Alkali Spreading Value Research Articles

Alkali spreading value and Image Analysis

Since its first appearance, the alkali test has been extensively employed in rice quality studies as an indirect estimation of the gelatinisation temperature and the cooking quality. Nevertheless, the modifications brought to this method during the years focused on the experimental conditions of the test without taking into account the subjective interpretation of the results. The aim of this study was the search for a reasonable substitute for the human visual decision-making process implicated in the alkali test and, in particular, for a digital image analysis method involving the use of a flatbed scanner (easy to use and available at low cost) to quantitatively measure the degree of dispersion of rice kernels during the test. Significant correlations were found between a new index, the rice kernel disintegration area, obtained from Image Analysis, and the alkali spreading value ( r = 0.942, P ≤ 0.01), the amylose content ( r = −0.855, P ≤ 0.01) and the micro-visco-amylographic gelatinisation temperature ( r = −0.928, P ≤ 0.01).

Relationship of cooked‐rice nutritionally important starch fractions with other physicochemical properties

AbstractSixteen rice cultivars representing five cytosine‐thymine repeat (CTn) microsatellite genetic marker groups were analyzed for their cooked rice nutritionally important starch fractions (NISFs, which include rapidly digestible (RDS), slowly digestible (SDS), and resistant starch (RS)), basic grain quality indices (apparent amylose (AM), crude protein (CP), alkali spreading value (AS), and gel consistency (GC)), pasting characteristics, and thermal properties. Chemometric tools (bivariate correlation, principal component analysis, multiple linear regression, and partial least squares regression) were used to establish the association of NISF with other milled rice physicochemical properties. CT11 was generally associated with high percentages of RS and SDS, and a low percentage of RDS. CT14 was associated with low SDS; whereas, CT17 and CT18 were associated with low RS. The CT20 cultivars were similar to CT11 in SDS and RS; and to CT14, CT17, and CT18 in RDS content. RDS, SDS, and RS were loaded on three different quadrants of the principal component similarity map. RDS was not significantly correlated with any of the physicochemical properties; whereas, SDS was positively correlated with GC. RS was positively correlated with AM, setback (SB) viscosity, total setback (TSB) viscosity, and peak gelatinization temperature; and negatively correlated with breakdown (BD) viscosity. Multivariate techniques indicated lack of robustness in predicting RDS and SDS as the models only explained <50% of the variance. More robust regression models were obtained for RS, explaining >60% of its variation. Basic grain quality indices explained NISF variations better than pasting and thermal properties.

PHYSICO-CHEMICAL AND TECHNOLOGICAL STUDIES ON SOME EGYPTIAN RICE VARIETIES

The present study was carried out to evaluate different varieties of rice (Black, Sakha 105 and Egyptian Yasmen) as brown and white rice physically, chemically and technologicaly as well as to investigate the possibility of using their rice flour as substitution materials of wheat flour in preparing biscuits. The obtained results revealed that, physical properties of paddy, brown and white rice varied from one variety to another. It was found that E. yasmine had the longest length when compared with other varieties. It had also the lowest width among all of the tested ones, whereas Sakha 105 had the highest value in grain index. The paddy rice of raw E. yasmine had the highest percentages of broken kernels and the lowest percentages of head and white rice as compared with other rice varieties. Water uptake of white rice was significantly higher than that of brown rice. Brown black rice had the longest cooking time (38 min) compared to the others. Gel consistency (GC) varied significantly between varieties in both brown and white rice. Alkali spreading value in brown rice varieties showed lower values in comparing with white rice varieties. Black rice had the highest amylase content and the lowest pasting characteristics values than those of Sakha 105. Furthermore, Black rice contains high content of ether extract, ash and crude fibers, but lower content of total carbohydrate, compared with other varieties. In addition, brown rice of all varieties had higher contents of crude protein, ether extract, ash and fiber but lower content of total carbohydrates, whereas the rice variety of black rice had a relatively high levels of mineral contents comparing with the other rice varieties. Results of Organoleptic evaluation indicated that, biscuit samples prepared using rice flour of the studied varieties as substitutions insted of wheat flour up to 50% were very acceptable. Where most samples have sensory characteristics scores higher than those of control (wheat flour biscuit).

