Starch Digestibility and Physicochemical and Cooking Properties of Irradiated Rice Grains

This study evaluated the starch digestibility, physicochemical properties and cooking characteristics of polished rice (varieties IRGA417 and IAC202) subjected to the doses of 0 (as the control), 1, 2 and 5 kGy of gamma radiation. The highest dose decreased the apparent amylose content, peak viscosity, water absorption and volume expansion. Irradiation increased the solid loss by 119% and 187% for IAC202 and IRGA417, respectively, when comparing the higher dose with the control. For IAC202, irradiation decreased the rapidly digestible starch and increased the slowly digestible starch (SDS) and resistant starch (RS). IRGA417 showed an elevation of SDS and a reduction in RS. And 1 kGy dose of gamma radiation generated the highest level of RS for both the two varieties and presented the smallest changes in other physicochemical and cooking properties.     

高直链淀粉突变体Goamy2的淀粉糊化特性及淀粉结构分析

以高直链淀粉及突变体材料Goamy2及其野生型亲本Ilpumbyeo米粉为材料,比较了它们在理化性质和糊化特性上的差别,并通过体积排阻色谱(Size Exclusion Chromatography,SEC)分析其水溶性和不溶性淀粉组成结构差别。从冷水溶性成分来看,Goamy2主要以小分子DP141～DP2(DP为聚合度)为主,而Ilpumbyeo中带分支的链DP4100～DP64也就是相对大分子所占的比例较高,达到33.3%。从热水溶性淀粉成分来看,突变体Goamy2直链淀粉和支链淀粉的比例大致为4∶1,而Ilpumbyeo直链淀粉和支链淀粉比例大致为1∶1。至于两个材料的热水溶性支链淀粉链长分布,长短链比例差别较大,Goamy2长短链比率为0.67,而Ilpumbyeo为0.32。从热水不溶性成分来看,两个材料均以支链淀粉为主,直链淀粉所占的比例很低,均不到5%。热水不溶性支链成分的链长分布中,野生型亲本Ilpumbyeo以短链为主,短链所占的比例高达72.5%,而突变体Goamy2短链和长链几乎各占一半。     

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Wxb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...     

Accurate Measurement of Pasting Temperature by the Rapid Visco-Analyser:a Case Study Using Rice Flour

Pasting properties are among the most important characteristics of starch,determining its applications in food processing and other industries.Pasting temperature derived from the Rapid Visco-analyser(RVA)(Newport Scientific),in most cases,is overestimated by the Thermocline for Windows software program.Here,two methods facilitating accurate where the pasting viscosity begins to increase,the other is to manually record the time(T1)when the pasting viscosity begins to increase and calculate the pasting temperature with the formula of(45/3.8)×(T1-1) 50 for rice flour.The latter method gave a manually determined pasting temperature which was significantly correlated with the gelatinization temperature measured by differential scanning calorimetry.     

Accurate Measurement of Pasting Temperature by the Rapid Visco-Analyser： a Case Study Using Rice Flour

Pasting properties are among the most important characteristics of starch, determining its applications in food processing and other industries. Pasting temperature derived from the Rapid Visco-analyser (RVA) (Newport Scientific), in most cases, is overestimated by the Thermocline for Windows software program. Here, two methods facilitating accurate measurement of pasting temperature by RVA were described. One is to change parameter setting to ‘screen’ the true point where the pasting viscosity begins to increase, the other is to manually record the time (T1) when the pasting viscosity begins to increase and calculate the pasting temperature with the formula of (45/3.8)×(T1–1)+50 for rice flour. The latter method gave a manually determined pasting temperature which was significantly correlated with the gelatinization temperature measured by differential scanning calorimetry.     

应用RVA测定米粉淀粉成糊温度

淀粉的糊化温度是稻米淀粉品质的重要指标,决定淀粉在食品及工业上的用途,也与食用稻米的蒸煮品质密切相关。淀粉的糊化温度可以用淀粉谱仪（如快速淀粉黏滞性测定仪,Rapid Visco analyser,RVA）间接测定,但用淀粉谱仪测定的是淀粉的成糊温度（pasting temperature,PT）,它是指淀粉黏度刚开始升高时的温度。在许多情况下,从RVA配套软件 Thermocline for Windows中测定的PT是过高的。提出了两种能够用RVA较准确测定成糊温度的方法。一种是改变参数设置来“筛选”出能反映真正成糊温度的点;另一种是手工记录下淀粉黏度刚开始升高时的时间,利用公式(45/3.8)×(T1-1)+50 计算出稻米的成糊温度。利用手工计算出的成糊温度与通过差示扫描量热仪测定的最高糊化温度呈极显著正相关(r=0.97)。     

