The physicochemical properties of Korean rice flour cultivars (Saemimyeon [SM], Hanareum No. 4 [HA], and Milyang No. 328 [MY]) with different amylose contents were analyzed and the effects of rice flour blending on their physicochemical property changes were investigated in this study. The swelling power of three different cultivars was similar at 60oC, but MY showed significantly enhanced swelling power at 80oC compared to SM and HA. In the pasting profile, MY showed significantly lower final and break-down viscosities than SM and HA due to its weak granular rigidity. In the case of the 1:1 blending of SM-MY and HA-MY, the measured values of swelling power and solubility were greatly decreased at 80oC, and the setback and final viscosity were significantly increased compared to their predicted arithmetic average values, showing the non-additive effects of blending. For the dynamic viscoelastic properties, SM-MY and HA-MY showed significantly decreased G’ and increased k’ and tanδ, compared to their predicted average values. In conclusion, the selected rice flour blends had non-additive effects on swelling power, solubility, pasting, and dynamic viscoelastic properties. These results showed the feasibility of the rice flour blending to diversify the physicochemical properties of rice flour for better processing suitability.

The relationship of in vitro starch digestibility and gel strength was investigated at various concentrations (10-30%) of rice cultivars with different amylose contents (27.9, 17.9, and 5.2%). As the rice flour concentration increased, predicted glycemic index decreased, but gel strength increased regardless of amylose contents. Gel strength correlated strongly with amylose content, whereas in vitro starch digestibility was more highly affected by rice flour concentration than by amylose contents. Moreover, the impact of degree of gelatinization on in vitro starch digestibility of high amylose rice was also examined in terms of structural features and rheological properties. The digestion rate of fully gelatinized flour was 1.7 times higher than that of native flour, while the disrupted structure with a different gelatinization degree during starch digestion was visually demonstrated through the X-ray diffraction and molecular distribution analysis. The rice flour changed from an A-type to a V-type pattern and showed difference in crystalline melting. The low molecular weight distribution increased with increasing degree of gelatinization during starch digestion. The apparent viscosity also increased with degree of gelatinization. These results demonstrated that the starch digestibility of rice was more affected by concentration than by amylose content, as well as by the degree of gelatinization due to structural difference.

In-vitro food mastication has been simulated by incorporating size reduction process, followed by incubation with human saliva. However, they do not suffice to simulate the actual oral breakdown process where disruption by mastication (chewing) and wetting/lubrication by salivation take place simultaneously. In this study, in-vitro oral digestion of rice gels with different amylose contents was simulated by instrumentally performing mastication and salivation. The hardness of artificial saliva-treated rice gels was distinctly lowered with increasing chewing cycles and the rice gels with high amylose contents showed the highest degradation rate. When the rice gels were subjected to non-destructive tomographic analysis, the high amylose rice gels were clearly shown to be favorably fragmented into smaller pieces by chewing, followed by the low and intermediate amylose samples. These results could be explained by their cohesive texture rather than hardness. Therefore, this study may help understanding the changes in the physical properties of cereal-based foods during oral digestion.

As one of the staple crops, rice has been widely applied to value-added products, giving the food industry new avenues of use. Although the quality attributes of various rice products have been reported, there is a lack of detailed information on the rheological behaviors of rice products during digestion that are related to their bioaccessibility in the human body. In this study, three rice varieties with different amylose contents were utilized to produce flours and extruded noodles. In-vitro methods simulating starch digestion processes were then established to monitor their oral-gastric-intestinal rheological behaviors. The rice flour with high amylose content exhibited lower values of water absorption index/swelling power and higher pasting parameters that were in good agreement with the Mixolab thermo-mechanical results. The extruded rice noodles showed lower cooking loss and higher hardness with increasing levels of amylose. When the in-vitro viscosities of rice flours and noodles were measured using a rotational rheometer with the custom-made starch cell, their viscosities had a tendency to decrease as the in-vitro digestion progressed. Specifically, the rice samples with high amylose content exhibited higher viscosity than those with low amylose content under the simulated oral, gastric, and intestinal conditions. Hence, this study was conducted to investigate the physicochemical and in-vitro rheological properties of rice flours and extruded noodles with different amylose content. The results provided a promising opportunity for the food industry to study in-vitro digestion of rice-based products with the advantages of being more rapid and less expensive.

