Moisture distribution in rice grains used for sake brewing analyzed by magnetic resonance imaging

Water absorption in individual white-core and non-white-core grains of rice varieties used in sake brewing was observed during soaking by magnetic resonance imaging (MRI). Water was absorbed faster in white-core grains than in non-white-core grains and was pooled in the core. Moisture distributions were compared using the line profiles of nuclear magnetic resonance signal intensities (SI profiles) generated from magnetic resonance images of grains soaked for 2 h. SI profiles of white-core and non-white-core grains overlapped despite slight differences in the central and intermediate regions of the grains. A white-core-like structure with loosely packed starch granules was found to exist in the endosperm of non-white-core grains. SI profiles of grains polished to 70% of the yield weight of brown rice were similar in shape to those of grains polished to 90% of the yield, but their overall moisture content was higher after the removal of the hydrophobic grain periphery. A varietal difference in the thickness of the intermediate region, which may affect fissuring resistance in the polishing process, was detected in SI profiles. Differences in water absorbability between parents and their offspring were also apparent from their SI profiles. MRI enabled the detection of variety-specific water-absorption properties in grains.     

Hardness Distribution and Endosperm Structure on Polishing Characteristics of Brewer’s Rice Kernels

Abstract

This study was designed to determine the effects of the hardness distribution and the endosperm structure on the polishing characteristics of brewer’s rice kernels. We used four brewer’s rice cultivars, Kairyo-omachi, Hattan-nishiki No. 1, Senbon-nishiki and Yamada-nishiki. The broken kernel ratios in Kairyo-omachi and Hattan-nishiki No. 1 were significantly higher than those in Senbon-nishiki and Yamada-nishiki. Vickers hardness (VH) values in white-core tissues in kernels differed among varieties, which were significantly lower in Kairyo-omachi and Hattan-nishiki No. 1. However, no varietal differences were observed in VH values in the peripheral translucent tissues surrounding the white-core tissues. The tissues along the dorsoventral axis were softer than those along the longitudinal axis of the kernels. The tissues on the ventral side were softer than those on the dorsal side. Scanning electron microscopy (SEM) observations revealed the presence of closely arranged compound starch granules and few varietal differences in the peripheral translucent tissues surrounding the white-core tissues. However, as compared with Yamada-nishiki and Senbon-nishiki, in Hattan-nishiki No. 1 and Kairyo-omachi, the starch granules were loosely packed and the airspaces between the starch granules were more numerous in the white-core tissues. A higher number of airspaces and less starch were present in the endosperm cells along the dorsoventral axis when compared with along the longitudinal axis and on the ventral side than on the dorsal side. The present study showed that polishing characteristics are closely related with the endosperm structure, which is characterized as the density of starch granules.     

Relationship between the Starch Properties of White-Core Tissue and Polishing Characteristics in Brewers’ Rice Kernels

References

The kernels of Hattan-nishiki No. 1 and Kairyo-omachi have larger air spaces in the white-core tissue and are broken easily during the process of polishing when compared with those of Senbon-nishiki and Yamada-nishiki. The polishing characteristics of brewers’ rice kernels are closely related with the structure of the white-core tissue of kernels. In this study, the varietal differences in the starch properties of white-core tissue of brewers’ rice kernels on polishing characteristics were studied. The starch properties were studied by rapid visco analysis (RVA) and differential scanning calorimetry (DSC); the amylose content of the rice flour of each variety was also analysed. No significant differences were observed in the amylose content among the four varieties. The two RVA parameters, peak viscosity and breakdown, were higher in Hattan-nishiki No. 1 and no significant differences were observed in them among Senbon-nishiki, Yamada-nishiki and Kairyo-omachi. The DSC parameters, gelatinization onset and peak and conclusion temperatures, were higher in Hattan-nishiki No. 1, lower in Senbon-nishiki and Yamada-nishiki, and intermediate between them in Kairyo-omachi. These results suggest that the polishing characteristics of brewers’ rice kernels are related with not only the endosperm structure but also the starch property of white-core tissue, except for Kairyo-omachi.     

