• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.77-85
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• 2018

This study was performed to understand the effects of filling stage temperature on the characteristics of starch and storage protein and the quality of rice grains. Eight early maturing rice varieties were cultivated in Cheolweon (latitude $38^{\circ}15^{\prime}N$) and Suwon (latitude $37^{\circ}16^{\prime}N$) areas in Korea. Rice grown in Suwon, with relatively high ripening period temperatures, showed significantly reduced head rice ratio and eating qualities, higher protein and lower amylose contents than rice grown in Cheolweon. In rice that ripened under high temperature conditions, the starch contained significantly less short-chain amylopectin (DP < 12) but more intermediate- (DP 13-24) and long- (DP > 25) chain amlylopectin compared to rice that ripened under normal conditions. In addition, the electrophoretic pattern of rice storage protein under high- temperature conditions revealed decreased prolamin and increased glutelin contents.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1350-1356
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• 1998

An attempt was made to investigate the effects of additives (3%) such as egg white, soybean protein, corn starch and Read Amity-N (green bean starch 85%+psyllium husk 10%) on the thermal properties and gel structures of mackerel surimi and to examine the quality of surimi by using differential scanning calorimetry (DSC), rheometry and scanning electron microscopy (SEM). The thermal transition temperatures of mackerel surimi protein were 40, 52, 67 and $79^{\circ}C$ after those temperatures were changed to 37, 46, 57 and $76^{\circ}C$ after adding salt (3% NaCl). Addition of Read Amity-N and corn starch to surimi showed new peak at the temperature of $90^{\circ}C\;and\;92^{\circ}C$, respectively. The enhancing effects of gel strengths of mackerel surimi cooked gels prepared from adding four kinds of additives, respectively, were egg white > soybean protein > Read Amity-N > corn starch in order. Scanning electron microscopy showed a difference in fine structures between the cooked gels which were prepared with and without additives. Dispersion profiles of protein were more thick in cooked gel prepared with additive than in cooked gel prepared without additive.

• Food Engineering Progress
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• v.21 no.1
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• pp.64-71
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• 2017

This study investigated the effects of the mixing ratio of tofu paste and normal corn starch on the characteristics of gluten-free (GF) muffins. Soft wheat flour for wheat flour-based muffins (control) was replaced with the mixture of tofu paste and normal corn starch (NCS). The mixing ratios of tofu paste and NCS were 1:6.4 (S100), 1:5.1 (S80), 1:3.8 (S60), 1:2.6 (S40), 1:1.3 (S20), and 1:0 (S00), based on their total solid contents. GF muffins of S40-S100 developed the porous, sponge-like structure without crumb collapse. The weight and baking loss did not significantly differ in the control and GF muffins. By decreasing NCS in GF muffin batters, the moisture content, firmness, and crumb redness/yellowness of GF muffins increased, while their volume, specific volume, and crumb lightness decreased. Nevertheless, these characteristics (except for firmness) of S100 were much closer to those of the control. In the preference test, however, S60 (possessing lower attributes than S100 and S80) was most favored among GF muffins, and was very similar in all evaluations (except for appearance) to the control. Overall, the mixture of tofu paste and NCS would be a potential material to replace soft wheat flour in muffins.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.3
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• pp.153-162
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• 2016

We investigated the physicochemical properties and starch structure of various rice varieties including 15 colored cultivars. NKHC showed the highest level of protein, lipid, and total dietary fiber levels. Reddish brown rice showed higher lipid content than that in black rice cultivars. Apparent amylose content of waxy and non-waxy colored rice varieties was within the range of 3~5% and 15~18%, respectively. IP exhibited the highest total starch (TS) content, whereas, NKHC and HJJ showed lower TS content than that in other cultivars. Pasting temperature of all colored rice cultivars, except IP, was about $68^{\circ}C$. Peak viscosity of IP, JJJ, Hong, and GGHM showed high values of 138, 130, 128, and 124, respectively. All the colored rice cultivars presented A-type X-ray diffraction pattern and polygonal shapes of starch granules were observed using scanning electron micrographs (SEM). Major groups of amylopectin chain lengths were B (12 < DP ${\leq}$ 24) and A (DP ${\leq}$ 12). SMHC showed the highest B chain content and the lowest A chain content (P < 0.05). These experimental results provided useful information for scientists and the food industry regarding colored rice starches.