The objective of this study was to determine the physico-chemical properties in the high-amylose rice varieties. The rice flours were analyzed by RVA, DSC, HPAEC, resistant starch kit, SEM, spectrophotometer, etc. According to the RVA measurement of rice flours, the pasting temperature of Dodamssal was higher than those of the others. The proportion of amylopectin short chains (DP 6-12) of the Dodamssal was significantly lower than that of the others. The contents of amylose and resistant starch in the high-amylose rice flours ranged from 19.03% to 38.71% and from 0.6% to 12.39%, respectively. In SEM images, starch granules within Ilmibyeo, Mimyeon, Saegoami rice flours displayed polyhedrons different from those (relatively spherical morphology) of Dodamssal rice flour. According to the DSC results of rice flours, there were significant differences in the onset, peak temperatures of the endothermic peak. Gelatinization enthalpy was 4.52-6.3 J/g, with the lowest change in Dodamssal rice flour.

In order to study the cooking characteristics of four rice cultivars of Seolhyangchal, Baegjinju, Ilpum and Haiami, we investigated the relationship between the textures of cooked rice and their physicochemical properties. Different levels in grain weight. length/width ratio and amylose content were observed among the four rice cultivars. There was no significant difference in the amylopectin chain length distribution among the cultivars. Water absorptions of rice grains during soaking were completed between 30 and 40 min, with Haiami showing the slowest absorption. Significant differences in the viscosity properties of rice flour were found by a Rapid Visco Analyser. Baegjinju with low amylose content had the highest viscosity in paste breakdown. According to the DSC results of rice starches, there were significant differences in the onset, peak and conclusion temperatures of the endothermic peak. Gelatinization enthalpy showed energy content changes between 4.20 and 6.97 J/g, with the lowest change in Haiami. Texture properties of cooked rice were assessed using a Texture Analyzer, which showed that the hardness of cooked rice was decreased with soaking than without soaking. However, this finding was not applicable for Haiami rice.

This study was conducted to determine the agronomic characteristics of low amylose lines which were derived from induced mutants by T-DNA insertion. The agronomic and physicochemical properties of the low amylose mutants were analyzed and compared with a donor cultivar 'Dongjin' and a low amylose cultivar 'Baekjinju'. The heading date of the low amylose mutants was similar to the donor cultivar 'Dongjin' and yield index of the mutants was 78~92% compared with 'Dongjin'. The amylose content of four mutants in brown rice was ranged from 16.1 to 16.7%. Among low amylose mutants, 'P50-4-4-5' was lower 3.6%(13.3%) than those of 'Dongjin'(16.9%) in amylose content of milled rice. The grain length of 'P50-4-4-5' was similar to the donor cultivar, however, thousand grain weight(18.9g) was lighter than those of 'Dongjin'. The score of alkali digestion in brown rice of 'P50-4-4-5'(5.5) was lower than that of 'Dongjin'(6.8) and similar to 'Baekjinju'(5.8). The gel consistency of 'P50-4-4-5'(84mm) in milled rice exhibited that was longer than 'Dongjin'(76mm) and 'Baekjinju'(81mm). The result of eating quality showed that 'P50-4-4-5'(78.8) was higher than those of 'Dongjin'(60.3) and 'Baekjinju'(67.2). Thus our data suggest that 'P50-4-4-5' will facilitate the development of a new cultivar with low amylose rice.

팽화미분을 활용한 타락죽의 제품화를 위한 기초자료를 제공하기 위해서 팽화미분 첨가에 따른 타락죽의 pH, 수분, 고형분, 총당, 아밀로스, 점도, 퍼짐성 그리고 색도 변화를 조사하였다. 타락죽의 pH는 갈은 쌀로 제조한 시료가 팽화미분으로 제조한 시료보다 높았다. 그리고 분유를 첨가한 시료도 우유를 첨가한 시료보다 높았다(p<0.05). 수분 함량은 갈은 쌀과 분유를 혼합한 타락죽이 84.56%로 가장 높았고, 팽화미분과 우유를 혼합한 타락죽은 81.04%로 가장 낮았다(p<0.05). 고형분 함량은 수분함량과 반대되는 결과를 보였다(p<0.05). 총당 함량은 조리 시 가열처리한 시료 사이에서 유의적인 차이가 없었고 가열처리하지 않은 시료보다 높았다(p<0.05). 팽화미분으로 제조한 타락죽의 아밀로스 함량이 갈은 쌀로 제조한 타락죽보다 높았다(p<0.05). 점도는 갈은 쌀 타락죽이 팽화미분 타락죽보다 높았으며(p<0.05) 아밀로스 함량과 반비례하는 결과를 보였다. 퍼짐성은 점도와 상반되는 결과를 보였다(p<0.05). L값은 갈은 쌀 타락죽이 팽화미분 타락죽보다 높았다. 적색도는 팽화미분 타락죽이 가장 높았으며(p<0.05), 갈은 쌀과 우유를 혼합한 시료가 가장 낮게 나타나 L값과 반대되는 결과를 보였다. 황색도는 a값과 유사한 경향을 보였다.