Properties of Starch and Protein of “Hattan-Type Varieties” of Rice Suitable for Brewing Original Hiroshima Sake

Abstract

By successive crossing using Hattan-type varieties originating from “Hattanso” as a parent, “Hattan-type varieties” of rice suitable for brewing the original Hiroshima sake have been bred. In this study, the difference in the properties of starch and protein among the Hattan-type varieties was examined. Six Hattan-type varieties, Hattanso, Hattan No.10, Hattan No.35, Hattan No.40, Hattan-nishiki No.1 and Hattan-nishiki No.2, were used. As the properties of starch, amylose content, pasting properties and gelatinization properties were examined. The pasting and gelatinization properties were examined using a rapid viscoanalyzer (RVA) and a differential scanning calorimetry (DSC), respectively. As the properties of protein, the compositional ratio of two types of protein bodies (PB-II/PB-I) was analyzed. However, no significant differences in the above properties were observed among these Hattan-type varieties. The above properties of starch and protein in Hattanso seem to be retained in all of these varieties. In these varieties, breeding might not have been aimed at improvement of the properties of starch and protein.     

Endosperm Structure of White-Belly and White-Core Rice Grains Shown by Scanning Electron Microscopy

Abstract:

White-belly and white-core are the major two types of grain chalkiness in japonica rice. This study aims to compare the morphological features of white-belly and white-core using a scanning electron microcope (SEM). A japonica rice cultivar Wuyujing3 and its mutants were used as materials. Nearly 1000 SEM images were observed, and 12 representative photos were selected. SEM images showed contrasting differences between white-belly and white-core in endosperm microstructure including the shape of endosperm cell, the size distribution of starch granules, and the amount of protein bodies. White-belly and white-core also varied markedly in morphological features of the cracked compound starch granules. Our findings should help to advance our understanding of the multi-faceted nature of grain chalkiness from the perspective of starch and protein accumulation, and should be of value for future work on rice grain chalkiness.     

Varietal Differences in Endosperm Structure Related to High-degree Polishing Properties of “Hattan Varieties” of Rice Suitable for Brewing Original Hiroshima Sake

Abstract

This study was conducted to clarify the effect of varietal differences in the endosperm structure on the high-degree polishing properties of Hattan varieties of rice suitable for brewing original Hiroshima sake. Four varieties were used: Hattan No.35, Hattan-nishiki No.1, Hattan-nishiki No.2, and Yamada-nishiki. Ellipsoidal-white-core grains occurred at a higher rate in Hattan-nishiki No.1 and No.2, whereas lined-white-core grains were observed at a higher rate in Hattan No.35 and Yamada-nishiki. Hattan No.35 and Yamada-nishiki showed low void polishing rates, and Hattan-nishiki No.1 and No.2 high void polishing rates after 50% polishing. Hattan-nishiki No.1 and No.2 showed inferior properties; that is, many broken and cracked grains, particularly cracked grains, after 50% polishing. The contents of broken grains and cracked grains in Hattan No.35 were higher than those in Yamada-nishiki and lower than those in Hattan-nishiki No.1 and No.2. In Hattan No.35 and Yamada-nishiki, fewer airspaces were observed between the amyloplasts at the center of the white-core as compared with Hattan-nishiki No.1 and No.2. This study showed that the differences in the endosperm structure of white-cores in the brewers’ rice grain are related to varietal differences in the tolerance to high-degree polishing.     

