Waxy Rice Cultivars Research Articles

Elucidating the effect of polyphenol-protein interactions on rheological properties of purple waxy rice

Processing purple rice causes interactions between polyphenols and protein. The effect of covalent and non-covalent interactions on the viscosity of non-pigmented (Neches) and purple (HB-1) waxy rice cultivars was studied by using dithiothreitol (DTT), urea, sodium chloride (NaCl), and acidic (pH 2) and alkaline (pH 12) environments. Urea did not affect pasting properties of both cultivars. The pasting viscosity of whole grain Neches and HB-1 and milled Neches increased by NaCl, but not that of milled HB-1. DTT reduced the pasting viscosity of Neches, whereas that of HB-1 decreased moderately. Whole grain Neches and HB-1 and milled Neches exhibited greater pasting viscosity at pH 2, whereas milled HB-1 was unaffected. Pasting viscosity of Neches was slightly affected at pH 12, whereas that of whole grain HB-1 increased and milled HB-1 decreased. Protein fractions of both cultivars shared similar molecular weight and secondary structures, but polyphenols affected the tertiary structure. The polyphenol-protein cross-links played the predominant role in the viscosity development of purple rice and may enhance the stability of the protein network at pH 2 and in the presence of DTT, but were disrupted at pH 12. Polyphenol-protein interactions may improve starch pasting properties without the need for chemical modifications.

Characterization of multi-scale structure and physicochemical properties of starch from diverse Japonica waxy rice cultivars

Eight Japonica glutinous rice cultivars, collected from seven different provinces in China, were selected to explore the structural and physicochemical properties of their starch. The apparent amylose content ranged from 0.07% to 1.5%. Of parameters related to molecular structure, aggregation (crystalline, short-range order and lamellar structure) and granule structure, the amylopectin A chain (DP 6–12) and B2 chain (DP 25–36), the crystallinity and the average repeat distance of lamella of the starch granule are important in influencing physicochemical properties of waxy rice starch. The A chain level of amylopectin in waxy rice starch was negatively correlated with the onset temperature, gelatinization enthalpy and setback viscosity, but positively correlated with α-amylase hydrolysis coefficient. However, the B2 chain level of the amylopectin and the crystallinity of waxy rice starch had opposite effects on these parameters. Also, higher percentage of A was correlated with less order of the lamellar structure of waxy rice starch. Waxy rice starch with smaller granule size was more easily hydrolyzed by α-amylase. The difference in multi-scale structure and physicochemical properties can contribute to the variation in the development of waxy rice starch starch-based products.

The Development of Two High-Yield and High-Quality Functional Rice Cultivars Using Marker-Assisted Selection and Conventional Breeding Methods.

Rice (Oryza sativa L.) is an important crop worldwide. Functional rice has exhibited health benefits. The aim of this study was to use marker-assisted selection (MAS) to introgress two genes, GE (giant embryo) and OsALDH7 (aldehyde dehydrogenase, golden-like endosperm) into colored rice and obtain high yield functional rice. CNY103108 and CNY103107 are two rice lines with golden-like endosperms and giant embryos. They were used as the donor parents. CNY922401, an elite purple waxy rice line, and TNGSW26, an indica red waxy rice cultivar were used as the recurrent parents. Foreground selection of the progenies was completed using functional markers for GE and OsALDH7, and background selection was completed using molecular markers to recover the background of the recurrent parents. MAS results showed a purple functional rice population (PFR) (CNY922401/CNY103108), with the recovery rate of the recurrent parental genome as 91.3%, and a red functional rice population (RFR) (TNGSW26/CNY103107) with the recovery as 89.8%. After five-season yield trials and several antioxidant activities analyses, PFR32 and RFR13 lines, which have similar yields and antioxidant activities, were selected as the recurrent parents with a golden-like endosperm and a giant embryo. For a biofortification purpose, they can become valuable products and be adapted to the current agricultural community.

