• Microbiology and Biotechnology Letters
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• v.16 no.3
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• pp.231-237
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• 1988

Several methods to produce ethanol from tapioca starch were examined. Among four methods tested, alcohol fermentation with extruded tapioca starch was the most effective, which alcohol yield was 460.5 f/ton. After 69hours reaction with Rhizopus sp. glucoamylase, 108.7mg/$m\ell$ of reducing sugar were produced from extruded tapioca and 43.8mg/$m\ell$ from raw tapioca starch. In alcohol fermentation with extruded tapioca, the high concentration of alcohol at early stage prevented bacterial contamination and the fermentation rate was increased due to the high saccharifying power of glucoamylase on the extruded starch, but extrusion temperature had no influence on the fermentability, Scanning electron microscopy showed that the extrusion process changed the structure of tapioca starch granule to more susceptible form to glucoamylase attack than the raw starch. And glucoamylase of Rhizopus sp. had stronger digestion activity on both extruded tapioca and raw tapioca starch than that of Aspergillus usamii.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.352-359
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• 1990

The synergistic effect of glucoamylase and a -amylase on the hydrolysis of raw corn starch in an agitated bead reaction system was studied by investigating the changes of sugar profiles, the granular structure, particle size distribution, and X-ray diffraction pattern of residual raw corn starch. The enzymatic hydrolysis of raw corn starch was greatly enhanced by synergistic effect of glucoamylase and $\alpha$ -amylase. Even though the sugar profiles were mainly determined by the mixing ratio of glucoamylase and $\alpha$-amylase; raw starch was mainly converted to glucose directly without accumulation of any significant amount of oligosaccharides. The cavity formation and fragmentation phenomena of raw corn starch granule subjected to enzyme reaction were analyzed by means of SEM and the particle size distribution. The X-ray diffraction pattern of raw starch was not changed at the initial stage of reaction but slightly changed at the late stage of hydrolysis, which may be caused by the preferential degradation of amorphous region by enzymatic reaction, not by the destruction of microcrystalline structure of raw corn starch.

• Applied Biological Chemistry
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• v.39 no.5
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• pp.379-383
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• 1996

The ultrastructure of the compound starch granules and the protein bodies of Odaebyeo rice of early matured variety were examined by light microscope and electron microscope. The endosperm cell appealed rectangular or octangular shape on the cross section. The thickness of cell wall containing of membraneous materials was about $0.5\;{\mu}m$ in diameter. The starch cell was filled compactly with globular or oval shaped compound starch granules with the size of $20{\sim}25\;{\mu}m$ in diameter. The compound starch granules were consisted of central core starch granule and concentrical $2{\sim}3$ layers of starch granules. The average thickness of the starch granules were about $5\;{\mu}m$. Most protein bodies were found in the aleurone layer The globular protin bodies were scattered near the compound starch granules and $2.5{\sim}3\;{\mu}m$ in diameter. The protein bodies composed of central electron dense materials and peripheral electron loose materials in limiting membrane.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.3
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• pp.210-218
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• 2018

This study was conducted to examine the influence of different transplanting dates on rice quality and starch properties (morphology and pasting properties) of rice varieties that may be used for the production of rice flour. Three rice flour varieties, 'Seolgaeng', 'Hangaru', and 'Milyang317', were transplanted on May 20, May 30, June 10, and June 20. The peak viscosity decreased with a delay in the transplanting date. However, the amylose content increased with a delay in the transplanting date, whereas that of protein decreased. Amylopectin short-branch chain content increased in the rice varieties that were transplanted on May 30. The morphology of the starch granule of the varieties was determined by SEM. No apparent external difference in the starch granules was observed for the different transplanting dates. These results indicate that the transplanting date influenced the amylopectin structure and pasting properties, which led to changes in the physicochemical characteristics of rice starch.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.138-142
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• 1999

