Temperature variations during grain filling obtained in growth tunnel experiments and its influence on protein content,polymer build-up and gluten viscoelastic properties in wheat     

Anette Moldestad  Bernt Hoel  Ulrike Böcker  Shiori Koga  Ellen Færgestad Mosleth  Anne Kjersti Uhlen 《Journal of Cereal Science》2014

The aim of this study was to investigate effects of temperature during grain filling on gluten quality characteristics at a lower to moderate temperature range. Experiments with two wheat varieties grown in field covered by polypropylene tunnels during grain filling were performed in two seasons. Mean day temperature differences achieved within the tunnel were approximately 2–2.5 °C from the open to the closed end. There were significant effects of temperature on grain maturity time, thousand grain weight and protein content. The resistance to stretching of the gluten doughs increased with the increasing day temperatures. This was reflected in the proportion of unextractable polymeric proteins (UPP). The results suggest that increases in temperature within this temperature range affect the polymerization of polymeric proteins, giving higher molecular weights, and hence increased Rmax and stronger gluten. The two varieties differed in their response to temperature. In addition, there were seasonal variations in gluten functionality that may be associated with fluctuations in day temperatures between the seasons.  相似文献   

Rheological properties of pasta dough during pasta extrusion: Effect of moisture and dough formulation     

Elena de la Peña  Frank A. Manthey  Bhavesh K. Patel  Osvaldo H. Campanella 《Journal of Cereal Science》2014

A study was conducted to investigate the effect of dough formulation and hydration level on the rheological properties of pasta dough during pasta extrusion. Semolina 100%, whole wheat 100%, and the following mixtures semolina-whole wheat (49:51), semolina-flaxseed flour (90:10), whole wheat-flaxseed flour (90:10), and semolina-whole wheat-flaxseed flour (39:51:10) were the formulations used for the experiments. Dough was hydrated at 30, 32, and 34% moisture content. Pasta was extruded with a capillary and a semi-commercial pasta extruder to determine the apparent viscosity of the dough during extrusion conditions and its relationship to the behavior of the dough during pasta processing. Results showed that non-traditional pasta dough behaved like a shear thinning fluid that can be described by the Power Law model. Increased hydration levels and/or presence of flaxseed flour on the dough formulation decreased the apparent viscosity of the dough, which correlated with extrusion pressure, mechanical energy, and specific mechanical energy that were required to extrude the dough in the pasta extruder. The strong correlations found between the apparent viscosity of the dough and the pasta extrusion parameters indicates the possibility of using a capillary rheometer to determine the appropriate hydration level of ingredient formulations before extruding with a pasta press.  相似文献   

Potential angiotensin I converting enzyme inhibitory peptides from gluten hydrolysate: Biochemical characterization and molecular docking study     

Ahmad Asoodeh  Leyla Haghighi  Jamashidkhan Chamani  Mohamad Amin Ansari-Ogholbeyk  Zahra Mojallal-Tabatabaei  Milad Lagzian 《Journal of Cereal Science》2014

The present study was carried out to characterize ACE inhibitory peptides which are released from the trypsin hydrolysate of wheat gluten protein. In silico proteolitic digestion of a high molecular weight glutenin subunit was performed. Among the resultant fragments, four peptides were selected for chemical synthesis based on the chemoinformatics studies and docking properties. The ACE inhibitory activity and kinetic parameters of the most important peptides were determined. Molecular docking simulation was also performed to predict the sites on ACE in which these peptides bind and displayed inhibition mechanisms. Two peptide sequences of IPALLKR (P4) and AQQLAAQLPAMCR (P6) showed higher ACE inhibitory activity among peptide collection. The IC₅₀ values of P6 and P4 were 43 ± 1.3 μM and 68 ± 2.8 μM, respectively. P6 peptide was proved to be a more potent ACE inhibitor than P4 peptide. Lineweaver-Burk plots revealed that P6 and P4 behaved as non-competitive and competitive ACE inhibitors, respectively. The simulations showed that P4 bound to the active site region. Conversely, P6 bound to the N-terminus entrance of substrate tunnel and obstructed the substrate access into the catalytic site. Overall, the results showed that these peptides would be considered as a model for discovering new bio-compatible ACE inhibitors.  相似文献   

Quantitative proteomic analysis of wheat grain proteins reveals differential effects of silencing of omega-5 gliadin genes in transgenic lines   总被引：1，自引：0，他引：1  

Susan B. Altenbach  Charlene K. TanakaPaul V. Allen 《Journal of Cereal Science》2014

Novel wheat lines with altered flour compositions can be used to decipher the roles of specific gluten proteins in flour quality. Grain proteins from transgenic wheat lines in which genes encoding the omega-5 gliadins were silenced by RNA interference (RNAi) were analyzed by quantitative 2-dimensional gel electrophoresis (2-DE). The precise effects of the genetic modifications on the proteome were assessed in four homozygous lines generated with the same RNAi construct. Two of the lines showed >80% decreases in omega-5 gliadins with only small changes in the levels of other gluten proteins. In the other two lines, omega-5 gliadins were not detectable by 2-DE. However, there were notable reductions in all omega-1,2 gliadins. Small decreases in several other gluten proteins were also detected in one of the lines. The other line showed notable decreases in three HMW-GS and an s-type LMW-GS, increases in two m-type LMW-GS and several alpha gliadins, as well as increases in both serpins and triticin. The study demonstrates that the same RNAi construct can have differential effects on the wheat grain proteome and highlights the importance of detailed proteomic analyses of transgenic grain prior to selecting lines for further assessment of flour quality and allergenic potential.  相似文献   

马来松香对木粉/HDPE复合材料流变性质的影响   总被引：2，自引：1，他引：1  

欧荣贤  王清文 《林业科学》2009,45(5)

