莲藕可溶性淀粉合成酶基因LrSSS的克隆与表达特性分析

以莲藕品种‘美人红’叶片为试材,利用RACE结合RT-PCR技术克隆得到全长4 080 bp的莲藕可溶性淀粉合成酶基因（LrSSS）cDNA序列（GenBank登录号：KP201636）,其中开放阅读框3 696 bp,编码1 231个氨基酸;该序列与甜瓜、葡萄SSS基因编码氨基酸序列同源性较高,分别达79%、69%。LrSSS 所编码的氨基酸序列包含3个典型的碳水化合物结合结构域（CBM_25）和1个淀粉合成酶催化域（Glyco_transf_5）。LrSSS 表达分析表明,莲藕根状茎膨大具3节段时,在终止叶叶片中的表达量最高,其次为后把叶叶片,终止叶叶柄表达量最少;在根状茎膨大至4节段时,LrSSS在第1、2节段根状茎中表达量较高,在第3、4节段根状茎中表达量较低,表明在第1、2节段根状茎形态基本建成后LrSSS在调控产物转化为淀粉过程中可能起到重要作用。     

复合食用胶对无矾马铃薯淀粉粉丝品质的影响

实验以魔芋胶、黄原胶、海藻酸钠、卡拉胶四种胶体替代明矾生产无矾粉丝,以马铃薯淀粉粉丝的糊汤品质和断条率作为试验指标,考察单一食用胶及复合食用胶对马铃薯淀粉粉丝品质的影响。结果表明,添加0.30%魔芋胶、0.10%黄原胶、0.10%海藻酸钠、0.50%卡拉胶时粉丝品质最佳,其断条率15.00%,糊汤透光率为87.7%。     

马铃薯高淀粉生理基础的研究——叶片组织结构与淀粉积累的相关性

本文 选用淀 粉含量高 低不同的 ８９２７３ 、农 牧７４３２ ２ 、３９０３６３ １８ 、３８８２２６ 单３ 、底西芮、紫花白、３８８２２１ ２ 七个品种 （ 系） 为材料, 研究了马铃薯生育期间叶片组织结构变化与块茎淀粉含量的相互关系。结果表明： 生育期间叶片肉总厚度、栅栏组织厚度、海绵组织厚度与淀粉含量呈正相关关系, 并在苗期和块茎增长期达到极显著或显著水平; 栅栏组织细胞密度、海绵组织细胞密度与淀粉含量呈正相关关系, 并在苗期和块茎形成期达到显著或极显著水平; 叶片上下表皮气孔密度与淀粉含量呈极显著正相关; 叶柄组织结构与淀粉含量没有明显的相关性。     

挤压大米啤酒辅料麦汁浸出物收得率研究

文章对以挤压膨化大米为辅料经糖化后制得的麦汁浸出物收得率进行研究,并且以麦汁的碘值、还原糖及滤渣中的淀粉含量为指标,考察其淀粉的降解程度,从而初步分析了挤压膨化大米做啤酒辅料比传统蒸煮大米做啤酒辅料其麦汁收得率高的原因。     

卷叶基因Rl（t）对杂交稻稻米品质性状的影响

 以3对卷叶近等基因系杂交组合为研究对象，设置两种施肥水平处理，研究Rl(t)卷叶基因对杂交稻稻米品质性状的影响。在正常肥力水平下，卷叶组合的精米率显著或极显著高于其对应组合，整精米率高于其对应组合，垩白率和垩白度均低于其对应组合。稻米淀粉RVA谱特征值中，卷叶组合的最高粘度、热浆粘度和崩解值均大于其对应组合，其他性状指标值在对应组合间的差异表现趋势不一致。增施穗肥，除汕优63外，各组合的糙米率、精米率和整精米率都有提高的趋势，各组合最高粘度、热浆粘度和崩解值均降低，消减值均增大，其他性状指标值变化趋势因组合而异。增施穗肥，卷叶组合的精米率和整精米率都高于其对应组合，其中卷叶汕优559与汕优559的整精米率差异达显著水平，其他性状指标值在对应组合间的差异没有明显的规律性，说明Rl(t)基因在一定条件下有利于提高稻米品质。     

散穗与密穗型水稻穗上不同部位粒位的粒重及抗性淀粉含量

以散穗型和密穗型水稻品系为材料,研究穗上不同部位和粒位的粒重及籽粒抗性淀粉含量的差异及其分布特点.结果表明:在稻穗同一部位,一次枝梗籽粒千粒重和抗性淀粉含量高于二次枝梗;一次枝梗籽粒千粒重上部最高,且变异度显著小于中、下部;散穗型水稻中部籽粒的抗性淀粉含量相对较高,密穗型以下部较高;同一枝梗不同粒位间抗性淀粉含量均表现...     