Comparison between microwave‐cooking and steam‐cooking on starch properties and in vitro starch digestibility of cooked pigmented rice

AbstractThe influence of two types of cooking method, that is, steam‐cooking and microwave‐cooking, on the morphological structure, starch fractions, and starch digestibility of cooked Thai pigmented rice (three cultivars) was examined. The relationship between starch hydrolysis and change in X‐ray diffraction (XRD) pattern, including the change of crystallinity degree during in vitro digestion, was also investigated. The results indicated that the cooked rice morphological structure and starch hydrolysis rate during in vitro digestion was varied by the cooking method. All non‐waxy rice cultivars exhibited Vh‐type crystallinity, whereas, no crystalline peak was detected in the waxy rice cultivar. However, the XRD pattern and crystallinity degree of steam‐cooked rice were dramatically changed after simulated small intestinal digestion for 360 and 480 min when compared with microwave‐cooked rice. Moreover, steam‐cooked rice showed a significantly lower percentage of equilibrium starch hydrolysis than that of the microwave‐cooked rice.Practical applicationsRice attributes and change of crystallinity in XRD pattern during in vitro digestion have found to correlate with rice starch digestibility, which varied depending on rice cooking methods. Steam‐cooking could enhance the degree of crystallinity during in vitro digestion, which would affect to retard rice starch digestion. This finding is interesting for the consumer on the selection of the optimized cooking process that promotes a healthier effect.

In situ Degradation and Characterization of Endosperm Starch in Waxy Rice with the Inhibition of Starch Branching Enzymes during Seedling Growth.

High-resistant starch cereal crops with the inhibition of the starch branching enzyme (SBE) have been widely studied. However, the effects of the inhibition of SBE on waxy cereal crops are unclear. A transgenic rice line (GTR) derived from a japonica waxy rice cultivar Guang-ling-xiang-nuo (GLXN) has been developed through antisense RNA inhibition of both SBEI and SBEIIb. In this study, GLXN and GTR were cultivated in the dark only in deionized H2O, and their shoot and root growth, starch in situ degradation, and starch property changes were investigated during seedling growth. Compared with GLXN, GTR showed a significantly slow seedling growth, which was not due to the embryo size and vitality. The slow degradation of starch in the seed restrained the seedling growth. GLXN starch was completely degraded gradually from the proximal to distal region of the embryo and from the outer to inner region in the endosperm, but GTR starch in the peripheral region of the endosperm was not completely degraded, and the starch residual was located in the outside of the compound starch though its degradation pattern was similar to GLXN. During seedling growth, GLXN starch had the same A-type crystallinity and a similar ordered structure, but the crystallinity changed from the CA-type to B-type and the ordered structure gradually increased in the GTR starch. The above results indicated that GTR had a heterogeneous starch distributed regionally in the endosperm. The starch in the peripheral region of the endosperm had a B-type crystallinity, which was located in the outside of the compound starch and significantly increased the resistance to in situ degradation, leading to the seedling slow growth.

Inhibition of starch branching enzymes in waxy rice increases the proportion of long branch-chains of amylopectin resulting in the comb-like profiles of starch granules

Starches with comb-like profiles have been detected in some cereal endosperms with inhibiting expression of starch branching enzyme (SBE). Although amylose is considered to be an important factor in the formation of the comb-like profile, the details remain unclear. In this study, a transgenic rice line (GLXN-SBEI/IIb−) was derived from japonica waxy rice cultivar Guang-ling-xiang-nuo (GLXN) through antisense RNA inhibition of both SBEI and SBEIIb. The expression and activity of SBEI, SBEIIb and SBEIIa were declined. The GLXN-SBEI/IIb− endosperm contained large and small starch granules, and these starch granules had the comb-like profiles. The comb-like profiles of starches were detected in GLXN-SBEI/IIb− endosperm after 10 days after flowering with gradually increasing proportion of long branch-chains of amylopectin. The long branch-chains of amylopectin were responsible for forming the comb-like profiles at the outer region of starch granules. The gradually decreasing expression of SBEs influenced the synthesis of amylopectin during endosperm development, resulting in different structure between the inner and outer regions of starch granules from GLXN-SBEI/IIb− endosperm. The above results indicated that the long branch-chains of amylopectin, not amylose, led to the formation of comb-like profiles of starch granules in cereal crops with inhibiting expression of SBEs.

