Physicochemical characterization and in-vitro digestibility of extruded rice noodles with different amylose contents based on rheological approaches

The physicochemical properties and in-vitro digestibility of extruded rice noodles with different amylose contents were characterized from a rheological point of view. Thermo-mechanical measurements showed that the rice flour with higher amylose contents exhibited greater stability to dual-mixing and higher degrees of starch gelatinization and retrogradation. In addition, greater elastic properties were clearly observed in the high amylose rice samples. The use of high amylose rice flour produced noodles with a harder texture, consequently contributing to reduced cooking loss. Furthermore, the rheological changes of extruded rice noodles were monitored in real time during the in-vitro starch digestion. The rice noodle digesta with higher amylose contents exhibited greater viscosities throughout the simulated oral-gastric-intestinal digestion steps. The flow behaviors of the rice noodle digesta consisted of the Power-law region and infinite shear plateau that were satisfactorily characterized by the Sisko model (R² > 0.99).     

辽宁省稻米蒸煮品质性状研究

以近年来辽宁省审定的61个水稻品种为试材,对辽宁省水稻品种蒸煮品质性状的现状及性状间的关系进行了分析。结果表明:辽宁省水稻品种间蒸煮品质性状差异较大,碱消值、直链淀粉含量优质率较高,直链淀粉含量与胶稠度存在着显著正相关。高直链淀粉含量的品种易出现较低级别的碱消值,中、低直链淀粉含量的品种则易出现较高级别的碱消值,这可作为间接选择的依据。辽宁省稻米蒸煮品质改良的重点应放在选择中、低直链淀含量的品种,并协调直链淀粉含量与胶稠度之间的关系。     

小麦淀粉与面条质量关系的研究进展

小麦淀粉品质对白盐面条的质量（尤其是煮后的感官特性）有重要影响。直链与支链淀粉的含量及比例是影响面条质量的重要因素,是造成不同小麦品种淀粉糊化和膨胀特性及面条质量差异的物质基础。较低直链淀粉含量的小麦粉具有较好的糊化和膨胀特性,制作的面条煮制时吸水率高,烹调损失低,具有较高的感官评分。优质白盐面条的直链淀粉含量应在22%左右。峰值黏度、稀懈值、峰值时间是影响面条质量的重要糊化参数,这3项参数高的小麦粉适合制作优质面条。高膨胀势或膨胀体积的小麦粉制作的面条中等偏软,光滑且富有弹性,可以作为面条用小麦的重要选择标准。一般认为,直链淀粉含量较低、峰值黏度和稀懈值高、峰值时间长、膨胀势或膨胀体积高的小麦粉适合制作优质白盐面条。其中,直链淀粉含量、峰值黏度和膨胀势是优质面条小麦评价的关键品质性状。     

Effect of zein extrusion and starch type on the rheological behavior of gluten-free dough

Previous research has shown that zein, above its glass transition temperature, may adopt molecular structures that are able to form doughs with viscoelastic properties comparable to those of wheat gluten. It is hypothesized that extrusion can promote molecular changes in zein and favor interactions with starch that enhance dough viscoelasticity. Thus, the effects of extruding zein at 90–160 °C on the rheological properties of doughs prepared with potato, rice, and maize starches were determined.Formulations were optimized to provide similar mixing profiles to that of a standard wheat dough. For all zein samples, creep-recovery tests demonstrated that doughs prepared with maize and potato starches were less elastic when compared to doughs prepared with rice starch. Zein doughs produced using rice starch were comparable to wheat-dough. Extensional tests showed that zein extruded at 160 °C provided a larger increase in strain-hardening behavior, which is important for bread production. These samples also exhibited larger extensional stresses. Gel electrophoresis of zein extruded at 160 °C revealed an increase in protein aggregates and the presence of smaller peptides when compared to samples subjected at lower extrusion temperatures.Scanning electron micrographs of doughs containing zein showed starch granules embedded within an amorphous material and fibrous structures, which is attributed to elongated zein.     

