regarding the sensory quality, no effects of the QG were found on all the eating quality attributes (color, flavor, juiciness, tenderness and acceptability) for both the belly and shoulder butt cuts (p>0.05). Thus, it may be concluded that the current pork carcass grading standards do not reflect the real quality and value of the belly and shoulder butt cuts.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.604-609
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• 2002

The sensory properties and flavor components of the white bread added with arrowroot juice. The lightness of bread crumb decreased significantly as arrowroot juice was added. While the yellowness increased slightly, redness increased remarkably. The hardness, chewiness and adhesiveness of the white bread added with arrowroot juice increased more than those of the control bread, but they had no statistical significance. While the gumminess increased significantly and springiness decreased significantly, the cohesiveness did not indicate significant differences among the comparison groups. In sensory evaluation, the texture, flavor and sweetness did not indicate significant difference among the comparison groups, while the color and overall acceptability indicated significant difference. The optimum concentration of arrowroot juice in the white bread was 25% based on the sensory evaluation scores. The main flavors components of the white bread added with 25% arrowroot juice were compounds translated by arrowroot juice and the compounds formed by amino-carbonyl reaction. The translated flavors were methoxy phenol, ${\beta}-damascenone$, benzylcyanide, and menthofuran. The compounds formed by amino-carbonyl reaction were alkyl pyrazines, pyrroles and furans.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.268-276
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• 2023

Alkyl butyrate with fruity flavor is known as an important additive in the food industry. We synthesized various alkyl butyrates from various fatty alcohol and butyric acid using immobilized Rhodococcus cutinase (Rcut). Esterification reaction was performed in a non-aqueous system including heptane, isooctane, hexane, and cyclohexane. As a result of performing the alkyl butyrate synthesis reaction using alcohols of various chain lengths, it was found that the preference for the alcohol substrate had the following order: C6 > C4 > C8 > C10 > C2. Through molecular docking analysis, it was found that the greater the hydrophobicity of alcohol, the higher the accessibility to the active site of the enzyme. However, since the number of torsions increased as the chain length increased, it became difficult for the hydroxyl oxygen of the alcohol to access the ^γO of serine at the enzyme active site. These molecular docking results were consistent with substrate preference results of the Rcut enzyme. The Rcut maintained the synthesis efficiency at least for 5 days in isooctane solvent. We synthesized as much as 452 mM butyl butyrate by adding 100 mM substrate daily for 5 days and performing the reaction. These results show that Rcut is an efficient enzyme for producing alkyl butyrate used in the food industry.

• KSBB Journal
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• v.31 no.2
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• pp.91-99
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• 2016

Tea is an aqueous infusion of dried leaves of the plant Camellia sinensis L. and is the second most widely consumed beverage around the world after water. Aroma compounds of tea differ largely depending on the manufacturing process, even from the same categories of different origins. The flavor of tea can be divided into two categories: taste (non-volatile compounds) and aroma (volatile compounds). In the present study, we review the formation mechanism of main aromas generated from carotenoids, lipids, glycosides as precursors, and Maillard reaction during the tea manufacturing process, with biological and chemical mechanisms.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2899-2904
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• 2009

Esterification is an important class of reactions in the preparation of perfumery and flavor chemicals, wherein homogeneous, solid acidic, and superacidic catalysts are normally used. Now, an efficient and selective protocol for protection of various functionalized alcohols employing carboxylic acids as protecting agents is realized through the catalytic mediation of simple heteropolyoxometallates. In this methodology, water is the only by-product and notably the aspect of effluent treatments does not arise. The advantages include the operational simplicity, recycle ability of the catalyst and mild reaction conditions. The present catalytic system may be a potential candidate not only for laboratory practice but also for commercial applications and offers an environmentally safer alternative to the existing processes.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.85-90
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• 2005

A downstream process was developed for the production of yeast extract from brewer's yeast cells. Various downstream processing conditions including clarification, debittering, and the Maillard reaction were considered in the development of the process. This simple and economic clarification process used flocculating agents, specifically calcium chloride ($1\%$). After the clarification step, a Maillard reaction is initiated as a flavor-enhancing step. By investigating the effects of several operation parameters, including the type of sugar added, sugar dosage, glycine addition, and temperature, on the degree of browning (DB), giucose addition and reaction temperature were found to have significant effects on DB. A synthetic adsorption resin (HP20) was used for the debittering process, which induced a compositional change of the hydrophobic amino acids in the yeast hydrolysate, thereby reducing the bitter taste. The overall dry matter yield and protein yield for the entire process, including the downstream process proposed for the production of brewer's yeast extract were 50 and $50\%$, respectively.

• The Korean Journal of Food And Nutrition
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• v.6 no.1
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• pp.1-7
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• 1993

19 Samples of koji-starters using in brewing were collected from Korea and Japan, and then 31 strains of koji-molds were isolated from them. After Identification of the Isolate, rice koji was made with each strains, and its saccharogenic activity, dextrogenic activity, proteolytic activity, acid Producing ability, browning reaction and flavor were tested. Among 31 strains of isolates, 10 strains were Identified as Asp nwamori var. kawachii, 18 strains as Asp. oryzae, 3 strains as Asp. usamii mkt. shirousamii. The koji-starters made in Korea were composed of single species of koji-mold with same strain, but those made in Japan were composed of the mixture of different two species or the mixture of different 2 ∼4 strains in same species. Judging from amylolytic and proteolytic ability by species, Asp. awamori var. kawachii H1, I1 and 11, Asp. owsae J2, L2, M2, P3 and P4, and Asp. usamii writ. shirousamii S1 were better than the others. Mold strains isolated from Korean koji-starters were much lower in amylolytic or proteolytic activity than those from Japanese koji-starters. The typical characteristics for the 3 species of koji-molds were that Asp. awamori var. kawachii was strong in acid producing ability, but week in amylolytic and proteolytic ability, that Asp. owzae had strong amylolytic activity and good aroma, but produced little amount of acid, and that Asp. usamii mut. shirousamii had strong Proteolytic activity but some off-flavor.