Effects of Dry-Milling and Wet-Milling on Chemical, Physical and Gelatinization Properties of Rice Flour

Rice flour from nine varieties, subjected to dry- and wet-milling processes, was determined for its physical and chemical properties. The results revealed that milling method had an effect on properties of flour. Wet-milling process resulted in flour with significantly lower protein and ash contents and higher carbohydrate content. Wet-milled flour also tended to have lower lipid content and higher amylose content. In addition, wet-milled rice flour contained granules with smaller average size compared to dry-milled samples. Swelling power at 90℃ of wet-milled samples was higher while solubility was significantly lower than those of dry-milled flour. Dry milling process caused the destruction of the crystalline structure and yielded flour with lower crystallinity compared to wet-milling process, which resulted in significantly lower gelatinization enthalpy.

Analysis of genetic relationships between grain milling quality traits and plant agronomic traits of rice

Since seed and maternal plant are in different generations,the grain milling traits and plant agronomic traits of rice are based on differentgenetic models.Using the genetic modelswhich could estimate covariance componentsbetween two traits with unequal design matri-ces,we analyzed the gentic relationships be-

Study on the Optimum Moisture Amount Added to Brown Rice once during the Wet Conditioning

In the experiment, the brown rice whose moisture content was 12.5% was used as raw material. The brown rice was grouped, then moisturized differently and milled. While milling, the energy consumption, the rate of broken rice and the crack rate were tested. It is confirmed that the stress crack owing to the moisture added to the brown rice can be avoided when the moisture amount added once is limited to no more than 1.5%. It is also proved that the energy consumption can be reduced, the yielding rate of rice can be increased and that the quality of rice can be improved.

Identification of QTLs associated with cadmium concentration in rice grains

Cadmium（Cd） contamination in rice has been a hot topic of research because of its potential risk to human health. In this study, a double haploid（DH） population derived from Zhongjiazao 17（YK17）（an early-season indica cultivar）×D50（a tropical japonica cultivar） was used to identify quantitative trait loci（QTLs） associated with Cd concentration in brown rice（CCBR） and Cd concentration in milled rice（CCMR）. Continuous and wide variation for CCBR and CCMR were observed among the DH population. Correlation analysis revealed a positive and highly significant correlation between the two traits. A total of 18 QTLs for CCBR and 14 QTLs for CCMR were identified in five different pot and field trials. Two pairs of QTLs for CCBR（qCCBR2-1 and qCCBR2-2, qCCBR9-1 and qCCBR9-2） and one pair of QTLs for CCMR（qCCMR5-1 and qCCMR5-2） were detected in multiple trials. The alleles increasing CCBR at the qC CBR2-1/qC CBR2-2 and qC CBR9-1/qC CBR9-2 QTLs were contributed by YK17 and D50, respectively, whereas the D50 allele at the qCCMR5-1/qCCMR5-2 QTLs increased CCMR. Eight pairs of QTLs for CCBR and CCMR, qCCBR2-2 and qCCMR2-2, qCCBR3 and qCCMR3, qCCBR4-2 and qCCMR4-1, qCCBR4-3 and qCCMR4-2, qCCBR4-4 and qCCMR4-3, qCCBR5 and qCCMR5-2, qCCBR7 and qCCMR7, and qCCBR11-1 and qCCMR11-2, co-localized on chromosomes 2, 3, 4, 5, 7, and 11, respectively. For all of these QTL pairs, except qCCBR5/qCCMR5-2, the additive effects came from YK17. In addition, four CCMR QTLs showing significant additive×environment interaction and two pairs of CCMR QTLs with bi-allelic epistatic interactions were identified. The results of this study could facilitate marker-assisted selection of breeding rice varieties with low Cd accumulation in grain.

Changes in Physicochemical,Cooking and Sensory Characteristics of Rice Shifted from Low-temperature Storage

The physicochemical, cooking, and sensory characteristics of stored rice were measured in order to investigate the quality changes in it after low-temperature storage. The quality of the stored rice was compared to that of the rice stored at ambient temperature(20℃, 30%–70% RH) at a 25 d interval during 200 d of storage. The rice was stored in a temperature controller at 4℃ for 3 months and later under a simulated condition similar to that of the main rice consumption areas in China(35℃, 80% RH and 30℃, 70% RH). The results showed that the fatty acid value, b value, and moisture content of rice stored at 35℃, 80% RH and 30℃, 70% RH had increased significantly, whereas its L value had decreased as compared to the rice stored at ambient temperature. Higher temperature storage caused a greater water uptake, whereas the dry mass in the residual cooking water notably reduced under the storage at 35℃ as compared to that at 20℃. Hardness increased and adhesiveness reduced under the storage at 35℃ as compared to that at 20℃. The shelf life of the stored rice which was shifted from a low temperature to three storage conditions used in this study was 75 d, 100 d and 150 d, respectively, in the main rice consumption areas of China.

Variation in Yield and Physicochemical Quality Traits among Mutants of Japonica Rice Cultivar Wuyujing 3

To select elite germplasms, 112 mutants derived from japonica rice cultivar Wuyujing 3 were evaluated. The yield components such as panicle number per square meter, grain number per panicle, and grain weight were measured. The quality traits such as percentage of chalky grains（PCG）, brown rice yield（BRY）, milled rice yield（MRY）, degree of milling（DM）, amylose content（AC）, protein content（PC）, and relationships among traits were inverstigated. Results showed that grain yield ranged from 2.15 to 12.49 t/hm2 with a mean of 6.4 t/hm2 and number of grains per square meter contributed for 94.64% in grain yield variation. For quality traits, all rice mutants had short size（grain length ≤ 5.5 mm） and bold shape（grain length to width ratio = 1.10-2.00）. Most of rice mutants（87.5%） had PCG values below 20%. All mutants had MRY values above 50%, AC values below 20%, and PC values below 10%. Percentage of chalky grains was significantly negatively correlated with MRY and positively correlated with DM. BRY and MRY were significantly negatively correlated with DM. PC was significantly and positively correlated with MRY and negatively correlated with DM, while AC had no significant correlation with these quality traits. It was concluded that there were 25 rice mutants which fulfilled the major requirements of Jiangsu standard japonica rice such as low percentage of chalky grains, low amylose content, optimal protein content, and which could be used as elite germplasms. Thus the mutants identified may lead to significant progress in improvement of rice quality.

Improved method for prediction of milled rice moisture content based on Weibull distribution

The loss on drying method,which is regarded as the standard method of rice moisture content analysis,provides the most reliable results but is both labor intensive and time consuming.In order to improve the detection efficiency of the loss on drying method,this study investigated the drying characteristics of milled rice and developed an information fusion algorithm with which to predict milled rice moisture content based on the Weibull distribution and Levenberg-Marquardt(LM)algorithm.Application of the Weibull distribution model was investigated regarding its description of the drying kinetics of milled rice during infrared drying.An adaptive mechanism was applied to algorithm design,with the starting point of the estimation algorithm determined by calculating the drying rate at each measuring point,and the end-point distinguished using a two-level threshold algorithm.The calculated results were then compared with the measured data regarding the infrared drying of milled rice.For milled rice samples varying in moisture content from 14.44%-17.67%(dry basis),the relative error between predicted and observed values ranged 0.0037-0.0589,with a reduction in test time of 50.71%-67.87%.