优质籼稻品种黄华占和扬稻6号稻米理化特性和淀粉精细结构比较

以携带相同Wx^b基因的籼稻品种黄华占和扬稻6号为试验材料,系统分析了这2个优质籼稻品种的理化特性和淀粉精细结构。结果表明,黄华占稻米蛋白质含量显著低于扬稻6号,而表观直链淀粉含量高于扬稻6号,其他理化品质如胶稠度、总淀粉含量和碱消值两者无显著差异;黄华占稻米具有较高的糊化温度和热焓值。黄华占和扬稻6号稻米淀粉粘滞曲线较为接近,但黄华占稻米具有较高的崩解值和较小的回复值。扫描电镜分析表明,淀粉粒形态和结构在2个样品间无明显差异;但淀粉精细结构分析表明,黄华占稻米淀粉含有较少的支链淀粉短链以及较多的支链长链和较多的直链淀粉短链;淀粉晶体结构分析表明,黄华占和扬稻6号淀粉均为A型晶体,但黄华占稻米淀粉的长程有序结构较扬稻6号淀粉高,而短程有序结构样品间无显著差异。上述研究为选育优质籼稻提供了参考。     

氮肥对粳稻籽粒腹白和心白发生及生化组成的影响

为探讨不同类型垩白水稻对氮肥的响应差异,以武育粳3号的高腹白突变体(WBRK)和高心白突变体(WCRK)为材料,设置不施氮肥(对照)和两个不同的基肥与穗肥比例处理(N5-5和N10-0)共3个处理,分析施氮对腹白米和心白米的发生及籽粒生化组分的影响。结果表明,施用氮肥显著增加了腹白米率和心白米率,且腹白较心白更易受氮肥影响。施氮对WBRK籽粒总淀粉、直链淀粉和支链淀粉含量无显著影响,显著增加了WCRK籽粒淀粉组分的含量,改善了WBRK和WCRK的碾磨品质。与对照相比,N5-5处理显著增加了WBRK籽粒蛋白质及其组分中球蛋白、醇溶蛋白和谷蛋白含量以及WCRK籽粒蛋白质含量。N10-0处理显著降低了WBRK和WCRK籽粒中的蛋白质和谷蛋白含量。N5-5处理下,WBRK和WCRK籽粒中大多数氨基酸含量有所增加,但组氨酸和精氨酸含量有所降低,WCRK表现得更明显。研究表明,氮素对不同类型垩白水稻品种腹白和心白发生及籽粒贮藏物质积累的影响存在差异,显示出生产中采用不同调优栽培措施的必要性。     

Physicochemical Properties of Eight Popular Glutinous Rice Varieties in Korea

Abstract

The physicochemical properties of eight popular glutinous rice varieties (Hwasunchal, Dongjinchal, Sangjuchal, Seolhyangchal, Jinbuchal, Sangnamchal, Hangangchal, Milyang-167) in Korea were evaluated. The starch granules in Seolyangchal, Sangnamchal, Hangangchal, and Milyang-167 rice showed greater crystallization than that of the other varieties, which were more loosely packed with larger air spaces in between granules. Dongjinchal rice showed lowest amounts of potassium and calcium with 44.51 and 3029.50 ppm, respectively. This variety also exhibited the highest sugar content with 1.30–16.82 μg g-¹ and fastest hydrolysis rate of 771.5 mg g-¹. Sangnamchal, Sangjuchal, and Jinbuchal varieties showed abundant amounts of essential amino acids and highest pasting values (73.6°C, 3.0 min). On the other hand, lowest pasting values (69.6°C, 2.7 min) and total amino acid content of 452.61 ng mg-¹ were observed in Milyang-167 rice. Hwasunchal and Sangnamchal samples contained the highest concentration of unsaturated fatty acids with 760 mg g-¹ and lowest level of saturated fatty acids with 230 mg g-¹. The highest viscosity values were obtained in Hangangchal variety, while the lowest values were found in Jinbuchal sample. This study illustrates the wide variation in the physicochemical properties of the glutinous rice varieties analyzed. The results could serve as baseline information for the quality evaluation of rice with unique characteristics suitable for specialty food processing.     

