• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.182-189
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• 2008

In this study, the effect of pH on the antioxidative activities of melanoidins formed as a result of the reaction between sugars, glucose (Glc) or fructose (Fru), and amino acids, L-asparagine (L-Asn) and D-asparagine (D-Asn) are examined. For this purpose, antioxidative activities were evaluated on the basis of reducing power, including ferric reducing/antioxidant power (FRAP) and free radical scavenging activity includes 1,1-diphenyl-2-picryl- hydrazil (DPPH) and 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS) and ferrous ion chelating activity. Ethylene diamine tetraacetate (EDTA) and trolox, a water-soluble analog of tocopherol, were used as reference antioxidant compounds. The antioxidative activities of the melanoidins at a pH of 7.0 were greater than those with a pHs of 4.0 and pH 10.0. Especially, it was found that the melanoidins formed from D-isomers are more effective antioxidants in different in vitro assays. The reducing power and chelating activity of the melanoidins formed from the Fru systems were higher than those of the melanoidins formed from the Glc systems. However, the ABTS radical scavenging activity of the melanoidins formed from the Glc systems were higher than those of the melanoidins formed from the Fru systems. In particular, the DPPH radical scavenging activity and the FRAP of the melanoidins showed different antioxidative activities according to pH level.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.333-341
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• 1999

This study was conducted to investigate physicochemical and functional properties of turnip. The concentrations of antocyanin in the rind of root was 3.24mg%, which was about 3.5 times higher than those in the flesh. Among free amino acids in each part of turnip, glutamic acid showed the highest concentrations(132.5mg%) in the root followed by alanine(25.0mg%), valine (23.3mg%), and serine (20.7mg%). Contents of minerals in the root of turnip were 395.7mg% for potassium, 187mg% for calcium, 53.6mg% for phosphate, and 40.7mg% for magnesium. According to dynamic heasdspace analysis, dimethyl disulfide was the most abundant flavor components from the juice of fresh turnip and other volatile components such as dimethyl trisulfide, 1 hexanal, 2 methyl 1 butamine, and 1 penten 3 ol were also identified. From the blanched turnip, however, 3 isothiocyanato 1 propene and 4 isothiocyanato 1 butene were mainly detected. Fresh and blanched turnips were extracted with water or 70% acetone to investigate percent yield. The concentrations of total polyphenols in the extracts of fresh turnip were higher than those of blanched turnip. The nitrite scavenging effects of water and 70% acetone extracts from fresh or blanched turnip were decreased as pH was increased. Between two water extracts, the 30oC water extracts showed the higher values of electron donating ability than 95$^{\circ}C$ water extracts.

• Plant Resources
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• v.8 no.1
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• pp.17-26
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• 2005

From the point of breeding view for our future, 20 Korean varieties of red pepper for the contents of capsaicinoids, free amino acids, free fatty acids and organic acids with powder product and eating qualities were chosen, and the sensory properties of their water and ethanol extract were compared in order to investigate the influence of the composition of test components on sensory acceptability of Korean red pepper. The composition of taste components in red pepper powder varied wildly depending on the varieties; total capsaicinoids content variety from 0.029 to $0.913\%$, free sugar 8.45 to $20.2\%$, and organic acid 4.58 to $19.54\%$. Capsaicinoid contents especially dihydrocapsaicin content, were highly correlated with pungent taste of the methanol extract of red pepper power, but did not show significant relationship to the overall sensory acceptability. However, the components analyzed here and eating and processing qualities include high variations and future breeding sources.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.924-933
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• 1998

Kochujang, fermented hot pepper-soybean paste, was prepared by two common varieties of red pepper and natural fermented (NF) or pure cultured (PC) meju (soybean mass that is soaked, steamed, mashed and fermented by natural microflora or pure strain) and monitored their taste related component, enzyme activity and microflora during fermentation at $25^{\circ}C$ for 120 days for confirming possibility of kochujang fermentation control. The reducing sugars, amino type nitrogen (reference quality factor) and amino acid content in PC kochujang were 11.4%, 0.58% and 1,372.9 mg% respectively, 7.1%, 0.42% and 1,038.7 mg% in NF kochujang. It is concerned higher ${\alpha}-{\;}and{\;}{\beta}-{\;}amylase$ and, acid and neutral protease in PC kochujang during fermentation. The meju fermented by selected pure strain (A. oryzae CBU) can be applied to produced better quality of kochujang instead of natural meju.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1140-1146
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• 1997