水稻籽粒蛋白质含量选择对杂种早代蒸煮食味品质的影响

选用品质和产量性状不同的4个粳稻品种配制2个杂交组合,研究籽粒蛋白质含量选择对水稻杂种早代蒸煮食味品质的影响。各品质性状变异系数的变化范围在9.73%~94.99%;直链淀粉含量与蛋白质含量间存在明显的动态关系;稻米味度值先是随着蛋白质含量的下降而增加,当蛋白质含量下降到某一临界值后,随蛋白质含量下降而下降,蛋白质与直链淀粉含量适中的后代株系味度值较高;在蛋白质含量水平较高时,稻米RVA谱特性随着蛋白质含量的下降有所改善,但蛋白质含量下降到一定程度后则又会导致RVA谱特性变劣;蛋白质含量过高或过低都会导致稻米蒸煮食味品质变劣,协调蛋白质与直链淀粉含量的平衡关系是提高稻米蒸煮食味品质的关键。     

Starch digestibility and the estimated glycemic score of different types of rice differing in amylose contents

Three types of rice cultivars (indica, japonica and hybrid rice) with four levels of amylose were selected for assessing variability in starch digestibility. A vitro enzymatic starch digestion method was applied to estimate the glycemic index in vivo based on the kinetics of starch hydrolysis in vitro. The results indicated that significant differences in term of glycemic response were observed in three types of rice. Amylose content had an obviously impact on the estimated glycemic score (EGS) value and resistant starch (RS) content. The contents of RS were increased with the increasing amylose in the same type of rice. Japonica rice was significantly lower in RS content compared to indica rice and hybrid rice with similar amylose. The high amylose rice cultivar ZF201, which was characterized by low major RVA parameters, i.e. peak viscosity (PKV), hot paste viscosity (HPV) and cool paste viscosity (CPV), were obviously higher in RS content and lower in EGS. The retrogradation of cooked rice led to a reduction of HI and EGS of all varieties. Starch hydrolysis tends to be more quick and complete for the waxy and low amylose rice than for the intermediate and high amylose rice.     

鲜湿米粉品质及其影响因素

米粉种类丰富,口感爽滑,质地柔韧,既可作为主食,又能当作早餐,深受广大消费者喜爱。因此,科学评价米粉品质、探究米粉品质影响因素始终受到研究者和企业的密切关注。本文综述了鲜湿米粉的分类与评价方法,从稻米品质、浸泡处理方式、磨粉工艺、辅料与食品添加剂、贮存保鲜方式等五个方面探讨了影响米粉品质的因素。目前,按成型工艺将鲜湿米粉分为切粉和榨粉。高直链淀粉含量品种做的米粉断条率和蒸煮损失率低,感官品质好,因此可将直链淀粉含量作为核心指标筛选出适宜作米粉的水稻品种。在调试出合适米水比的条件下,半干法研磨安全环保,对淀粉损伤较小,生产出的米粉品质与湿法研磨无显著差异。盐类或单甘脂等添加剂与保鲜方式结合使用,对鲜湿米粉保鲜效果更好。     

Effect of Nitrogen Application on Yield,Rice Quality and Processing Characteristics in Rice Noodle-specific Varieties

【Objective】We aimed to investigate the influence of nitrogen application on yield, rice quality and processing characteristics in noodle-specific rice.【Method】The experiments were conducted with three rice varieties suitable for making rice noodles(R0734, R2149, Jiazao 66), one variety commonly used for making rice noodles(Zhenguiai) and one variety unable to be processed into rice noodles(R0711) at three nitrogen levels with 90, 140, 190 kg/hm2 in 2018 and 2019.【Result】1) With the increasing nitrogen application levels, the yield of each varieties increased, but for R0734 and R2149 the grain yield maximized under the medium nitrogen level of 140 kg/hm2 in 2019; noodle-specific rice varieties, R2149 and Jiazao 66, had extremely high yield advantages, achieving the highest yield at the nitrogen levels of 140 kg/hm2 and 190 kg/hm2. Nitrogen application increased the effective panicle number, while the 1000-grain weight decreased. 2) As more nitrogen was gradually applied, gel consistency and protein content increased while amylose content decreased, fluctuating between 21.4% and 26.5%, which also brought about a downward trend in peak viscosity, trough viscosity and final viscosity. Breakdown reduced significantly and setback increased significantly. 3) With the increase of nitrogen application, the broken rate and cooked loss rate of rice noodle increased significantly, but both were below 10%. R2149 and Jiazao 66 were more sensitive to nitrogen levels than R0734, but had better processing properties.【Conclusion】The amylose contents ranging from 21% to 27%(about 24% is the best) are favorable, so that the amylose content will not seriously exceeded the suitable range for processing at different nitrogen application levels in field cultivation. Moreover, due to the increase in the amount of nitrogen application, the processing characteristics of noodle-specific rice are deteriorated. Thus it is necessary to apply relatively low nitrogen in condition of its high yield level. In the breeding, the major parents with moderate amylose contents and better processing characteristics should be selected for high-yielding noodle-specific rice variety.     

