• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.269-275
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• 2014

We developed a competitive indirect enzyme-linked immunosorbent assay (ciELISA) for determining the buckwheat content in processed foods by using rabbit polyclonal antibodies against buckwheat proteins (BWP). The detection limit of this assay was $0.05-100{\mu}g/mL$. The cross-reactivities of the anti-BWP antibodies toward BWP, buckwheat flour, whole buckwheat, and cereals (wheat flour, whole wheat, black bean, mung bean, red bean, brack rice, brown rice, glutinous rice, white rice, millet, African millet, nonglutinous millet, adlay, and rye) were 100, 17.9, 11.8, and 0%, respectively. Thus, the antibodies were found to be specific for buckwheat only. When buckwheat flour was heated for 30 min, the mean assay recoveries of BWP were 83.0% at $60-90^{\circ}C$ and 44.5% at $100^{\circ}C$. The spike test showed that the mean assay recoveries of buckwheat from raw noodle, boiled noodle, starch gel, and cereal flour were 99.1, 98.6, 81.1, and 104%, respectively. For the 22 commercial items tested, the qualitative coincidence ratio of assay result and the corresponding value indicated on the item's package label was 100%. However, the average quantitative coincidence ratios from 12 commercial items were 31.6%. Thus, the results suggest that ciELISA is an efficient tool to detect buckwheat in processed foods.

• Applied Biological Chemistry
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• v.38 no.6
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• pp.554-562
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• 1995

Effect of the modification of rice protein by protease and 2-mercaptoethanol on physicochemical and gelatinization properties was investigated for the three cultuvars of rice. Total amylose contents of Chucheongbyeo(japonica type), Chosengtongilbyeo(tongil type, indica x japonica) and IR 36 (indica type) were in the range of $20{\sim}25%$. Total amylose and insoluble amylose content of IR 36 were higher than the others. The differential scanning calorimetric and X-ray diffraction results revealed higher relative crystallinity of IR 36 than the others. Water uptake was increased and amylographic viscosity was significantly decreased by 2-mercaptoethanol treatment. Amylographic viscosity was significantly decreased and hot water-soluble carbohydrate content was increased by protease treatment. The proportions of high molecular weight of soluble carbohydrate fractionated by gel filtration chromatography were increased by protease treatment. These effects were most significant in IR 36. This results suggested that starch gelatinization be accelerated by alteration of the protein with protease and reducing agent.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.3
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• pp.264-274
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• 1993

This study was carried out to assess the agronomic characters and physicochemical properties of floury and chalky-endosperm mutant lines induced by chemical mutagen treatment to rice varieties, Hwacheongbyeo and IR24. Linkage analysis of a floury-endosperm gene was carried out using linkage testers. The grain size of brown rice of the mutants was smaller than that of the original varieties. The l, 000-grain and 1$\ell$ weight were lighter in the mutants compared with those in the original varieties. The compound starch granules in the endosperm cell of the mutants showed a loosely-packed crystalline structure. Amylose contents in mutants ranged from 16.9 to 28.5%. Crude protein contents of the mutants were not significantly different from the original rice variety, Hwacheongbyeo, but white core mutant(line 47106) derived from IR24 showed higher protein(l1.32%) compared with IR24(8.30%). The mutants showed slightly harder gel characteristics, and much lower viscosity in Amylograph than original varieties. Steamed rice-cakes from mutant lines showed greater volume than those from original varieties. During the process of alcohol fermentation, Brix in the mutants(especially floury mutants) decreased faster and the alcohol production after 10-day fermentation was much greater in the mutants than in the original varieties. Three different gene loci for floury endosperm characteristics were identified from the allelism test among mutant lines, and the genes were tentatively symbolized as flo-a, flo-b and flo-c, respectively. A floury gene, flo-a, was linked with lg(liguleless) gene in the linkage group N, with R.V. 5.76$\pm$1.72%.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.670-678
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• 1994

The effects of amylase addition during extrusion cooking of rice on the physico-chemical properties of the extrudates were investigated in order to develop rice-based Korean style weaning food products. A laboratory-built single screw extruder was used, the enzymes used were Termamyl 120LS(amylase from Bacillus licheniformis, NOVO Co.), BAN 240L(amylase from Bacillus amylolichuefaciens, NOVO Co.) and malt powder. By the addition of enzymes, the water soluble index of the extrudates increased by 3 times compared to that of the extrudates without enzyme and the concentration of reducing sugar in the extrudates increased drastically at 28 feed moisture. The gel permeation chromatographic pattern showed that the large molecular starch fractions diminished by the addition of enzyme during extrusion and the low molecular fraction increased. The residual enzyme activity in the extrudate were 27% for the most thermo-resistance enzyme by treating at $140^{\circ}C$ in the metering section of the extruder. The sediment volume of the extrudate dispersion increased as the metering section temperature increased to $140^{\circ}C$ . By the addition of enzymes the viscosity of extrudate dispersion was redused $1/4{\sim}1/200$ of that of the extrudates without enzyme. It allowed to use 1.8 times of solid material to the weaning food formulation to attain the same level of consistency as the commercial products. It proves that the addition of amylase during rice extrusion is effective to increase the energy density of weaning food by starch degradation, which results in the increases of water solubility, reducing sugar content, dispersibility and fluidability.

• Food Science and Preservation
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• v.31 no.1
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• pp.149-160
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• 2024

Dextran is a glucose homo-polysaccharide with a predominantly α-1,6 glycosidic linkage of microbial source and is known to be produced primarily by lactic acid bacteria. However, it can also be obtained through the dextran dextrinase of acetic acid bacteria (Gluconobacter oxydans). The dextrin-based dextran was obtained from rice starch using G. oxydans fermentation of rice hydrolysate, and its properties were studied. Both dextrin- and rice hydrolysate-added media maintained the OD value of 6 after 20 h of incubation with acetic acid bacteria, and the gel permeation chromatography (GPC) analysis of the supernatant after 72 h of incubation confirmed that a polymeric material with DP of 480 and 405, which was different from the composition of the substrate in the medium, was produced. The glucose linkage pattern of the polysaccharide was confirmed using the proton nuclear magnetic resonance (¹H-NMR) and the increased α-1,4:α-1,6 bond ratio from 0.23 and 0.13 to 1:2.37 and 1:4.4, respectively, indicating that the main bonds were converted to α-1,6 bonds. The treatment of dextrin with a rat-derived alpha-glucosidase digestive enzyme resulted in a slow release of glucose, suggesting that rice hydrolysate can be converted to dextran using acetic acid bacteria with glycosyltransferase activity to produce high-value bio-materials with slowly digestible properties.