• Preventive Nutrition and Food Science
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• v.4 no.4
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• pp.215-220
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• 1999

The Physical properties of corn starch were investigated by scanning electron microscopy, X-ray diffractometry and differential scanning calorimetry during the formation of enzyme-resistant starch(RS). Samples were studied in their native states and after annealing at 50, 55, 60 and 65℃ in excess water(starch : water=1:3) for 48hr. Starch granules became smaller and more rounded after annealing than in their native state. Annealing did not change the X-ray profile of native corn starch. After autoclaving-cooling cycles, native starch lost most of its crystallinity but annealed ones showed some of their crystallinity left as diffuse or poor B-type, which didn't relate to increasing Rs yields. During formation of RS, however, both native and annealed starches changed their X-ray profile from A-type to poor B-type of retrograded amylose. Annealing caused an increase in gelatinization temperature and enthalpy, but a narrowing of gelatinization temperature range. Only starch annealed at 65℃, however, showed a decrease in enthalpy even though its gelatinization temperature increased, which appeared to be due to the partial gelatinization in the amorphous region during annealing. Peak height index(PHI), the ratio of ΔH to Ti-To, increased by annealing. PHI values, therefore, showed the possibility as an indicator to predict RS yield which cannot be differentiated by differential scanning calorimetry and X-ray diffraction data.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.201-205
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• 1984

Some physicochemical properties of ginger root (Zingiber officinale) starch were compared with those of cross-linked corn starch. The ginger root starch that contained 23.5% amylose had a water-binding capacity of 99.1% and a B-type X-ray diffraction pattern. The optical transmittance of the ginger root starch suspension increased from $70^{\circ}C$ and showed a similar pattern to cross-linked corn starch. Solubility studies revealed that both ginger root and cross-linked corn starches had low swelling power and solubility in water up to $90^{\circ}C$, and reduced solubility in potassium hydroxide. Brabender amylograph data indicated that the ginger root starch (7%) had a relatively high initial pasting temperature $(81.5^{\circ}C)$ and was stable against heat and mechanical shear, which resembled to the cross-linked corn starch.

• 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.

• Korean journal of food and cookery science
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• v.10 no.2
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• pp.87-93
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• 1994

The sensory and instrumental characteristics of defatted and lipid-reintroduced kidney bean, mung bean and corn starch gels stored for 3 hrs and 24 hrs at room temperature were investigated. In sensory evaluation of starch gels, acceptability was highly correlated with hardness, bend property, cohesiveness and springiness. Mung bean starch gels showed sinigficantly highest value and followed by corn and kidney bean starch gels. Generally as for these factors, defatted starch gels were higher than untreated ones. The properties of defatted and lipid-reintroduced corn starch gels were similar to those of mung bean starch gels. In instrumental analysis, hardness was more important factor than any other ones. Hardness showed significantly higher value in the other of mung bean, corn and kidney bean starch gels, but it was highest in defatted starch gels among all treated gels. Hardness and springiness of defatted and lipid-reintroduced corn starch gels were similar to those of mung bean starch gels. Hardness of 24 hr stored starch gels increased more than that of 3 hr stored ones, but other textural factors did not change.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1410-1414
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• 1999

The granular size and shape of durian seed starch were $2.0-10.0\;{\mu}m$ and oval and polygonal. Amylose contents of durian seed, corn, sweet potato and potato starch were 28.3%, 27.5%, 20.3% and 21.7%, respectively. Blue value of durian seed (0.370) higher than that of corn (0.368), sweet potato (0.332), and potato starch (0.338). Alkali numbers of durian seed, corn, sweet potato and potato starch were 7.39, 9.02, 7.08 and 5.43, respectively. Swelling power of durian seed starch was similar to that of sweet potato starch. X-ray diffraction patterns of durian seed starch showed an A-type crystalline structure. According to pasting properties by Rapid Visco-Analyzer, the gelatinization temperature of durian seed starch $(76.6^{circ}C)$ was higher than that of corn $(73.0^{circ}C)$, sweet potato $(72.3^{circ}C)$ and potato starch $(70.2^{circ}C)$. The breakdown of durian seed starch were lower than that of corn, sweet potato and potato starch.

• Food Engineering Progress
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• v.13 no.4
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• pp.335-340
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• 2009

This study was performed to analyze changes in the molecular structural and physical properties of modified corn starch, in which particle structure was broken using high impact planetary mill and ultra fine pulverizing techniques. The average diameter and specific surface area of the modditied corn starch after pulverization decreased 50% and increased 567%, respectively. Content of low molecular substances mersured using gel permeation chromatography (GPC) increased from 21.0% to 86.5% after pulverizing corn starch. Damaged starch content also increased from 9.63% to 83.57% after pulverizing corn starch. After pulverization, gel formation capacity corn starch was reduced compared to that of control by structure breakdown.

