等离子体辅助玉米醇溶蛋白自组装纤维化的工艺

植物蛋白纤维由于其独特的结构和极高的纵横比可作为良好的疏水性生物活性物质的递送载体。为了提高玉米醇溶蛋白在酸热诱导下的纤维化程度,该研究采用低温等离子体技术辅助完成玉米醇溶蛋白自组装纤维化,探究诱导过程中各因素对玉米醇溶蛋白纤维化程度的影响机制,并通过单因素和响应面试验获得最优纤维化工艺。硫黄素T（ThT）荧光强度结果显示,采用等离子体辅助酸热诱导可以有效提高玉米醇溶蛋白的纤维化程度。通过单因素和响应面优化试验获得了制备纤维化玉米醇溶蛋白的优化工艺为等离子体处理功率64 W,处理时间61 s,加热时间为10 h,加热温度70 ℃,蛋白质量浓度30 mg/mL。在此条件下纤维化玉米醇溶蛋白ThT荧光强度可达2 272±23,显著高于未经等离子体处理的纤维化玉米醇溶蛋白（1 239±19）（P＜0.05）。对傅里叶变换红外光谱中酰胺I 区结果分析表明,等离子体处理使玉米醇溶白中β-折叠结构增加,α-螺旋结构减少。透射电子显微镜观察到玉米醇溶蛋白经过纤维化后颗粒粒径明显下降,其纤维结构是由球状蛋白颗粒沿水平方向线性聚集而成,采用等离子体辅助可诱导形成更多的玉米醇溶蛋白纤维体结构。研究结果为疏水性植物蛋白实现高效自组装纤维化提供参考。     

Variation among maize (Zea mays L.) accessions of Bendel State,Nigeria

Summary Variability in maize zein protein band mobilities in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was characterized to classify 27 maize accessions (OTUs) collected from Bendel State, Nigeria. The classification of the OTUs was achieved using two numerical procedures: average linkage cluster analysis and principal component analysis (PCA). Five clusters were delineated by the cluster analysis whereas the PCA complemented the cluster analysis by separating the OTUs with yellow kernels into one group and OTUs with early maturity into another. OTUs from the same geographical contiguity commonly grouped together. However some regional overlappings of the OTUs occurred. Results of the PCA revealed that zein bands that stained less intensely more strongly separated the OTUs into various clusters than did those that stained more intensely.     

玉米醇溶蛋白在草莓贮藏保鲜中的应用

用玉米醇溶蛋白涂被剂保鲜草莓,不仅可延长草莓的贮藏期,还可减少草莓在贮藏期间的营养成分损耗.采用正交实验方法筛选最佳涂被剂配方的结果表明,玉米醇溶蛋白1.75%,甘油0.18%,蔗糖0.3%,并辅以0.02%乳化剂与防腐剂保鲜草莓效果最佳.     

超声辅助玉米醇溶蛋白基乙烯吸附膜的制备及其香蕉保鲜性能

【目的】乙烯是影响水果品质及货架期的关键植物激素。本研究利用高场强超声波(HIU)对玉米醇溶蛋白(zein)进行物理改性处理,使其蛋白结构舒展,内部活性官能团暴露;利用超声改性zein膜中的活性官能团(如巯基等)与乙烯发生“点击反应”吸附乙烯,从而达到延长水果货架期的目的。【方法】将5 g zein溶于80%醋酸溶液中,选用频率为20 kHz、功率为400 W的超声波经不同时长(0、5、15和30 min)的预处理后,分别取2 mL蛋白溶液移至培养皿(55.0 cm²)中,放置于40℃烘箱干燥24 h,分别得到zein-0膜、zein-5膜、zein-15膜、zein-30膜,通过圆二光谱、内源性荧光、粒径电位仪和扫描电镜分析不同条件超声处理后蛋白结构及形貌的变化;借助物性分析仪和VOC检测仪表征zein膜的力学性能和乙烯吸附性能。以香蕉为研究对象,将超声处理后的zein膜与香蕉放置于同一塑封袋中,室温密闭放置10 d,基于香蕉表皮的褐变程度、香蕉果肉的硬度变化和香蕉失重率分析zein膜延长水果货架期的性能。【结果】高场强超声波处理对蛋白质的高级结构具有修饰作用,...     