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。     

灌浆期不同时段高温对稻米淀粉理化特性的影响

【目的】研究灌浆期不同时段高温对稻米淀粉组成、结构和理化特性的影响,揭示高温对稻米淀粉理化特性影响的时段效应,阐明高温、结构和功能之间的关系。【方法】以耐热水稻品种黄华占和热敏感的9311近等位基因系为实验材料,利用人工气候箱设置高温[38℃(昼)/30℃(夜)]和对照[28℃(昼)/22℃(夜)],研究灌浆前期(齐穗期后1－15 d)和后期(齐穗期后16 d至成熟)高温对稻米的加工品质、外观品质、淀粉组成、支链淀粉链长分布、粒度分布、胶稠度、黏度特性、糊化特性、结晶特性和颗粒形态的影响。【结果】灌浆期高温使糙米率、精米率、整精米率显著下降,使垩白粒率和垩白度显著升高,导致加工品质和外观品质变差。灌浆期高温使总淀粉含量、直链淀粉含量、短支链淀粉含量、大淀粉粒占比、直/支链淀粉比显著下降,而中等支链淀粉含量、小中淀粉粒占比、糊化温度和糊化焓显著上升,黏度特性显著改变,结晶类型不变但结晶度显著改变,淀粉颗粒表面出现小孔,表面变得凹凸不平,导致淀粉颗粒更加碎片化和蒸煮食味品质变劣。灌浆期不同时段高温对稻米品质的影响不同,灌浆前期高温对稻米淀粉的影响大于灌浆后期,耐热品种受影响小于热敏感品种。灌浆前期高温处理下供试材料具有较高的消减值和较低的崩解值,黏度特性变差;灌浆后期高温处理下供试材料具有较低的消减值和较高的崩解值,黏度特性变好。【结论】灌浆前期高温对淀粉理化特性的影响最大,进而导致稻米的加工品质、外观品质和蒸煮食味品质变劣,灌浆后期高温提升了黏度特性。     

Physiochemical Properties of Resistant Starch and Its Enhancement Approaches in Rice

With changes in food preferences and life styles,more and more attentions have been focused on healthier food.Nowadays,resistant starch(RS)which can resist digestion in the human intestine has been recognized and accepted.High RS diet shows great benefit for the human health,and breeding high RS rice variety is a great target for realizing dietary intervention.To provide guidance for RS improvement in rice,this review summarized the unique physiochemical properties of RS and the possible approaches,i.e.genetic regulation,for enhancing RS content in rice,and proposed the potential ways to obtain rice variety with high RS content.     

水稻糯性突变对淀粉理化特性的影响

比较了籼、粳两个糯性突变品种与原亲本品种淀粉的理化特性。糯性突变后除了直链淀粉含量显著降低外,淀粉的糊化温度变高、胶稠度增大、RVA谱(rapid viscosity analyzer)参数下降。RVA谱参数降低的幅度从高到低依次是消减值>回复值>冷胶粘度>热浆粘度>最高粘度>崩解值,表明控制直链淀粉含量的Wx位点对淀粉糊化特性和粘滞性是有影响的,存在多效性。同时,两个糯稻品种之间的RVA谱差异较大,其中崩解值和最高粘度差值均大于糯性突变对它们的影响,说明除直链淀粉外,支链淀粉也影响淀粉的理化特性。对Wx位点鉴定的结果显示扬辐糯4号wx基因第一内含子剪切位点＋1位的碱基由原品种的G突变成了T,扬糯2号与其原品种相同(均为T);两个糯稻突变品种wx基因前导区的(CT)n微卫星重复序列与原品种相比都发生了变化。     

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.     

