• 한국작물학회지
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• 제61권4호
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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.

• 한국식품과학회지
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• 제27권1호
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• pp.105-111
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• 1995

밥의 식미가 다른 일반계와 통일계 쌀을 대상으로 아밀로펙틴과 그 베타-한계덱스트린의 분자구조적 특성을 조사하고 밥의 텍스쳐와의 관련성을 검토하였다. 쌀 전분의 아밀로펙틴 분자구조는, 아밀로펙틴과 베타-한계 덱스트린의 사슬분포로 보아, $\overline{DP}$ 12.4의 A 사슬, $\overline{DP}$ 20.6의 짧은 B 사슬, $\overline{DP}$ 26.3의 중간 B 사슬, $\overline{DP}$ 45의 긴 B 사슬과 $\overline{DP}$ 55 이상의 초장쇄로 이루어진 polymodal이었다. 아밀로펙틴의 초장쇄는 긴 직쇄를 가진 사슬로서 아밀로펙틴의 평균 사슬길이, 고유점도, 베타-아밀라아제 분해한도와 정의 상관을 보이나 요오드 복합체의 최대흡수파장과는 부의 상관을 보였다. 아밀로펙틴과 베타-한계 덱스트린의 분자구조적 성질은 일반계와 통일계 쌀 시료간 차이를 보였다. 아밀로펙틴의 A 사슬에 대한 B 사슬의 비율은 일반계가 통일계 보다 약간 높았으나 초장쇄의 분포 비율은 일반계가 통일계 보다 더 낮았다. 아밀로펙틴의 분자구조와 밥의 텍스쳐와의 관계에서, 고유점도, 베타-아밀라아제 분해한도와 사슬길이 그러고 초장쇄는 밥의 경도와 정의 상관을, 부착성과는 부의 상관을 보였다. 따라서 밥의 식감은 아밀로펙틴의 긴 사슬이 적고 짧은 사슬이 많이 분포할 수록, 밥의 경도가 낮고 부착성이 높았다. 이러한 결과는 아밀로펙틴의 분자구조가 밥의 텍스쳐와 밀접한 관계가 없음을 나타내고 있다.

• 한국식품과학회지
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• 제27권5호
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• pp.757-761
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• 1995

밥의 텍스쳐에 대한 일련의 연구에서 식미와 관련성이 있는 열수 가용성 쌀 전분에 대하여 분자 구조적 측면에서 그 관련성을 구명하고자 하였다. 열수 가용성 쌀 전분의 분자 구조는 분자 크기가 작은 아밀로오스와 평균 사슬길이 $10{\sim}20$ 글루코오스 단위로 된 아밀로펙틴이 7 : 3 정도로 결합하고 있었다. 열수 가용성 쌀 전분의 용출율은 아밀로오스의 분자 크기가 작을수록, 아밀로펙틴의 초장쇄가 적을수록 높았으며, 전분의 열수 가용화는 전분의 분자 구조와 밀접한 관계가 있었다. 또한, 밥의 텍스쳐는 열수 가용성 쌀 전분의 용출율이 높을수록 경도는 낮고, 부착성은 높았다. 이러한 결과들로 볼때, 밥의 텍스쳐는 쌀 전분의 분자 구조와 밀접한 관계가 있음을 알 수 있었으며 전분의 열수 가용화 되는 성질은 쌀의 식미 평가 지표로서의 가능성이 시사되었다.

• 한국식품조리과학회지
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• 제30권6호
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• pp.716-725
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• 2014

Gelatinization properties and the molecular structure of Korean waxy rice starchesisolated from two japonica types, Sinseonchal, and Dongjinchal, as well as an indica type, Hangangchal 1 were investigated. Sinseonchal is preferred cultivar for making Korean traditional rice cakes and cookies. Sinseonchal starch was the highest in crude protein, amylopectin, damaged starch contents, and water binding capacity among the cultivars tested. The initial pasting temperature ($72.75^{\circ}C$), peak (360.54 RVU), breakdown (162.21 RVU) and setback (30.83 RVU) viscosities of Sinseonchal had the highest values (p<0.05). Onset and peak temperatures by differential scanning calorimeter were also the highest in Sinseonchal. The molecular weight of Sinseonchal amylopectin was 5.46 107higher than those of the other cultivars, but its peak height and area were the lowest among them. The amylopectin peak by HPSEC showed a shoulder in the lower molecular weight portion and its relative area decreased in the following order; Sinseonchal > Dongjinchal > Hangangchal 1. On the branch chain length distribution of amylopectin, the proportion of DP13-24 and DP25-36 showed reverse trends, with higher japonica type amylopectin in DP13-24.

• 한국식품과학회지
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• 제31권5호
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• pp.1171-1177
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• 1999

쌀전분으로부터 분리한 아밀로오스와 아밀로펙틴이겔을 형성할 수 있는 최저농도로 아밀로오스와 아밀로펙틴 혼합겔을 제조하여 주사전자현미경과 X-선 회절기를 이용하여 겔 구조를 관찰하였다. 겔을 형성할 수 있는 최저농도인 용해성 아밀로오스 1.08% 농도에 아밀로펙틴을 $1.5%{\sim}7%$ 첨가하면 겔 그물망구조가 잘 형성되었고, 아밀로펙틴을 2%와 3% 첨가한 겔은 저장에 따라 $2{\theta}\;=\;17.0^{\circ}$에서 피크가 커졌다. 15% 아밀로오스/아밀로펙틴 혼합겔을 저장했을 때 아밀로오스 함량이 높을수록 단단하고 안정된 그물망구조를 이루었으며 생전분에서의 겔형성 양상과는 달리 아밀로오스와 아밀로펙틴이 함께 겔메트릭스를 이루는데 참여하는 것으로 생각되었고, 아밀로오스 함량이 증가할수록 $2{\theta}\;=\;17.0^{\circ}$에서 피크의 크기와 결정강도는 커졌다.