• Korean Journal of Plant Resources
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• v.20 no.6
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• pp.530-539
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• 2007

Genetic variation and structure of 9 subpopulations of Symplocarpus renifolius Schott ex Tzvelev on Mt. Cheonma, in Korea, were determined via starch-gel electrophoresis. The genetic diversity at 10 loci for 8 isozymes ($P_{99}=66%,\;A=2.26,\;H_o=0.212,\;H_e=0.230$) was found to be considerably higher than that seen in other long-lived perennial plants. On the whole, the genotype frequencies were in accordance with Hardy-Weinberg expectations. Approximately 5%($\theta=0.049$) of the total variability was among subpopulations. The high levels of observed genetic diversity in S. renifolius were attributed to a universal outcrossing system and other specific factors like differences in age classes and widely scattered individuals around the main distribution. Heterozygosity was highest at a mid-range of elevation($450m{\sim}600m$). The lowest heterozygosity at lower elevation was attributed to the possible origin of seeds transported by water from upstream regions during the monsoon season. Spatial structure in a subpopulation evidenced a strong autocorrelation between closer individuals within $3{\sim}4m$ of distance. This was assumed to be attributable to the restricted seed dispersal characteristics of S. renifolius. In accordance with the findings generated in this study, some implications regarding the conservation of S. renifolius at the Mt. Cheonma were also presented.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.235-241
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• 2016

Three different transplanting dates for two rice cultivars grown in Daegu, Republic of Korea, were examined to identify the changes in growth, rice quality, and characteristics of amylopectin. An early transplanting date caused a reduction in the number of panicles in both rice cultivars compared to that in the optimal and late transplanting dates. The 1000-grain weight in the two rice cultivars was significantly increased in the late transplanting date. The rice cultivar tolerant to high temperatures, Donganbyeo, exhibited the lowest milky grain rate in the late transplanting date. The highest rate of head grain was observed in the late transplanting date in both rice cultivars. Regarding the pattern of pasting properties, peak viscosity increased with delayed transplanting dates. With respect to changes in the amylopectin branch-chain length distribution, the amylopectin structure of the translucent Dongan rice cultivar transplanted on April 25 was characterized by a significant increase in A chains with DP > 12, and a decrease in long chains $DP{\geq}37$ compared to that transplanted on June 25. In contrast, the amylopectin structure of the chalky Dongan rice cultivar transplanted on April 25 exhibited further decrease in 13 < DP < 19 than that transplanted on June 25. In the Ungwang rice cultivar, the amylopectin structure of the translucent Ungwang rice cultivar transplanted on April 25 and June 25 was characterized by a significant decrease in the lengths of total amylopectin chains. Furthermore, the amylopectin structure of the chalky Ungwangbyeo rice cultivar transplanted on April 25 was characterized by a significant increase in 7 < DP < 30, while a significant decrease was observed in that transplanted on June 25. These results indicate that the amylopectin structure is altered by different transplanting dates depending on the characteristics of the rice cultivar.

• Korean journal of food and cookery science
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• v.11 no.5
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• pp.479-486
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• 1995

The reological properties of doughs blended with cereal flours were investigated in the study. The doughs were prepared of wheat flours mixed with 10％, 20%, 30% and 40% ratio of rice flour, waxy-rice flour, brown-rice flour and soybean flour. Amylogram, farinogram, extensogram and SEM were used to measured thier special properties with graphs and photos. The results were obtained as followes; 1. Wheat dough formation after fermantation, showed "stringing" structure of small starch granules on the SEM photo. But the large starch granules contributed little to the structure formation in rice flours dough, and played relatively a little role in the structure formation of blended doughs of waxy-rice, brown-rice and soy- bean flours. 2. The absorption of flour composited rice and brown-rice, was lower than that of the control by Farinograph. It was decreased the farinograph absorption with the increase of replacement ratio of cereal flours. Dough development time of cereal blended flours decreased, but that time of waxy-rice and brown-rice were very similiar. Farinograph stability of rice, waxy-rice, brown-rice and soybean blended flours, had shorter than that of wheat-flour. 3. The results showed that cereal blended flours decreased the resistance to extention (elasticity) without affecting the extensibility in fermented dough by Extensograph. 4. The gelatinization temperature of wheat, rice, waxy-rice, and brown-rice were 55.0$^{\circ}C$, 64.0$^{\circ}C$, 58.0$^{\circ}C$ and 61.0$^{\circ}C$. But that of all cereal blended flours showed 58.0$^{\circ}C$ except 20% or 30% soybean blended flours. According to the amylogram, each maximum viscosity of rice flour and wheat flour was 1760 B.U.,760 B.U.. Soybean composite flours had significantly lowe. amylograph peak viscosity (300 B.U.) than that of the other composite flours (450 B.U.-1100 B.U.).

