• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.6
• /
• pp.637-645
• /
• 1991

Physicochemical factors affecting cooking and eating quality of rice and their mechanisms were investigated. The stickiness of cooked rice was negatively correlated with amylose content(r=0.58, p<0.05) and protein content(r=-0.72, p<0.01), but not affected by crude fat content of rice. The ultrastructure of cooked rice grain showed the progressive gelatinization of starch from the periphery toward the center of the endosperm as water and heat energy diffused into. The rate of water diffusion appears to be dependent on the cell arrangement in the endosperm and the protein content of milled rice. Once water and heat reach the starch granules, the rate of in situ gelatinization of starches appears to be dependent on their own gelatinization temperature range and amylose content. Protein acts as a barrier for the swelling of starch and water diffusion in two ways : 1) by encasing starch granules in the starchy endosperm, and 2) by forming a barrier between the subaleurone layer and the starchy endosperm. Therefore, the separation and fragmentation of the outermost layers of the endosperm occurred more easily in the low-protein content rices, and was associated with increases of solids lost in cooking-water at 95$^{\circ}C$ and stickiness of cooked rice.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.58 no.3
• /
• pp.274-282
• /
• 2013

This study was carried out to find out the physicochemical properties of rice grains of 8 varieties having various amylose content. Amylose contents of 8 varieties were ranged from 6.3 to 30.9% and could be classified into 4 groups, such as waxy, low-amylose, nonglutinous, and high-amylose. Protein contents were ranged from 5.8% to 7.5% varied depending on variety, but there was no significant difference in protein contents among groups. The hardness of milled rice grains in low-amylose and non-glutinous was stronger than waxy and low-amylose group. Whiteness of waxy group grains was the highest while non-glutinous group was the lowest. The alkaline digestive values were evenly distributed from 5.2 to 6.9 and highly correlated with amylose content. There was significant difference in pasting properties of rice flours among groups. High-amylose group showed the highest initial pasting temperature and total setback viscosity, and the lowest peaks for trough and breakdown viscosity. Low-amylose group showed the highest breakdown viscosity but the lowest setback viscosity as well as high peak viscosity. Although amylose content was significantly correlated with alkali spreading value in milled rice, initial pasting temperature, and total setback, but it was negatively correlated with toyo-meter value and setback viscosity.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.273-273
• /
• 2022

The increasing number of Westernized eating patterns based on wheat flour in Korea has led to an increase in the rate of diseases such as obesity and diabetes, which has become a social problem. Wheat consumption is increasing due to changes in eating habits, but domestic wheat has low price competitiveness and has stagnated recently, so it is necessary to secure new resources to differentiate from imported wheat. Resistant starch, a newly created resource in domestic wheat, can act as a prebiotic similar to dietary fiber in the body, inducing microbial changes in the gut and having beneficial effects on metabolic syndrome. Wheat research on resistant starch was carried out based on the breeding of high amylose. A genome-wide association study (GWAS) was used to perform SNP identification and expression analysis related to wheat amylose through phenotype and genotype. 561 wheat core collection gene sources were investigated for amylose content in wheat, and related genes were extracted and analyzed. In the GWAS analysis, the model formulas BLIMK, FarmCPU, GLM, MLM, and MLMM were used to derive results such as QQ plots and Manhattan plots through phenotypic data. Among these models, BLAST was conducted to find the association between the SNPs identified using FarmCPU and genes related to starch, and 15 were found. Using the identified markers, it becomes easier to develop and browse related wheat cultivars according to their amylose content.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.229-229
• /
• 2017

