• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.166-172
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• 1997

Aspergillus niger was selected as a strain producing the potent raw starch hydorlyzing enzyme. These experiments were conducted to investigate the conditions of the glucoa- mylase production, the purification of the enzyme, some characteristics of the purified enzyme and hydrolysis rate on various raw starches such as com, rice, potato, glutinous rice, sweet potato, wheat and barley. The optimum cultural temperature and time for the enzyme production on wheat bran medium were $30^{\circ}C$ and 96hrs, respectively. The respective addition of yeast extract and nutrient broth on wheat bran medium increased slightly the enzyme production. The enzyme was purified by ammonium sulfate fractionation and DEAE-cellulose column chromatography. The specific activity of the purified enzyme was 30.7u/mg-protein and the yield of enzyme activity was 25.8%. The purified enzyme showed a single band on polyacrylamide disc gel electrophoresis and its molecular weight was estimated to be 56,000 by SDS-polyacrylamide disc gel electrophoresis. The isoelectric point for the purified enzyme was pH3.7. The optimum temperature and pH were $65^{\circ}C$ and pH 4.0, respectively. The purified enzyme was stable in the pH range of pH 3.0-9.5 and below $45^{\circ}C$, and its thermal stability was slightly increased by the addition of $Ca^{2+}$. The purified enzyme was activated by $Co^{2+},\;Sr^{2+},\;Mn^{2+},\;Fe^{2+},\;Cu^{2+}$. Raw rice starch, raw corn starch, raw glutinous rice starch, raw sweet potato starch, raw wheat starch and raw barley starch showed more than 90% hydrolysis rate in 48hrs incubation. Even raw potato starch, most difficult to be hydrolyzed, showed 80% hydrolysis rate. The purified enzyme was identified as glucoamylase.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.876-881
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• 1997

The relationship between the molecular structure of acid-hydrolyzed rice starch and the retrogradation rate of starch gel was investigated. The molecular structure of starch was modified by acid hydrolysis with 1 N HCl at $35^{\circ}C$. The molecular weight of starch decreased as acid hydrolysis time was increased. At the early stage of hydrolysis up to 3 hr, the branching point of amylopectin was degraded and thereafter both ${\alpha}-1,4\;and\;{\alpha}-1,6$ linkages were hydrolyzed. The starch gel (50%) stored at $20^{\circ}C$ revealed that the rapid retrogradation occurred during 4 hr of storage which was more pronounced as the hydrolysis time increased. The degree of retrogradation of starch gels after 4 hr storage showed a linear relationship with the yield of hydrolyzate. These results suggested that the retrogradation of starch gel was accelerated by degradation of ${\alpha}-1,6$ linkages with acid.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.190-195
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• 1992

In the polyethylene glycol/dextran aqueous two-phase systems, volume ratio was increased and partition coefficient was decreased with the increase of potyethylene glycol molecular weight and concentration. However the volume ratio was decreased and the partition coefficient was increased with the increase of dextran molecular weight. On the other hand, the volume ratio and the partition coefficient were decreased with the increase of dextran concentration. Continuous enzymatic hydrolysis of soluble starch with $\alpha$-amylase which was produced by Bacillus amyloliquefaciens IF0 14141 was investigated in polyethylene glycol/dextran aqueous two-phase systems. Nonreacted soluble starch and $\alpha$-amylase were reused in these systems. $\alpha$-Amylase activity was maintained more than 100 hrs by recycling of $\alpha$-amylase from bottom of settler to reactor.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.475-478
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• 1994

The hydrolyzability of chemically modified starches and ramen staches was determined by hog pancreatic ${\alpha}-amylase$ in vitro test. The extents of hydrolysis were 64.5% and 59.3% in native and acetylated potato starch, 70.5% and 60.4% in native and hydroxypropylated corn starch, and 65.2% and 57.3% in native and hydroxypropylated high amylose corn starch, respectively. The hydrolysis extents of waxy corn starch derivatives were shown in the descending order of pregelatinized (74.3%)>native (72.1%)>acetylated (66.5%)>acetyl distarch adiphate (56.4%)>hydroxypropyl distarch phosphate (50.7%). In the test on starches of container and regular ramen cooked by practical way, no significant difference was observed between ramen products of five different makers. Although the hydrolysis rate and extent of chemically modified starches were lower than those of native starches, the digestibility of ramen seemed to be not affected in the common diet as the use level of modified starch was relatively low.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.6
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• pp.78-87
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• 2013

Even though the notice No. 2010-11 of the Ministry of Food and Drug Safety Administration that has been applied to analyze the content of the water soluble residue eluted from multi-layer paperboard was abolished in 2011, its application for the analysis on evaporation residue is still valid. There are very high possibilities that the noticed existing method gives the misleading result on the evaporation residue due to the water soluble starch eluted from the multi-layer paperboard. The quantitative analysis on water-soluble residue with starch content correction has been carried in the study using UV/Vis spectroscopy and HPLC. The UV/Vis spectroscopy absorbance analysis showed the large amount of the oxidized starch obtained from the aqueous residue eluted out of the multi-layer paperboard after the iodine, ${\alpha}$-amylase reaction, and starch hydrolysis. The residual content decreased by the correction through the enzyme hydrolysis.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1260-1265
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• 2007

Magnetically separable enzyme-coated nanofibers were developed for the hydrolysis of starch. Stability of ${\alpha}-amylase-coated$ nanofiber was greatly improved and its residual activity was maintained over 92.7% after 32 days incubation at room temperature and under shaking conditions (200 rpm). The recovery of enzyme was high and enzyme activity after 10 recycle was 95.2% of its original activity. Developed enzyme-coated nanofibers were used for the hydrolysis of starch. When 0.5 mg of magnetically separable enzyme nanofibers was used, 40 g/l of starch (2 ml) was completely degraded within 40 min. The continuous enzyme reactor was developed and used for starch hydrolysis and 76% of starch (30 g/l) was hydrolyzed with 1 hr residence time.