早生で倒伏に強い水稲糯品種「里の白雪」の育成

早生で倒伏に強い水稲糯品種「里の白雪」の育成

Comparison of Starch Physicochemical Properties of Waxy Rice Cultivars with Different Hardening Rates

The objective of this study was to investigate the starch characteristics of a novel waxy rice cultivar Hitachimochi 36 (H36) with an extremely slow hardening rate of waxy rice cake and the relationships between starch physicochemical properties and texture of waxy rice cake. Starch isolated from H36 showed significantly higher digestibility than that from other waxy rice cultivars, and the starch digestibility highly correlated with the starch crystallinity. The compressive force of the starch gel prepared from H36 was significantly lower than that from other cultivars when stored at 5°C for five days, which reflected the differences in endothermic enthalpies corresponding to retrograded amylopectin. Various textural parameters of cooked waxy rice cake prepared from H36 were also remarkably different from those of cooked waxy rice cake prepared from other waxy rice cultivars. The cooked waxy rice cake prepared from H36 exhibited the lowest compressive force and breaking force by tensile and rupture tests, respectively. The analysis of amylopectin chain length distribution indicated that amylopectin of H36 contained higher proportions of the short chains. The difference in amylopectin chain length distribution and lower crystallinity of starch contributed to the unique textural properties of waxy rice cake prepared from H36.

A (1)H HR-MAS NMR-Based Metabolomic Study for Metabolic Characterization of Rice Grain from Various Oryza sativa L. Cultivars.

Rice grain metabolites are important for better understanding of the plant physiology of various rice cultivars and thus for developing rice cultivars aimed at providing diverse processed products. However, the variation of global metabolites in rice grains has rarely been explored. Here, we report the identification of intra- or intercellular metabolites in rice (Oryza sativa L.) grain powder using a (1)H high-resolution magic angle spinning (HR-MAS) NMR-based metabolomic approach. Compared with nonwaxy rice cultivars, marked accumulation of lipid metabolites such as fatty acids, phospholipids, and glycerophosphocholine in the grains of waxy rice cultivars demonstrated the distinct metabolic regulation and adaptation of each cultivar for effective growth during future germination, which may be reflected by high levels of glutamate, aspartate, asparagine, alanine, and sucrose. Therefore, this study provides important insights into the metabolic variations of diverse rice cultivars and their associations with environmental conditions and genetic backgrounds, with the aim of facilitating efficient development and the improvement of rice grain quality through inbreeding with genetic or chemical modification and mutation.

Emulsifying Properties of Proteins Isolated from Various Rice Cultivars

The emulsifying properties of rice proteins isolated from various non-waxy and waxy rice cultivars were studied to evaluate their potential application as oil-in-water (O/W) emulsifier and to compare the emulsifying properties of the rice proteins isolated from various rice cultivars. The solubility of the rice proteins was measured at different pHs (2–10), and O/W emulsions were prepared with the proteins at pH 2, 7, and 10. The rice protein-stabilized O/W emulsions were analyzed by measurement of particle size and zeta-potential, and observation under an optical microscope. The results indicated the potential of the rice proteins as emulsifiers at low and high pH values, and that, in particular, rice proteins isolated from waxy-rice cultivars could form stable emulsions even at neutral pH. The information obtained in this study may be useful for development of emulsion-based food products using rice protein isolate.

Baking Aptitude of Low-amylose and Waxy Rice Cultivar for a Rice Bread using Low-protein Hard Wheat

Baking Aptitude of Low-amylose and Waxy Rice Cultivar for a Rice Bread using Low-protein Hard Wheat

