• Korean journal of food and cookery science
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• v.32 no.4
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• pp.524-530
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• 2016

Purpose: The properties of starch and starch gel prepared from a newly inbred sweet potato, Daeyumi were compared to the properties of starch and starch gel prepared from Sinyulmi which is a well known mealy type sweet potato. Methods: The starch was isolated by using the alkaline steeping method. Physicochemical, pasting, and thermal properties, and crystallinity were measured. The texture properties of starch gel (10%, w/w) were examined. Results: The amylose contents of Daeyumi and Sinyulmi starches were 25.57% and 22.59%, respectively. The initial pasting temperature of Daeyumi starch was significantly higher than that of Sinyulmi starch (p<0.05), but other paste viscosities were not different. The peak and conclusion temperatures of Daeyumi starch were higher than those of Sinyulmi starch by differential scanning calorimetry. The shape of Daeyumi starch gel was more clear and rigid than the shape of Sinyulmi starch gel. The surface and the upper side of Daeyumi starch gel were smoother than the surface and the upper side of Sinyulmi starch gel. Hardness and gumminess were higher in Daeyumi starch gel than in Sinyulmi starch gel. The crystallinity types of Daeyumi and Sinyulmi starches were $C_b$ and A types, respectively, but starch gels showed an amorphous type. Conclusion: Therefore, it is suggested that Daeyumi starch would have better physicochemical properties and higher quality of starch gel than Sinyulmi starch.

• Korean journal of food and cookery science
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• v.3 no.1
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• pp.54-63
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• 1987

The amino acids ana fatty acids of cowpea were determined and physicochemical properties of cowpea starch and rheological properties of cowpea starch gel were investigated. The results were as following: The proteins of cowpea were particularly rich in glutamic acid (20.02%) and aspartic acid (12.21%) and contained considerable amount of leucine (8.99%), lysine (7.20%) and tryptophan (1.81%), whereas were poor in sulpho-containing amino acids. The lipids of cowpea were mainly composed of 31,43% linoleic acid, 28.34% linolenic acid, 22.9% palmitic acid and 7.63% oleic acid and the small amount of myristic, arachidonic and behenic acid was contained. The ratio of the saturated to the unsaturated in cowpea oil was 32~33/67~68. Cowpea starch gel showed lower values for hardness and brittleness than mung been starch gel, whereas a higher value for cohesiveness than mung bean starch gel, Cowpea starch gel showed lower values for $E_H$, $E_V$ than mung bean starch gel, whereas higher values for $n_V$, $n_N$ than mung bean starch gel. Cowpea starch gel had a lower value for elasticity than mung bean starch gel and had a higher value for viscosity than mung bean starch gel.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.6
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• pp.672-676
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• 1992

Retrogradation properties of cowpea and mung bean starch gels were investigated by rate of retrogradation, X-ray diffraction patterna and syneresis of gels. Retrogradation time constant of mung bean starch gel(30%) by Avrami equation had a similar value to that of cowpea starch gel. X-ray diffraction patterns of the two retrograded starch gels(10%) were B-type. The extent of retrogradation determined by syneresis showed that cowpea starch gel was a little larger than that of mung bean starch gel(6~10%).

• Journal of the Korean Home Economics Association
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• v.26 no.3
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• pp.93-102
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• 1988

Rheological properties of cowpea and mung bean starch gels and pastes were investigated and compared with Instron Universal Testing machine and Brabender Viscometer. As the result of puncture test of gels, yield point force of mung bean starch gel was higher than that of cowpea starch gel. Compression coefficient of cowpea starch gel calculated by Bourne's equation was lower than that of mung bean starch gel. the stress relaxation test showed that viscoelastic properties of cowpea and mung bean starch gels may be represented by six element Maxwell model consisting of three Maxwell element in parallel. Cowpea and mung bean starch pastes showed bingham pseudoplastic behavior in 3, 5, 6, 7 and 8%. The consistency index in 7∼8% of cowpea starch paste were lower than those of mung bean starch paste. concentration dependence on consistency index and yield stress in mung bean starch were higher than those of cowpea starch. The yield stress of starch pastes was significantly correlated with yield point force by puncture test (r=0.996).

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1046-1052
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• 2003

Viscoelastic behavior of oxidized starch gel, modified with sodium hypochlorite (NaOCl) and the adding effects of protein in oxidized starch gel was studied by dynamic viscoelastic measurement. The storage modulus(G′) of starch gel increased with the increase of starch concentration. They showed higher value when starch suspension was treated to 95$^{\circ}C$ rather than 85$^{\circ}C$. Consistency of starch gel was decreased over 1.0% active Cl/g starch when heated to 95$^{\circ}C$, which means that the swelling of starch granules increased with concentration of NaOCl and showed more sensitive against shear. As the extent of oxidation increased, starch granules were easily destroyed. Therefore, it is hard to separate between compartment of leached-out amylose and that of amylopectin, which means that the ability of gel formation was reduced. When oxidized starches were gelatinized in presence of soy protein and sodium caseinate, it was found that G′ decreased, and frequency dependence of G′ and G" increased with the increased degree of oxidation in starch. The reduce of starch-protein interaction was thought to be through the dissociation of the branched amylopectin, which playa leading role in protein interaction, with the oxidation of starch.

