• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.3
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• pp.99-105
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• 2023

Starch characteristics and pasting properties of Tongil-type rice varieties with different amylose content were analyzed. Three different Tongil-type rice varieties and one Japonica-type rice variety were examined for their properties. Tongil-type rice varieties have longer panicles and higher rice yield (721-765 kg per 10a) than Boramchan, a Japonica-type high-yield rice variety. The protein content of the Tongil-type rice variety was higher than that of Boramchan. Japonica-type rice varieties had lower amylose content than Japonica-type rice varieties, except for Amimyeon (Milyang355). Amimyeon had higher protein content than the other varieties, and its amylose content was particularly high at 39.2%. The distribution of starch granule sizes of the four varieties was similar, and the particle size corresponding to D50 was approximately 87.8-81.9 ㎛. The pasting properties of rice flour varied among varieties. The Dasanbyeo and Hanarum2 amylogram patterns were similar. These two varieties had a higher peak viscosity (PV) and lower setback (SB) than Boramchan. In the case of Amimyeon, the hot paste viscosity (HPV), cool paste viscosity (CPV), and SB were significantly higher than those of the other Toingil-type varieties, and the breakdown (BD) was very low, showing pasting properties significantly different from that of the other varieties. The onset (T_o), peak (T_p), and conclusion temperature (Tc) of gelatinization of rice flour from Amimyeon were lower than those of the other tested varieties. In addition, the gelatinization temperature, measured using differnetial scanning calorimetry (DSC), and BD, measured using al rapid visco analyzer (RVA) were low in Amimyeon. Amylose content showed a high positive correlation with pasting time (PTi), HPV, and SB and a negative correlation with PV and BD.

• Food Science and Preservation
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• v.24 no.4
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• pp.491-496
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• 2017

Paddy rice is typically stored during postharvest until rice grain is processed into brown rice and milled rice by hulling and milling procedure, respectively. Recently, instead of storing paddy rice, storage of brown rice has been in the spotlight because it is more convenient and economically feasible. Different brown rice cultivars with varying amylose contents including waxy rice, medium-waxy rice, and non-glutinous rice were stored in room temperature storage for four months, and the changes in grain qualities of brown rice were evaluated. Amylose content significantly affected pasting properties in which rice cultivar with higher amylose content showed longer pasting time and higher peak viscosity. Storage also affected pasting viscosities, showing an increase in peak viscosity, but a decrease in breakdown viscosity. The changes in pasting viscosity during storage could be an important starch property for aged brown rice utilization. Waxy brown rice showed the weakest aging property in terms of free fatty acids (FFA) accumulation, whereas non-glutinous rice was more substantial grain quality against aging. The FFA values of two months storage were not significantly different from the initial FFA contents, suggesting that brown rice stored in room temperature for two months could be feasible for direct consumption of brown rice.

• Korean Journal of Food Science and Technology
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• v.51 no.2
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• pp.109-113
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• 2019

The soft rice varieties, Hangaru and Singil, were developed via mutation breeding using N-methyl-N-nitrosourea treatment to obtain dry-milled rice flours. The physicochemical, morphological, and pasting properties of these starches were compared with those of Seolgaeng and Chuchung starches. Singil starch was found to exhibit the highest amylose content and initial pasting temperature, whereas Hangaru starch exhibited the highest water binding capacity and swelling power. Hangaru starch's granule size at $d_{50}$ was the largest among the four different starch types. Some Seolgaeng, Hangaru, and Singil granules were observed to have a round-faced polygon shape. Furthermore, the crystallinity of all four starch types was type A. The peak, trough, and final viscosities of the soft rice starches were also lower than those of normal starches. Notably, Hangaru starch showed the highest breakdown viscosity, but the lowest total setback viscosity among the four starches. From these results, the starch characteristics of the soft rice flours were discovered to be different based on the rice variety.

• Preventive Nutrition and Food Science
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• v.10 no.3
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• pp.207-213
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• 2005

Molecular structures and functional properties of starches isolated from normal, waxy, and zero amylose barleys were examined. Amylopectins from zero amylose starch had the largest molecular weight $(M_w)$, whereas those from high amylose starch, the smallest. A good correlation between the $(M_w)$ and the radius of gyration $(R_g)$ was observed among amylopectins from various starches, indicating similar polymeric conformation in solution even with the differences in the $(M_w)$. The debranched amylopectin molecules from different types of barley starches exhibited similar profiles, implying that the packing geometry of double helices in the different types of barley starches may be similar. Zero amylose starch showed the highest peak viscosity (326 RVU) in RV A viscograms at lower pasting temperature $(67.6^{\circ}C)$, compared to normal and high amylose starches. Relationship between RVA peak viscosity and amylose content suggested that the presence of amylose inhibited the development of granular swelling of barley starches during cooking. A rapid retrogradation, traced by differential scanning calorimetry (DSC) and strain-controlled rheometry, occurred in the high amylose starch sample during storage, while zero amylose starch showed a very good resistance to retrogradation, indicating excellent storage stability.