This research study was conducted to analyze the characteristics of different rice cultivars in abnormal temperature conditions (low temperature) for ripening period abnormalities, and to investigate the physiological causes behind the abnormalities. Four Korean high quality japonica-type rice cultivars, Jinbu (JB), Junamjosaeng (JJ), Geumyoung (GY), Hwawang (HW) were used in the experiment. The following day after flowering, they were then moved into two phytotrons under natural daylight with 65% RH but controlled at different temperatures - one at $19/29^{\circ}C$ (night/day) and the other at $13/23^{\circ}C$ as the low - temperature study on ripening. For the cultivars at $13/23^{\circ}C$ (low temperature study), JB and JJ had a ripening rate of 93% which is similar to the ripening rates of cultivars at $19/29^{\circ}C$ at 45 days after heading (DAH). In contrast, GY and HW recorded lower ripening rates of 86% and 57% respectively. However, when the cultivars at $13/23^{\circ}C$ were harvested at 61 DAH (when the accumulated temperature reached $1100^{\circ}C$), the difference in ripening rates compared to the 4 cultivars of $19/29^{\circ}C$ harvested at 45 DAH was not obvious (JB 94%, JJ 97%, GY 97%, HW 88%). Starch content showed little difference among the 4 cultivars at different temperature conditions while amylose content was higher for cultivars at $13/23^{\circ}C$ compared to those at $19/29^{\circ}C$. In addition, the enzyme activities of starch biosynthesis were about 5~10 days slower in cultivars at $13/23^{\circ}C$ compared to cultivars at $19/29^{\circ}C$. The grain-filling rate showed highly significant correlations with the enzyme activities of Sucrose synthase ($R^2=0.70^{***}$), ADP glucose pyrophosphorylase ($R^2=0.63^{***}$), UDP glucose pyrophosphorylase ($R^2=0.36^{***}$), Starch synthase ($R^2=0.51^{***}$), and Starch branching enzyme ($R^2=0.59^{***}$). Among the enzymes, Sucrose synthase activity had the highest correlation coefficient with grain-filling rate. In conclusion, the activity of enzymes such as Sucrose synthase, UDP glucose pyrophosphorylase, ADP glucose pyrophosphorylase, Starch synthase, Starch branching enzyme in starch biosynthesis is proven to be highly related to the grain filling process. Notably, the decrease in the activity of Sucrose synthase and Starch branching enzyme and the late increase in ADP glucose pyrophosphorylase activity at low temperature in the ripening stage are considered to be disadvantageous as they delay ripening and increased amylose content.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.70-70
• /
• 2017

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 amylose contents estimated by NIRS in the standard rice were Sinseonchal (6.881%) 4.994%, Chucheong (19.731%) 18.633%, Goami (23.246%) 20.548%. Protein contents were Sinseonchal (6.890%) 6.824%, Chucheong (6.350%) 6.869%, Goami (6.777%) 7.839%. The NIRS analysis showed that 1.1-2.7%point lower in amylose and 0.4-0.6%point higher in protein than standard contents. The average amylose content of the germplasm was 20.39% with a range of 3.97-37.13%. The average protein content was 8.17% with a range of 5.20-17.45%. Amylose contents with a range of 20.06-27.02% represented 62.20% of the germplasm. Protein contents with a range of 6.78-9.75% represented 81.60% of the germplasm. Korean landrace comprised 24.9% among the 4,948 germplasm collected from 41 countries. A specific range of amylose contents showed in Korea 16.58-20.06%, in Japan 20.06-23.25%, in North Korea 23.25-27.02% and in China 27.02-37.13%. Protein contents exhibited 5.20-17.45% evenly in the whole landraces, whereas Chinese landrace particularly observed with 6.78-8.27% and 9.75-17.45%. Fifty resources were selected with low and high amylose ranging from 3.97-6.66% to 30.41-37.13% respectively. Similarly fifty resources were selected with low and high protein ranging from 5.20-6.09% to 13.21-17.45% respectively. Landraces with higher protein should be adapted to practical utilization of food sources.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.12
• /
• pp.1797-1801
• /
• 2011