종자의 수분흡수속도가 찰벼 품종별 발아특성과 침윤초기 Guaiacol Peroxidase활성에 미치는 영향

찰벼 4품종을 두 온도조건(저온; <TEX>$15^{\circ}C$</TEX>, 대조; <TEX>$25^{\circ}C$</TEX>)에서 왕겨의 유무에 따라(정조 및 현미) 발아특성을 조사한 결과, 현미 발아율은 품종간 차이가 없었으나 정조 발아율은 저온에서 품종간 차이가 컸다. 종자를 침윤시키면 온도나 왕겨의 유무에 관계없이 수분이 급격히 증가하다가 30%에서 더이상 증가하지 않고 정체하는데 이때 정체기에 도달하는 시간은 온도가 높을수록, 정조보다 현미가 빨랐다. 그러나 수분정체기에 도달하는 시간은 품종간 차이가 있고 저온에서 차이가 컸다. 수분흡수시간은 발아율, 발아세, 발아속도, 평균발아일수와 모두 높은 부의 상관을 보여 초기 수분흡수시간이 빠를수록 발아를 촉진하는 것으로 나타났다. 침윤 24시간 뒤 guaiacol peroxidase활성은 처리 및 품종간에 큰 차이를 나타냈으며 발아세와 발아속도와 정의 상관이 있었으나 최종발아율과는 상관이 낮았다. Catalase활성은 발아율, 발아속도 등과 상관이 매우 낮았으며, 용해성 단백질함량 및 maltose농도도 발아특성과 상관이 낮았다. 종자활력검사(TTC활력검사)와 표준발아율검사(<TEX>$25^{\circ}C$</TEX>)에서 발아율이 높더라도 정조는 저온에서 품종간 발아율의 변이가 커 종자활력검사만으로 발아율을 예측하기 힘들었다. 따라서 초기의 종자활력은 TTC검사와 guaiacol peroxidase활성을 함께 고려하는 것이 더 정확한 것으로 생각된다. 또 품종간 발아율의 변이를 줄이고 발아속도를 높혀 균일한 발아를 유도하기 위해서는 적정범위에서 가능한 온도를 높혀 수분흡수를 촉진시켜야 한다. Germination is controlled by internal factors of seeds and external factors such as water, temperature and light. We investigated the relationship between germination characteristics of four waxy rice cultivars and patterns of water uptake, antioxidant enzymes and free soluble sugars during early imbibition. Seed viabilities by tetrazolium test of four different rice cultivars were higher than 95% and germination rates of the hulled rice seeds were on 95% average. However, germination rate of intact rice among four cultivars showed a big difference depending on temperature. Water uptake of hulled and intact rice seeds during imbibition reached a stationary phase at around 30% moisture content. Although rates of water uptake were faster in hulled rice and high temperature than intact rice and low temperature condition, difference of those among cultivars was greater under low temperature than high temperature. The time required for rice seeds to uptake 30% water was negatively correlated with percentage of germination, germination energy, germination speed and mean germination time. Guaiacol peroxidase activity at 24h of imbibition was correlated with germination energy and germination speed but not percentage of germination. Catalase activity, soluble protein and maltose concentration at 24h of imbibition were not correlated with characteristics of germination. These results suggest that a time required for rice seeds to uptake 30% of water significantly correlated with germination and guaiacol peroxidase activity during early imbibition plays an important role in initiation of germination.

Variation on Starch Properties and the Relationship to Single Nucleotide Polymorphism in SSIIa in Waxy Rice Collected from Central of Vietnam

Twenty two waxy rice cultivars originated from Central Vietnam were used for studying the variation on starch properties and the relationship to single nucleotide polymorphism in the SSIIa gene. A wide range of alkali digestibility level among 22 waxy rice cultivars was observed and recorded as low, intermediate and high alkali digestibility groups. All 22 waxy rice cultivars has significantly higher proportion of fa (DP≦12) and markedly lower proportion of fb1 chains with DP from 12 to 24 whereas the little difference was observed in proportion fb2 (25≦DP≦36) and fb3 (DP≧37) between waxy cultivars tested and IR36. The nucleotide changes in three exons (exon 1, exon 2 and exon 8) were observed in 22 waxy rice cultivars. Of the six single nucleotide polymorphism (SNPs) in the coding region, two SNPs, C/T (at site 516 bp) in exon 2 and G/T (at site 3903) in exon 8, were silent substitution while other four caused amino acid replacement. The SNP at position 264 bp in exon 1, was found an G–to–C transition causing change of glutamic to aspartic while the SNP at 3,799 bp in exon 8, resulting in glycine to serine change. The SNP at 4,198 bp, causing methionine to valine. The SNP at 4,329–4330 bp was observed a GC–to–TT transition leading to change of glycine–leucine change to glycine–phenylalanine. The study suggested that the wide variation on alkali digestibility and amylopectin fine structure in waxy rice starch was caused by the nucleotide diversity of SSIIa gene besides of other starch synthase genes involving in amylopectin synthesis.