• Korean journal of food and cookery science
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• v.32 no.4
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• pp.426-432
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• 2016

Purpose: The consumption of noodles has increased domestically. However, noodles with high carbohydrate content can cause an increase in blood glucose compared with other foods. Therefore, in this study, Naengmyeon with high resistant starch was prepared for decreasing blood glucose by the addition of 0.5% citric acid (CN), 1% guar gum (GN) or 0.5% citric acid and 1% guar gum (CGN), and then it was incubated in a refrigerator for 3 days, and stored in a freezer for 1 month. Methods: The quality characteristics of these Naengmyeon noodles was evaluated based on total starch, resistant starch, water absorption, cooking loss, turbidity, in vitro starch hydrolysis, and in vivo glucose response. Results: There was no significant difference in the total starch, cooking loss, and turbidity. The resistant starch of GN (1.70%) and CGN (1.84%) was significantly increased when compared with that in Naengmyeon with no additives (N) and CN. In terms of water absorption, CN (86.01%) was the lowest in samples, followed by GN (92.17%), N (94.20%), and CGN (99.16%). CGN with high resistant starch was the lowest in in vitro starch hydrolysis in samples. However, it had no effect on the in vivo glucose response. In vitro starch hydrolysis exhibited a significant positive correlation (r=0.533; p<0.01) with in vivo glucose response. Conclusion: Therefore, future studies are needed to establish the standard for resistant starch contents in processed carbohydrate foods for delaying the increase in blood glucose. If this standard is established, it might help to develop processed foods for diabetic patients.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.398-402
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• 1984

These experiments were conducted to investigate the substrate specificity, the hydrolysis products on the various carbohydrates and the hydrolysis rate on the various raw starches of the two purified glucoamylase produced by Rhizopus oryzae. Both of the glucoamylases hydrolyzed amylose, amylopectin, glycogen, soluble starch, pullulan, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose and maltooctaose, but did not act on ${\alpha}-cyclodextrin$, ${\beta}-cyclodextrin$, raffinose, sucrose and lactose. When the reaction mixture of glucoamylase and polysaccharides were incubated $37^{\circ}C$for 32 hours, glucoamylase I hydrolyzed amylopectin, soluble starch and amyloses completely, but hydrolyzing glycogen up to only about 88%. Glucoamylase II hydrolyzed the previous four polysaccharides up to about 100%. Both of the glucoamylases produced only glucose for various substrates and did not have any ${\alpha}-glucosyl$ transferase activity. Both of the glucoamylases hydrolyzed raw glutinous rice starch almost complety, wheras they acted on raw potato starch, raw green banana starch, raw arrow root starch, raw corn starch, raw yam starch and raw high amylose corn starch weakly. Glucoamylase II hydrolyzed raw starches at the higher rate than glucoamylase I.

• Journal of Microbiology
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• v.37 no.2
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• pp.80-85
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• 1999

The purification system of glucoamylase (glucan 1,4-${\alpha}$-glucosidase, EC 3. 2. 1. 3), some characteristics of the purified enzyme and hydrolysis rate of various raw starch were investigated through several experiments. The enzyme was produced on a solid, uncooked wheat bran medium of Aspergillus oryzae NR 3-6 isolated from traditional Korean Nuruk. The enzyme was homogeneously purified 6.8-fold with an overall yield of 28.3% by the criteria of disc- and SDS-polyacrylamide gel electrophoresis. The molecular weight was estimated to be 48 kDa by SDS-PAGE. The optimum temperature and pH were 55$^{\circ}C$ and 4.0, respectively. The enzyme was stable at a pH range of 3.0∼10.0 and below 45$^{\circ}C$. Enzyme activity was inhibited about 27% by 1mM Hg2+. The hydrolysis rate of raw wheat starch was shown to be 17.5-fold faster than the hydrolysis rate of soluble starch. The purified enzyme was identified as glucoamylase because the product of soluble starch by the purified enzyme was mainly glucose by thin layer chromatography.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1145-1149
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• 2009

Physicochemical properties of native and acid-modified Job's tears (Coix lachryma-jobi L.) starches were investigated. Starch extracted from Job's tears was treated with 2.2 N hydrochloric acid for different length of time (3, 6, 12, and 18 hr). The hydrolysis pattern of starches with the acid proceeded rapidly up to 12 hr and then the approached constant values. The swelling power of acid-modified starches measured at all temperatures was lower than that of its native counterparts and the water solubility index increased as temperature and hydrolysis time increased. Rapid visco analyzer viscograms of acid-modified starches demonstrated a very low viscosity as compared with that of native starch. However, Xray diffraction did not show any significant alteration in the crystallinity after acid-modification.