• 한국작물학회지
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• 제63권3호
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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.

• 한국작물학회지
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• 제62권4호
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• pp.311-316
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• 2017

The relationship between mean air temperature after heading and starch characteristics of colored rice grains was investigated using three colored rice cultivars. Pasting temperature within each rice cultivar with different harvest times differed. The pasting temperatures of two rice cultivars, Hongjinju and Joseongheugchal, reached the highest at 40 days after heading and decreased during the late harvest time. Distribution of amylopectin in the Hongjinju rice cultivar at the earlier harvest time contained a greater number of very short chains with the degree of polymerization (DP) between 6 and 12 and fewer chains with a DP from 13 to 24 than that of the later harvest time. However, there was little difference in the distribution of the longer chains of $25{\leq}DP{\geq}36$ and $37{\leq}DP$ for latter harvest times compared to that of the earlier ones. It was suggested that the structure of amylopectin affected the varietal differences in patterns of chain length of amylopectin during grain filling. In addition, the control of ripening was different from that causing the pigment effects in the fine structure of amylopectin in the three colored rice cultivars. Larger starch granules were observed in the Joseongheugchal rice cultivar and smaller granules occurred in the Hongjinju rice cultivar. The present study revealed that later harvest times led to a clear increase in the mean granule size of starch in the three colored rice cultivars.

• 한국식품조리과학회지
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• 제13권1호
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• pp.7-15
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• 1997

The composition and polymeric structure of starch are the most important factors to determine the functional properties of rice. In an effort to relate the structural characteristics and its functional properties of starch in rice, molecular structural properties of starch from 6 rice cultivars were analysed. To relate the structure and function of starch the texture of Jeung-pyun made of rice were analyzed during retrogradation. The polymeric structure of rice starch was analyzed by debranching with isoamylase after gelatinization and fractionated with Sephadex G-75 gel filteration. The size fractionated debranched starch was categorized into four groups such as Fraction I, II, III and Intermediate Fraction depending in their max, The fractions with the max higher than 620 nm were designated as Fraction I, while those in the range of 600-620 nm and 540-600 nm as the Intermediate Fraction and Fraction II, respectively. The Fractions with the max lower than 540 were described as Fraction III. The average degree of polymerization (DP) of the Fraction I was estimated to be higher than 200, and those of other fractions, i.e. the Intermediate Fraction I, Fraction II and III were 150,45 and 25, respectively. The levels of Fraction I were varied from II to 35％ of total sugar. The Fraction I showed the linear relationship with the amylse contents, and the Intermediate Fraction, which might contain the mixture of short chain of amylose and debranched long chain of amylopectin, were measured to be in the range of 2.7∼8.4%. The levels of fraction II and III, both to be considered as the branches of amylopectin, were ranged 14.5∼23.6% and 39.7∼73.0%, respectively. The ratio of Fraction III to Fraction II describing the degree of branch or compactness of amylopectin was estimated to be around 4.0 for waxy varieties and around 2.0 for high amylose cultivars. With these results, it can be suggested that the degree of branch of the amylopectin may effect on amylose contents of starch or rice versa, To invertigate processing aptitude of different rice cultivars for the preparation of Jeung-pyun, its texture was analyzed by Instron, hardness, cohesiveness, elasticity, gumminess and chewiness of Jeung-pyun made of rice showed the significant relationship with the amylose content. Hardness was increased during retrogradation of product, but the relationship between hardness and amylose content due to not only difference in amylose content but also difference in structural characteristics of starch. In analysis of relationship between structure of rice starch and mechanical properties of Jeung-pyun during retrogradation elasticity did not show any relationship before retrogradation bur during retrogradation showed significant correlation. With these result, it can be suggested that the degree of branch of the amylopectin may effect on elasticity during retrogradation. However hardness, cohesiveness, gumminess and chewiness which were significant different before retrogradation, showed some correlation with structure of rice starch during retrigradation.

• Food Science and Biotechnology
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• 제17권1호
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• pp.176-179
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• 2008

Amylose contents and amylopectin chain architecture of sorghmn and waxy sorghum starches were determined and compared with those of other common cereal and tuber starches. Also, in vitro digestibility of sorghum starch was estimated using a novel methodology. The absolute amylose content of sorghum starch was similar to that of com and wheat starches. The side chain length distribution patterns for sorghum and waxy sorghum amylopectin were very similar to those of com and waxy com, respectively. The $k_{cat}/K_m$ values for sorghum and potato amylopectin did not show a significant difference. The kinetic parameters could be used as novel indicators for starch digestibility.

• 한국작물학회지
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• 제51권6호
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• pp.523-526
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• 2006

When $GA_{4}$ was applied to heading stage, it was examined to understand the change of plant hormones and starch during grain filling and ripening. Exogenous gibberellin caused a dramatic decrease in endogenous ABA content. Endogenous $GA_{4}$ content in both superior and inferior part was more promoted in $GA_{4}-treated$ rice grain than in the control. $GA_{1}$ content of an inferior part was not detected in the control and $GA_{4}-treated$ rice otherwise $GA_{4}$ was detected in all grain parts. Ripened grain rate in $GA_{4}-treated$ rice grain was lower than that of the control plant. Amylopectin from $GA_{4}-treated$ grain contained more very short chains with degree of polymerization (DP) between 4 and 8 than amylopectin from the control plant. It suggests strongly that fine structure of rice endosperm may be changed by exogenously applied $GA_{4}$ in rice plants.