水稻胚乳淀粉体被膜的降解和复粒淀粉粒概念的探讨

运用电子显微镜技术,系统观察了水稻胚乳发育过程中淀粉粒的发育、淀粉体被膜的降解和复粒淀粉粒的形态。多个淀粉粒可以同时在1个淀粉体内发生与发育,淀粉粒形态从近球形到椭球形,最后彼此接触,接触面呈多角形。淀粉体被淀粉粒充实后,淀粉体被膜开始降解,降解的被膜片段发生卷曲包裹细胞质基质形成环形被膜结构。发育良好的呈多角形的淀粉粒在淀粉体内排列紧密,淀粉体被膜降解后,这些淀粉粒仍聚集在一起维持淀粉体的轮廓,胚乳细胞不易被断开,成熟籽粒表现为透明性状。发育不良的呈球形或椭球形的淀粉粒在淀粉体内排列疏松,淀粉体被膜降解消失后,这些淀粉粒不能维持淀粉体的轮廓,胚乳细胞易被断开,成熟籽粒表现为垩白性状。还对复粒淀粉粒的概念进行了探讨。     

水稻长粒和短粒品种稃片的发育及细胞学差异

 以籼稻长粒品种明恢63和短粒品种川7为材料,利用石蜡制片技术研究了水稻稃片发育过程,并比较长粒和短粒品种稃片发育的细胞学差异。结果表明,小花原基时,稃片纵向各区段均匀分裂,随着发育的进行,稃片上部细胞最早停止分裂,基部细胞分裂结束最晚。至花粉母细胞末期,稃片细胞结束分裂。花粉母细胞减数分裂期,稃片细胞开始进入快速伸长生长阶段,至小孢子晚期稃片长度达到最大值,而且稃片的中、基部细胞对其长度的贡献大于上部细胞。长粒和短粒水稻稃片发育过程基本一致,但长粒和短粒水稻内稃薄壁细胞数目在稃片发育过程中,始终存在极显著差异,细胞长度在稃片长度定形时并没有明显区别。稃片达终长度时,长粒品种内稃薄壁细胞数目比短粒品种多60.98％,而中、基部细胞长度仅增加1.81％和8.05％。因此,细胞数目是导致水稻长粒和短粒品种稃片长度差异的主要因素。     

不同淀粉脱支酶对菠萝蜜种子淀粉分子结构的影响及糊化特性研究

采用普鲁兰酶和异淀粉酶制备脱支菠萝蜜种子淀粉(debranched jackfruit seed starch,DS)及脱支菠萝蜜种子支链淀粉(debranchedjackfruitseedamylopectin,DAP),旨在研究所得DS和DAP之间的差异。结果表明,DS具有较宽的分子量分布,而DAP具有较窄的分子量分布。普鲁兰酶水解α-1,6糖苷键更完全,所以普鲁兰酶DS和DAP平均分子量更低。普鲁兰酶水解较短侧链更有效,异淀粉酶则可水解外分支链。异淀粉酶DAP具有高比例B2链、B3链和长平均链长,导致其具有低的峰值黏度、谷值黏度、崩解值、最终黏度和回生值,但糊化温度高。因此,淀粉脱支酶的选择和直链/支链淀粉组成均能导致淀粉分子结构和糊化特性显著不同(p<0.05),可根据特定需要选择合适制备方法增强或抑制菠萝蜜种子淀粉固有性质或赋予其新的特定性质。     

Relationship Between Degree of Starch Gelatinization and Quality Attributes of Parboiled Rice During Steaming

Paddy rice samples were parboiled by soaking at 65 °C for 180 min and steaming at 96 °C for 2–10 min, and then dried to achieve the final moisture content of 11% ± 1%. The degree of starch gelatinization(DSG) and several quality attributes(head rice yield(HRY), color value and hardness) of parboiled rice were measured. Results showed that DSG(46.8%–77.9%), color value(18.08–19.04) and hardness(118.6–219.2 N) all increased following steaming. In contrast, the HRY increased(64.8%–67.1%) for steaming times between 2–4 min but decreased(67.1%–65.0%) for steaming times between 4–10 min. Linear relations between DSG and color value(R~2 = 0.87), and DSG and hardness(R~2 = 0.88) were observed. The suitable DSG of parboiled rice leading to the highest HRY was found to be 62.5%, obtained following 4 min of steaming.     