Tarakjuk with different amylose content was made up using roasted rice flours that consisted of the highest enzyme-resistant starch (RS), while differential scanning calorimetry (DSC) was also utilized to measure the gelatinization temperature of these roasted rice flours in order to establish cooking temperature of tarakjuk. The following qualities of tarakjuk with different amylose content were studied: color, viscosity, spreadability, starch fractions involving total starch (TS), rapidly digestible starch (RDS), slowly digestible starch (SDS) and RS, in vitro starch digestibility (IVSD) and sensory properties. During experimentation, it was found that as the amylose content of the rice flour decreased, the L value of tarakjuk decreased, whereas a value increased significantly (p〈0.05). Also, while viscosity showed to increase significantly (p〈0.05), on the opposite end, the property of spreadability decreased. TS ranged from 15.95~17.31%, RDS 9.36~10.16%, SDS 5.46~6.91% and RS 0.33~1.07%, on a dry basis. Although the amylose content of rice flours decreased, IVSD increased, however showing no significant difference. When testing the sensory properties of tarakjuk, color and viscosity increased, whereas clumpiness decreased. Ilpum tarakjuk showed the highest score for nutty taste and overall acceptance levels. In fact a high correlation was shown between nutty taste and overall acceptance level (p〈0.01), which leads one to believe that nutty taste is a prime factor that greatly influences overall acceptance. Furthermore, viscosity was positively correlated with both a and b values, however negatively correlated with L value (p〈0.05). Moreover, roasted nutty taste and overall acceptance were positively correlated with a value (p〈0.05), respectively. In conclusion, the above results suggest that tarakjuk could be made by choosing the appropriate rice flour based on the nutritional or sensory purpose.

This study was carried out to build a database system for amylose and protein contents of rice germplasm based on NIRS (Near-Infrared Reflectance Spectroscopy) analysis data. The average waxy type amylose contents was 8.7% in landrace, variety and weed type, whereas 10.3% in breeding line. In common rice, the average amylose contents was 22.3% for landrace, 22.7% for variety, 23.6% for weed type and 24.2% for breeding line. Waxy type resources comprised of 5% of the total germplasm collections, whereas low, intermediate and high amylose content resources share 5.5%, 20.5% and 69.0% of total germplasm collections, respectively. The average percent of protein contents was 8.2 for landrace, 8.0 for variety, and 7.9 for weed type and breeding line. The average Variability Index Value was 0.62 in waxy rice, 0.80 in common rice, and 0.51 in protein contents. The accession ratio in arbitrary ranges of landrace was 0.45 in amylose contents ranging from 6.4 to 8.7%, and 0.26 in protein ranging from 7.3 to 8.2%. In the variety, it was 0.32 in amylose ranging from 20.1 to 22.7%, and 0.51 in protein ranging from 6.1 to 8.3%. And also, weed type was 0.67 in amylose ranging from 6.6 to 9.7%, and 0.33 in protein ranging from 7.0 to 7.9%, whereas, in breeding line it was 0.47 in amylose ranging from 10.0 to 12.0%, and 0.26 in protein ranging from 7.0 to 7.9%. These results could be helpful to build database programming system for germplasm management.