利用RVA谱快速鉴别不同表观直链淀粉含量早籼稻的淀粉粘滞特性

采用粘度速测仪分析了浙江省新近培育的早籼稻新品种（系）的淀粉粘滞特性,结果表明不同品种（系）具有特征性RVA谱。依消减值可有效区分出品种（系）表观直链淀粉含量（AAC）的高低。低AAC品种（系）的消减值一般为负值,中等或高AAC品种（系）的消减值为正值。中等AAC品种（系）间食用品质的优劣,可根据消减值和崩解值判断。RVA谱的崩解值与胶稠度和米饭口感相关,消减值与米饭质地关联。上述结果表明, RVA谱特性可望作为理化标记在优质稻米育种中发挥重要作用。     

Effects of inhibition of starch branching enzymes on starch ordered structure and component accumulation in developing kernels of rice

Three rice varieties, Te-qing (TQ), Wu-xiang 9915 (WX) and Guang-ling-xiang-nuo (GLXN) with different amylose contents, and their derived lines with inhibition of starch branching enzyme I and IIb (SBEI/IIb) (GLXN-, WX- and TQ-SBEI/IIb^–) were used to investigate and compare the starch ordered structure and component accumulation in developing kernels. The starches in developing kernels of TQ, WX and GLXN all showed a typical A-type crystallinity and had similar short-range ordered structure, but their relative crystallinities gradually decreased in TQ and WX and had no significant change in GLXN with kernel development. For wild-type rices, starch components gradually increased in developing kernels. With inhibition of SBEI/IIb, the accumulation of amylose and amylopectin long branch-chains in kernels was slightly affected, but amylopectin short branch-chains seriously decreased, resulting in a significantly lower dry weight and starch content in kernel. The B-type crystallinity in developing starch gradually accumulated with kernel development of TQ-, Wx- and GLXN-SBEI/IIb^– lines. The inhibition of SBEI/IIb decreased the relative crystallinity but increased the short-range ordered structure of starches. The effects of inhibition of SBEI/IIb on starch ordered structure and component accumulation mainly appeared after 10 days after flowering, and were the most conspicuous for indica rice TQ. Though the inhibition of SBEI/IIb influenced the ordered structure and component accumulation of starch, the starch content and components in developing kernels all showed significantly positive correlations with kernel dry weight.     

Physicochemical and Mochi-making Properties of the Native Red and Black-Kerneled Glutinous Rice Cultivars

Abstract

The physicochemical and mochi-making properties of native red and black-kerneled glutinous rice (RKGR) and white-kerneled glutinous rice (WKGR) of japonica and indica varieties, were examined. In both the japonica and indica varieties, RKGR cultivars contained more protein than WKGR cultivars, the difference being 2.1% and 1.9%, respectively. In both varieties, no significant difference in amylose contents of RKGR and WKGR was observed. The amylographic characteristics of RKGR varied considerably with the variety. In the japonica variety, RKGR cultivars tended to have higher mean maximum viscosity and breakdown values than WKGR cultivars, although the difference was not significant. By contrast, in the indica variety, the mean maximum viscosity and breakdown values of RKGR cultivars were significantly (p<0.05, t-test) lower than those of WKGR cultivars. In both varieties, the difference in gelatinization temperature between RKGR cultivars and WKGR cultivars was not significant. Cooked RKGR cultivars had a higher hardness and a higher hardness/adhesion ratio than WKGR cultivars, although a significant difference between the adhesion of RKGR cultivars. The hardening speed of mochi made from RKGR cultivars tended to be lower than that of mochi made from WKGR cultivars. The hardening speed of mochi showed a significant positive correlation with the atmospheric temperature during the ripening period. The palatability of mochi of RKGR cultivars in both varieties tended to be inferior to that of WKGR cultivars. The particularity of physicochemical and mochi-making properties of RKGR cultivars is considered to be excellent as the processing material and to develop new processed-rice products     

