• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1386-1392
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• 2008

A gene (sll0158) putatively encoding a glycogen branching enzyme (GBE, E.C. 2.4.1.18) was cloned from Synechocystis sp. PCC6803, and the recombinant protein expressed and characterized. The PCR-amplified putative GBE gene was ligated into a pET-21a plasmid vector harboring a T7 promoter, and the recombinant DNA transformed into a host cell, E. coli BL21(DE3). The IPTG-induced enzymes were then extracted and purified using Ni-NTA affinity chromatography. The putative GBE gene was found to be composed of 2,310 nucleotides and encoded 770 amino acids, corresponding to approx. 90.7 kDa, as confirmed by SDS-PAGE and MALDI-TOF-MS analyses. The optimal conditions for GBE activity were investigated by measuring the absorbance change in iodine affinity, and shown to be pH 8.0 and $30^{\circ}C$ in a 50 mM glycine-NaOH buffer. The action pattern of the GBE on amylose, an $\alpha$-(1,4)-linked linear glucan, was analyzed using high-performance anion-exchange chromatography (HPAEC) after isoamylolysis. As a result, the GBE displayed $\alpha$-glucosyl transferring activity by cleaving the $\alpha$-(1,4)-linkages and transferring the cleaved maltoglycosyl moiety to form new $\alpha$-(1,6)-branch linkages. A time-course study of the GBE reaction was carried out with biosynthetic amylose (BSAM; $M_p{\cong}$8,000), and the changes in the branch-chain length distribution were evaluated. When increasing the reaction time up to 48 h, the weight- and number-average DP ($DP_w$ and $DP_n$) decreased from 19.6 to 8.7 and from 17.6 to 7.8, respectively. The molecular size ($M_p$, peak $M_w{\cong}2.45-2.75{\times}10^5$) of the GBE-reacted product from BSAM reached the size of amylose (AM) in botanical starch, yet the product was highly soluble and stable in water, unlike AM molecules. Thus, GBE-generated products can provide new food and non-food applications, owing to their unique physical properties.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.306-312
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• 1995

In order to know properties in rice starch during storage of rice, rice starch from stored rice(stored at $5^{\circ}C$, R.H. 65% and $30^{\circ}C$, R.H. 85%, for 16 weeks) used in this experiment. Water binding capacity of rice starch increased for 8 weeks, and then it decreased. As the storage period took longer, swelling power and solubility, optical transmittance, blue value, total amylose content and soluble amylose content decreased. For the same periods, changes in rice starch from stored rice$(30^{\circ}C$, R.H. 85%) were made more than those in rice starch at $5^{\circ}C$, R.H. 65%. The granule shape of rice starch, irrespective of storage periods and conditions, didn't make a significant difference. The relative crystallinity of the rice starch by X-ray diffraction didn't distinctly changed till the second week. But, at the fourth week, that by X-ray diffraction significantly decreased, and then slightly decreased. As the storage period took longer, gelatinization temperature, melting temperature and melting enthalpy measured by DSC got higher, but gelatinization enthalpy got lower. For the same storage period, gelatinization temperature, melting temperature, gelatinization enthalpy and melting enthalpy of rice starch stored at $30^{\circ}C$, R.H. 85% made changes more than those of rice starch stored at $5^{\circ}C$, R.H. 65% did.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.4
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• pp.304-313
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• 2018

The objective of this study was to investigate the resistance starch(RS) content and in vitro hydrolysis index of roasted rice flours for low GI food development. This study used intermediate and high amylose rice varieties containing resistant starch. The intermediate amylose rice varieties 'Ilmi' and high amylose rice varieties, 'Goami4' and 'Dodamssal' were tested. The crude fat and crude protein contents of the rice cultivars ranged 2.12~3.08% and 6.2~7.63%, respectively. The RS and amylose contents of Dodamssal and Goami4 were higher than those of Ilmi. RS content of Ilmi was not significantly different before and after roasting treatment. The RS content of Goami4 before roasting was significantly higher than that of Dodamssal, but the RS content of Dodamssal was higher than that of Goami4 at temperatures above $210^{\circ}C$ of roasting. The soluble starch decreased after roasting in Goami4 and Dodamssal. Starch hydrolysis index (HI) and expected glycemic index (GI) were higher in order of Imi, Goami4 and Dodamssal regardless of roasting treatment. The sensory evaluation showed high scores in Dodamssal for color, flavor, bitter taste, bitter taste, sweet taste and sweetness at $240^{\circ}C$ for 10 min and $210^{\circ}C$ for 30 min. The results of this study indicate that Dodamssal was suitable varieties for powder meal with low GI.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.636-643
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• 2001