玉米醇溶蛋白提取工艺的研究

通过单因素试验和多因素水平的正交试验对玉米醇溶蛋白的提取工艺进行了研究,试验结果表明,最佳工艺条件为提取温度60℃,提取时间1．5h,料液比1：10,乙醇浓度80％。     

Effects of polymerization changes in maize proteins during nixtamalization on the thermal and viscoelastic properties of masa in model systems

Although nixtamalization is widely used in the food industry, a comprehensive understanding of the influence of proteins on the viscoelastic behavior and thermal properties in masa is still lacking. In this work, the effect of protein changes and its influence on the masa viscoelastic behavior were studied using model systems. Mixtures of lime-starch, zein-starch and lime-zein-starch were cooked at 90 °C from 20 to 150 min. Zein changes during cooking were analyzed by SDS-PAGE. Thermal transition temperatures and enthalpies were determined using differential scanning calorimetry (DSC). Dynamic oscillatory tests were undertaken on model system samples with 50% (w/v) moisture content, using a strain-controlled rheometer. SDS-PAGE showed that zein polymerizes during cooking. In the zein-starch model system, no visible protein bands were found after 30 min cooking; however, when lime was present, five bands were observed in all samples. Thermal transitions were observed around 55–62 °C for all model systems, probably corresponding to starch retrogradation. Rheological studies showed that protein exhibited higher influence in the gel strength by increasing the elastic character of the system. It was hypothesized that the combined effects of lime on starch, zein polymerization and the formation of calcium-zein bonds during cooking, yield a stronger and more elastic gel structure.     

根癌农杆菌介导的甘薯遗传转化及转基因植株的再生

以甘薯优良品种"新大紫”的茎尖培养再生植株为试材,经根癌农杆菌介导将甘薯块根贮藏蛋白启动子(Sporaminpromoter)调控下的10kD玉米醇溶蛋白基因导入到"新大紫”中,并获得了转化植株.甘薯品种"新大紫”再生植株的茎切段,与携带有表达载体质粒pSP10Z的根癌农杆菌菌株LBA4404共培养后,在含75mg/L卡那霉素(Kan)的筛选培养基上可     

玉米醇溶蛋白的提取及酶解工艺研究

【目的】优化水解醇溶蛋白生产功能肽的工艺,提高玉米醇溶蛋白的应用价值.【方法】通过正交试验获得从玉米蛋白粉中提取醇溶蛋白的最佳提取时间、提取温度、料液比、乙醇浓度等提取条件;通过碱性蛋白酶和蛋白酶K对玉米醇溶蛋白进行水解生产玉米多肽.【结果和结论】通过正交试验获得了从玉米蛋白粉中提取醇溶蛋白的最佳条件,即:料液比1∶4(g/mL),60℃水浴加热,乙醇体积分数为75%,提取3 h.两步酶解法效率高于单酶解法,两步酶解法先加蛋白酶K反应后再加碱性蛋白酶时水解效果最佳.     

超高压处理玉米醇溶蛋白的流变性和热特性分析

为了阐明超高压处理对玉米醇溶蛋白流变行为和热性能的影响及其作用规律,采用旋转黏度计测定了不同温度条件下超高压处理玉米醇溶蛋白溶液的流变特性参数,应用幂定律拟合了剪切应力(τ)与剪切速率(γ)的关系曲线,建立了黏度(η)和温度(T)的数学模型;利用差示扫描量热仪(DSC)测定了超高压处理前后玉米醇溶蛋白的结晶温度(Tc)、熔融温度(Tm)、结晶焓(ΔHm),并利用扫描电子显微镜(SEM)对其进行了表征。结果表明,超高压处理后玉米醇溶蛋白溶液逐渐偏离牛顿流体,具有假塑性流体特性。随着压力增大,黏度呈现先增加后减小再增加的趋势,当压力为400MPa时,黏度达到最高;随着温度升高,黏度开始下降,当温度为40℃时,黏度降到最低;而随着剪切速率的增大,黏度随之下降,但当剪切速率接近100s-1时,黏度变化不明显。超高压处理后玉米醇溶蛋白粉的熔融温度升高,结晶焓减小,DSC热特性曲线变性峰(Tm-Tc)有变宽的趋势。SEM显示超高压处理后部分玉米醇溶蛋白颗粒凝聚成环状或者链状结构。