酿酒专用小麦籽粒品质特性研究

为探明酿酒专用小麦的主要籽粒品质特征,对12个常用酿酒小麦品种及6个非酿酒小麦品种的主要籽粒品质指标进行了分析与比较。结果表明,12个酿酒小麦品种的硬度指数均小于45%,角质率均小于70%,平均总淀粉含量大于60%,其中支链淀粉占比大于70%;籽粒硬度指数、角质率、饱满度及淀粉含量与弱筋小麦皖西麦0638相近;蛋白质、湿面筋含量显著低于非酿酒小麦西农20、周麦36,符合中国中筋小麦标准。相关性分析表明,酿酒小麦籽粒硬度指数与角质率呈极显著正相关,与千粒重呈极显著负相关;支链淀粉含量与千粒重呈显著正相关。通过聚类分析将12种酿酒小麦分为3个类群,类群Ⅰ包括9个品种,较其他2个类群总淀粉含量、支链淀粉含量高,硬度、蛋白质含量适中。综上所述,供试酿酒小麦籽粒具有软质、饱满、胚乳呈粉质-半角质、蛋白质含量适中、支链淀粉含量高等特点;籽粒特性和淀粉含量接近弱筋小麦并具备中筋小麦的蛋白质、湿面筋含量的小麦品种具有更大优势成为酿酒小麦。     

Temperature during grain ripening affects the ratio of type-II/type-I protein body and starch pasting properties of rice (Oryza sativa L.)

The starch and protein properties of rice grain are important factors for sake brewing and these properties are reported to be influenced by temperatures during grain ripening. Amylose content, nitrogen content, protein composition, pasting properties measured by a Rapid Visco Analyser (RVA), and their relationship to temperatures during ripening were investigated in a rice cultivar, Yamadanishiki, which was grown under various conditions in the same experimental field. The average temperature after heading was significantly correlated with amylose content and RVA properties, but not with nitrogen content. Under high temperatures during ripening, a decrease in prolamin, which accumulated in type I protein body (PB-I), and an increase in glutelin, which deposits in type II PB (PB-II), were recognized. The ratio of PB-II/PB-I and RVA pasting temperatures were distinctly increased as the temperature became higher. High temperatures during grain ripening would lead to difficulties in digesting steamed rice grains by Aspergillus oryzae, together with ease in digesting rice protein. The average temperature of 11–20 days after heading showed a higher correlation coefficient than that of 1–10 or 21–30 days, implying that temperatures during the middle stage of grain development would be important in determining the rice component that relates to brewing properties.     

Study of kernel structure of high-amylose and wild-type rice by X-ray microtomography and SEM

Rice kernels of a transgenic high-amylose rice line and its wild type were examined by a high-resolution X-ray microtomography (XMT) and an environmental scanning electron microscope. Two-dimensional (2-D) cross-sectional images and 3-D objects from XMT were reconstructed and analyzed to elucidate their structural features. The lack of two isoforms of starch branching enzyme, termed SBEI and SBEIIb in high-amylose rice (HAR), resulted in a distinctly different grain inner density than wild-type rice (WTR). HAR had smaller, elongated starch granules with air spaces inside the kernels resulting in an opaque grain, whereas WTR had a tight endosperm with little air space and polygonal starch granules. XMT allowed a full 3-D characterization of the rice kernel structure and revealed that air space distribution was not uniform in the HAR kernel.     

Changes in the properties of rice varieties with different amylose content on dry heat parboiling

Dry heat parboiling is a unique paddy processing technique that has been scarcely exploited. Dry heat parboiling at high temperature for short time and low temperature for long time on physical and physicochemical properties of three rice varieties differing in amylose content were studied. Hardness of the kernels increased from 66.4 N, 68.8 N and 59.8 N in raw samples to 89.1 N, 86.9 N and 59.8 N in parboiled high amylose, low amylose and waxy rice samples respectively. Rapid migration and evaporation of water from severely heated kernels caused cavity formation at the centre. Irreversible damage of amylopectin structures to leachable fractions caused continuous rise of the pasting curve. Crystallinity was thereby reduced. Parboiled high amylose samples gave X-ray diffraction patterns with peaks characteristic of A, B and V-type starch crystallinity. Crystalline starch-lipid complexes were observed in low amylose and waxy rices. The significant increase in the amount of rapidly digestible starch from 56.7%, 61.7% and 66.6% in raw samples to 92.1%, 90.8% and 94.8% respectively in severely processed rice samples and subsequent reduction in resistant starch from 24.5%, 21.2% and 18.4% to 0.4%, 1.9% and 0.1% indicated possibilities for targeted food use of the dry heat parboiled samples.     