• Korean journal of food and cookery science
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• v.32 no.4
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• pp.524-530
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• 2016

Purpose: The properties of starch and starch gel prepared from a newly inbred sweet potato, Daeyumi were compared to the properties of starch and starch gel prepared from Sinyulmi which is a well known mealy type sweet potato. Methods: The starch was isolated by using the alkaline steeping method. Physicochemical, pasting, and thermal properties, and crystallinity were measured. The texture properties of starch gel (10%, w/w) were examined. Results: The amylose contents of Daeyumi and Sinyulmi starches were 25.57% and 22.59%, respectively. The initial pasting temperature of Daeyumi starch was significantly higher than that of Sinyulmi starch (p<0.05), but other paste viscosities were not different. The peak and conclusion temperatures of Daeyumi starch were higher than those of Sinyulmi starch by differential scanning calorimetry. The shape of Daeyumi starch gel was more clear and rigid than the shape of Sinyulmi starch gel. The surface and the upper side of Daeyumi starch gel were smoother than the surface and the upper side of Sinyulmi starch gel. Hardness and gumminess were higher in Daeyumi starch gel than in Sinyulmi starch gel. The crystallinity types of Daeyumi and Sinyulmi starches were $C_b$ and A types, respectively, but starch gels showed an amorphous type. Conclusion: Therefore, it is suggested that Daeyumi starch would have better physicochemical properties and higher quality of starch gel than Sinyulmi starch.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.118-123
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• 2009

In order to find out the effect of low level of starch acetylation on physicochemical properties of potato starch, amylose content, digestibility of raw and gelatinized starch, thermal properties, pasting properties, and the swelling power of native and acetylated potato starches were measured. The amylose content was significantly lower in acetylated starch than in their counterpart native starches. Though a tendency in the decrease in digestibility of raw starch was observed with starch acetylation, acetylation did not alter the proportion of readily digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) of both raw and gelatinized potato starches. No clear increase in the swelling power was observed, however, the peak and onset gelatinization temperatures and the enthalpy required for starch gelatinization decreased with starch acetylation. Peak and breakdown viscosities were reduced due to acetylation of potato starch while final viscosity and set back were increased.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.783-788
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• 2007

An advantage to the extrusion of raw potatoes is a reduction in the energy input required to process potato products; however, the effects of extrusion on the properties of raw potato have not been studied. The purposes of this study were to develop a workable extrusion process for raw potato and to study the effects of extrusion conditions on the pasting properties of extruded potato products. The peak viscosity, final viscosity, pasting temperature, water solubility index, and water absorption index of pressed and pressed-dried potato extrudates decreased as die exit temperature increased, whereas they did not change as screw speed increased. The peak viscosity, final viscosity, and water solubility of steam-cooked potato products decreased with extrusion processing; however, they did not change with increasing die exit temperature and screw speed. Potato products with different degrees of depolymerization of extruded potato starch, depending on die exit temperature, were produced from raw potatoes.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1291-1297
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• 2000

Particle size distribution, pasting properties by Rapid Visco Analyser, and textural properties of acorn, mungbean and buckwheat starches, which are the basic raw materials for mook, are compared. The major particle size of mungbean starch was $10{\sim}30$ micron, whereas acorn and buckwheat starches were $5{\sim}20$ micron. At the same starch concentration, mungbean starch had the highest peak viscosity, breakdown and setback. Acorn starch showed the lowest peak viscosity and breakdown. The peak viscosity of buckwheat starch was close to that of mungbean, however the trough and final viscosity were comparable to those of acorn starch. At the same peak viscosity, mungbean starch showed the lowest trough and final viscosity and the highest breakdown and setback. Acorn starch was differentiated from buckwheat starch in that the former had the higher value of setback. The textural properties of mungbean starch gel were significantly different from others. The texture of gels from acorn and buckwheat starches revealed that only the hardness and gumminess were different each other. The hardness of starch gels were negatively correlated with trough and final viscosity, and positively correlated with setback.

• Applied Biological Chemistry
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• v.49 no.1
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• pp.49-54
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• 2006

Physicochemical properties of cross-linked rice starches were investigated. Swelling power of cross-linked rice starch increased at relatively lower temperature $(60^{\circ}C)$ than native rice starch $(70^{\circ}C)$. Cross-linked rice starch showed lower solubility $(1.7{\sim}6.1%)$ than native rice starch $(2.2{\sim}13.8%)$ and solubility is not significantly different with the amount of phosphorus oxychloride. Pasting temperature $(69.2{\sim}70.6^{\circ}C)$ and peak viscosity $(2,874{\sim}3,175\;cp)$ of cross-linked rice starch were lower than native starch $(71.6^{\circ}C,\;3,976\;cp)$, but holding strength $(2,177{\sim}2,708\;cp)$ and final viscosity $(3,424{\sim}3,826 \;cp)$ of cross-linked rice starch were higher than native starch (1,000 cp, 2,312 cp). DSC thermal transitions of cross-linked rice starches were shifted to a lower temperature than native rice starch but there was no significant difference in gelatinization enthalpy between native and cross-linked rice starches. X-ray diffraction pattern of both native and cross-linked rice starches showed typical A-type crystal indicating that cross-linking had not affected the crystalline region of starch.

• 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.