An experiment was carried out to find out the changes in morphology, sugars, and $\alpha$-amylase activity during the priming of rice seeds (Oryza sativa L. cv. ＇Ilpumbyeo＇). For priming, seeds were soaked in -0.6 MPa PEG solution at 15$^{\circ}C$ for 4 days (properly primed) and at $25^{\circ}C$ for 4 and 10 days (over-primed) and dried at room temperature. The size of coleoptile and differentiated leaves of properly primed seeds were bigger and coleoptile was separated from the other part of embryo compared with non-primed and over-primed seeds. As priming of seeds advanced, compound starch grains in the endosperm disintegrated into tiny starch granules, and small holes were found in the tiny starch granules and a cavities developed between embryo and endosperm. The radicle and plumule of properly primed germinating seeds developed faster than non-primed and overprimed germinating seeds. Sucrose, maltose, and raffinose contents of properly primed seeds decreased, while content of glucose and fructose and $\alpha$-amylase activity increased. However, sugar content and $\alpha$-amylase activity of over-primed seeds were lower compared with non-primed seeds or properly primed seeds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.2
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• pp.35-46
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• 2023

The transplanting period limit considering the rice yield in the Dague region, the inland plains of Gyeongsangbuk-do, was estimated to be July 15^th for early and mid-maturing rice and July 5^th for mid-late maturing rice. However, as the transplanting time was delayed, the characteristics of rice starch changed significantly. In the case of early and mid-maturing rice varieties, the starch granule size increased as the transplanting time was delayed; the opposite tendency was observed for mid-late maturing varieties. In all mature rice types, the late transplanting resulted in a longer pasting time and a higher pasting temperature. In addition, the peak viscosity, breakdown, and gelatinization temperature were significantly lowered, the relative crystallinity degree decreased, and the setback was significantly increased. In the case of Ilpum, a mid-late maturing rice variety, the distribution of amylopectin short chains tended to increase when rice was transplanted on June 30^th.

• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.272-275
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• 1991

Physicochemical properties of commercial corn, sweet potato, potato, wheat and mungbean starches were investigated. Amylose contents of each starch were 23, 20, 24, 28 and 39%, whereas water binding capacities were 92, 87, 83, 79 and 77%, respectively. Average granule size of potato starch was considerably higher than that of other starches. In terms of color, lightness and whiteness of sweet potato starch were relatively lower than those of other starches. Comparing with other starches, the viscosity of potato starch was the highest level. The results also showed that textural properties of potato and sweet Potato starch gels were similar. Corn starch gel had lower hardness and higher cohesiveness than others.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.6
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• pp.526-530
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• 1994

This study was conducted to investigate photosynthetic response to four sequential air influx rate with rice(Oryza sativa L.)plants moved from a natural condition to constant condition with automatic regulation selected environmental variables on 13th~15th days after anthesis. In time course of photosynthetic response to increasing air influx rate(200-280-360-440 ml / min.), stomatal conductance decreased rapidly at the beginning after treatment and then oscillated with a free-running period of a approximately 1 hour to 1 hour 30 minutes until reached up to steady-state condition. Similar change was also observed $CO_2$ assimilation rate. Stomatal conductance decreased throughout the air influx rate sequence, but the rate of decrease was similar to the decrease in $CO_2$ assimilation rate observed under continuous air influx rate conditions. In starch granules during grain filling period under air influx rate(440 ml / min.) , compound starch granules were loosing and a number of hollows were observed in surface of single starch granules. Evidences from several approaches indicate that synchronization of stomatal conductance and$CO_2$ assimilation rate was closely inter-related tinder increase of air influx rate and increase of air influx rate influenced the$CO_2$ uptake in photosynthetic processes and compound starch granule, as 'end products' of photosynthesis.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.243-249
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• 2005

The chemical and toxicological studies were conducted with acetamiprid 2% granules including different controlling agents for development of controlled-release acetamiprid 2% granule. The fundamental formulation recipe of acetamiprid 2% granule was prepared by the insoluble matrix using polyethylene wax. Starch, cellulose and mineral (calcium carbonate) were used as controlling agents. As a result of studies, release rate of active ingredient from granules into water static condition at $25^{\circ}C$ was increased by addition of starch and cellulose, but was decreased by addition of calcium carbonate. We could select calcium carbonate as controlling agent and make three granules which there were difference in release profiles of active ingredient according to contents of polyethylene wax. 24 hours-release rates of acetamiprid from three granules into water static condition at $25^{\circ}C$ were respectively 75, 50 and 25% when contents of wax were 2, 10 and 20%. The granule which 24 hours-release rate was 25% showed lower acute toxicity against mice and rats.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.10a
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• pp.263-263
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• 2017