Storage stability of ginger paste product was investigated from the standpoint of the inhibition of nonenzymatic browning and loss of gingerol contents. For the experimentations, control, 0.04% of N-acetyl-L-cysteine in ginger paste(NAcCys), and combination treatment of NAcCys, 0.92 of water activity and 6.30 of pH in ginger paste (mixed treatment) were stored at 3$0^{\circ}C$ for 40 days and analyzed for browning and gingerol contents. In addition the changes in sugars, organic acids, ascorbic acids, amino acids, and sensory quality were determined. The results revealed that the mixed treatment agent was effective in preventing both nonenzymatic browning and loss of gingerol contents. The inhibition by combination treatment might be resulted from the control of radical formations by sulfhydryl groups of NAcCys and the increase of diffusion resistance in lower water activity. Browning development and total gingerol contents were found to be correlated to some physicochemical characteristics of ginger paste; that is, browning development to amino acid and color value in sensory evaluation, and total gingerol contents to flavor in sensory evaluation.

• Journal of the Korean Magnetic Resonance Society
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• v.26 no.3
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• pp.24-33
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• 2022

The browning phenomenon of fruits can be easily observed when fruits or vegetables (apples, pears, bananas, potatoes, etc.) are cut with a knife and the part turns brown. When this browning occurs, changes in taste, color, and nutrients usually are introduced. The cause of this browning phenomenon has been well studied for a long time, but these studies have mainly focused on preventing deterioration of processed foods during food processing or storage. Resultantly, there are few studies on how much changes in nutrients (saccharides, amino acids, fats, water-soluble low molecular weight ammonium ions, etc.) are caused by browning. The purpose of this study is to determine the change in nutrients during browning using apple as a model fruit. We conducted a comparative study on how much the nutrient fluctuations differ depending on the presence or absence of pretreatment such as the application of heat. All analysis was conducted using ¹H NMR. The ANOVA analysis showed that the concentrations of 4 amino acids (alanine, asparagine, isoleucine, and valine), 3 types of sugars (fructose, glucose, and xylose), 1 type of organic acid (lactate) and choline were significantly increased in samples showing browning. In addition, the groups before and after browning were clearly separated using multivariate statistical analysis methods (PCA, PLS-DA), which was greatly contributed by two sugar components (fructose and glucose) present in high concentrations in apples.

• Applied Biological Chemistry
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• v.18 no.4
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• pp.203-218
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• 1975

In order to investigate the compositional change oil composts during the growing of cultivated mushroom (Agaricus bisporus), composts and mushrooms during the period of filling to ending under commercial conditions were subjected to chemical analyses. The results are summarized as follows and the mechanism of composting for mushroom cultivation was proposed. 1) The temperature change of growing bed and room was observed and the yield of mushroom for each cropping time was recorded to get $15.6kg/m^2$ in total crops. 2) Composts after filling showed pH 8.2 which dropped to 6.4 after casing and continued so up to ending. 3) On the dry weight basis of composts, crude ash increased whereas total nitrogen, ether extract and crude fibre decreased gradually to bring about the lowering of organic matter. 4) Total nitrogen of composts decreased gradually and more insoluble nitrogen was lost than soluble nitrogen. The C/N ratio of composts was initially 21 which was gradually lowered to 16. 5) The losses of ${\alpha}-cellulose$, pentosan and lignin in composts were 87%, 75%, and 60%, respectively, in which ${\alpha}-cellulose$ decreased markedly after casing. 6) Free reducing sugars of composts increased continuously. Gradually increased free amino acids till second cropping decreased again thereafter. Composts at the filling stage contained alanine, glutamic acid, glycine and serine in which glycine decreased markedly whereas proline increased remarkably upon mushroom cultivation. 7) Among minerals of composts, phosphorus and zinc tended to decrease, potassium and copper tended to increase anti sodium showed no marked change. 8) In comparison of mushrooms from different cropping time with respect to proximate composition, minerals, free reducing sugars and amino acids, no marked difference was observed. However, a little higher values were observed in crude fat, free reducing sugars and sodium content for early crops and in free amino acids and phosphorus content for late crops. Twelve free amino acids including alanine, serine, threonine, and glutamic acid were detected in the cultivated mushroom. 9) According to above experimental results, it was possible to support the mechanism of compositing that the formation of ammonia and decomposition of carbohydrates by mesophiles are followed by protein biosynthesis, formation of microbial bodies and nitrogen-rich lignin humus complex by thermophiles, thus supplying necessary nutrients for mushroom growth, along with residual carbohydrates.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.5
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• pp.816-828
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• 1995