찰벼 품종별 이화학적 특성 및 물성 비교

This study was carried out to compare the varietal difference in physiochemical properties and textural properties of waxy rice cultivars. Crude protein had 5.9-7.2% varietal difference while crude lipid and crude ash contents were within the range of 0.8-2.0% and 0.3-0.6% and had a similar tendency as non-waxy rice. The amylose content was within the range of 1.79-1.93% and did not show significant differences among the tested cultivars. The water binding capacity of Hwaseonchal of the japonica cultivars scored the highest, Sinseonchal showed the lowest, while tongil-type Hangangchal showed a lower value, which can be due to a higher internal density. Baekseolchal showed the highest alkali digestion value and Sinseonchal showed the lowest. In amylogram characteristics, Baekseolchal showed the lowest value and Hwaseonchal and Sangjuchal showed higher initial temperature. Hangangchal scored higher in peak viscosity, breakdown viscosity, and final viscosity. It was prospective for all the cultivars to show slow retrogradations due to low setbacks compared to non-waxy rice and Hangangchal which showed the lowest setback. X-ray diffraction of waxy rice starch particles was typical A pattern. Hangangchal scored the highest and Hwaseonchal scored the lowest in crystallinity. One of the characteristics of cooked rice made from waxy rice is the hardness, which shows degrees of retrogradations, increased in storage time. Hangangchal showed a higher range of transformation with time and a higher retrogradation rate.

Efficiencies of Chemical Techniques for Rice Grain Freshness Analysis

Two chemical methods which are commonly used for rice grain freshness determination were investigated for their efficiencies. Method 1 is made of bromothymol blue indicator, and the principle is based on indicator's color which is changed in according to pH of the stored rice grains. Method 2 is based on peroxidase activity which deteriorates during storage of rice grains. Both methods were used for determination of fresh-aged rice index of six Thai-rice cultivars, four from non-waxy rice cultivars (KDML 105, Chai Nat 1, Chai Nat 2 and Phitsanulok 2) and two from waxy rice cultivars (San-pah-tawng and RD6). Rice samples were kept in the forms of paddy and polished rice. Fresh-aged rice indices were determined using both methods every two weeks over the storage period of 24 weeks (six months). It was found that both methods were capable of detecting fresh-aged rice indices. The color of chemical solutions changed with regards to the age of rice grains and it could be detected spectrophotometrically. Rice grains which have been kept as paddy provided more consistent results. Method 1 is recommended for industrial application as it is simple, efficient and inexpensive.

Effect of amylose content on structure, texture and α-amylase reactivity of cooked rice

The susceptibility of cooked rice to α-amylolysis were studied in four Taiwanese rice cultivars differing in amylose contents, i.e. Taichung Native 1(TCN1, indica), Taigung 9 (TG9, japonica), Taichung Sen Waxy 1 (TCSW1, indica waxy), and Taichung Waxy 70 (TCW70, japonica waxy). In addition, the correlation between α-amylolysis and the microstructure and textural properties of the four rice cultivars was investigated. The hardness, gumminess and chewiness of cooked rice followed the order of TCN1>TG9>TCSW1>TCW70. However the waxy rice cultivars showed a higher extent and rate of α-amylolysis. Using scanning electron microscopy, the microstructure revealed that the low-amylose rice and waxy rice cultivars contained hollow in the central endosperm. The internal hollow disappeared after α-amylolysis, indicating that α-amylase had penetrated the cooked grain, resulting in the inside-out hydrolysis. These results indicated that the textural properties of cooked rice are influenced mainly by its amylose/amylopectin ratio, followed by influencing the pattern of α-amylolysis.