Impact of pre-germination on amylopectin molecular structures,crystallinity, and thermal properties of pre-germinated brown rice starches

Ungerminated brown rice (UGBR) and pre-germinated brown rice (PGBR) obtained from different pre-germination durations were studied to investigate the changes in total starch contents of flour, amylopectin molecular structures, crystallinity, and thermal properties of starches as affected by pre-germination. Each paddy of three rice cultivars with different amylose contents (RD6, waxy; KDML105, low amylose; and RD31, high amylose) was soaked in water at 30°C for 12 h and incubated over different periods until the three stages of embryonic growth length (EGL) were achieved. The total starch contents of three-stage PGBR flour from all rice cultivars decreased when pre-germination durations were increased. The three-stage PGBR starches from the three rice cultivars had lower weight-average molecular weight (Mw) and number-average molecular weight (Mn) than UGBR starches. All starches from the three rice cultivars displayed an A-type X-ray diffraction pattern (XRD). Isolated UGBR starch from RD6 had the highest (31.33%) relative crystallinity (RC), while RD31 showed the lowest RC (26.79%). The slight increases in the RC of three-stage PGBR starches from three rice cultivars were found after pre-germination. Isolated PGBR starches from the three rice cultivars had higher gelatinization temperatures and enthalpy, but lower retrogradation enthalpy and %retrogradation than UGBR starches.     

水稻杂种后代籽粒直链淀粉含量选择与品质和产量性状的关系

 选用4个稻米直链淀粉含量有显著差异的粳稻品种配制两个杂交组合（系选1号×通769和东农423×藤系180）,研究其杂交后代籽粒直链淀粉含量选择对品质和产量性状的影响。结果表明,籽粒直链淀粉含量选择对杂种后代蒸煮食味品质和产量相关性状有不同程度的影响,其影响程度因杂交组合及性状不同而异;在蒸煮食味品质性状中,淀粉黏滞性谱的崩解值和消减值受直链淀粉含量选择的影响较大,而在产量相关性状中抽穗期、单株有效穗数、结实率、单株粒重等受直链淀粉含量选择的影响相对较大;通过直链淀粉含量的连续定向选择可以从杂种后代中分出直链淀粉含量不同的后代,粳稻杂种后代低直链淀粉含量的定向选择效果优于高直链淀粉含量的选择效果,更容易得到超低亲的变异类型;直链淀粉含量的选择对杂种后代产量性状的影响较复杂,存在有利或不利的影响,低直链淀粉含量的选择将会导致单株粒重的下降。     

氮肥施用对米粉专用稻产量、米质及加工特性的影响

目的 为了探明氮肥施用量对不同米粉稻品种的产量、稻米品质和加工特性的影响,【方法】2018-2019连续两年以筛选出的适宜作米粉专用稻的3个品种(R0734, R2149, 嘉早66)、生产上常用作米粉加工的品种（珍贵矮）以及加工米粉未能成型的品种（R0711）作为供试材料,设置90、140、190kg/hm²三个纯氮水平。结果 1）各品种产量随着施氮量的增加而增大,但2019年R0734和R2149品种在中氮条件140 kg/hm²下产量达最高;其中米粉专用稻R2149和嘉早66极具产量优势,两者分别在140和190 kg/hm²施氮水平下达到最高。氮肥施用使有效穗数增大,而千粒重减小。2）随着施氮量的增加,米粉稻直链淀粉含量显著降低,在21.4%~26.5%波动,胶稠度增长,蛋白质含量增大;最高黏度、热浆黏度和最低黏度有减小趋势,崩解值显著减小,消减值显著增大。3）随着施氮量的增加,米粉稻断条率和蒸煮损失率显著增大,但均在10%以下;品种R2149和嘉早66较R0734来说,虽然对氮肥更敏感,但加工特性较佳。结论 米粉专用稻应选择直链淀粉含量在21%~27%范围的品种,24%左右则最佳,这样在实际生产中直链淀粉含量受氮肥影响不至于严重偏离适宜加工的范围;又由于施氮量的增加使米粉稻加工特性变差,因此,米粉专用稻栽培过程中,需在保证丰产同时,结合生产实际施用相对较低的氮肥;在米粉专用稻选育上,应选择直链淀粉含量适中、加工特性更佳的骨干亲本作为中间材料,培育高产米粉专用稻。     

Relationship Between Variation in Activities of Key Enzymes Related to Starch Synthesis During Grain Filling Period and Quality of Eating and Cooking in Rice

Eating or cooking quality is one of the important quality of rice. Amylose content, RVA properties and taste meter value are three important indexes for evaluating cooking and eating quality of rice, which are determined by the chemical and physical com- …     