Bacillus sp. AIR-5, a strain from soil, produced an extracellular maltopentaose-forming amylase from amylose and soluble starch. This bacterium produced 8.9 g/l of maltopentaose from 40 g/l of soluble starch in a batch fermentation and the maltopentaose made up 90 % of the maltooligosaccharides produced (from maltose to maltoheptaose). The culture supernatant was concentrated using a 30 K molecular weight cut-off membrane and purified by DEAE-Cellulose and Sephadex G-150 column chromatographies. The purified protein showed one band on a native-PAGE and its molecular mass was estimated as 250 kDa. The 250-kDa protein was composed of tetramers of a 63-kDa protein. the isoelectric point of the purified protein was pH 6.9, and the optimum temperature for the enzyme activity was $45^{\circ}C$. The enzyme was quickly inactivated above $55^{\circ}C$, and showed a maximum activity at pH 8.5 and over 90% stability between a pH of 6 to 10. The putative N-terminal amino acid sequence of AIR-5 amylase, ATINNGTLMQYFEWYVPNDG, showed a 96% sequence similarity with that of BLA, a general liquefying amylase.

• Journal of the Korean Society of Food Culture
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• v.26 no.5
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• pp.513-520
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• 2011

This study was carried out to investigate the physicochemical properties of mung bean starch and the texture of cold-stored (5$^{\circ}C$ for 0, 24, 48, and 72 hours) mung bean starch gels added with soy bean oil (0, 2, 4, 6%). The swelling power of mung bean starch added with soy bean oil did not significantly change, whereas solubility increased significantly. Soluble carbohydrate content of mung bean starch added with soy bean oil decreased without any significant differences, whereas soluble amylose content decreased significantly. In RVA viscosity, pasting temperature and peak viscosity of mung bean starch added with soy bean oil were not significantly different, whereas minimum viscosity decreased and breakdown and consistency increased significantly. In RVA viscosity, there were no differences according to concentration of soy bean oil. DSC thermograms show that onset temperature of mung bean starch added with soy bean oil did not significantly change, whereas the enthalpy increased in the case of 4% and 6% oil addition. Rupture properties of freshly prepared mung bean starch gels added with soy bean oil increased in the case of 2% and 4% oil addition, and oil addition to mung bean starch gels suppressed changes in rupture properties during cold storage. There were no significant differences in the texture of freshly prepared mung bean starch gels added with soy bean oil, whereas hardness, chewiness, and gumminess of cold-stored mung bean starch gels added with soy bean oil decreased. In the above textural charactristics, there were no differences due to concentration of soy bean oil. Thus, the addition of 2-4% soy bean oil to mung bean starch is appropriate for improving the quality characteristics of cold-stored mung bean starch gels.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.49-53
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• 1996

Acid-modified starch was prepared by treating a warm aqueous starch suspension with dilute mineral acid$(0.2\;N\;HCl,\;45^{\circ}C,\;20\;mim{\sim}1\;h)$. The swelling power and solubility of acid-modified red bean starches increased and the changes occurred at tower temperature. According to gel chromatography of starches, the amylose and amylopectin moieties of red bean starches were not affected very much by hydrolysis conditions used. The elution profiles of soluble carbohydrate showed that the larger molecules were leached as the heating temperature increased. Total amounts of soluble carbohydrate were increased by acid-modification. The gel strength of acid-modified starches at each temperature increased, whereas cohesiveness decreased in acid-modified starch gels except at $85^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.1
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• pp.45-54
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• 1994

