Small-scale mashing procedure for predicting ethanol yield of sorghum grain

A small-scale mashing (SSM) procedure requiring only 300 mg of samples was investigated as a possible method of predicting ethanol yield of sorghum grain. The initial SSM procedure, which was conducted similarly to the mashing step in a traditional fermentation test, hydrolyzed just 38.5–47.2% of total sorghum starch to glucose. The initial procedure was simplified to contain only one liquefaction step, which did not influence subsequent saccharification. Thereafter, parameters such as temperature, pH, enzyme dosage, and saccharification time were optimized. Results showed that 91.2–97.5% of the total starch in 18 sorghum hybrids had been hydrolyzed to glucose using the following conditions: liquefaction at 86 °C for 90 min, 20 μL of α-amylase per 30 g of sample; pH adjustment by adding 50 μL of 2 M acetate buffer at pH 4.2 to each microtube; saccharification at 68 °C for 90 min, 200 μL of amyloglucosidase per 30 g of sample. There were strong linear correlations between completely hydrolyzed starch (CHS) from SSM and ethanol yields from both traditional (R² = 0.86) and simultaneous saccharification and fermentation (SSF, R² = 0.93) procedures. CHS was a better indicator for predicting ethanol yield in fermentation than total starch.     

玉米光周期敏感特性研究及长日照光周期诱导差减文库构建

以热带玉米自交系CML288为材料,通过对比研究表明,CML288对光周期非常敏感。通过长、短日照挪移试验发现,CML288短日照处理条件下,6～7叶期是光周期反应最敏感时期,7～9叶期是光周期敏感持续期,但敏感效应明显减弱。以CML288敏感期叶片与茎尖为材料,利用SSH技术构建了对长日照敏感而特异表达的基因文库,3 000多个单克隆被有效富集。对差减文库中分离的64个特异表达EST序列分析表明,16个EST序列与玉米已知功能的蛋白序列具有较高的同源性;41个序列与其它物种编码序列同源性较高;7个EST没有同源的序列,可能代表了新基因。     

小麦籽粒淀粉合成酶基因表达与酶活性特征的研究

为研究小麦籽粒淀粉合成酶基因表达与酶活性的特征,以普通小麦品种秦麦11(粒重36.942 mg/粒,淀粉含量61.02%)和中优9507(粒重50.636 mg/粒,淀粉含量68.36%)为材料,采用实时荧光定量RT-PCR方法,对灌浆期籽粒淀粉合成酶相关基因的表达进行了研究,并对其表达量与相应酶活性的相关性做了分析.结果表明,腺苷二磷酸葡萄糖焦磷酸化酶基因(AGPase)、束缚态淀粉合成酶基因(GBSSI)、可溶性淀粉合成酶基因(SSS)、淀粉分支酶基因(SBE)表达均呈单峰曲线变化,在花后3 d 内检测不到其表达,花后4～6 d 这些基因开始表达.AGPase和SSS在花后12 d左右表达量达到高峰,GBSSI和SBE在花后15 d左右的表达量最大.自花后18 d开始,各基因的表达量均显著下降.中优9507在表达高峰期(即花后第12、15、18 d)的酶基因相对表达量均显著高于秦麦11,且差异均达显著水平.整个灌浆期间中优9507的四种淀粉合成酶活性高于秦麦11,尤其在灌浆中期差异更显著.相关分析表明,AGPase、SSS、SBE基因在花后15 d的相对表达量与相应酶活性间呈极显著正相关,而GBSS基因的相对表达量与GBSS酶活性间相关不显著,暗示AGPase、SSS、SBE基因在籽粒淀粉合成过程中属于转录水平调控,而GBSSI基因属于转录后调控.     

小麦淀粉粒蛋白表达差异及其与淀粉糊化特性的关系

为探明小麦淀粉粒蛋白与淀粉糊化特性的关系,对河南省18个主栽小麦品种淀粉粒蛋白进行分离,并对淀粉粒蛋白类型、淀粉含量、糊化特性参数进行了研究.结果表明,18个小麦品种分离出了8种主要的淀粉粒蛋白,9种组合带谱,并以组合类型Ⅰ和组合类型Ⅶ所占比例最高,为55.56%,均表现为7条谱带.通过对淀粉粒蛋白条带数量以及谱带光密度总量和淀粉特性的相关性分析表明,淀粉粒蛋白光密度总量和直链淀粉含量、峰值黏度、低谷黏度、最终黏度呈显著负相关,表明淀粉粒蛋白表达量影响淀粉的糊化特性.同时选取6个小麦品种,分别采用盐、SDS、蛋白酶对淀粉进行处理后,淀粉峰值黏度显著提高,其中以盐处理提高幅度最大,且不同处理之间差异达显著水平.对处理后淀粉粒蛋白进行电泳分析表明,处理后的条带明显减少,说明处理后小麦淀粉粒蛋白含量下降.综合试验结果,不同小麦品种淀粉粒蛋白表达存在差异,同时淀粉粒蛋白表达量高低影响淀粉峰值黏度.     