Melting the secrets of gelatinisation temperature in rice

Gelatinisation temperature (GT) is one of the key traits measured in programs for breeding rice (Oryza sativa L.). It is commonly estimated by the alkali spreading value (ASV), and less commonly by differential scanning calorimetry (DSC). Using a diverse set of germplasm, it was determined that DSC values associate poorly with ASV, are not correlated with amylose content but correlate with cooking time. Rice varieties are traditionally grouped into three classes of GT based on ASV: high, intermediate and low. However, the distribution of DSC values of 4000 samples shows only two classes: high and low. Large differences in the distributions of chain lengths synthesised by starch synthase IIa (SSIIa) support the two classes as the major grouping, two haplotypes associating with each peak. Each peak of DSC values spanned 10°C. The chain length distribution of the amylopectin molecules from varieties at the upper boundary of each peak showed significantly more chains that span both the crystalline and amorphous lamellae of a cluster than varieties at the other end of that distribution. Improved varieties, classified as intermediate GT by ASV, belong to both of the classes defined by DSC, implying that some enzyme, other than SSIIa is involved in intermediate GT.

Parallel and interlaced recurrent selection (PAIRS): Demonstration of the feasibility of implementing PAIRS to improve complete and partial resistance to blast ( Magnaporthe grisea) and some other main traits in rice

The best generation for the evaluation and selection of a trait depends on its polygenic level and heritability. Little attention has been paid to integrating, in the same rice recurrent selection (RS) scheme, the separation of breeding generations. The option we propose is a new parallel and interlaced RS (PAIRS) scheme. We evaluated and selected earliness and grain size in the S0 generation, complete resistance to leaf blast in S1 plants, partial resistance to leaf and neck blast, earliness and yield components in S2 lines, gelatinization temperature, estimated by the extent of alkali spreading in S3 grains, and tolerance to rice delphacid ( Tagasodes orizicolus) mechanical injuries in S3 plants. Although this innovative scheme may seem complicated overall, this first application of PAIRS highlights that the improvement of every methodological step is very easy. Through a complete recurrent selection and genetic recombination cycle, we obtained good progress for grain length, partial resistance to leaf blast and gelatinization temperature (alkali spreading value), and excellent progress for targeted earliness, complete resistance to leaf blast, partial resistance to neck blast and yield. The population size and the number of plants or lines chosen were adequate and we can recommend them to partners.

Ethylene and ACC levels in developing grains are related to the poor appearance and milling quality of rice

The possible relationship between the levels of ethylene and 1-aminocylopropane-1-carboxylic acid (ACC) in the grains and the quality of rice (Oryzasativa L.) were investigated by using 12 rice cultivars. The results showed that both the ethylene evolution rate and ACC content in grains during the grain filling period correlated negatively with head rice production and positively with chalky kernels, chalky size, and chalkiness. The levels of ethylene and ACC were not significantly correlated with alkali spreading value and amylose content. Application of ethephon, an ethylene-releasing agent, or ACC to panicles at the early grain filling stage significantly reduced the rates of brown rice, milled rice, and head rice, and significantly increased the percentage of chalky kernels, chalky size, and chalkiness. Application of aminoethoxyvinylglycine, an inhibitor of ACC synthase, had the opposite effect. Chalkiness appears to be a senescence related phenomenon which is stimulated by ethylene. The results suggest that ethylene and ACC in grains play an important role in regulating rice quality, and that grain appearance and milling quality would be improved though the reduction of ethylene and ACC in grains during grain filling.