Cooking characteristics of ninety five non-glutinous and twenty six glutinous varieties were checked for understanding the varietal variation and interrelationship between the cooking and physicochemical properties of rice grain. The greatest variation in non-glutinous and glutinous rice varieties was observed in iodine blue value and the next large variation was recognized in amount of soluble solid in cooking water. Average values of volume expansion rate, iodine blue value and amounts of soluble solid in cooking water were different among domestic-bred japonica, Korean local and foreign rice varieties. Korean-bred japonica rice cultivars can be classified into several groups having same cooking quality such as <Jangan.·Seoan>, <Jinmi·Ilpum· Daeseong>, <Seohae·Namwon·Yeongduk>, <Chucheong·Bongkwang>, <Odae·Keumo> and <Hwacheong·Donghae·Palgong> by the distribution on the plane of 1st and 2nd principal components contracted from four cooking characteristics. Glutinous rice cultivars can be grouped into several different cooking quality types such as <Nonglimna 1·Suwon 357·Jodo·Inbujinado>, <Sangnambatbyeo·Jeokdo>, <Mujudo·Daigol-mochi>, <Daegoldo·Jindo>, <Jinbuchal·Colored Daegoldo>, <Shinseonchal·Hung-Tsan> and <Agudo·Irakdo> by the same analysis. Positive correlation was found between volume expansion rate and water absorption rate at 21℃. Iodine blue value was correlated negatively with amounts of soluble solid, and positively with amylose content in non-glutinous rices. In glutinous rices volume expansion rate showed positive relationship with iodine blue value, amounts of soluble solid and gel consistency. Iodine blue value was also positively correlated with alkali digestion value in glutinous rice.

• Journal of Microbiology and Biotechnology
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• v.5 no.2
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• pp.61-67
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• 1995

To investigate the role of induction on CGTase production for alkalophilic Bacillus firm us var. alkalophilus H609, the constitutive mutants that form a halo around its colonies at non-inducible AG agar media containing amylose and glucose were selected. The selected constitutive mutants could produce CGTase in the range of 18.9 to 28.8 units/ml $\cdot A_{600}$ in the alkaline basal medium, and finally a constitutive mutant Bacillus firmus var. alkalophilus CM46 was selected. The constitutive nature of CM46 was also confirmed in protein level using SDS-PAGE. The effects of induction and catabolite repression for both parent strain Bacillus firmus var. alkalophilus H609 and constitutive mutant CM46 were also compared by adding soluble starch and glucose during cultivation. The selected mutant CM46 was a non-inducible but a catabolite regulated type mutant. Even though inductive regulation was released, the specific CGTase activity defined as CGTase activity per cell concentration was not increased compared with that of parent strain. The cell growth and CGTase production patterns of constitutive mutant Bacillus firmus var. alkalophilus CM46 were compared with the parent strain to identify CGTase production characteristics.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.269-269
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• 2017

Germination is one of the techniques used to enhance the texture properties and nutritional value of the brown rice (BR). Therefore, germinated BR (GBR) has received significant attention during the last decade. Physicochemical and cooking properties of brown rice were examined before and after germination. Germination raised the cooking properties, such as water absorption, expanded volume and soluble solid of cooked BR (brown rice). The texture, measured using tensipresser, was significantly improved by germination. The hardness of cooked BR was decreased by germination, but the GBR was sticker. In RVA, all viscosity value (peak viscosity, break down, set back, and final viscosity) of germinated rice flour was also reduced while gelatinization temperature did not change. Amylose content and amylopectin chain length distribution of BR starch were slightly changed by germination. Overall results revealed that germination was an effective tool to improve texture and cooking properties of BR.

• Applied Biological Chemistry
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• v.34 no.1
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• pp.21-25
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• 1991

Twenty-six japonica and 19 Tongil type milled rices were grouped based on water uptake rate at $23^{\circ}C$ and interrelationships between starch properties and hydration group were investigated. There were no significant differences in relative crystallinity, transmittance increase rate of 0.1% starch suspension and soluble amylose between japonica and Tongil type rices. The gel volume of starch n 3M KSCN solution of Tonsil type rice starch was significantly higher than that of japonica one. However, no correlations were observed between starch properties and hydration groups.