• Korean Journal of Food Science and Technology
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• v.19 no.4
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• pp.366-370
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• 1987

Rheological properties of gelatinized rice starch solutions (5%) were examined with a Brookifield viscometer. Gelatinized rice starch solutions showed pseudoplastic flow having yield stress, i.e., Binghamplastic flow behavior. The yield stress of gelatinized rice starch solutions was reduced by the phosphate. Phosphate increased the pseudoplasticity of gelatinized nonwaxy rice starch solutions. but decreased that of gelatinized waxy rice starch solution. The yield stress of gelatinized nonwaxy rice starch solutions held for one hour at $90^{\circ}C$ was slightly decreased, but that of waxy starch solution was reduced by 10-fold. Phosphate reduced the yield stress for both gelatinized nonwaxy and waxy rice starch solutions. Phosphate decreased the consistency index, but did not affect the flow behavior index of the gelatinized rice starch solutions.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.360-365
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• 1991

Rheological properties of Shinsunchalbyeo(Japonica) and $Hangangchalbyeo(J{\times}Indica)$ waxy-rice starches gelatinized with thermal or alkali solutions were investigated with rotational viscometer(Brabender Viscotron). The two starches showed Bingham pseudoplastics behavior in $4{\sim}8%$ thermal or alkali gelatinized starch solutions. The shear stress of Hangangchalbyeo starch solution gelatinized with thermal or alkali showed higher values than that of Shinsunchalbyeo starch and the difference of the two varieties gelatinized with alkali showed higher values than that gelatinized with thermal. Consistency index and yield stress values of Hangangchalbyeo starch showed higher than that of Shinsunchalbyeo starch in the two gelatinized methods and the difference of the two varieties gelatinized with alkali showed higher values. And it was higher that the deffendence of consistency index on starch concentration and initial starch concentration of yield stress in the alkali gelatinized samples than those of in the thermal gelatinized ones.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.57-61
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• 1991

Rheological properties of Tongjinbyeo(Japonica) and Samgangbyeo($J{\times}Indica$) rice starches gelatinized with thermal or alkali solutions were investigated with rotational viscometer(Brabender Viscotron). The two starches showed Bingham pseudoplastics behavior in $4{\sim}8%$ thermal or alkali gelatinized starch solutions. Rheological properties of thermal gelatinized starch solutions were similar between the two varieties. However, alkali gelatinized Samgangbyeo starch solutions showed higher values of yield stress and consistency index than that of Tongjinbyeo starch. The values of pseudoplasticity, yield stress and consistency index were higher in the thermal gelatinized samples than those of in the alkali gelatinized ones.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.742-748
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• 1989

Rheological properties of gelatinized millet starch dispersions were evaluated. Gelatinized nonwaxy and waxy millet starch dispersion were typical pseudoplastic fluids. At constant shear rate, gelatinized waxy millet starch dispersion showed higher shear stress than nonwaxy millet starch dispersion. Flow behaviours of gelatinized nonwaxy and waxy millet starch dispersion were well fitted to Herschel-Bulkley equation and flow behaviour index (n) and consistency index (K) were strongly concentration dependent. There was a linear relationship between concentration of gelatinized starch dispersion and square root of yield stress. The concentrations of gelatinized nonwaxy and waxy millet starch dispersion where yield stresses become zero were estimated as 2.19 and 1.69%, respectively. Pseudoplastic constant (m) approaches to a constant value in each type of millet starch when the concentration of gelatinized starch dispersion was increased. As the measuring temperatures increase, n value was increased, whereas, K value was decreased. The activation energies of gelatinized nonwaxy and waxy millet starch dispersion were 2.89 and 3.18kcal/mol, respectively.

• KSBB Journal
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• v.13 no.5
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• pp.621-625
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• 1998

The raw starch hydrolysis by amylase prepared from alkaline-tolerant Bacillus sp. were investigated. Degree of hydrolysis(%) of 5%(w/v) raw rice, corn and potato starch by this enzyme were about 40, 25 and 20%, respectively. The hydrolysis action on raw starch by change of blue value was similar to the action pattern of exo ${\beta}$-amylase. The hydrolysis products of rice starch were mainly glucose and maltose. Oligosaccarides were also detected. From the above results, this enzyme was considered as exo type ${\alpha}$-amylase. This enzyme activity on the raw starch and the gelatinized starch were 28.40 and 86.60 IU/mg protein, respectively, and the ratio of raw starch-digesting activity to gelatinized starch-digesting activity (raw starch digestivity) was about 32%. The Km values for the raw and the gelatinized starch were 4.22 and 3.0mg/mL, respectively, and the VmaX values were 0.20 and 0.31mg/mL/min, respectively.