Seed physicochemical characteristics of field-grown US weedy red rice ( Oryza sativa) biotypes: Contrasts with commercial cultivars

Red rice in the US is an aggressive weed that reduces the yield of rice and contaminates its grain. It is the same species as rice, which provides an opportunity for intercrossing. This genetic similarity complicates the management of red rice in fields and rice mills, but also indicates a potential for its use in rice breeding or niche markets. Physicochemical and cooking quality characteristics, which are important components of consumer desirability for rice, are virtually unknown for red rice. Thus, a survey of red rice accessions and rice × red rice crosses was conducted to characterize these traits. Grain amylose levels of most indigenous red rice accessions were similar to those of high amylose indica cultivars from Asia. Amylose levels in crosses were highly variable, ranging as low as those in medium-grain commercial rice to as high as those in long-grains. Alkali spreading value was generally greater in awned than in awnless red rice accessions and the aroma chemical, 2-acetyl-1-pyrroline, was detected in two red rice crosses. The generally high seed amylose levels in red rice indicate that its cooking quality would not be suitable for most common uses of US rice, but may be acceptable for niche uses.

Rice RVA Profile Characteristics and Correlation with the Physical/ Chemical Quality

In this paper, we determined rice RVA profile characteristics and their physical/chemical quality indicators of 124 varieties grown in Sichuan Province, and studied the relationship among RVA profile characteristics and between RVA profile characteristics and physical/chemical indicators. To study the differences of RVA profile characteristics of rice varieties with dif-ferent amylose contents (AC), we divided these varieties into six groups, including waxy rice, low AC, moderate lower AC, mod-erate AC, moderate higher AC, high AC, and analyzed the differences of RVA profile characteristics between the latter five groups of no-waxy varieties, and the influence of AC on RVA profile characteristics. There were no significant correlation between peak viscosity (PKV) and cool paste viscosity (CPV), and between PKV and consistence (CSV), but significant correlations among other RVA profile characteristics with each other at P = 0.01 except hot paste viscosity (HPV) with breakdown (BDV) at P = 0.05. CPV significantly positive correlated to CSV, with the correlation coefficients of 0.94. Six RVA profile characteristics had signifi-cant correlations with AC and gel consistency (GC) at P = 0.01, AC significantly positively correlated to GC, with the correlation coefficients of ?0.82 at P = 0.01; alkali-spreading value (ASV) had no significant correlation with AC, GC, and six RVA profile characteristics. Varieties with different AC had different RVA profile characteristics, when AC was higher, setback (SBV) and CSV were higher and BDV lower.

Selected Quality Attributes of Fine Basmati Rice: Effect of Storage History and Varieties

Storage period, temperature and moisture are the key traits, accountable for variation in chemical, cooking and sensory attributes of rice. The study of two promising varieties of fine Basmati rice stored at various temperatures revealed pronounced influence of storage on various quality traits i.e. volume expansion ratio, water absorption ratio, elongation ratio, alkali spreading value, amylose contents and sensory attributes. The cooking quality was affected significantly in the months following harvesting. Freshly harvested Basmati varieties (Basmati Super and Basmati-385) were aged for a period of sixteen weeks (4 months) at different temperatures (5, 25, 35, and 45°C). Aging of rice played imperative role in establishing the aforesaid quality traits. Storage condition resulted in increased moisture, water absorption ratio, volume expansion ratio and elongation ratio while amylose content and alkali spreading value of both rice varieties were decreased. The protein content showed insignificant differences. Storage of both varieties at 35°C gave best results for sensory attributes like taste and over all acceptability. Basmati Super showed better performance in cooking and eating quality than that of Basmati-385 during storage.

Variation in biological characteristics of purified pea ferritin (Fer) transgenic rice

AbstractAfter seven generations of self-crossing assisted by β-glucuronidase (GUS) detection, 26 homozygous transgenic rice lines were obtained. Transgene effects on iron content, agronomic traits, rice quality and stress tolerance were studied. The results indicated that the average iron content in the milled grain of the transgenic (pea ferritin, Fer) rice (Oryza sativa) was 10.37 μg/g among all the homozygous lines, and only four lines (Fer34, Fer36, Fer39 and Fer65) had significantly higher iron contents than that of the control, Xiushui11 (6.46 μg/g). Significant differences in main agronomic traits, such as days from sowing to heading, plant height, main panicle length, total grains of main panicle, seed setting rate, 1000-grain weight, and yield per plant were observed among some homozygous lines, but similar flag leaf length and number of panicles per plant were found. This showed that insertion of the foreign gene (Fer) had a slight impact on the main agronomic traits, but that the transgene had no negative effects. The quality traits of homozygous rice lines, such as the percentage of brown rice, milled rice and full milled rice, grain length, grain width, ratio of grain length and width, and amylose content were all similar to those of the control. However, variations were noticed in chalkiness, translucency, alkali spreading value and gel consistency among partial homozygous lines. Responses of homozygous lines to low and high temperatures were not significantly correlated with the iron contents, and resistance to rice blast (Pyricularia oryzae), bacterial blight (Xanthomonas oryzae) and brown planthopper (Niaparvata lugens) were enhanced with increased iron contents.