A statistical analysis for 3651 genetic resources collected from China (1,542), Japan (1,409), Korea (413), and India (287) was conducted using normal distribution, variability index value (VIV), analysis of variation (ANOVA) and Ducan’s multiple range test (DMRT) based on a data obtained from NIRS analysis. In normal distribution, the average protein content was 8.0%, whereas waxy type amylose and common rice amylose were found to be 8.7% and 22.7%, respectively. The protein contents ranged from 5.4 to 10.6% at the level of 95%. The waxy amylose and common rice amylose ranged from 5.9 to 11.5%, and from 16.9 to 28.5% at 95% confidence level, respectively. The VIV was 0.59 for protein, 0.64 for low amylose, and 0.81 for high amylose contents. The average amylose contents were 18.85% in Japanese, 19.99% in Korean, 20.27% in Chinese, and 25.46% in Indian resources, while the average protein contents were found to be 7.23% in Korean, 7.73% in Japanese, 8.01% in Chinese, and 8.17% in Indian resources. The ANOVA of amylose and protein content showed significant differences at the level of 0.01. The F-test for amylose content was 158.34, and for protein content 53.95 compared to critical value 3.78. The DMRT of amylose and protein content showed significant difference (p<0.01) between resources of different countries. Japanese resources had the lowest level of amylose contents, whereas, the lowest level of protein content was found in Korean resources compared to other origins. Indian resources showed the highest level of amylose and protein contents. It is recommended these results should be helpful to future breeding experiments.

We investigated physicochemical properties of puffed snacks with intermediate and high amylose rice varieties. The intermediate amylose rice varieties ‘Sindongjin’ and high amylose rice varieties newly developed for food processing, ‘Dodamssal’ and ‘Goami4’ were tested for this study. The crude fat and crude protein contents of the rice cultivars ranged 1.47-3.08% and 6.30-7.63%, respectively. The resistant starch and amylose contents of Dodamssal and Goami4 were higher than those of Sindongjin. The hardness of rice was the highest in Sindongjin and Dodamssal. Also, Hardness of puffed snacks decreased by 72.07% for Sindongjin, 88.21% for Dodamssal and 66.67% for Goami4 compared to raw rice samples. The sensory evaluation showed that the highest scores in taste, texture and overall acceptability of puffed snacks were obtained in Dodamssal. The results of this study indicate that Dodamssal was suitable varieties for puffed snacks. Also, the physicochemical properties of Dodamssal were improved by the extrusion process. Therefore Dodamssal can be used for the industrial production of puffed snacks.

This study was conducted to characterize the amylose and protein contents of 4,948 rice landrace germplasm using the NIRS model developed in the previous study. The average amylose content of the germplasm was 20.39% and ranged between 3.97 and 37.13%. The amylose contents in the standard rice were 4.99, 18.63 and 20.55% in Sinseonchal, Chucheong and Goami, respectively. The average protein content was 8.17% and ranged from 5.20 to 17.45%. Protein contents in Sinseonchal, Chucheong and Goami were 6.824, 6.869 and 7.839%, respectively. A total of 62% germplasm were distributed between 20.06% and 27.02% in amylose content. Germplasm of 81.60% represented protein content of 6.78-9.75%. The distinguishable ranges of amylose contents according to origin were 16.58-20.06% in Korea, 20.06-23.25% in Japan, 23.25-27.02% in North Korea, and 27.02-37.13% in China. In the protein content, approximately 30% of Chinese resources ranged from 9.75 to 17.45%, whereas less than 10% were detected in other origin accessions. Fifty resources were selected with low and high amylose ranging from 3.97-6.66% and 30.41-37.13%, respectively. Similarly, fifty resources were selected with low and high protein ranging from 5.20-6.09% and 13.21-17.45%, respectively. Landraces with higher protein could be adapted to practical utilization of food sources.

The objective of this research was to develop Near-Infrared Reflectance Spectroscopy (NIRS) model for amylose and protein contents analysis of large accessions of rice germplasm. A total of 511 accessions of rice germplasm were obtained from National Agrobiodiversity Center to make calibration equation. The accessions were measured by NIRS for both brown and milled brown rice which was additionally assayed by iodine and Kjeldahl method for amylose and crude protein contents. The range of amylose and protein content in milled brown rice were 6.15-32.25% and 4.72-14.81%, respectively. The correlation coefficient (R 2 ), standard error of calibration (SEC) and slope of brown rice were 0.906, 1.741, 0.995 in amylose and 0.941, 0.276, 1.011 in protein, respectively, whereas R 2 , SEC and slope of milled brown rice values were 0.956, 1.159, 1.001 in amylose and 0.982, 0.164, 1.003 in protein, respectively. Validation results of this NIRS equation showed a high coefficient determination in prediction for amylose (0.962) and protein (0.986), and also low standard error in prediction (SEP) for amylose (2.349) and protein (0.415). These results suggest that NIRS equation model should be practically applied for determination of amylose and crude protein contents in large accessions of rice germplasm.