• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.6
• /
• pp.1293-1297
• /
• 1999

Effect of rice protein and lipid on rheological properties of gelatinized rice flour solutions(4%) with three rice varieties(Dongjin, Jinmi, Tamjin) known for varying taste of cooked rice was investigated with Haake viscometer. The rheological behaviors of all rice flour solutions were illustrated by Herschel Bulkley equation and exhibited pseudoplastic behavior with yield stress. When rice flour solutions treated with protease and dithiothreitol, there was decreased in flow behavior index value. Flow behavior index was decreased by dealbumin and deglutelin rice flour solutions among deprotein groups. The Jinmi rice flour solutions exhibited slightly lower consistency index than Dongjin and Tamjin. Defatted rice flour solutions exhibited lower consistency index than rice flour solutions, while dealbumin, deglutelin rice flour solutions exhibited high consistency index. Protease treated rice flour solutions exhibited increase in Dongjin and Tamjin. The yield stress was increased in sequence eating quality. Yield stress of defatted rice flour solutions was decreased, while deglutelin and rice starch flour solutions was increased. The time dependent charac teristics of all rice flour solutions appeared forming hysteresis loop and thixotropic behavior showed. The time dependent characteristics was appeared in sequence eating quality. Rice starch and deglutelin flour solutions appeared greatly time dependent characteristics, but defatted rice flour solutions appeared very little.

• Korean Journal of Food Science and Technology
• /
• v.16 no.4
• /
• pp.451-456
• /
• 1984

Rheological properties of gelatinized rice starch solutions were investigated with Brookfield rotational viscometer. The 8% starch solution showed thixotropic behavior with yield stress. The alkali gelatinized starch was more thixotropic than the thermal gelatinized one. The time dependent characteristics of starch solutions followed Tiu's model. The value of rate constant $(a_1)$ in Tiu's model increased linearly with shear rate, and was exponentially dependent on concentration and temperature. Temperature dependency of rate constant and apparent viscosity followed Arrhenius type equation and the activation energy were about 14.3 and 6.8 Kcal/g mole, respectively. The $a_1-value$ was found to be useful to evaluate changes in structaral decay on the shearing time of gelatinized rice starch solutions.

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

• Korean journal of food and cookery science
• /
• v.10 no.2
• /
• pp.138-141
• /
• 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
• /
• v.27 no.5
• /
• pp.773-775
• /
• 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
• /
• v.24 no.3
• /
• pp.273-281
• /
• 2008

To determine the nutritional quality and physical properties of ginseng-chicken meat porridge, 10 kinds of ginsengchicken meat porridge samples containing waxy and/or non-waxy rice were analyzed for in vitro protein digestibility and their degree of starch hydrolysis. Viscosity and spreadness were determined for the gelatinized pastes of the porridge samples. Microphotographs of the starch granules and pastes were studied to confirm structural changes in the rice starch during cooking. The starch paste from non-waxy rice porridge had higher viscosity than the starch paste from the waxy rice porridge; however, in the case of the ginseng-chicken meat porridge, the difference in viscosity was negligible. Microphotograph comparisions between the waxy rice porridge and non-waxy rice porridge indicated apparent differences in the shapes of their starch granules and gels. The granule surface of the non-waxy rice was very rough while that of the waxy rice was very smooth; this difference would lead to organoleptical discrepancy. The added ginseng increased the protein digestibility of the chicken meat; however, the protein digestibility of the ginseng-chicken meat porridge was lower than that of the chicken meat or rice porridge due to inhibited protein digestion by the gelatinized starch. Finally, the rice porridge had increased starch hydrolysis with additions of chicken meat and vegetables.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.1
• /
• pp.89-99
• /
• 2007