Correlation Analysis of Mineral Element Contents and Quality Traits in Milled Rice (Oryza stavia L.)

The relationships among potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) contents in milled rice (Oryza stavia L.) of 274 genotypes and the relationships between these mineral element contents and other rice quality traits including 3 cooking quality traits, 17 amino acid contents, and protein content were investigated. The results showed that there were significant correlations among most of mineral element contents. Mg, Fe, and Mn contents were significantly correlated with most of the other mineral element contents, while Cu content had significantly negative associations with the K and Mg contents of rice. The relationships between mineral element contents and cooking quality traits showed that gel consistency (GC) was significantly correlated with K, Cu, and Mn contents of rice. Amylose content (AC) was significantly associated with K, Na, Mg, Cu, and Mn contents. The alkali spreading value (ASV) had closely positive relationships with Ca, Mg, and Mn contents. In addition, 8 mineral element contents had obvious correlations with different amino acid contents. Mg, Ca, and Zn contents were significantly correlated with most of the 17 amino acid contents, but Na content did not correlate with amino acid contents except aspartic acid of rice. Furthermore, significant associations were found between protein content and Na, Mg, Zn, Cu, or Mn content. Six principal components were extracted to explain 84.50% of the total variances and contained the information provided by the original 29 variables according to the principal component analysis.

Changes in head rice yield and whiteness during milling of rough rice ( Oryza sativa L.)

This study has been undertaken to model head rice yield (HRY) and whiteness changes during milling in relation to the physicochemical properties such as amylose content, alkali spreading value, gel consistency and protein content of 10 rice varieties. It was found that the reduction in HRY was a power function of the milling duration with R 2 of fitting ranging from 0.974 to 0.997 and root mean square error (RMSE) values of below 1% among the selected varieties. Also, the parameters of the model describing reduction in HRY during milling were the function of the physicochemical properties of rice. The major contributing physicochemical properties were amylose content (AC) and gel consistency (GC). It was possible to estimate HRY during milling from the physicochemical properties using these functions within ±10% of the actual values. The milled rice whiteness could be satisfactorily modeled by a two parameters non-linear model with R 2 of fitting ranging from 0.972 to 0.997 and RMSE values of below 1.0 whiteness index (WI) for all selected varieties. Further, it was found that the parameters of the model representing whiteness during milling were the functions of the physicochemical properties of the rice. The important contributing physicochemical properties were alkali spreading value (AS) and protein content (PC). The whiteness could be estimated from the physicochemical properties using such functions within ±5% of the actual values. Thus, it was concluded in the study that HRY and whiteness could be successfully modeled during milling operation in relation to the physicochemical properties of rice.

Characterization of indica-type giant embryo mutant rice enriched with nutritional components