Puroindoline b位点近等基因系对小麦籽粒淀粉含量和组分及其特性的影响

为了研究不同硬度等位基因与小麦籽粒淀粉组分含量及特性的关系,为小麦品质改良提供依据,以7个硬度Puroindoline b位点近等基因系为试材,研究了不同硬度基因型对小麦籽粒淀粉组分含量及特性的影响。结果表明,Pina-D1b/Pinb-D1a基因型的籽粒硬度值、支链淀粉含量最高;Pina-D1b/Pinb-D1a基因型的淀粉溶解度最高,而Pina-D1a/Pinb-D1d溶解度最低,两者差异达显著水平;不同基因型之间籽粒淀粉酶解力没有显著差异;冻融失水率以基因型Pina-D1a/Pinb-D1b最低,表明Pina-D1a/Pinb-D1b基因型冻融稳定性最好,可能较适宜冷冻食品的制作;对于抗性淀粉,Pina-D1a/Pinb-D1b基因型的抗性淀粉含量最高、Pina-D1a/Pinb-D1d最低,表明Pina-D1a/Pinb-D1b基因型有助于籽粒中抗性淀粉含量的提高。     

木薯AGPase酶活性及其同工酶位点检测

本文以3个亲缘关系较远的高产木薯品种（SC124,SC8和Arg7）为材料,对块根发育过程中的AGPase活性和淀粉含量进行了测定,并利用AGPase同工酶电泳技术（非变性聚丙烯酰胺凝胶电泳）对AGPase酶活性较高时期同工酶位点进行检测,旨在分析木薯块根AGPase同工酶位点与AGPase酶活性和淀粉积累的关系。结果表明：木薯块根发育过程中AGPase酶活性和淀粉含量呈极显著正相关（R=0．80212）,Arg7的AGPase酶活性和淀粉含量在块根发育都显著高于SC124和SC8。同工酶分析表明,木薯至少有6个同工酶位点（AGPa,AGPb,AGPc,AGPd,AGPe和AGPf）,且品种间具有多态性。其中,3个品种共有的4个同工酶位点分别为AGPa、AGPc、AGPd和AGPf,AGPe位点只在Arg7中出现,初步判断同工酶位点AGPe可能与其较高的酶活性和淀粉含量有关。本研究为系统研究木薯品种间AGPase酶活性与淀粉积累的关系提供了参考。     

Suitability of tef varieties in mixed wheat flour bread matrices: A physico-chemical and nutritional approach

Wheat flour replacement from 0 to 40% by single tef flours from three Ethiopian varieties DZ-01-99 (brown grain tef), DZ-Cr-37 (white grain tef) and DZ-Cr-387 (Quncho, white grain tef) yielded a technologically viable ciabatta type composite bread with acceptable sensory properties and enhanced nutritional value, as compared to 100% refined wheat flour. Incorporation of tef flour from 30% to 40% imparted discreet negative effects in terms of decreased loaf volume and crumb resilience, and increase of crumb hardness in brown tef blended breads. Increment of crumb hardness on aging was in general much lower in tef blended breads compared to wheat bread counterparts, revealing slower firming kinetics, especially for brown tef blended breads. Blended breads with 40% white tef exhibited similar extent and variable rate of retrogradation kinetics along storage, while brown tef-blended breads retrograded slower but in higher extent than control wheat flour breads. Breads that contains 40% tef grain flour were found to contain five folds (DZ-01-99, DZ-Cr-387) to 10 folds (DZ-Cr-37) Fe, three folds Mn, twice Cu, Zn and Mg, and 1.5 times Ca, K, and P contents as compared to the contents found in 100% refined wheat grain flour breads. In addition, suitable dietary trends for lower rapidly digestible starch and starch digestion rate index were met from tef grain flour fortified breads.     

The final established physicochemical properties of steamed bread made from frozen dough: Study of the combined effects of gluten polymerization,water content and starch crystallinity on bread firmness

The gluten polymerization behavior, water content, starch crystallinity and firmness of Chinese steamed bread made from frozen dough were investigated and their correlations were also established in this study. The decreased degree of gluten polymerization in steamed bread was observed by the enhanced SDS-extractable proteins (SDSEPs) upon frozen storage. Less incorporation of glutenin in the glutenin–gliadin crosslinking of steamed bread mainly contributed to the decreased degree of gluten polymerization. The decreased moisture of steamed bread had a significant negative correlation with the sublimated water in frozen dough (r = −0.8850, P < 0.01). Frozen storage also induced an increase in starch crystallinity and bread firmness. A multiple linear regression model with SDS-extractable proteins, water content and melting enthalpy of starch crystals of steamed bread accounted for 86% of the variance in the natural logarithm of firmness and further revealed that starch crystallinity mainly contributed to bread firmness.     

香草兰花芽分化期蛋白质及碳水化合物变化研究

以墨西哥香草兰花芽分化期花芽、混合花芽、叶芽及其功能叶为研究对象,研究香草兰花芽分化期蛋白质及碳水化合物变化及其差异,结果表明：香草兰叶芽蛋白质含量持续下降,花芽和混合花芽的蛋白质含量在花序分化初期上升至顶峰而后下降,说明香草兰花芽在花序分化前需要累积大量蛋白质。叶芽的可溶性糖、蔗糖含量均无显著变化,花芽和混合花芽均存在明显的上升和下降趋势;在整个花芽分化期,花芽可溶性糖和蔗糖含量均高于叶芽。叶芽的淀粉含量呈升高趋势,花芽和混合花芽的淀粉含量呈先上升后下降趋势。在整个花芽分化期过程中,花芽、混合花芽功能叶C/N比均高于叶芽功能叶,且花芽功能叶和叶芽功能叶间差异达显著水平。     

木薯苹果酸脱氢酶基因克隆和表达分析

为从木薯块根中获得苹果酸脱氢酶(MDH)基因,并研究其在转录水平的表达变化规律,利用RACE技术从木薯“华南8号”块根中克隆得到了苹果酸脱氢酶基因,其cDNA全长1 175 bp,包含999 bp的开放阅读框,共编码332个氨基酸.从木薯“华南8号”中获得的MDH氨基酸序列,与其它物种的该序列相似度达84％～94％,包含细胞质苹果酸脱氢酶中高度保守的NAD结合基元“TGAAGQI”和催化基元“IWGNH”.木薯MDH基因与块根淀粉合成相关,在块根发育前期表达量较低,膨大期表达量较高,膨大后期表达量逐渐降低.