• Korean journal of food and cookery science
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• v.15 no.5
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• pp.533-538
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• 1999

${\alpha}$-amylase was investigated as an antistaling agent for Backsulgie, a traditional rice cake. Rice powder was mixed with ${\alpha}$-amylase, fermented for 2 hr at 37$^{\circ}C$, and steamed for 20 min. Rice cake was stored at room temperature or freezer for 4 days, and analyzed to determined the changes of chemical and sensory properties. When ${\alpha}$-amylase was added to rice cake, the content of reducing sugars and the yellow color of the cake were increased, and the water activity was decreased. Soft and moist textural properties were apparent in ${\alpha}$-amylase-added rice cakes by sensory evaluation. X-ray diffraction showed a V pattern after 4 days of storage which indicated the starch of rice cake was not retrograded. However, there was no significant difference in moisture content between enzyme-treated and non-treated rice cakes. Above results suggest that ${\alpha}$-amylase treatment produced dextrins which consequently bound with water and inhibited the retrogradation of rice cake.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.803-810
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• 1998

The mechanical and thermal properties of solutions of acorn starch were investigated, to determine the effect of sucrose on the retrogradation. The contents of moisture and amylose of purified acorn starch was 9.35, 27% respectively. From the moecular weight distribution, Mw and Mn of acorn starch were 1,220,432 and 137,201 relatively and the polydispersity of acorn starch was 8.8952. The creep compliance of acorn starch with and without sucrose were decreased with increasing sucrose concentration in the short term. The temperatures of DSC curve of 15% acorn starch solution containg sucrose shifted slightly to higher temperatures with increasing sucrose content. The enthalpy change associated with the gelatinization was increased with increasing sucrose content. After 7 days storage, the creep compliance of acorn starch gel with sucrose were shown higher than acorn starch gel. Regelatinization enthalpy of acorn starch/sucrose/water system was decreased with increasing sucrose content and increased with storage time. In addition, the characteristic temperatures such as onset temperature, peak temperature and conclusion temperature was increased by sucrose addition. Retrogradation ratio decreased with increasing sucrose content, thus sucrose inhibit retrogradation in the long term. Sucrose acts as an antistaling reagents and retatards the retrogradation.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.681-684
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• 2005

A maltopentaose-producing amylase (G5-amylase) from Bacillus megaterium KSM B-404 was applied to retard bread retrogradation. Retrogradation rates were determined by differential scanning calorimetry. Gel permeation chromatography determined changes in maltooligosaccharide composition and the molecular weight profiles of carbohydrate tractions. The baking process produced maltopentaose and maltotriose by the hydrolysis of starch molecules into small units. Amylose and amylopectin degradation as well as maltooligosaccharides produced by the enzyme were likely responsible for retarding starch retrogradation. Overall, addition of G5-amylase reduced the starch retrogradation rate, and was as effective as Novamyl(R), a commercial enzyme.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1438-1443
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• 2009

The effects of adding additives such as gum, emulsifier, and enzyme both individually and as mixtures to frozen rice bread dough on baking quality were examined. Rice flours containing 17% vital gluten, and gum/emulsifier/enzyme blends were mixed and stored in a freezer at $-20^{\circ}C$ for 4 weeks. The rice doughs were removed from the freezer, thawed, and then followed the rice baking procedure. The dough freezing and frozen storage resulted in decreased volume of rice bread. The addition of guar gum/sodium stearoyl lactylate (SSL)/fungal $\alpha$-amylase blend improved volume of the rice bread obtained from rice dough during frozen storage. An increase in firmness of crumb was observed in rice breads during 3 days of storage at $25^{\circ}C$. Compared to the control dough without additives, addition of guar gum/ SSL blend or guar gum/ SSL/ fungal $\alpha$-amylase blend into frozen dough significantly reduced the crumb firmness of rice bread, indicating a significant antistaling effect.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.289-293
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• 1997

The effects of different types of additives(sucrose fatty acid ester(SE), oligosaccharide and alum) on 40% nonwaxy rice starch gels stored at $20{\pm}1^{\circ}C$ were investigated by ${\alpha}-amylase-iodine$ method, X-ray diffractometry and differential scanning calorimetry. The addition of SE retarded the retrogradation of gels throughout storage period and the antistaling effect of SE was increased with increasing concentration. Oligosaccharide(0.1%) inhibited the retrogradation, but oligosaccharide(0.1% or 0.5%) retarded the retrogradation at early stage of storage, and stimulated the retrogradation after 3 days. Alum of 0.1% level retarded the retrogradation, but 0.3% level activated the retrogradation after 24 hours and 0.5% level did after 12 hours. The effect of additives on the retrogradation of rice starch gels showed the different tendencies at the level of additives. On 0.1% level, the effect of those was similar but on 0.5%, the degree of retardation increased in order of oligosaccharide, SE1170, alum, no addition for up to 2 days of storage and SE1170, no addition, oligosaccharide, alum for 3 days of storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.6
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• pp.761-766
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• 2008

The effects of various enzymes and emulsifiers on the loaf volume and crumb hardness of rice breads were studied. Four different enzymes [fungal ${\alpha}$-amylase (AMYL), maltogenic bacterial ${\alpha}$-amylase (NMYL), glucose oxidases (GO), and xylanase+hemicellulases (PTP)] and four emulsifiers [sorbitan monostearate (SMS), glycerol monostearate (GMS), sodium stearoyl lactylate (SSL), and glycerol ester+propylene glycol ester+sucrose ester+sorbitan ester (SP)] were supplemented to rice dough. The addition of AMYL, GO, and GO+AMYL increased loaf volume of rice breads. The highest loaf volume was observed in rice bread supplemented with AMYL. Rice breads supplemented with enzymes firmed at lower rates during storage, and AMYL, NMYL, and GO considerably decreased crumb hardness of rice breads, exhibiting a significant antistaling effect. The addition of emulsifiers produced rice breads with better specific loaf volume and crumb texture, and continuously retarded crumb hardness of rice breads during storage. Especially, rice bread supplemented with SSL demonstrated the highest loaf volume and the lowest crumb hardness during storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1262-1269
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• 2003

In this study, enzymes were investigated as an antistaling agent for a Korean rice cake. Thermograms by a DSC demonstrated that the gelatinization-onset temperature of the Korean rice cake was at its lowest temperature of 71.1$^{\circ}C$ with the GP (glucoamylase+pullulanase) treatment, followed by $\beta$-amylase and $\alpha$-amylase. The gelatinization peak temperature of the Korean rice cake with enzyme treatment was relatively lower compared to the control. Furthermore, the Korean rice cake with GP treatment showed the lowest peak temperature. Melting enthalpy of the Korean rice cake increased with the enzyme treatment, with $\beta$-amylase, followed by $\alpha$-amylase and GP. Melting enthalpy of the Korean rice cake with GP treatment was significantly lower compared to the $\beta$- and $\alpha$-amylase treatment. Recrystallinity in the case of GP treatment was also significantly lower than control. The range of Avrami exponent (n) was 0.90 ∼ 1.20 and the time constant of retrogradation (1/k) of the Korean rice cake crystalline decreased in the following order: GP, $\beta$-, $\alpha$ -amylase and control. Textural characteristics of the Korean rice cake with enzyme treatment differed greatly from that of control. The L＊ values of all the Korean rice cakes made without $\beta$-amylase decreased and the a＊ values were significantly different at p<0.05. The GP treatment altered the b＊ value toward blue color, whereas $\beta$-and $\alpha$-amylase changed to the direction to yellow color. In sensory evaluation, the Korean rice cake with enzyme treatment showed higher evaluation compared to control.