Five giant embryo mutants, described as MH-gel, MH-ge2, MH-ge3, MH-ge4 and MH-ge5, which were derived from the same indica rice cv. ‘Minghui 86’ and characterized by 2.0, 1.88, 2.08, 1.93 and 1.88 times enlarged embryo than that of wild type, were selected for the current study. The mutated giant embryos were controlled by a single recessive gene, and except mutated locus with MH-ge1 other four loci were allelic to each other and the previous reported locus ge in japonica rice cv. ‘Kinmaze’. No obvious differences in physicochemical properties such as apparent amylose content (AAC), alkali spreading value (ASV), gel consistency (GC), and starch paste viscosity were observed between giant embryo mutants and wild type. Significant increases in the contents of crude lipid (LC), crude protein (PC), Vitamin B1 (VB1), Vitamin B2 (VB2), Vitamin E (VE), essential amino acids such as Arginine (Arg), Aspartic acid (Asp), Glutamic acid (Glu), Lysine (Lys), Methionine (Met), and mineral elements such as calcium (Ca), iron (Fe), potassium (K), phosphorus (P) and zinc (Zn) were detected in brown rice (BR) of giant embryo mutants. The amounts of gamma aminobutyric acid (GABA), an inhibitory neurotransmitter, were similar in the BR of giant embryo mutants and wild type, and more GABA content was observed in germinated brown rice (GBR) than BR. Significant enrichments were detected in the GBR of giant embryo mutants, basically corresponding to the enlarged embryo.

Genetic basis of 17 traits and viscosity parameters characterizing the eating and cooking quality of rice grain

A recombinant inbred line population derived from a cross between Zhenshan 97 and Delong 208 was used to analyze the genetic basis of the cooking and eating quality of rice as reflected by 17 traits (or parameters). These traits include amylose content (AC), gel consistency (GC), alkali spreading value (ASV), cooked rice elongation (CRE), and 13 parameters from the viscosity profile. All the traits, except peak paste viscosity (PKV), time needed from gelatinization to peak (BAtime), and CRE, can be divided into two classes according to their interrelationship. The first class consists of AC, GC, and most of the paste viscosity parameters that form a major determinant of eating quality. The second class includes ASV, pasting temperature (Atemp) and pasting time (Atime), which characterize cooking process. We identified 26 QTL (quantitative trait locus or loci) in 2 years; nine QTL clusters emerged. The two major clusters, which correspond to the Wx and Alk loci, control the traits in the first and second classes, respectively. Some QTL are co-located for the traits belonging to the same class and also for the traits to a different class. The Wx locus also affects on ASV while the Alk locus also makes minor contributions to GC and some paste viscosity parameters. The QTL clusters on other chromosomes are similar to the Wx locus or Alk locus, although the variations they explained are relatively minor. QTL for CRE and PKV are dispersed and independent of the Wx locus. Low paste viscosity corresponds to low AC and soft gel, which represents good eating quality for most Chinese consumers; high ASV and low Atemp, together with reduced time to gelatinization and PKV, indicate preferred cooking quality. The genetic basis of Atemp, Atime, BAtime, peak temperature, peak time, paste viscosity at 95 degrees C, and final paste viscosity is newly examined to reveal a complete and dynamic viscosity profile.

Mapping of quantitative trait loci for basmati quality traits in rice (Oryza sativa L.)

Traditional basmati rice varieties are very low yielding due to their poor harvest index, tendency to lodging and increasing susceptibility to foliar diseases; hence there is a need to develop new varieties combining the grain quality attributes of basmati with high yield potential to fill the demand gap. Genetic control of basmati grain and cooking quality traits is quite complex, but breeding work can be greatly facilitated by use of molecular markers tightly linked to these traits. A set of 209 recombinant inbred lines (RILs) developed from a cross between basmati quality variety Pusa 1121 and a contrasting quality breeding line Pusa 1342, were used to map the quantitative trait loci (QTLs) for seven important quality traits namely grain length (GL), grain breadth (GB), grain length to breadth ratio (LBR), cooked kernel elongation ratio (ELR), amylose content (AC), alkali spreading value (ASV) and aroma. A framework molecular linkage map was constructed using 110 polymorphic simple sequence repeat (SSR) markers distributed over the 12 rice chromosomes. A number of QTLs, including three for GL, two for GB, two for LBR, three for aroma and one each for ELR, AC and ASV were mapped on seven different chromosomes. While location of majority of these QTLs was consistent with the previous reports, one QTL for GL on chromosomes 1, and one QTL each for ELR and aroma on chromosomes 11 and 3, respectively, are being reported here for the first time. Contrary to the earlier reports of monogenic recessive inheritance, the aroma in Pusa 1121 is controlled by at least three genes located on chromosomes 3, 4 and 8, and similar to the reported association of badh2 gene with aroma QTL on chromosome 8, we identified location of badh1 gene in the aroma QTL interval on chromosome 4. A discontinuous 5 + 3 bp deletion in the seventh exon of badh2 gene, though present in all the RILs with high aroma, was not sufficient to impart this trait to the rice grains as many of the RILs possessing this deletion showed only mild or no aroma expression.