水稻灌浆过程中籽粒淀粉合成关键酶活性与蒸煮食味品质

选用稻米蒸煮食味品质有显著差异的4个粳稻品种,对水稻籽粒灌浆过程中淀粉合成关键酶的活性变化及其与蒸煮食味品质关系进行了研究。 不同品质类型的品种间籽粒直链淀粉和支链淀粉含量在灌浆前、中后期表现出差异,这种差异主要表现在灌浆不同时期淀粉积累速率上。籽粒灌浆过程中,不同品质类型的品种中ADPG焦磷酸化酶和可溶性淀粉合成酶活性出现峰值的时间无差异,但淀粉分支酶活性出现峰值的时间,劣质品种明显早于优质品种,而且优质品种灌浆中、后期仍然保持较高水平的酶活性。ADPG焦磷酸化酶、可溶性淀粉合成酶、淀粉分支酶的活性与直链淀粉含量、支链淀粉含量、味度值、RVA谱特性间的相关性和程度因灌浆时期不同而发生变化。在整个灌浆过程中,可溶性淀粉合成酶活性与味度值间的相关均不显著,但灌浆前期和中、后期的ADPG焦磷酸化酶和淀粉分支酶的活性与味度值间呈显著或极显著相关。选择灌浆前期酶活性低或灌浆后期酶活性高的材料,将有利于提高稻米蒸煮食味品质。     

The composition of floury and vitreous endosperm affects starch digestibility kinetics of the whole maize kernel

Maize grain starch is the major energy source in animal nutrition, and its high digestion and utilization largely depend on endosperm traits and the structure of the starch-lipoprotein matrix. The aim of this work was to determine floury and vitreous endosperm traits and its relation to starch digestibility rate. In total, kernels of 30 hybrids were manually dissected, and amylose, total zein and starch and non-starch lipids were determined in both vitreous and floury endosperm. Starch digestibility of the whole kernel was determined based on glucose released during a two-step in vitro pig model of enzymatic digestion, and starch digestibility rate was calculated according to the first-order kinetics. The vitreous endosperm of tested hybrids had higher contents of amylose (204.6 vs 190.4 g/kg), zein (63.2 vs 40.4 k/kg) and starch lipids (5.6 vs 4.9 g/kg), and lower content of non-starch lipids (7.3 vs 9.6 g/kg) than floury endosperm. Digestibility coefficients varied among hybrids, and starch digestibility rate varied from 0.73 to 1.63 1/h. Lipids in both vitreous and floury endosperm negatively correlated with the most of digestion coefficients, whereas zein correlated in vitreous and amylose in the floury endosperm (P < 0.05). Starch digestibility rate negatively correlated with all traits, except amylose content in vitreous endosperm. As a result, a linear regression model with four variables including contents of zein and starch lipids in vitreous and zein and amylose in floury endosperm can predict more than 65% variability of starch digestibility rate of tested hybrids.     

稻米淀粉RVA谱特征与品质性状的相关性

 通过对106份水稻材料稻米外观品质、蒸煮品质和RVA谱特征值的测定,研究了淀粉黏滞性（RVA谱）特征值与各项品质指标的相关关系。RVA谱特征值与外观品质中的垩白率关系最为密切,其中垩白率与崩解值(BDV)和消减值(SBV)的相关系数分别为-0.43**和0.40**;RVA谱特征值与低直链淀粉含量(AC)品种和糯稻品种的蒸煮品质指标呈显著或极显著相关,与中高直链淀粉含量品种的指标相关性不显著,特别是高直链淀粉含量品种的AC与RVA谱特征值相关性均不显著,而糯稻品种的AC与RVA谱特征值（BDV和 SBV除外）的相关系数均在0.85以上。由此认为,水稻品种的AC越低,AC与RVA谱特征值的关系越密切。     

灌浆成熟期温度对水稻籽粒淀粉合成关键酶活性及品质的影响

 选用蒸煮食味品质不同的3个粳稻品种，利用温室高温和自然常温，研究了灌浆成熟期温度对水稻籽粒淀粉合成关键酶活性及蒸煮食味品质的影响。结果表明，灌浆成熟期高温条件下，水稻籽粒蛋白质含量提高，直链淀粉含量和味度值降低，劣质品种提高或降低的程度大于优质品种；RVA谱特性对灌浆成熟期温度的反应因品种和特性而异；灌浆过程中，籽粒ADPG焦磷酸化酶、可溶性淀粉合成酶和淀粉分支酶活性随灌浆进程，酶活性逐渐增加，达到峰值以后，酶活性又逐渐下降，呈单峰曲线，但不同品种酶活性达到峰值的时间和同一时期的酶活性大小有差异；ADPG焦磷酸化酶和可溶性淀粉合成酶的活性表现对温度的影响反应较为迟钝，而淀粉分支酶活性表现对温度变化的反应较为敏感，温度过高过低都降低该酶活性。     

