• Applied Biological Chemistry
• /
• v.34 no.1
• /
• pp.26-31
• /
• 1991

The physicochemical properties of starches from dry(Suwon 147) and moist type(Hwangmi) sweet potato were investigated and molecular structural properties of their amylopectins were also studied by gel chromatography. Suwon 147 starch bad lower swelling power and higher gelatinization temperature than Hwangmi starch. $\beta-Amylolysis\;limit(%)$ of Suwon 147 and Hwangmi amylopectin were 57.6% and 57.0%, respectively. Average unit chain length of amylopectins were 24.8 glucose units for Suwon 147 and 21.9 for Hwangmi. The elution profiles by Sephadex G-50 after debranched amylopectins of the two starches were similar but DPs of each peak were different.

• Korean Journal of Food Science and Technology
• /
• v.27 no.1
• /
• pp.105-111
• /
• 1995

The relationship betwwen the molecular structure of amylopectin and the texture of cooked rice was investigated using Korean rice [3 varieties of Japonica type and 3 varieties of Tongil type(Japonica-Indica breeding type)]. The molecular structure of rice amylopectin was polymodal and distributed A chain of $\overline{DP}$ 12.4, short B chain of $\overline{DP}$ 20.6, B chain of $\overline{DP}$ 26.3, long B chain of $\overline{DP}$ 45 and super long chain of above $\overline{DP}$ 55. The super long chain of amylopectin was composed of long linear chain with poorly branched chain. Also, the super long chain of amylopectin showed positive correlated with average chain length, inherent viscosity and ${\beta}-amyloysis$ limit$({\%})$, but negative correlated with ${\lambda}max$ of iodine reaction of amylopectin. The structural properties of amylopectin in Japonica type were different from those of amylopectin in Tongil type. In relationship between molecular structure of amylopectin and texture of cooked rice, the average chain length, inherent viscosity, ${\beta}-amyloysis$ limit and super long chain of amylopectin was showed a positive correlation with hardness, but a negative correlation with adhesiveness of cooked rice. The long chain of rice amylopectin is the less, the eating quality of cooled rice was the better. These results suggest that the molecular structure of rice amylopectin could be responsible for the texture of cooked rice.

• Korean Journal of Food Science and Technology
• /
• v.31 no.5
• /
• pp.1171-1177
• /
• 1999

The changes on microstucture of recombinated gels with different ratio of amylose(A) and amylopectin(AP) which were isolated from nonwaxy rice starch were investigated by scanning electron microscope(SEM) and X-ray diffractometer. As the concentration of amylose was above 3%(1.08% of soluble amylose) in the amylose suspension, gel matrix became like a three-dimensional network. The microstructure of amylose gels showed a network including macroporous structure, but the higher the ratio of amylopectin content were, the firmer network were formed. In case of A/AP mixed gels(15%) with different amylose/amylopectin percent ratios ; 0/5, 5/10, 10/5, 15/0%, as the storage time of gels and the percent ratio of amylose content were increased, network was formed harder with thick films. While X-ray diffractograms of waxy rice starch which contained 100% amylopectin showed A type, those of purified amylose and amylopectin showed V type and amorphous patterns, respectively. Amylose(3%) gels added $2{\sim}3%$ amylopectin and A/AP mixed gels(15%) showed peak at $2{\theta}\;=\;17.0^{\circ}$which were shown B type crystallinity similar af retrograded starches. Also as the percent ratio of amylose content in mixed gels was increased, peak intensity wat increased.

• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.500-506
• /
• 2000

The effects of sodium stearoyl lactylate(SSL) on the thermal properties of wheat starch and amylopectin, and the crystallinity properties of amylopectin were investigated using differential scanning calorimetry(DSC) and X-ray diffractometer. On the rescan(second heating), amylopectin produced the featureless thermogram shown at the second heating, and SSL alone melted at $40{\sim}55^{\circ}C$, while the mixture of amylopectin containing 8% water and SSL(10:1), presenting the evidence of AP-SSL complex, showed differentiate melting temperature(other crystallinity) from SSL alone. Also, the melting enthalpy of AP and SSL mixture by subsequent heating and cooling were continuously increased. Further, the mixtures of wheat starch: SSL (5:1, w/w) and amylopectin: SSL(5:1, w/w), indicated AP-SSL complex, showed the reversible melting peak at temperature range of $60{\sim}70^{\circ}C$ together with melting peak of SSL observed at temperature range of $40{\sim}55^{\circ}C$. AP-SSL complex in the X-ray diffraction, compared V-form of amylose-lipid complex, exhibited characteristic peaks($2{\theta}$, 5.57, 20.903, 23.227). The gelatinization enthalpy value of wheat starch in the presence of SSL, observed at temperature range of $50{\sim}70^{\circ}C$, was decreased at total water content 60%, whearas had no significant effect at total water content 40, 50%, and also, SSL increased melting enthalpy of amylose-lipid complex. The extent of AP and wheat starch retrogradation wasreduced significantly by SSL.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.61 no.1
• /
• pp.1-8
• /
• 2016

The objective of this study was to evaluate quality properties, including amylopectin content, and texture analysis of brown rice and germinated brown rice cultivars in Korea for rice processing products. The amylopectin short chain content of germinated brown rice was significantly higher than that of brown rice. Texture analysis test showed that germinated brown rice Jinbo had the lowest hardness and toughness as well as and highest stickiness and adhesiveness. The correlation between degree of polymerization of amylopectin and texture analysis was also evaluated. In particular, germinated brown rice, short-chain amylopectin showed a negative correlation with hardness and toughness, whereas long-chain amylopectin showed a positive correlation with hardness, toughness, and adhesiveness. These results indicate that there is a relationship between degree of polymerization and texture analysis.

• Applied Biological Chemistry
• /
• v.33 no.1
• /
• pp.34-38
• /
• 1990

The molecular structural properties of amylopectins of Chunmabyeo(Japonica), Yongmunbyeo($Indica{\times}Japonica$) and Mahatma(Indica) rice were investigated. The intrinsic viscosity of Chunmabyeo, Yongmunbyeo and Mahatma amylopectin were 148.3 ml/g, 156.6 ml/g and 167.5 ml/g, and ${\beta}-amylolysis$ limit(%) were 54.6, 55.4 and 52.9 respectively. Average unit chain length(${\overline{CL}}$) and average inner chain length(${\overline{ICL}}$) of Mahatma amylopectin were longer than other varieties. Elution profiles by Sephadex G-50 chromatography of debranched amylopectins with ${\beta}-amylase$ showed two peaks (void volume, ${\overline{DP}}$3) and the elution profiles of debranched amylopectins with pullulanase showed three peaks(void volume, ${\overline{DP}}$35-45, ${\overline{DP}}$10-20). The ratio of Peak III(${\overline{DP}}$10-20) to Peak II (${\overline{DP}}$ 35-45) of Chunmbyeo, Yongmunbyeo and Mahatma amylopectin were 3.9, 3.4 and 3.3, respectively.

