• Korean Journal of Food Science and Technology
• /
• v.25 no.6
• /
• pp.626-631
• /
• 1993

The effects of mugwort on some physicochemical properties of rice flour, on the viscosity of rice flour pastes (2 and 4%), on the hardness and the freeze-thaw stability of rice flour gels (20 and 40%), and on the degree of gelatinization (DG) of pastes and gels were investigated. By addition of mugwort, water holding capacity, swelling power, and solubility of rice flour were increased. The rice flour pastes became thicker by addition of mugwort, but viscosities of both the rice flour pastes and the rice flour-mugwort pastes, without noticeable difference between them, were decreased during storage at $25^{\circ}C\;and\;4^{\circ}C$ for 7 days. The rice flour gels became firmer by addition of mugwort and hardnesses of both the rice flour gels and the rice flour-mugwort gels were increased during storage, especially at $4^{\circ}C$. DGs, measured by glucoamylase digestion, of pastes and gels were decreased slightly during storage. Freeze-thaw stability of gels was not affected by addition of mugwort.

• Journal of the Korean earth science society
• /
• v.24 no.1
• /
• pp.46-60
• /
• 2003

In Namyang Bay of western Korea, macrotidal-flat deposits are divisible into three late Quaternary units: Unit M1 of upper marine mud, Unit T1 of middle siderite-bearing terrestrial clay, and Unit M2 of lower marine mud. Unit M1 represents typical Holocene intertidal mudflat deposits, showing a coarsening-upward textural trend. It probably resulted from the continual retrogradation of tidal flat during the mid-to-late Holocene sea-level rise. Reddish brown-color Unit T1 consists of homogeneous clay with abundant freshwater siderite grains and plant remains. Unit T1 is clearly separated from the overlying Unit M1 by a sharp lithologic boundary. Radiocarbon age, siderite grains and lithologic features indicate that Unit T1 is originated from freshwater bog or swamp deposition infilling the localized topographic lows during the early Holocene age. Overlain unconformably by early Holocene swamp clay, Unit M2 is orange to yellow in color and mottled, suggesting significant degree of weathering during the sea-level lowstand. Such subaerial oxidation is confirmed in the vertical profiles of geotechnical properties, clay mineral assemblages and magnetic susceptibility. Unit M2 appears to be correlated with the upper part of the late Pleistocene tidal deposits developed along the western Korean coast. The sedimentary succession of the Namyang-Bay tidal-flat deposit provides stratigraphic information for the Holocene-late Pleistocene unconformity and also permits an assessment of the preservation potential of the late Pleistocene marginal marine deposit along the western coast of Korea.

• Korean Journal of Food Science and Technology
• /
• v.5 no.2
• /
• pp.95-100
• /
• 1973

In order to study the effect of gamma-ray on the storage stability and quality of polished wheat, the grain was irradiated at $50{\sim}1000$ krad levels and quality assessment was made for three-month storage period. The results are summarized as follows: 1) Growth of molds was apparent at equilibrium moisture content above 14.8% of the grain, but their growth was retarded at 250 krad level. 2) Irradiation at 250 krad level had no adverse effect on fat acidity, reducing sugar content and color of the grain. 3) Irradiation of the grain caused the increase of degree of gelatinization and the decrease of viscosity. 4) Irradiation at 250 krad level brought about higher digestibility of the grain but had no effect on the rate of retrogradation.

• Korean Journal of Food Science and Technology
• /
• v.18 no.6
• /
• pp.421-426
• /
• 1986

The carbohydrate characteristics and storability of two Korean traditional confections Seban-kangjeong (a Korean fried waxy-rice cookie) and starch-dashik (a Korean pressed starch cookie) were studied as compared with two Western confections fried cookie and biscuit. Seban-kangjeong showed lower contents of starch and sucrose and higher content of reducing sugar whereas starch-dashik showed higher contents of starch and sucrose and lower content of reducing sugar. Moisture content was higher in Korean confections than in Western confections. The degree of gelatinization was higher in Seban-kangjeong and fried cookie which were made through a frying process. Moisture adsorption isotherms were constructed for the four products. In storage test for 6 months under different temperature and humidity conditions, the relative humidity maintaining the initial moisture content of products was 68% for Seban-kangjeong and starch-dashik and 20% for fried cookie and biscuit. The ratio of retrogradation in storage was 15% in Seban-kangjeong, 20% in starchdashik and 28% in fried cookie and biscuit, showing the lowest progress in freezer storage.

