• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.794-800
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• 1988

The retrogradation properties of waxy starches isolated from waxy rice(Shin sun, Tong il), waxy barley(Suwon # 227), waxy indian millet. waxy millet and Jobs tears(Yullmoo) were investigated. The extent of retrogradation determined by the glucoamyase method during freeze-thaw treatment and storage in low temperature$(0{\sim}5^{\circ}C)$ showed that six kinds of waxy starches were very slowly retrograded. The order of the retrogradation tendencies of these starches were waxy indian millet > Suwon # 227 Waxy millet > Yullmoo > Tong il > Shin sun. Waxy indian millet and Suwon # 227 starches were distinctively retrograded compared with other starches. Retrogradation properties observed during freeze-thaw 30 cycles were similar to those of storage for 30 days at $0{\sim}5^{\circ}C$. Suwon # 227, which has been the only recommened variety in our nation, was composed of 15% of non-waxy starch and 85% of waxy starch granule.

• 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.