• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1515-1515
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• 2001

Retrogradation of starch is one of important quality indexes for food based on starch such as rice. Therefore, in this research, possibility of near infrared spectroscopy to determine the degree of the retrogradation was examined. The degree of the retrogradation was indicated as the degree of geratinization analyzed by BAP(-amylase-pullulanase) method. 20 samples which have a wide range of the degree of the retrogradation were prepared and the NIR spectra of the samples were measured in reflectance mode with the NIR Systems 6500. In the correlation plots calculated from the 2nd derivative values of the MSC treated spectra and the degree of the geratinization, the major negative peaks of 1544 nm and 2258 nm, and the major positive peaks of 1460 nm, 1602 nm, 1766 nm and 2136 nm could be observed, indicating that NIR absorption at the positive peak wavelengths became strong while the absorption at the negative peak wavelengths became weak as the degree of the retrogradation increased. Because there is negative correlation between the degree of the retrogradation and the degree of the geratinization. As a result of MLR using the 2nd derivative values of the MSC treated spectra and the degree of the geratinization, good calibration equation which include 2258 nm as the first wavelength and 1764 nm as the second one could be obtained, indicating that NIR spectroscopy has a possibility to detect the retrogradation of starch. In order to find the assignment of the bands observed in the correlation plots, further study may be needed.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1171-1177
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• 1999

The changes on microstucture of recombinated gels with different ratio of amylose(A) and amylopectin(AP) which were isolated from nonwaxy rice starch were investigated by scanning electron microscope(SEM) and X-ray diffractometer. As the concentration of amylose was above 3%(1.08% of soluble amylose) in the amylose suspension, gel matrix became like a three-dimensional network. The microstructure of amylose gels showed a network including macroporous structure, but the higher the ratio of amylopectin content were, the firmer network were formed. In case of A/AP mixed gels(15%) with different amylose/amylopectin percent ratios ; 0/5, 5/10, 10/5, 15/0%, as the storage time of gels and the percent ratio of amylose content were increased, network was formed harder with thick films. While X-ray diffractograms of waxy rice starch which contained 100% amylopectin showed A type, those of purified amylose and amylopectin showed V type and amorphous patterns, respectively. Amylose(3%) gels added $2{\sim}3%$ amylopectin and A/AP mixed gels(15%) showed peak at $2{\theta}\;=\;17.0^{\circ}$which were shown B type crystallinity similar af retrograded starches. Also as the percent ratio of amylose content in mixed gels was increased, peak intensity wat increased.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.331-337
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• 1988

The thermal properties of typical five Indica and five Japonica rice varieties were investigated by Differential Scanning Calorimetry (DSC). There was no significant difference in gelatinization temperature between Indica and Japonica varieties, but the average enthalpy of gelatinization was larger in Indica types than that in Japonica. However, the enthalpy of melting of amylose-lipid complex was larger in Japonica types than that in Indica types. The DSC thermogram of hydrolyzed rice residue included a smaller peak of gelatinization with narrow range of temperature. Retrogradation of gelatinized rice kernel was also determined with DSC theremograms. The endothermic peak areas clearly increased with increasing storage time at $4^{\circ}C$ so that the area could be used as a measure of the relative degree of retrogradation. The results indicated that Samgang variety(Indica) retrograded more rapidly than Chuncheong variety(Japonica).

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.690-696
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• 1995

Properties of dry milled rice flours made of paddy with different moisture content (12.6, 18.4 and 24.4%) were compared with those of wet milled rice flour. Among dry milled rice flour, the higher moisture content of paddy the finer particle size and the more distinct shape of starch were observed. As the moisture content of paddy increased, L (lightness) value and water absorption index of rice flour were increased, while setback in amylogram and water soluble index were decreased. Lower gel consistency and gel strength were found in dry milled rice flours than in wet milled rice flour, while no significant difference was found among dry milled rice flours. Enthalpy for melting crystalline of retrograded gels was higher in dry milled rice flours made of paddy with 24.4% moisture content than in other dry milled rice flours. Wet milled rice flour had lower retrogradation enthalphy than dry milled rice flours.