• Applied Biological Chemistry
• /
• v.43 no.4
• /
• pp.241-246
• /
• 2000

In order to investigate structural properties of Chindo black rice(grown in Chindo, Chonnam) starch and its amylopectin, Chindo black rice was investigated in comparison to Shinsun waxy rice. The maximum absorbance wave and intrinsic viscosity of Chindo black rice starch and Shinsun waxy rice starch were 523 nm, 521 nm and 183 ml/g, 178 ml/g, respectively. ${\beta}-amylolysis$ limit(%) of Chindo black rice and Shinsun waxy rice starch were 62.8% and 60.3%, respectively. Chindo black rice was determined to be a waxy rice due to the results of iodine reaction and elution profile on Sephroce CL-2B. The chain of amylopectins in Chindo black rice distributed fraction 1$(F_1)$ of above degree of polymerization$({\overline{DP}})$ 55, fraction 2$(F_2)$ of ${\overline{DP}} $40{\sim}50$ and fraction 3$(F_3)$ of ${\overline{DP}} $15{\sim}20$, and the ratio of $F_3$ to $F_2$ for Chindo black rice was higher than that for Shinsun waxy rice. The super long chain of amylopectin in Chindo black rice was consisted much more than that of Shinsun waxy rice. ${\beta}-limit$ dextrins in Chindo black rice amylopectin distributed $F_1$ of above ${\overline{DP}} 55, $F_2$ of ${\overline{DP}} $30{\sim}45$ and $F_3$ of ${\overline{DP}} $10{\sim}20$. Little difference was shown between elution patterns of the pullulanase treated ${\beta}-limit$ dextrins of Chindo black rice amylopectin and Shinsun waxy rice amylopectin. These results suggest that Chindo black rice starch was similar to Shinsun waxy rice starch.

• Korean Journal of Food Science and Technology
• /
• v.19 no.4
• /
• pp.371-376
• /
• 1987

The structral properties of rice starch and its components were investigated. The intrinsic viscosities of rice starch, amylose and amylopectin solutions were 1.053, 1.772 and 1.596 ml/g, respectively. ${\beta}-amlolysis$ limits of rice starch was 73% and those of amylose and amylopectin were 106 and 56%, respectively. The outer chain length $({\overline{OCL}})$ and inner chain length $({\overline{ICL}})$ of amylopectin were 1.56 and 7.7, respectivety. Debranching of rice starch with pullulanase yield two peaks on Sephadex G-75. The peak I at void volume was principally amylose components and peak II at ${\overline{dp}}$ 25-10, constituted of branched amylopectin. However, the elution profile of debranched amylopectin by pullulanase revealed a bimodal peak distribution at ${\overline{dp}}$ 35-25 hydrolyers and ${\overline{dp}}$ 25-10, and no distinct peak at void volume. The elution profile of the debranched, ${\beta}-amylase$ hydrolyrates of starch and amylopectin yielded major peak at ${\overline{dp}}$ 2-10.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.9
• /
• pp.1388-1393
• /
• 2014

To enzymatically prepare amylopectin cluster (APC), cyclodextrin glucanotransferase (CGTase I-5) and its mutant enzyme from alkalophilic Bacillus sp. I-5 were employed, after which the hydrolysis patterns of CGTase wild-type and its mutant enzyme toward amylopectin were investigated using multi-angle laser light scattering. CGTase wild-type dramatically reduced the molecular weight of waxy rice starch at the initial reaction, whereas the mutant enzyme degraded waxy rice starch relatively slowly. Based on the results, the molecular weight of one cluster of amylopectin could be about $10^4{\sim}10^5g/mol$. To determine production of cyclic glucans from amylopectin, matrix-assisted laser desorption ionization time-of-flight mass spectrometry was performed. CGTase I-5 produced various types of cyclic maltooligosaccharides from amylopectin, whereas the mutant enzyme hardly produced any.

• Applied Biological Chemistry
• /
• v.35 no.2
• /
• pp.92-98
• /
• 1992

Some physicochemical properties and molecular structure of cow pea, mung bean and acorn starches(mook-forming starches) and red bean, wheat and sweat potato starches(mook-unforming starches) were investigated. Amylose contents of cow pea, mung bean and acorn starch were higher than the others. Cow pea starch was similiar to mung bean starch in gelatinization characteristics by Brabender amylogram but cold viscosity of red bean starch and peak viscosity of sweet potato starch were especially high. Whereas viscosity of wheat starch was low in whole temperature range. Amylose molecules of larger molecular size$(above\;5{\times}10^5\;molecular\;weight)$ of three mook-forming starches were more than shoes of red bean and wheat starch. Chain distribution ratios$(DP\;35{\sim}55\;to\;DP\;10{\sim}20)$ of cow pea, mung bean and acorn amylopectin were higher than thoes of red bean, sweet potato and wheat amylopectin.