Dimensional changes in milled rice ( Oryza sativa L.) kernel during cooking in relation to its physicochemical properties by image analysis

The present study was aimed to develop model for describing the changes in dimensions of milled whole kernels during cooking in excess water. Samples of ten Thai rice varieties ranging from low to high amylose content (16–29% d.b.) with three initial moisture levels (approximately, 8%, 12% and 16% d.b.) were used to investigate the influence of initial moisture content and variety manifested by the physicochemical properties such as amylose content (AC), alkali spreading value (AS), gel consistency (GC) and protein content (PC) on the kernel dimensional changes. It was found that the kernel initial moisture content did not affect the dimensional changes during cooking. The changes in kernel dimensions during cooking could be best expressed by either an exponential relationship with the R 2 for fitting ranging, respectively, from 0.969 to 0.997, 0.921 to 0.973, 0.936 to 0.997 and 0.968 to 0.995 or by a Peleg model with the R 2 for fitting ranging, respectively, from 0.969 to 0.997, 0.921 to 0.977, 0.937 to 0.997 and 0.968 to 0.995 for kernel length, width, perimeter and projected area for all rice varieties. The regression coefficients of the fitted relationship for describing changes in kernel dimensions during cooking were found to be the function of physicochemical properties, namely, AC, AS and PC of rice varieties and could be estimated within ±5% of actual values. It was observed that the regression coefficients of the power model describing kernel expansions in terms of water absorbed during cooking were the function of the physicochemical properties of the milled rice. It was concluded that the kernel expansions due to water uptake could be estimated from the physicochemical properties, namely, AC and AS during cooking.

Relationship Between Root Chemical Signals and Grain Quality of Rice

This study was designed to elucidate the relationship between root chemical signals and the quality of rice. Various rice genotypes were used. Zeatin (Z) + zeatin riboside (ZR), abscisic acid (ABA), 1-aminocylopropane -1-carboxylic acid (ACC), and organic acids in roots during grain filling and the appearance quality, cooking/eating quality were investigated. The correlations among them were analyzed. The results showed that Z + ZR concentrations in the roots at mid- and late-grain-filling stages were significantly and positively correlated with the gel consistency and alkali spreading value ( r = 0.72 * – 0.90 **), whereas negatively correlated with the amylose content ( r = −0.68 * – −0.78 **). ABA concentrations in roots at mid-grain-filling stage were significantly and negatively correlated with the gel consistency and alkali spreading value ( r = −0.90 ** – −0.91 **), and positively correlated with the amylose content ( r = 0.87 **). ACC concentrations in root exudates at mid-grain-filling stage were very significantly correlated with the percentage of chalky grains and chalkiness ( r = 0.97 ** − 0.98 **), and those at late-grain-filling stage were significantly correlated with chalkiness and chalky size ( r = 0.69 * −0.96 **). The more the malic acid and succinic acid exuded from roots for a cultivar, the greater the breakdown values and the smaller the setback values in the starch profile, and the results were reversed for a cultivar with more tartaric acid and citric acid exuded from roots during the grain-filling period. The cultivar with more lactic acid in exudates had smaller gel consistency and alkali spreading values, but had greater amylose content. When roots were treated with exogenous ZR, ABA, and ACC during grain filling, effects of the chemicals on the rice quality were consistent with the relationships of the endogenous hormones (Z + ZR, ABA, and ACC) with the quality indexes. Using rape cake as organic fertilizer can increase the concentrations of malic acid and succinic acids exuded from roots as well as the breakdown value in starch profile and reduce the setback value. The results suggest that root chemical signals play important roles in the formation of rice quality, and rice quality could be improved through regulating the signals.