用马来松香对木粉进行流动性能改善处理,与高密度聚乙烯(HDPE)熔融复合,挤出成型制备木粉/HDPE复合材料(WF-HDPE).利用傅里叶变换红外光谱(FTIR)和X-射线光电子能谱(XPS)技术,分析经马来松香改性前后木粉表面官能团的变化和元素的变化,采用旋转流变仪研究.WF-HDPE的流变行为.FrIR与XPS分析表明,马来松香分子中的酸酐基团与木粉表面的羟基发生了酯化反应,并且马来松香是以单酯的形式接枝到木粉表面,同时产生一游离羧基.WF-HDPE流变学研究表明:复合材料的复合黏度(η*)、储能模量(G′)和损耗模量(G″)随马来松香用量的增加先减小后增大最后减小,但体系的黏度和模量总体呈下降趋势,木粉经马来松香改性后复合熔体的流变性能显著改善,这不仅有利于提高复合材料的成型加工效率,而且适当的马来松香处理也能够提高复合材料的拉伸强度和弯曲强度,后者被静态力学试验结果所证实.  相似文献   

Strain Hardening Properties and Extensibility of Flour and Gluten Doughs in Relation to Breadmaking Performance     

J.J. Kokelaar  T. van Vliet  A. Prins 《Journal of Cereal Science》1996,24(3):199-214

The mechanical properties of flour–water doughs and hydrated gluten of different wheat cultivars were determined. Measurements were performed at small deformations (dynamic measurements) as well as at large deformations (biaxial extension measurements). Results of dynamic measurements of flour doughs related poorly to breadmaking quality. For hydrated gluten doughs, all having the same water content, it was found that glutens from wheat cultivars with good baking quality had higher values for the storage modulus,G, and lower values for the loss tangent. The relevant type of deformation around an expanding gas bubble is biaxial extension. Wheats with a good baking performance exhibited greater strain hardening and greater extensibility. The differences in strain hardening observed at 20 °C were also present at 55 °C. No clear effects of NaCl or emulsifiers on the biaxial extension properties of flour dough were found. Extensograms as well as Alveograms from the flour doughs showed that, in general, good baking flours exhibited stronger resistance to extension and a greater extensibility, but differences found were not directly related to the results of the baking tests. The results indicate that the baking performance of dough is related to a combination of at least three different rheological characteristics.  相似文献   

软质小麦品质性状与酥性饼干品质参数的关系研究   总被引：31，自引：0，他引：31  

张岐军  张艳  何中虎  R J Pe 《作物学报》2005,31(9):1125-1131

选用我国17份软质小麦品种（系）在3点种植2年，研究软质小麦品质性状与酥性饼干品质的关系，探讨优质饼干品种的筛选指标。结果表明，粉质仪和拉伸仪参数与饼干品质的相关系数较小；吹泡仪弹性、吹泡仪弹性/延伸性、碱水保持力（AWRC）、碳酸钠溶剂保持力（SRC）和蔗糖SRC与饼干直径关系密切，相关系数分别为－0.79、－0.75  相似文献   

A simulated experiment on the high titanium slag rheological behavior     

BAI Chen-guang  HUANG Run  QIU Gui-bao  YU Yao-wei  PAN Cheng  MAO Lei 《保鲜与加工》2011,(3):64-68

The rheological property of high titanium slag is a main factor to influence the vanadium titanomagnetite smelting in blast furnace. It plays a great role in discharging slag, separating iron and slag and even the life of blast furnace hearth. The acrylonitrile-butadiene-styrene multipolymer(ABS) dense suspension is taken to simulate the system of high titanium slag. Apparent viscosity is measured by a NXS-11A rotating cylinder viscometer. The impact of temperature, volume fraction and particle sizes on the suspension apparent viscosity is studied. The results show that temperature and volume fraction have a strong influence on the suspension apparent viscosity, while the particle size has a weak effect. The suspension shows Bingham behavior within a wide concentration range. The dependence of the appear viscosity on temperature and amount of solid addition can be described by a binary function equation.  相似文献   

土壤质地对冬小麦淀粉积累的影响   总被引：1，自引：0，他引：1  

阎凌云  郭天财  高松洁  王应君  韩巧霞 《河南农业科学》2006,(11):26-29

以3种筋力型冬小麦品种为试材,研究其在不同土壤质地上,池栽条件下淀粉的积累动态。结果表明:壤土上淀粉积累速率最大,粘土上次之,砂土上最小。不同土壤质地强筋品种淀粉积累呈不规则抛物线趋势,但差异不大;中筋品种在不同土壤质地上积累动态呈不规则抛物线,其中,在壤土上淀粉积累量最大;弱筋品种在不同土壤上淀粉积累均呈抛物线型,在壤土上淀粉积累量最大。  相似文献   

化学合成面筋蛋白外啡肽B5对鸡淋巴细胞体外免疫活性的影响   总被引：1，自引：0，他引：1  

周业飞  周梅仙 《西北农业学报》2015,24(3):39-43

面筋蛋白外啡肽B5是一种通过面筋蛋白的体外酶解所获得的阿片肽,具有一定的免疫学功能,有望成为一新型免疫增强剂。本研究通过化学合成方法制备,并将其加入鸡外周血单个核细胞中,以观察其对淋巴细胞的增殖效应和对IFN-γ和IL-4mRNA水平影响。结果显示,化学合成获得了高纯度的外啡肽B5(HPLC质量分数大于98.435 7%);外啡肽B5能显著促进鸡淋巴细胞的增殖,并能显著提高IFN-γ的mRNA水平(P0.05),对IL-4mRNA无显著影响。  相似文献