• Journal of the Korean Society of Food Culture
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• v.18 no.6
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• pp.592-600
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• 2003

Male rats were fed a purified diet containing one of 3 experimental diets, gelatinized rice starch that was not modified physically (RC), gelatinized physically modified rice starch using ultrasonic homogenizer(RU), gelatinized physically modified rice starch using hydroshear homogenizer(RH) during 28 days. RC was used as the rice starch control. Feeding a physically modified rice starch (RU) caused an increase in liver weight and RH increased RNA and protein contents in kidney significantly although there were no differences in food intakes compared to feeding a RC diet. The wet weight of liver, kidney and heart were higher in RU. The wet weights of fecal output of the rats fed RH was greater than in rice control group. The gut transit time was longer in the rats fed RH than in the rice control group significantly. Serum GOT, GPT, total bilirubin concentration were tended to be lower and blood urea nitrogen was significantly lower in RH group. The maturation index of kidney was higher in RU than in RC. These results suggest that physically modified rice starch improved growth performance and physiological functions in organs of growing rats.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.755-759
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• 1989

Starches obtained from Seipoong and Daeji potato were classified into go starch granules $(>41{\mu}m)$ and small starch granules $(<3{\mu}m)$. Rheological properties of heat-gelatinized starch paste were studied to elucidate difference of the fractionated starches. Heat-gelatinized starch paste of potato showed Bingham pseudo-plastic behavior. The consistency index and yield stress of small starch granule paste were greater than those of large starch granule paste. As starch paste concentration increased, consistency index and yield stress of heat-gelatinized small starch granule paste increased more than those of large one. As measuring temperature increased, consistency index of heat-gelatinized starch paste decreased and temperature depedence was greater in small starch granule paste than in large one.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.773-775
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• 1995

The effect of alum$(Al{\cdot}K(SO_4)_2{\cdot}12H_{2}O)$ on the activity of raw starch-digesting enzyme produced by alkali-tolerant Bacillus sp. was investigated. In adding alum of 0.5%(w/w), activities of raw starch-digesting enzyme on the gelatinized and raw rice starches have not been inhibited. In case of adding alum of 5%(w/w), competitive and uncompetitive inhibition were observed for the gelatinized and raw rice starches, respectively. The inhibitory effect on the raw starch was much higher than that on the gelatinized starch.

• Korean journal of food and cookery science
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• v.10 no.2
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• pp.138-141
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• 1994

Whole, peeled sweetpotatoes were subjected to four different processes: 15 min microwave heating followed by 15 min baking (1), 90 min baking (2), 15 min microwave heating (3), and 15 min boiling followed by 15 min microwave heating (4). Samples of green and cured roots were used in the study. Scanning electron photomicrographs revealed that cured roots contained larger numbers of starch granules in the parenchyma cells than green roots, most of them compounded. The starch in cooked green roots was gelatinized while for cured roots it was mostly hydrolyzed into dextrins and sugars. Starch in process (3) roots was mostly gelatinized while in process (1) and process (2) roots gelatinized starch appeared in little quantity, thus it was primarily converted to dextrins and sugars. The process (4) resulted in little conversion of starch. The process (1) product resulted in a similar product to the process (2) product.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.29-36
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• 1984

Flow behaviors of rice starch-water systems containing 3-9% (w/v) of native and gelatinized starch solutions were studied with the capillary tube rheometer in the temperature range of $30-80^{\circ}C$. Flow behaviors of rice starch-water systems showed non-Newtonion behavior which could be expressed as ${\gamma}{\;}=\;{\psi}(^{\tau}g_c-{\tau}_yg_c)^N$. Flow parameters ${\psi}$, N and $^{\tau}_y$ were determined for native and gelatinized solutions. These parameters indicated that native rice starch solution shows a dilatancy and the gelatinized solution ranges from pseudoplastic to mixed type flow behavior with increasing concentrations. The value of flow behavior index for gelatinized solutions was about 1.2 in all samples but for native solutions, the values were 0.87-0.90. The values of yield stress, which were negligible below 5%, were increased with the increase in concentration from 5 to 9%. The value of consistency index was exponentially dependent on concentration and temperature. The values of activation energy for native and gelatinized solutions were 0.13-2.71 and 5.39-9.57 kcal/g mole, respectively.