Effects of plastic film mulching cultivation under non‐flooded condition on rice quality

AbstractPlastic film mulching cultivation under non‐flooded condition (PFMC), a new high‐efficiency and water‐saving cultivation technique, has been adopted and developed in many regions of china since the 1980s. Field experiments were conducted to evaluate the effects of PFMC on rice quality in three agro‐ecosystems (plain, basin and mountainous area) in 2001. The experiment consisted of three treatments, which were conventional flooded cultivation (CFC), PFMC and non‐mulching cultivation (NMC) under non‐flooded condition in a randomized complete block design with three replications. Compared with CFC, PFMC increased head‐milled rice recovery (with the exception of plain area), rice transparency and alkali spreading value, but slightly decreased gel consistency and obviously decreased chalky grain rate. Compared with NMC, those quality traits under PFMC were changeable at different sites. There were no significant differences for brown rice rate (except hilly area), milling rice quality and amylose content across treatments. In addition, nutritional quality under PFMC was notably improved in comparison with CFC and NMC. With few exceptions, the protein content, total amino acid content, individual amino acid content and Lys content of rice decreased in the order of PFMC > NMC > CFC. In general, rice quality is affected by each agro‐ecosystem and cultivation system to different degrees. PFMC had more influence on rice quality in hilly region than plain and basin regions. Copyright © 2006 Society of Chemical Industry

Modeling changes in milled rice ( Oryza sativa L.) kernel dimensions during soaking by image analysis

Tests were performed for milled whole kernels of ten Thai rice varieties ranging from low to high amylose content (16–29%) with three initial moisture levels (approximately, 8, 12 and 16% d.b.) for monitoring the dimensional changes in rice kernels during soaking in relation to the varietal differences manifested by the physicochemical properties. It was observed that the two-dimensional shape factor of the milled rice kernel remains constant during whole soaking duration. The change in kernel dimension during soaking could be best expressed by a modified exponential relationship with the R 2 for fitting ranging, respectively, from 0.983–0.999, 0.985–0.999, 0.984–0.999 and 0.985–1.000 for kernel length, width, perimeter and projected area for all rice varieties. The parameters of the fitted relationship for describing changes in kernel dimensions during soaking were found to be the function of initial moisture content and physicochemical properties of rice varieties under study. The dimensional features, namely, length, width, perimeter and projected area of milled rice kernel during soaking could be estimated from its initial moisture content and physicochemical properties such as amylose content, alkali spreading value, and protein content within ±5% of the experimental value.

Analysis of quantitative trait loci for some starch properties of rice (Oryza sativa L.): thermal properties, gel texture and swelling volume

To understand the genetic basis of gelatinization temperature (GT), gel textural traits and flour swelling volume, quantitative trait loci (QTL) were mapped for these traits using a doubled haploid (DH) population derived from a cross between indica variety Zai-Ye-Qing 8 (ZYQ8) and japonica variety Jing-Xi 17 (JX17). The results indicated that the starch property parameters were continuously distributed among the DH lines, and some DH lines showed transgressive segregation for all the parameters. A total of 16 QTLs were identified for seven traits. A major QTL, the alk gene on chromosome 6 was significant for the three GT traits, onset temperature (To), peak temperature (Tp), and completion temperature (Tc). This locus could explain 49.4, 38.9, and 28.3% of the total variance, respectively, indicating that GT parameters were substantially controlled by the alk gene which has previously been identified for alkali spreading value (ASV). The additive effects of alk on To,Tp and Tc were from ZYQ8. Another two QTLs on chromosomes 1 and 7 were also identified for the three GT parameters, whose positive effects were contributed from JX17. Another QTL on chromosome 10 with the positive effects coming from ZYQ8 was significant only for Tc. However, the enthalpy (ΔH) of gelatinization was controlled by two minor QTLs on chromosomes 1 and 7. A major QTL, the Wx gene on chromosome 6 was identified for gel hardness and flour swelling volume which explained 58.8 and 36.6% of the total variances, respectively. Another two QTLs were also detected for flour swelling volume, one of which (qSV-7) could explain 21.4% of the total variance. However, gel cohesiveness was controlled by a major QTL located between alk and Wx on chromosome 6.