Comparison of Physicochemical Properties of the Grains between Old- and New-Types of Rice Cultivars in Japan

Abstract

The physicochemical properties of the grains of 16 old- and 21 new-type rice cultivars in Japan were investigated in 1995 and 1996. Among the old- and new-type cultivars, we found a similar pattern of varietal differences in physicochemical properties in both years, and in both the fields with and without nitrogen fertilizer applied. Between the two types, no significant differences in the mean protein and amylose contents in the rice grain were observed. The old-type rice cultivars tended to be lower in mean maximum viscosity and breakdown values than the new- type cultivars, although the difference was not significant. Cooked rice of the old-type cultivars tended to be higher in mean hardness/adhesion ratio (H/-H) and hardness/adhesiveness ratio (H/A₃) than that of the new -type cultivars. The physicochemical properties which showed superior values in the standard partial regression coefficients against the taste of cooked rice were the protein content, breakdown value and H/-H. These, physico-chemical properties can be efficient indicators for evaluating the taste of cooked rice. The coefficient of parentage of each cultivar to cultivar Koshihikari showed tight negative correlations with amylose content, H/-H and H/A₃, and tight positive correlations with maximum viscosity and breakdown values. The coefficients showed a loose positive correlation with protein content. However, Sasanishiki, Domannaka, Chiyonishiki, Nakate shinsenbon and Rikuu 132 were superior in their physicochemical indicators, in spite of their small coefficients of parentage to Koshihikari. This suggests that a highly palatable cultivar that is widely different from Koshihikari can be developed by utilizing genetic resources with superior physicochemical indicators.     

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.     

两个垩白突变体的鉴定及突变基因的图位克隆

【目的】研究两个水稻垩白突变体胚乳垩白的形成机制,为稻米品质改良提供理论基础。【方法】以从中花11的EMS突变体库中筛选出的两个稳定遗传的垩白突变体eb6、eb7为材料,对其进行农艺性状、稻米理化性质和遗传学分析,并利用eb6与南京11衍生的F2群体对控制垩白的基因进行图位克隆。同时对候选基因的表达模式及淀粉合成相关基因在突变体及野生型中表达情况进行了分析。【结果】与野生型相比,两个突变体胚乳中央部位呈现白色且不透明,淀粉复合颗粒形状不规则且排列疏松,而突变体胚乳边缘部位与野生型无异,都为半透明状,淀粉复合颗粒呈多面体且排列致密。相对于野生型,突变体eb6、eb7成熟种子中的直链淀粉含量和胶稠度显著降低,蛋白质含量显著升高。RVA谱分析显示突变体淀粉黏滞性明显低于野生型。同时,支链淀粉聚合度分析显示突变体eb6中聚合度(DP)小于16的短链显著增加,DP为16~23的中长链显著减少。遗传分析表明突变体eb6、eb7胚乳垩白表型由单隐性核基因控制,并且它们为一对等位突变体。利用突变体eb6与南京11杂交衍生的F2群体将突变体基因定位在第1染色体长臂上物理距离86.6 kb的区间内。该区间包含22个开放阅读框(ORF),其中ORF13编码腺苷二磷酸葡萄糖焦磷酸化酶大亚基2(Os AGPL2)。序列分析发现eb6与eb7分别在Os AGPL2第3、第7外显子上发生1个单碱基替换,并分别导致一个氨基酸替换。RT-PCR及原位杂交结果显示,Os AGPL2主要在水稻发育中的籽粒中表达。同时Os AGPL2的突变导致了多个淀粉合成相关基因在水稻籽粒灌浆过程中的表达模式发生改变。【结论】突变体eb6、eb7籽粒胚乳出现严重垩白表型为Os AGPL2突变所致。本研究进一步证明了Os AGPL2在调控水稻籽粒胚乳中淀粉的合成、淀粉复合颗粒的形成及稻米理化性质的平衡中起着重要的作用。     

Structural and Histochemical Characterization of Developing Rice Caryopsis

The development of pericarp, seed coat, starchy endosperm and aleurone of the rice caryopsis was investigated, histochemically and structurally, from the time of flowering to maturity. The results showed that during its growth, the maximum length of the caryopsis was attained first, followed by width and then thickness. Histochemical examination of the caryopsis showed that starch was mainly accumulated in the endosperm, but the endosperm showed no metabolic activity, while embryo and pericarp contained a few starch grains, and embryo and aleurone were strongly active. Aleuronic cells contained many aleurone grains and spherosomes, and aleurone in the dorsal region developed earlier and contained more layers of cells. Amyloplasts in endosperm contained many starch granules and were spherical at early stages but polyhedric at late stages. The protein bodies appeared later than amyloplasts, and the number of protein bodies in subaleurone was greater than those in the starchy endosperm. The white-belly portion of endosperm might be relative to the status of amyloplast development.