A genomics and multi-platform metabolomics approach to identify new traits of rice quality in traditional and improved varieties

Using a novel approach combining four complementary metabolomic and mineral platforms with genome-wide genotyping at 1536 single nucleotide polymorphism (SNP) loci, we have investigated the extent of biochemical and genetic diversity in three commercially-relevant waxy rice cultivars important to food production in the Lao People’s Democratic Republic (PDR). Following cultivation with different nitrogen fertiliser regimes, multiple metabolomic data sets, including minerals, were produced and analysed using multivariate statistical methods to reveal the degree of similarity between the genotypes and to identify discriminatory compounds supported by multiple technology platforms. Results revealed little effect of nitrogen supply on metabolites related to quality, despite known yield differences. All platforms revealed unique metabolic signatures for each variety and many discriminatory compounds could be identified as being relevant to consumers in terms of nutritional value and taste or flavour. For each platform, metabolomic diversity was highly associated with genetic distance between the varieties. This study demonstrates that multiple metabolomic platforms have potential as phenotyping tools to assist breeders in their quest to combine key yield and quality characteristics. This better enables rice improvement programs to meet different consumer and farmer needs, and to address food security in rice-consuming countries.

Genes coding for starch branching enzymes are major contributors to starch viscosity characteristics in waxy rice (Oryza sativa L.)

Granule-bound starch synthase (GBSS) encoded by the Waxy (Wx) gene determines the synthesis of amylose; while, starch branching enzymes encoded by Sbe genes are involved in the formation of amylopectin. Both amylose and amylopectin form starch in the endosperm of seeds. Here, we report on the effects of the wx gene and the two Sbe genes, Sbe1 and Sbe3, on starch paste viscosity in waxy rice. Molecular markers for both Sbe1 and Sbe3 have been developed based on sequence diversity between the rice subspecies indica and japonica. All Sbe- and Wx- linked markers have been used to investigate 40 waxy rice cultivars. For the wx locus (null Wx locus in waxy rice), four classes of (CT)n repeats, including (CT)16, (CT)17, (CT)18, and (CT)19, were detected in the putative leader sequence. Moreover, a unique sequence, AGTTATA, is also present at the 5′ splice junction site of the putative leader intron. Overall, the wx locus has no effect on starch paste viscosity characteristics. Among all 40 waxy rice cultivars, five genotypes are observed at the Sbe1 and Sbe3 loci. Polymorphisms in both Sbe1 and Sbe3 loci account for ∼70% of the observed variations in both hot and cool viscosities, and for 40% of the observed variations in both peak viscosity and consistency.

Development of quick-cooking meat congees using multi-level sensory evaluation

The study developed quick-cooking meat congees (QCMCs) arroz caldo and goto based on Philippine recipes using multi-level sensory evaluation. The QCMC prototypes of arroz caldo and goto consisted of basal quick-cooking rice (QCR) prepared from Philippine waxy rice cultivar Malagkit Sungsong, dehydrated spring onions, textured vegetable protein (TVP) as chicken meat analogue for arroz caldo, dehydrated ox tripe for goto and, spices. The rehydrated QCMCs arroz caldo and goto were found to be comparable with their conventionally prepared counterparts in terms of consumer acceptance including, color, aroma, consistency, texture, and overall quality as evaluated by 50 consumer panelists at 5% level of significance. The study was able to typify the flavors of arroz caldo and goto basically with the use of hydrolyzed vegetable proteins (HVP) and powdered equivalents of spices in the original formulations of conventionally prepared congees.

Detection of Waxy Maize Starch Adulteration in Waxy Rice Cake by Use of Stable Carbon Isotope Ratio Analysis.

Waxy rice cake, a popular New Year food in Japan, is occasionally adulterated with waxy maize starch. The stable carbon isotope ratios (13C/12C) of 132 samples of 71 waxy rice cultivars grown in Japan and 54 samples of maize starch have been determined by isotope ratio mass spectrometry. The 13C/12C values of fully-milled waxy rice and maize starch ranged from -24.4 to -27.3 parts per thousand (per mil) and from -9.6 to -11.1 per mil, respectively. Rice cakes with δ13C values higher than -24.2 per mil, 3 standard deviations from the mean of fully-milled rice, should be considered adulterated.