• Korean Journal of Food Science and Technology
• /
• v.23 no.3
• /
• pp.317-324
• /
• 1991

Gelatinization behaviours and gel properties of hydroxypropylated corn starches (HPCS) were investigated with differential scanning calorimeter, amylograph and rheometer. Gelatinization temperature of HPCS decreased as degree of substitution increased. The retrogradation of corn starch was greatly reduced by hydroxypropylation, indicating that the association of starch molecules was sterically hindered by hydroxypropyl groups. In HPCS, gel was formed slowly and gel strength decreased resulting in soft and sticky texture. Texture profiles of HPCS gels were similar to those of tapioca and waxy corn starch. HPCS has shown a remarkable increase of paste transparency compared to native corn starch.

• Korean Journal of Food Science and Technology
• /
• v.28 no.3
• /
• pp.528-537
• /
• 1996

Qualify changes of microwave-reheated cooked rice aseptic-packaged with different lid materials and oxygen absorbers were determined during storage at $20^{\circ}C,\;30^{\circ}C$ and $40^{\circ}C$. Springiness cohesiveness and adhesiveness increased as storage temperature increased, while gumminess and hardness decreased. Lid materials oxygen absorbers, and storage temperatures showed no significant effect on the textural properties of cooked rice after microwave reheating. Degree of gelatinization was increased as storage temperature increased and was restored after microwave reheating. Scanning electron micrograph showed that the surface of cooked rice became rough and hollowed after microwave reheating for 1.5 min, indicating starch was regelatinized, while there was no difference with respect to lid materials. Photomicrographs of the cross-section of aseptic-Packaged cooked rice showed that a compact and solid structure increased and retrogradation occured in starch as storage temperature decreased, while a compact and solid structure was decreased and starch was regelatinized after microwave reheating.

• Journal of the Korean Society of Food Culture
• /
• v.24 no.1
• /
• pp.69-76
• /
• 2009

This study was conducted to determine the optimal cooking conditions for brown rice using an electric pressure rice cooker. The effects of steeping conditions and cooking pressure on the hydration, gelatinization, texture and palatable properties of cooked brown rice were evaluated. Based on water uptake and DSC data, the optimal steeping time and temperature for brown rice were determined to be 25 minutes and ${\sim}60^{\circ}C$, respectively. The cooking conditions for brown rice were then divided into the following 6 categories: steeping at $25^{\circ}C$ for 25 minutes and cooking at an atmospheric pressure of 1.7 (25P) or 1.9 (25HP), steeping at $57^{\circ}C$ for 25 minutes and cooking at an atmospheric pressure of 1.7 (57P) or 1.9 (57HP), steeping at $85^{\circ}C$ for 15 minutes and cooking at an atmospheric pressure of 1.7 (85P) or 1.9 (85HP). The susceptibility of cooked brown rice starch to degradation into maltose by ${\alpha}$-amylase, which is related to the degree of gelatinization and in vitro digestibility, were then determined. The amount of maltose produced by cooked brown rice samples was highest in the 57HP group, followed by the 57P and 85HP groups. Storing cooked brown rice at $73^{\circ}C$ for 24 hours resulted in significantly higher amounts of starch being degraded into maltose in the 57P, 57HP and 85HP groups than in the other groups. Textural analysis demonstrated that the 57P, 57HP and 85HP groups had significantly lower gumminess and chewiness values when compared to the other groups, and that 57HP received had the lowest hardness of all treatments. These results were confirmed by the results of the sensory evaluations. Furthermore, the 57P and 57HP groups were found to have a higher glossiness, stickiness aroma and taste score than the other groups. These findings were taken to indicate that steeping conditions and pressure exerted a positive synergistic effect on the cooking quality of brown rice. The texture analyzer also revealed that storing the cooked rice at $73^{\circ}C$ for 24 hours only led to significantly lower scores in gumminess, hardness and chewiness in the 57P and 57HP groups, which indicates that these groups underwent a lesser degree of retrogradation than other groups. Taken together, the results of the present study demonstrate that steeping brown rice at $57^{\circ}C$ for 25 minutes and a higher cooking pressure improved the palatability and in vitro digestibility of brown rice significantly.