• Food Quality and Culture
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• v.3 no.2
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• pp.53-58
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• 2009

This study was conducted to investigate the quality characteristics of frozen stored mungbean starch gels added with sucrose fatty acid ester (SE). The study showed a delay of gelatinization of mungbean starch by SE addition through the measurements conducted by using Rapid Visco Analyzer (RVA) and Differential Scanning Calorimeter (DSC). In the color of SE added frozen stored gels, lightness (L) and yellowness (b) values were increased compared to those of values measured from freshly prepared gel, whereas redness (a) value was decreased. The addition of 1% SE on mungbean starch gel prevented the color change during frozen storage. Rupture stress and rupture energy of frozen stored gel was higher than those of freshly prepared gel, whereas rupture strain of frozen stored gel was lower than that of freshly prepared gel. The addition of 1% SE on mungbean starch gel prevented the change of rupture characteristics during frozen storage. Texture profile analysis(TPA) characteristics revealed a significant change of the gel texture during frozen storage by showing an increase of hardness of the frozen stored gels compared to the freshly prepared gels with newly discovered fracturability, which resulted to show a large difference of gel texture by showing the disappearance of adhesiveness and large reduction of cohesivenes. The addition of 1% SE on mungbean starch gel prevented the change of TPA characteristics during frozen storage. Scanning electron micrographs showed that network structure of frozen stored gel was more rough than that of freshly prepared gel, and the addition of 1% SE on mungbean starch gel could suppress the breakdown of network structure. Thus the addition of 1.0% SE on mungbean starch gel was appropriate method for remaining gel characteristics during frozen storage.

• The Korean Journal of Food And Nutrition
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• v.26 no.4
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• pp.638-645
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• 2013

This study was conducted to investigate the effects of persimmon powder on the antioxidant activity and quality characteristics of mung bean starch gel. Mung bean starch gels were prepared with different amounts (0%, 1%, 3%, 5%, 7% and 9%) of persimmon powder. The antioxidant activity was estimated by the DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity and by the total phenolic acid content in the persimmon powder and mung bean starch gel. For analyzing the quality characteristics, syneresis, pH, color, texture profile analysis, and sensory evaluations were measured. The syneresis in the control group was higher than that in the treated group, but the mung bean starch gel prepared with 9% persimmon powder was higher than that of the control group (p<0.001). The pH, b values, total phenolic acid content, and DPPH free radical scavenging activity of mung bean starch gels significantly increased with increasing persimmon powder (p<0.001), while the L values and a values of the mung bean starch gels significantly decreased with increasing persimmon powder (p<0.001). In the texture profile analysis, the mung bean starch gel with 9% persimmon powder showed significantly lower levels of chewiness, gumminess, and cohesiveness (p<0.05). The hardness and springiness of the mung bean starch gel did not show any significant difference. The consumer acceptability score for the mung bean starch gel prepared with 7% persimmon powder ranked significantly higher than that for the other groups in overall preference, appearance, flavor, and color (p<0.05). From these results;we suggest that persimmon powder is a good ingredient for increasing consumer acceptability and the functionality of mung bean starch gel.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.533-537
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• 2022

Flexible zinc-air batteries have many merits, including low cost, high safety, environmentally friendliness applicability, etc. One of the key factors to improve the performance of flexible zinc-air batteries is to use a gel electrolyte. In this study, gel electrolytes were synthesized from potato, sweet potato, and corn starch. In a comparison of each starch, the corn starch-based gel electrolyte showed the highest discharge capacity of 12.41 mAh/cm² in 20 mA and 6.47 mAh/cm² in 30 mA. It also delivered a higher specific discharge capacity of 7.06 mAh/cm² than the other materials after 100° bending. In addition, the electrochemical impedance spectroscopy (EIS) was analyzed to calculate the ionic conductivity. The potato, sweet potato, and corn starch-based gel electrolytes showed electrolyte resistances (Re) of 0.306, 0.298, and 0.207 Ω, respectively. In addition, the corn starch-based gel electrolyte delivered the highest ionic conductivity of 0.121 S cm^-1 among the other gel electrolytes. Thus, the corn starch-based gel electrolyte was verified to improve the performance of flexible zinc-air batteries.

• Journal of the Korean Home Economics Association
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• v.23 no.1
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• pp.33-47
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• 1985

The rheological properties of acorn starch gel were investigated in region of small and large deformation. The properties were compared with those of potato and wheat starch gel. On the physical characteristics and the effect of tannin contents of acorn starch were examined. RESULTS : 1. X-ray diffractogram of acorn starch showed C-type and its granules swelled gradully with heating. 2. Hardness, brittleness and both small and large deformation of the acorn starch gel were remarkably large, also the concentration dependence of the acorn starch gel could be recognized in small deformation and hardness. 3. The Young's modulus of Hookean body in small deformation and the rupture stress in large deformation differed obviously from the parameters of rheological properties in various gels. 4. It was found that the selling power, viscosity and rhelogical properties were affected obviously by the tannin.

• Preventive Nutrition and Food Science
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• v.1 no.2
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• pp.190-195
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• 1996

Texture-modifying and freeze-thaw stabilizing effects of different wheat gluten and modified starches on surimi based-product were evaluated. The different incorporation manners of wheat gluten and modified wheat starch in surimi gel were also examined to evaluate their effects of textural properties on surimi gel. The addition of wheat gluten reduced the gel strength of surimi, but after freeze-thaw cycle it significantly improved freeze-thaw stability by reducing freexe-thaw expressible moisture and also by preventing rubbery texture development, Gluten-1 incorporated surimi gel showed higher functionality in forming cohesive gel determined by compressive and penetration force as wall as expressible moisture after freeze-thaw cycle. Surimi gel containing modified wheat starch showed better freeze-thaw stability that of modified potato starch. When a preblended mixture of wheat gluten and starch are incorporated into surimi gel, it made gel texture significantly softer as so in high sensory score. The compertition for moisture between gluten and starch is a main reason to show different way of textural modification.