淀粉表面结合脂对板栗淀粉糊化特性的影响

以中国不同板栗产区16个品种板栗为试材,研究淀粉表面结合脂对板栗淀粉糊化特性影响。结果表明:板栗淀粉RVA糊化黏度在升温过程中逐渐升高并达到峰值,随后黏度降低并在整个温度保持阶段持续降低并降到谷值;在冷却过程中,淀粉糊黏度再次缓慢升高直至整个糊化过程结束。板栗淀粉RVA糊化黏度特征曲线按形状可分为4种类型,脱脂处理虽不改变淀粉糊化黏度特征曲线的形状,但对板栗淀粉RVA糊化黏度特征值产生影响,使峰值黏度、谷值黏度和最终黏度升高,糊化温度降低,峰值时间影响不大,对稀懈值和回冷值有显著影响。当板栗淀粉表面结合脂含量为0.96%～4.50%时,峰值黏度、谷值黏度、最终黏度和稀懈值受到显著影响,从而影响淀粉的糊化特性。     

Effects of glutelin and globulin on the physicochemical properties of rice starch and flour

The effect of two rice endosperm proteins, glutelin and globulin, on the physicochemical properties of rice starch and flour was investigated. Albumin, globulin, prolamin and glutelin were sequentially extracted from defatted rice flour with de-ionised water, 1.5 M NaCl, propan-2-ol and 0.1 M NaOH, respectively, followed by dialysis and lyophilisation. Globulin and glutelin were then added to pure rice starch at various concentrations, separately and together, and the pasting and textural properties of mixtures were analysed by the Rapid Visco Analyser (RVA) and TA-XT2 textural analyser, respectively. The presence of glutelin in rice starch caused an increase in pasting temperature but a decrease in the viscosity parameters of the starch paste. The concentration of glutelin was also positively correlated with the hardness and adhesive properties of the starch gel. The presence of globulin, on the other hand, resulted in a decrease in all the pasting and textural parameters except gel hardness and the changes were linearly correlated with the concentration of the protein for most of the physical parameters. When the two proteins were added to rice starch together, the outcomes in pasting and textural properties were generally dependent upon the relative concentrations of the two proteins, but were also influenced by the presence of the other two protein fractions, albumin and prolamin. The presence of globulin initially accelerated the rate of water absorption by starch during cooking while the presence of glutelin slowed it down, but in both cases, the ultimate amount of water absorbed was significantly lower than that by pure starch. The contrasting effects of the different protein fractions mean that it might be possible to manipulate the textural properties of rice starch and flour to achieve desirable sensory outcomes by varying the proportions of the protein fractions in product formulations.     

Production of gluten-free wheat starch by peptidase treatment

The potential of peptidase-containing bran extracts from germinated cereals (wheat, emmer, barley) and a peptidase preparation from Aspergillus niger (AN-PEP) to degrade gluten in wheat starch below the threshold for gluten-free foods of 20 mg/kg was compared. The gluten-specific peptidase activity of the peptidases was determined by using gliadin as a protein-based substrate as well as the two celiac-active peptides PQPQLPYPQPQLPY (α-gliadin) and SQQQFPQPQQPFPQQP (γ-hordein). The peptidase activity of AN-PEP exceeded the activities of bran from germinated cereals by a factor up to 690,000. Three wheat starches with initial gluten contents of 110, 1679, and 2070 mg/kg, respectively, were incubated with bran extracts and AN-PEP, lyophilized, and residual gluten was quantitated by a competitive ELISA. Unlike peptidases from bran extracts, AN-PEP was capable of degrading gluten below 20 mg/kg in all starches. The absence of gluten in AN-PEP-treated starches was confirmed by liquid-chromatography-mass spectrometry. The properties of gluten-free starches were comparable to the native starches with the exception of a reduced viscosity after AN-PEP treatment. This problem could be overcome by using higher enzyme concentrations and shorter incubation times or by optimizing AN-PEP production for lower residual α-amylase activity.     

Carbohydrate metabolism during tuber initiation in potato: A transient surge in invertase activity marks the stolon to tuber transition

Summary The relationship between carbohydrate metabolism and tuber initiation in potato was determined by monitoring changes in the amount of starch and sugars along with the activities of sugar metabolizing enzymes upon transfer of plants to tuber-inducing conditions (TI; short days, cold nights) from non-inducing conditions (NTI: long days, warm nights). Switch to TI conditions caused an immediate slow-down in plant growth and triggered swelling of stolon tips, which went on to develop into tubers. Leaves of plants moved to TI conditions accumulated less starch and sugar while their stolon tips showed a sudden upsurge in starch content and a sharp decline in sugars even before any tip swelling was detectable. These changes were paralleled by a transient surge in the activity of cell wall invertase (74%) and soluble invertase (30%) in stolon tips of plants transferred to TI conditions in two unrelated cultivars under different experimental conditions. As the surge in invertase activity faded, it was replaced by a substantial increase in sucrose synthase activity as the tuber enlargement proceeded. The transient increase in invertase activity just prior to tuber initiation appears to mark a turning point in the transition of stolon tip to tuber.