A Feeding trial was conducted to study the effects of three different sources and two levels of dietary gelatinized carbohydrate (GC) on nutrient utilization, growth, tissue composition and tissue enzyme activities of fingerlings of Catla catla (15.1-15.3 g). Six isocaloric (17.1-17.5 kJ/g) semi-purified diets were prepared either with rice, corn or tapioca at 40 or 50% GC each. The crude protein (CP) level used in the diet was 35% and 25% for 40% and 50% GC level, respectively to study the protein sparing effect of GC. The degree of gelatinization was higher for corn and tapioca than rice under similar cooking conditions. After a 60-d feeding trial, dry matter, carbohydrate, protein and lipid digestibility were higher in tapioca fed groups at both the levels of GC. However, the highest specific growth rate (SGR) and protein efficiency ratio (PER) were observed in the corn fed groups at 50% GC level indicating better utilization of nutrients from gelatinized corn. Feed conversion ratio (FCR) was almost similar in corn and tapioca fed groups between two levels of GC but in rice fed groups, FCR was lower in 40% GC than 50% GC level. The results indicated higher protein-sparing effect in corn and tapioca fed groups than rice fed groups. The order of gelatinized carbohydrate utilization in Catla catla fingerlings at 50% GC level was corn>tapioca>rice. At 40% GC level, corn and tapioca were comparable and more efficiently utilized than rice. In the corn fed groups, 50% GC was comparable with 40% GC level, whereas in rice and tapioca fed groups the 40% GC was better in terms of nutrient utilization. Liver glycogen content and hepatosomatic index were significantly (p<0.05) higher in those groups fed high GC (50%) irrespective of carbohydrate sources. Higher intestinal amylase and glucose-6-phosphate dehydrogenase activities were observed in higher GC fed groups than the lower GC groups. No mortality was found in any groups at any levels of GC.

• Applied Biological Chemistry
• /
• v.29 no.3
• /
• pp.248-254
• /
• 1986

The product specificity of Bacillus ${\alpha}-amylase$ on raw rice starch has teen studied by using HPLC and scanning electron microscopy (SEM). Analysis of starch degradation products digested by ${\alpha}-amylase$ showed considerable differences between raw and gelatinized rice. The hydrolysis of raw rice starch resulted in formation of more glucose and maltose than those of gelatinized starch. SEM revealed characteristic enzyme degradation patterns. Hollow curvatures were observed in gelatinized starch, indicating the substrate is hydrolyzed in the interior of the starch chain by Bacillus ${\alpha}-amylase$. In contrast, raw starch were hydrolyzed from the end of the substrate, resulting in pinholes over the surface of the starch granules.

• Korean Journal of Food Science and Technology
• /
• v.29 no.4
• /
• pp.705-709
• /
• 1997

Changes in retrogradation degree of nonwaxy milled rice cooked at different pressure and stored in electric rice cooker at $74^{\circ}C$ were investigated. The moisture contents of nonwaxy milled rice cooked at $1.0{\sim}1.9\;atm\;and\;1.2{\sim}1.5$ water/rice ratio were $59.9{\sim}64.3%$. When nonwaxy milled rice was cooked at high pressure, X-ray diffraction patterns of cooked rice exhibited the V-type having nearly no crystallinity. Retrogradation peak of cooked rice from DSC thermogram was observed in the temperature range of $41.9{\sim}62.4^{\circ}C$ and was not appeared in cooked rice above 1.5 atm. During storage at cooker for 24 hr, retrogradation enthalpy of cooked rice was increased and retrogradation peak was not appeared above 1.7 atm. In cooking and storage of cooked rice, retrogradation degree measured by ${\alpha}-amylase-iodine$ method in high pressure gelatinized samples was lower than that in low pressure gelatinized ones.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.5
• /
• pp.700-706
• /
• 2005

The objectives of this research were to analyze physicochemical properties of physically modified rice starch which was prepared by hydro-shear homogenizer and ultrasonic homogenizer. The 5:1 of water to starch ratio, 20,500 rpm of hydro-shear homogenizer, and 5 sec of pulse and 40 kHz of frequency of ultrasonic homogenizer, which were operated for 10 min. The 1/3 of size reduction of raw rice starch and gelatinized rice starch, and reduced of particle size were achieved by above processing conditions. The homogenization of raw rice starch and gelatinized rice starch were higher values of specific area, transmittance, solubility and swelling power than control. While, these had lower value of apparent viscosity than control. In raw rice starch, the gelatinization characteristics of ultrasonic homogenizer treated rice starch had some higher values of gelatinization temperature, peak temperature and enthalpy than those of control. While, those of hydro-shear homogenizer treated rice starch had similar values to those of control.