• KSBB Journal
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• v.23 no.3
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• pp.276-280
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• 2008

In this study, the productivity of bioethanol obtained from various domestic raw materials (barley, brown rice, corn and sweet potato) by simultaneous saccharification and fermentation (SSF) process was estimated. Also, optimal conditions of temperature, time and enzyme concentration in gelatinization and liquefaction process were investigated. As a result, corn showed high ethanol yield of 90.45% and sweet potato had a rapid fermentation time. Productivity of bioethanol increases in accordance with the starch value of raw materials except brown rice. Therefore, it is very important to understand the structure of starch. Further studieson the characteristics of raw materials are necessary to enhance the productivity of bioethanol.

• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1555-1563
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• 2008

A novel $\alpha$-amylase ($\alpha$-1,4-$\alpha$-D-glucan glucanohydrolase, E.C. 3.2.1.1), ScAmy43, was found in the culture medium of the phytopathogenic fungus Sclerotinia sclerotiorum grown on oats flour. Purified to homogeneity, ScAmy43 appeared as a 43 kDa monomeric enzyme, as estimated by SDS-PAGE and Superdex 75 gel filtration. The MALDI peptide mass fingerprint of ScAmy43 tryptic digest as well as internal sequence analyses indicate that the enzyme has an original primary structure when compared with other fungal a-amylases. However, the sequence of the 12 N-terminal residues is homologous with those of Aspergillus awamori and Aspergillus kawachii amylases, suggesting that the new enzyme belongs to the same GH13 glycosyl hydrolase family. Assayed with soluble starch as substrate, this enzyme displayed optimal activity at pH 4 and $55^{\circ}C$ with an apparent $K_m$ value of 1.66 mg/ml and $V_{max}$ of 0.1${\mu}mol$glucose $min^{-1}$ $ml^{-1}$. ScAmy43 activity was strongly inhibited by $Cu^{2+}$, $Mn^{2+}$, and $Ba^{2+}$, moderately by $Fe^{2+}$, and was only weakly affected by $Ca^{2+}$ addition. However, since EDTA and EGTA did not inhibit ScAmy43 activity, this enzyme is probably not a metalloprotein. DTT and $\beta$-mercaptoethanol strongly increased the enzyme activity. Starting with soluble starch as substrate, the end products were mainly maltotriose, suggesting for this enzyme an endo action.

• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1077-1083
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• 2012

Previously, an extracellular ${\alpha}$-amylase (BKA) had been purified from the culture of Bacillus sp. KR8104. Subsequently, the crystal structure of the active enzyme revealed a 422 amino acids polypeptide. In this study, the bka was cloned into E. coli, which encoded a polypeptide of 659 amino acids including two additional fragments: one 44 residues N-terminal fragment and another 193 residues C-terminal fragment. In order to investigate the role of the C-terminal fragment, two constructs with and without this region [$BKA{\Delta}$(N44) and $BKA{\Delta}$(N44C193)] were designed and expressed in E. coli BL21. The optimum pH, thermal stability, and the end-products of starch hydrolysis were found to be similar in both constructs. The $K_m$ and $V_{max}$ values for $BKA{\Delta}$(N44) were lower than $BKA{\Delta}$(N44C193), using either starch or ethylidene-blocked 4-nitrophenylmaltoheptaoside as a substrate.