Acetylation of intact white rice grains to alter the physicochemical properties

The effect of acetylation of milled rice grains of selected varieties (TDK 8, YRW 4, Reiziq, Amber 33, and SHZ 2) with varying apparent amylose contents (3.8–26.6%) on their physicochemical properties was investigated. Milled rice samples were treated with different acetic anhydride concentrations (0.004–0.04 g per 100 g of milled rice samples in 225 mL of water). Results showed that glutinous (TDK 8), very low amylose (YRW 4) and low amylose containing varieties (Reiziq) were prone to acetylation even with 0.004 g of acetic anhydride. X-ray diffraction patterns showed an increase in the crystallinity in acetylated samples and formation of V-type crystals, suggesting the possible interaction of acetic anhydride with starch. Acetylation of rice grains resulted in reduced peak and final viscosities and gel strength, particularly in glutinous (TDK 8) and very low amylose (YRW 4) rice. Differential calorimetric study showed that acetic anhydride treatment resulted in reduced thermal transition temperatures and enthalpy of all varieties. Although increase in the retrogradation thermal temperatures was observed, the enthalpy of retrogradation was reduced with increasing acetylation, suggesting that the extent of starch retrogradation was lower in all varieties with more prominent reduction in the glutinous type. Furthermore, the texture of cooked acetic anhydride treated rice grains was less hard and showed more adhesiveness. This study demonstrated that the acetylation of rice grains (instead of flour) was successfully achieved, showing the potential of applying acetylation to alter the textural, pasting, thermal and retrogradation properties of rice.     

Texture determinants in cooked, parboiled rice. I: Rice starch amylose and the fine stucture of amylopectin

The constituent starches from eleven cultivars of non-waxy rice with different degrees of cooking hardness were subjected to detailed analysis. No significant differences were observed in the granule morphology, crystallinity and size distribution of the starch granules that could be correlated with the textures of the cooked, parboiled rices. Differences in the contents of amylose and the fine structures of amylopectin were detected, however, which did correlate with texture. It appeared that the texture of the rices was critically controlled by the proportion of the longest (DP 92–98) and shortest (DP&lE25) amylopectin chains but not the intermediate (DP 43–68) chains. Hard cooking rice tended to have a higher amylose content (or amylose:amylopectin ratio) and more longer chain amylopectin than soft cooking rice, which feature is thought to encourage more extensive intra and/or inter molecular interactions with other components in rice grain, such as protein, lipid and non-starch polysaccharides and results in a firmer texture. The different amylopectin structures may explain why rices that possess similar amylose contents can have different textural properties. Such a correlation suggests that the structure of the starches determined from the SE–HPLC profile of the debranched amylopectin could be useful as a sensitive screening method in the classification of cooked rice texture.     

Changes in Activities of Key Enzymes for Starch Synthesis and Glutamine Synthetase in Grains of Progenies from a Rice Cross During Grain Filling

The progenies differed in amylose and protein contents in grains, which derived from a rice cross, Dongnong 423×Toukei 180, were used to study changes in the activities of ADP-glucose pyrophosphorylase (AGPP), soluble starch synthetase (SSS), starch branching enzyme (SBE) and glutamine synthetase (GS) in rice grains during grain filling. The activities of AGPP, SSS and SBE gradually increased and then declined as a single-peak curve with the process of grain filling in the progenies with high and low amylose contents in grains. The progenies with high amylose content peaked earlier in the AGPP, SSS and SBE activities and had higher AGPP, SSS and SBE activities at the early grain filling stage than those with low amylose content. The GS activity peaked earlier and was higher at the late stage of grain filling in the progenies with high protein content than in those with low protein content. It is suggested that the activities of key enzymes for starch synthesis and glutamine synthetase could be changed in oriented breeding for amylose and protein contents in grains.     

北方两系杂交粳稻品质相关性状的分析

杂交粳稻尤其是两系杂交粳稻的发展缓慢,两系杂交粳稻品质性状较差严重的影响其发展。为此本研究以辽宁盐碱地利用研究所最新育成的两系杂交粳稻为试验试材,主栽常规稻品种为对照,对北方两系杂交粳稻外观品质,蒸煮品质,食味营养品质等相关稻米品质指标进行了测定。相关结果如下:与常规粳稻相比,两系杂交粳稻存在显著的产量优势,但外观品质、蒸煮品质和食味得分略有不足。研究结果所得提高稻米光泽,适当减少稻米直链淀粉含量和蛋白质含量将有助于提高两系杂交粳稻的品质。