• Korean Journal of Food Science and Technology
• /
• v.23 no.2
• /
• pp.235-240
• /
• 1991

Starch phosphates were prepared from the corn starch mixed with 2% sodium tripolyphosphate by twin-screw extruder with a feed rate of 20 kg/hr and an extrusion temperature of $130^{\circ}C$, and the effects of extrusion variables on the physicochemical properties (target parameters) of starch phosphates were investigated. Interrelations of system parameters (specific mechanical energy and extrudate moisture) and rheological properities of starch was analyzed by using the response surface analysis. Degree of substitution (DS) was increased with increasing the feed moisture, and showed the maximum value at the screw of near 250 rpm, Degree of gelatinization was proportionally increased with increasing the screw speed and decreasing the feed moisture. Apparent viscosity of the paste was increased with increasing the feed moisture, but it was not significantly affected by the screw speed. It was found by scanning electron microscopy that the starch microgranules were much more degradaded, and as consequent result, the intrinsic viscosity was decreased, whereas, water solubility index was increased. The rate of retrogradation of the gels was retarded with increasing DS and decreasing viscosity.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.3
• /
• pp.426-434
• /
• 2011

In order to increase the use of rice, ginseng Garaedduks and Topokki were made and the physicochemical and sensory properties were investigated. Topokki and Garaedduks were added with 0, 1, 3 and 5% ginseng powder and stored at $20^{\circ}C$ for 48 hours. The moisture contents were not different to the increasing amount of ginseng powder and increasing storage time for 48 hours. The moisture content of Garaedduks for control and 5% added ginseng powder were 48.08% and 49.62%, respectively. The L value in color of uncooked ginseng Garaedduk decreased according to the added amount of ginseng powder, and the b value in color increased significantly according to the added amount of ginseng powder and during 48 hours storage at $20^{\circ}C$. Textural analysis, measured using a texture analyzer, of Garaedduk revealed that hardness, cohesiveness, chewiness decreased significantly and adhesiveness increased according to the added amount of ginseng powder. In sensory evaluation, 5% ginseng Garaedduk (uncooked, cooked) scored higher in overall acceptability than those of the other samples. In cooking properties, water absorption and solid contents increased according to the added amount of ginseng powder. Therefore, Garaedduk containing 5% ginseng powder was the most preferable. These results implied that the degree of retrogradation of ginseng Garaedduk might be low due to its high dietary fiber content.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.7
• /
• pp.926-934
• /
• 2009

The study investigated the quality of pound cake prepared with various concentrations of cherry powder (obtained from ground fruit of Prunus serrulata L. var. spontanea Max. wils.). Pound cake was evaluated for their sensory property and physical quality stored for 10 days at $25^{\circ}C$. The pH of the batter decreased with rising cherry powder concentration. The specific loaf volume and height decreased (from 2.95 to $2.60\;cm^3/g$) with increasing in cherry powder. The baking loss rate of the pound cake tended to increased by $11.47{\sim}12.67%$, but with no significant differences. The lightness, redness, and yellowness values were significantly decreased with increases in cherry powder except for redness of pound cake crumb. As the concentration of cherry powder increased, the mechanical characteristics of the pound cake did not differ significantly. The hardness tended to increase, while adhesiveness and springiness decreased with increases in powder. The retrogradation degree of pound cake prepared with cherry powder was higher than the control but there were no significant differences. For the antioxidative activity measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, pound cake prepared with 10% and 15% added cherry powder showed high antioxidant activities. The pound cakes containing 10 and 15% cherry powder had acceptable sensory properties, such as flavor, taste, softness, moisture, and overall acceptability. The results exhibited that adding the cherry powder into the pound cake increased antioxidant activity with the highest quality improvement obtained by incorporating 10% (w/w) of cherry powder into the pound cake formula.