Two brown rice samples differing in amylose content, 20.1 (normal) and 7.3% (low amylose) were milled by different milling methods, and their physicochemical properties were tested. Particle size of brown rice flour prepared by dry milling using a pin mill (DM) was lower than that prepared by wet milling using a roll mill (WM). Particle size was further reduced by successive dry milling of the flour after wet milling and drying (WM/DM). Damaged starch contents in the wet milled brown rice flour were 14.6 and 15.6% for the normal and low amylose samples, respectively, whereas they were only 4.2 and 4.8% for the dry milled samples. WM/DM method resulted in a lower damaged starch (%) than DM, despite a reduced flour particle size. Water absorption index (WAI) of the brown rice flour was the lowest after WM/DM, and the water solubility index (WAI) was higher in the order of DM, WM/DM, and WM. Brown rice flour with normal amylose content appeared to have significantly higher pasting viscosities, as determined using a Rapid Visco Analyzer (RVA). Compared to dry milled brown rice flour, wet milled brown rice flour showed lower peak viscosity and higher final viscosity, resulting in increased setback value.

• Korean Journal of Plant Resources
• /
• v.31 no.5
• /
• pp.498-514
• /
• 2018

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.

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

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.57 no.3
• /
• pp.271-279
• /
• 2012

Total twenty cultivars of potato (Solanum tuberosum L.) were grown at Gangneung where is located in low land of Korea. Their tubers were harvested from 100 to 120 days after planting, and over 150 g of tubers were selected for quality evaluation. Dry matter, starch, amylose in starch, ascorbic acid, protein, individual sugars and mineral were analyzed and mealiness of cooked potatoes were also evaluated by panel test. Dry mater content was the highest in 'Haryeong', 'Jayoung' and 'Shepody', and the biggest starch granules were observed in 'Jayoung' and 'Sinnamjak'. In addition, the content of amylose was highest in 'Haryeong', 'Chudong' and 'Goun'. Mineral content showed the slight difference between cultivars, but it's tendency was not clear. Vitamin C content was highest in 'Jayoung' as 62.5 $mg{\cdot}100g^{-1}$ FW, and 'Chugang' exhibited the highest content of protein. Sugar content was lower in cultivars for single one than double cropping. The lowest sugar content was observed in 'Atlantic' and 'Namseo' among cultivars for single cropping, and in 'Goun' for double cropping. As a result of analysis for quality factors, we could select nine cultivars ('Atlantic', 'Gahwang', 'Gawon', 'Goun', 'Hareong', 'Irish Cobbler', 'Jasim', 'Jayoung' and 'Shepody') with high dry matter content and low reducing sugar as a cultivar group for processing. Additionally, seven cultivars ('Chugang', 'Gawon', 'Goun', 'Hareong', 'Irish Cobbler', 'Jasim' and 'Seohong') with high mealiness and amylose content and five cultivars ('Atlantic', 'Chudong', 'Gahwang', 'Jopung' and 'Jowon') with low mealiness and amylose content were classified as groups for boiled or steam cooking and for soup or pot dishes, respectively.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.8
• /
• pp.1102-1105
• /
• 2006

The effect of heat treatments on in vitro starch hydrolysis of proso millet, sorghum, Job's tears, and buckwheat by pancreatic ${\alpha}-amylase$ was investigated. Grain samples were tested raw, boiled in water, or steamed/roasted. Starch content of the grains varied from 59.5% in Job's tears to 65.5% in proso millet, and amylose content varied from 5.3% in Job's tears to 36.3% in buckwheat. The in vitro starch hydrolysis of raw and heat-treated grains continuously increased during 60 min of hydrolysis. The starch hydrolysis (%) of raw grains after 60 min incubation was in the order of buckwheat (5.7%), proso millet (33.0%), Job's tears (51.2%), and sorghum (57.6%). Grains treated with steaming/roasting appeared to have higher starch hydrolysis rates than those with boiling except proso millet. Hydrolysis rates of buckwheat with a high amylose content appeared to be lower, compared to proso millet, sorghum, and Job's tears containing low amylose contents.