• Food Science and Preservation
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• v.21 no.2
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• pp.286-293
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• 2014

In this study, one GRAS strain was screened from doenjang, a traditional Korean fermented food, as a microorganism producing amylase due to the formation of a clear zone on the medium including soluble starch. From the analysis of the gene sequence of 16S ribosomal RNA, the strain was identified as Bacillus subtilis and was therefore named Bacillus subtilis CBD2. When the nutrient broth medium was prepared with 3% NaCl, 5% glucose, and the initial medium pH 7.0, the B. subtilis CBD2 showed maximum growth. Among soluble starch, corn starch, maize amylopectin, and wheat starch, soluble starch was the most effective carbon source in the production of amylase by B. subtilis CBD2. The amylase from B. subtilis CBD2 showed the highest activities at pH 8.0 and $50^{\circ}C$, and corn starch was the most proper substrate for the enzyme activity. When corn starch was used as a substrate, the production of sugars through enzyme activity increased for 24 h, and then the enzyme activity became constant.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.582-592
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• 1995

To measure rheological properties of the starch dough, an Extrusion Capillary Viscometer(ECV) cell was self-made and attached to Instron machine(Model 1140). Apparent viscosities of corn and waxy corn starch doughs were measured and their gelatinization degrees were determined by enzymatic analysis. When corn and waxy corn starch doughs with $36{\sim}52%$ moisture content were heated at $60{\sim}100^{\circ}C$, come-up time of the cold point of doughs decreased from 220 sec to 140 sec with increased in the moisture content. In the measurement range of $36{\sim}52%$ moisture content and $60{\sim}100^{\circ}C$ heating temperature, both corn and waxy corn starch doughs showed pseudoplastic flow behaviors. At the same shear rate, both shear stress and viscosity of starch dough decreased as the moisture content increased. At the moisture content above 44%, the shear stress and viscosity of starch dough decreased as the heating temperature increased from $60^{\circ}C\;to\;70^{\circ}C$, but increased as the heating temperature increased from $80^{\circ}C\;to\;100^{\circ}C$. When the moisture content increased and heating temperature, the gelatinization degree of starch dough increased from about 10% to about 62%. The gelatinization degree of waxy corn starch dough was $15{\sim}20%$ higher than that of corn starch dough under the same gelatinization conditions. The effects of moisture content on the viscosity of starch dough were examined by Arrhenius equation. As the moisture content increased, viscosity of starch dough decreased. But the effect of moisture content was greater in the range of $80{\sim}100^{\circ}C$ than in the range of $60{\sim}70^{\circ}C$ heating temperature.

• Korean journal of food and cookery science
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• v.12 no.2
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• pp.207-213
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• 1996

Effects of replacement of corn starch with Amylomaize Vll starch and addition of enzyme-resistant starch on texture characteristics of com bread (CON) were investigated. Amylomaize-substituted corn bread (AMZ) was made by replacing corn starch with Amylomaize Vll starch. 15% (RSl5) and 30％ (RS30) of butter, was replaced with enzyme-resistant starch (RS) from Amylomaife Vll starch, respectively. Textu,e describing terms were classified according to their physical properties. Result of sensory evaluation characteristics showed that the size of air cells increased as butter replacement level decreased and that hardness increased but springiness decreased as com starch was replaced with Amylomaize Vll starch. The results of Texture Profile Analysis with deformation of 30% and 50% showed that hardness inclosed but cohesiveness decreased as cooling time increased.

• Preventive Nutrition and Food Science
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• v.3 no.4
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• pp.303-308
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• 1998

Influence of amylose content on formation and characteristics of enzyme-resistant starch (RS) was investigated by scanning electron microscopy, X-ray diffractometry and differential scanning calorimetry. RS yield increased up to 36.1 % as the amylose content of corn starch increased. Starch granules of Amyulomaize V and Ⅶ were more rounded and smaller than those of regular corn ; some were elongated and had appendages. After autoclaving -cooling cycles, the granular structure disappeared and a continous spongy-like porous network was visible in regular corn starch ; the granular structure was stillevident in parts in Amylomaize V and Ⅶ starches. In all isolated RS residues , the porous structures were no longer visible and more compact formations predominated. While regular corn starch showed an A-type X-ray profile, Amylomaize V and Ⅶ starches exhibited a combination of B- and V-types. Regular corn starch lost most of its crystallinity during autoclaving , but the crystallinity was still left in Amylomaize starches as diffuse or poor B-types. All RS residues showed the presence of poor B-type regardless of amylose contents. Transition temperatures and enthalypy of native starches were a little higher in Amylomaize V and Ⅶ starches than those of regular corn starch . Regardless of amylose contents, all RS residues exhibited an endothermic transition over a similar temperature range (135 $^{\circ}C$~169$^{\circ}C$), with a mean peak temperature of ~154$^{\circ}C$, which is generally foud for retrograded amylose crystallities. Higher transition temperature, enthalypy, and RS yield of AMylomaize V and Ⅶ starches were related granular stability shown by the microscopic and crystallographic studies.