During the industrial preparation and the storage of foods, the side chain of some protein-bound amino acids can react chemically each other or with other molecules present in the food. The following reactions have been described : destruction of amino acids, racemization, protein-protein interactions, reactions of proteins with reducing sugars, oxidizing agents, or polyphenols. Apart from total destruction, the main reacitons are the forming of Maillard reactions products(e.g. fructoselysine) and the crosslinking with other amino acids in the same or in another protein molecule(e.g. lysinoalanine). The most often involved amino acid is lysine because of its free functional ${\varepsilon}-amino$ acid group. Generally derivatives of amino acids or crosslinks in polypeptides influence the bioavailability and the overall digestibility of the protein. This work reviews the technological, analytical, nutritional, and physiological problems related to the formation of fructoselysine and lysinolalnine in human foods, and evaluates the possible health risk for humans. A summary of the available information is of help in considering whether or not the presence of fructoselysine/lysinoalanine in foods represents a danger to man. The reduction in protein quality through these reactions is not a problem for the general population, but it is extremely important in infant foods, since infants are often nourished with a limited number of food product(e.g. formular foods) which are sensitive to the Mailard reaction.

• Food Science and Preservation
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• v.10 no.1
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• pp.65-69
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• 2003

This paper was performed to analyze the nutritional components for the basic of studies to estimate the nutritional and functional valuation of mushroom(Sarcodon aspratus) The contents of moisture, ash, crude protein, crude fat and carbohydrate in mushroom were 89.93, 1.18, 3.67. 0.96 and 4.26%, respectively. The major free sugar were glucose, sucrose, trehalose, xylose, and cantained more trehalose than other sugars. The total content of amino acids was 796.85mg/100g-fr.wt. And the contents of essential and non-essential amino acid of hydrolyzed amino acid was 300.77 and 486.08mg/100g-fr.wt, respectively. Mushroom contained mush valine, leucine, threonine, Iysine, alanine, glycine, aspartic acid, and glutamic acid. The contents of essential and non-essential amino acid of free amino acid was 124.95, 138.52mg/100g-fr.wt., respectively. and were cantained mush methionine, Iysine, valine arginine, Aspartic arid, and tyrosine. The content of Amino acid derivatives 46.81 mg/100g-fr.wt., and were contained mush mornithine, sarcosine, ${\beta}$-alanine, and phosphoserine. The content of vitamin C was 5.43 mg/100g-fr.wt. The contents of sodium and potassium were 375.73, 61.82mg/100g, respectively.

• Applied Biological Chemistry
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• v.30 no.2
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• pp.192-197
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• 1987

Natto was produced by fermenting local soybeans Bacillus subtilis S.N.U. 816. The changes of chemical composition, enzyme activity and texture of NATTO during the fermentation were investigated. The amount of amino type and watr soluble nitrogens were increased as the fermentation progressed, although the former seemed to reach a plateau at about 20 hours of the fermentation, of the protease activity were increased until 16 hours of fermentation at which time they tended to reach plateaus. Among the inspected free sugars (fructose, glucose, sucrose, maltose), remarkable increases in the levels of fructose and glucose were observe3 after 4 hours of the fermentation. Since then their contents, however, were reduced very low as the processing went on, and sucrose contents dropped drastically to about 10% level and stayed low thereafter. Free amino acid contents of natto during 20 hours of the fermentation were or 2 times greater than those of the unfermented steamed soybean, the 24 hours ferment, respectively. Sensory evaluation revealed that 20 hours of fermentation produced the best quality products based on taste, odor, and color, considering all the data, it seems possible to conclude that the optimum of time for fermentation of natto at $42^{\circ}C$ is 20 hours.