早籼稻米RVA谱特性的品种间差异及其温度效应特征

采用粘度快速测定仪分析了10个不同食味类型早籼品种的淀粉粘滞（RVA谱）特性,并通过人工气候箱控温处理试验对早籼稻米淀粉粘滞特性与水稻灌浆结实期温度间的关系进行了分析。结果发现,食味较优的早籼水稻品种一般具有较大的崩解值和较小的消减值、回冷恢复值,而食味较差的早籼品种则相反,普遍有着较小的崩解值和较大的消减值、回冷恢复值,具有较明显的规律性;而不同食味类型早籼品种在最高粘度、热浆粘度、最终粘度等指标上差异规律则不明显;水稻灌浆结实期温度处理对早籼稻米淀粉粘滞特性的影响主要表现在淀粉糊化过程的回冷特性上,与高温处理相比,水稻在适温处理下灌浆,其稻米淀粉的最终粘滞度、消减值和回冷恢复值呈现出明显的上升趋势,而崩解值的变化则相对较为复杂。适温处理下稻米淀粉RVA谱特征的最终粘滞度、消减值和回冷恢复值等指标的变化,可能正是部分早籼品种“翻秋”种植后其蒸煮食味品质明显变好的一个重要理化指标。     

籼稻RAPD标记遗传距离与杂种后代稻米味度及RVA谱特性的相关分析

 选用8个籼稻品种按Griffing双列杂交方法Ⅳ配制28个F1杂交组合，分析了RAPD分子标记籼稻遗传距离与稻米味度及淀粉粘滞性谱（RVA谱）杂种优势的关系。结果表明， 利用297个多态性RAPD标记位点计算8个亲本间分子标记遗传距离，其范围在0.197~0.349，平均为0.269，8个亲本可划分为2个类群；味度值和RVA谱的中亲优势平均而言介于双亲之间，分子标记遗传距离与F1味度值和RVA谱的表现以及杂种优势间的相关均不显著，味度值和RVA谱杂种优势与亲本间的遗传差异大小无关；双亲味度和RVA谱平均值与杂种味度和RVA谱之间均呈极显著的正相关，双亲味度值和RVA谱的平均值高，杂种味度值和RVA谱也就高。     

稻米中蛋白质对淀粉RVA特征谱的影响

通过分析蛋白酶或还原剂二巯基苏糖醇（DTT）分别去除稻米蛋白质或打破蛋白质二硫键后,稻米RVA（Rapid Visco Analyzer）特征谱形成和特征值的变化,研究蛋白质对淀粉RVA特征谱的影响,以及对米饭食味品质的作用。在淀粉糊化过程中,蛋白质使RVA特征谱的峰值黏度、冷胶黏度等值升高,改变RVA线性上升段的斜率。蛋白质可能通过二硫键结合形成的蛋白质网络本身和通过吸水减少淀粉水合的有效水量,协同提高糊化多相体系的浓度,增强分散相与黏稠相的互作。蛋白质影响米饭食味品质,可能通过改变米粒的吸水性而起作用。     

水稻结实期米质动态变化研究

 通过对9个水稻品种、3个播期连续4年灌浆结实期中，稻米粒重和13个单一品质性状的观察分析表明，稻米综合品质在齐穗后先有一个近乎线性的快速增长期，30 d以后品质变化(品种和播期间稍有差异)趋于稳定，用二次或三次回归曲线模拟效果最好，综合品质与粒重的变化有极显著或显著正相关关系。