• Korean journal of food and cookery science
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• v.15 no.5
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• pp.533-538
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• 1999

${\alpha}$-amylase was investigated as an antistaling agent for Backsulgie, a traditional rice cake. Rice powder was mixed with ${\alpha}$-amylase, fermented for 2 hr at 37$^{\circ}C$, and steamed for 20 min. Rice cake was stored at room temperature or freezer for 4 days, and analyzed to determined the changes of chemical and sensory properties. When ${\alpha}$-amylase was added to rice cake, the content of reducing sugars and the yellow color of the cake were increased, and the water activity was decreased. Soft and moist textural properties were apparent in ${\alpha}$-amylase-added rice cakes by sensory evaluation. X-ray diffraction showed a V pattern after 4 days of storage which indicated the starch of rice cake was not retrograded. However, there was no significant difference in moisture content between enzyme-treated and non-treated rice cakes. Above results suggest that ${\alpha}$-amylase treatment produced dextrins which consequently bound with water and inhibited the retrogradation of rice cake.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.60-68
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• 2007

This study was perform to examine the feasibility of cooking processing using the rice added the 70% ethanol extract of pigmented rice bran layer. Four rice samples, including normal rice, glutinous rice, pigmented-normal rice, and pigmented-glutinous rice were compared the properties of physico-chemical, texture, and sensory evaluation. Pigmented rice varieties had a higher amylose content, but shorter length in glucose chains than non-pigmented rice varieties. The enthalpy for gelatinization was found to increase in pigmented rice, which need more energy for gelatinization of starch in cooking. The hydrolysis rate by glucoamylase in rice added pigmented bran extract was higher than pigmented rice. Rice with pigmented bran extract had higher glutamine content, but lower asparagine content and no difference in fatty acid composition, which affect palatability. Cooked rice added pigmented bran extract was less retrograded than pigmented rice during the storage period. Moreover, cooked rice added pigmented bran extract was more acceptable in sensory evaluation. Based on the results, the use of rice added pigmented bran extract instead of pigmented rice in grain processed food have advantageous effects in palatability of polished rice and phytochemicals of pigmented non-polished rice. This study will help develop new health-promoting rice products.

• Korean journal of food and cookery science
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• v.17 no.2
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• pp.156-164
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• 2001

Four different oligosaccharides used to determine their effects on gelatinization and retrogradation of Backsulgies(BSG), Korean traditional rice cake, were cyclodextrin, isomaltooligosaccharide, fructooligosaccharide and maltotetrose, with 3 or 6%(w/w), based on the rice flour. From the Amylograph and blue value data, adding 6% cyclodextrin into the rice flour fastened the gelatinzation process, and delayed the retrogradation in stored BSG at 4$\^{C}$ for up to 3 days, probably due to its cyclic structure. Using rheometer, the hardness of freshly made BSG added with cyclodextrin was significantly lower than that of control BSG, and increased with storage time in all BSGs at refrigerated temperature. When using maltotetrose in rice flour, the hardness of BSG was also significantly low, but slightly higher than that of cyclodextrin. Hunter “L” value in BSG decreased with the addition of oligosaccharides, but the higher the level of oligosaccharide in BSG, the insignificant the Hunter “a”,“b” values of BSG. From the X-ray diffraction studies, the rice flour showed typical A pattern, and the crystallinities of all BSG gave amorphous V type. The highest peaks of X-ray patterns in BSG added with 6% cyclodextrin or maltotetrose were, however, lower than that of the control, meaning the less crystalline, retrograded starch in the former BSGs. Based on sensory evaluation, BSG added with all oligosacchrides were not significantly different in taste, flavor, chewiness, moistness and overall preferences, with slightly darker color with longer storage time, compared to the control BSG.