玉米品质基因聚合对子粒氨基酸组分及醇溶蛋白的影响

以玉米o2、sh2、su1、wx这4个品质基因聚合的单基因、双基因、三基因近等基因系为研究对象,对子粒氨基酸组分与醇溶蛋白SDS-PAGE带谱进行检测分析。结果表明,与郑58相比较,su1、wx、su1wx氨基酸组分变化较小,o2、sh2单基因以及含有o2、sh2的双基因、三基因近等基因系中氨基酸组分变化较大,o2sh2、o2su1、o2sh2su1赖氨酸含量较高。SDS-PAGE显示,o2与sh2、su1聚合导致19 kD和22 kDα-醇溶蛋白合成受到显著抑制。     

非常规饲料原料饲喂肉牛育肥的试验研究

[目的]本研究旨在分析全混合日粮中添加苹果渣、玉米纤维及玉米酒精糟三种非常规饲料原料对育肥肉牛采食量、增重效果、产肉性能及经济效益的影响。[方法]选用体重（455±10）kg、健康年龄相近的西门塔尔杂交品种育肥牛14头,随机分为2组,每组7头,设对照组和试验组。分别饲喂未添加非常规饲料原料和添加非常规饲料原料的饲料。[结果]显示：试验组较对照组日增重、屠宰率、净肉率、胴体产肉率、眼肌面肌分别提高了1.1%、2.1%、2.1%、3.3 cm2。出售活牛试验组头均盈利比对照组多出205.2元、牛副产品头均盈利值多出586.8元。[结论]表明在肉牛育肥中,应用推广苹果渣、玉米酒精糟及玉米纤维等非常规饲料原料,具有扩大饲料来源、降低饲养成本等优点,能进一步提高肉牛的增重速度与产肉性能,增加养殖的经济效益。     

玉米花粉超低温长期保存后遗传稳定性的研究

玉米自交系黄早四和郑１１４２的花粉在超低温（－１９６℃）保存１－２年后，冷冻花粉的过氧化物酶同工酶谱类型没有发生变化。冷冻保存的郑１１４２花粉授粉后所结的种子的过氧化物酶同工酶和醇溶蛋白电泳图谱同对照相比也没有变化，保持原自交系特征。冷花粉后代种子产生的植株，花粉母细胞染色体数目和结构正常。田间农艺性状正常，保持原自交系特征。     

Gliadin and zein show similar and improved rheological behavior when mixed with high molecular weight glutenin

Small amplitude and lubricated squeezing flow tests were performed to investigate the effect of high molecular weight glutenin (HMWG) on the rheological properties of gliadin and zein dough composites. It was hypothesized that addition of small amounts of HMWG to zein cause changes in its viscoelastic properties in the same way as its addition to gliadin. Starch (87%, w/w) and protein/protein composites (13%, w/w), and water were mixed into dough. The water content of prepared dough was in the 41.7–45.3% range. Composites were gliadin-HMWG and zein-HMWG. Phase angle and complex modulus (G*) were obtained from frequency sweep tests at 0.5% strain amplitude over a 0.01–100 rad/s frequencies. Lubricated squeezing flow test were carried out at a range of strain rates to determine the sample extensional viscosities.     

Physical properties of zein films containing salicylic acid and acetyl salicylic acid

Zein films containing salicylic acid (SA) and acetyl salicylic acid (ASA) between 2 and 10% (initial zein weight basis) with or without glycerol were evaluated for structure, mechanical and dissolution properties. The random coils, α helices and β sheets mainly governed the secondary structure of zein, depending on glycerol and level of model molecules. Adding ASA resulted in an increase in α helices whereas β sheets increased at the expense of α helices when SA was used. Including SA or ASA decreased the tensile strength and the stiffness of films containing glycerol indicating the synergistic effect of SA and ASA. The strain at failure decreased with increasing content of SA but increased with increasing level of ASA. The dissolution properties were glycerol and drug dependent. ASA release in comparison to SA was quite low. The release was only observed above 10% ASA whereas it was detected in all films containing SA. The possible interactions between active components and proteins are discussed together with their implications on the physical properties of zein films.     

玉米opaque2突变体子粒表型及营养成分分析

通过回交转育构建o2突变型的近等基因系CAL58/o2,对其子粒进行扫描电镜和透射电镜观察,发现与CAL58相比,CAL58/o2中淀粉颗粒排列松散,形状更加规则,CAL58/o2子粒中蛋白体体积变小。分析子粒的营养成分,CAL58/o2赖氨酸含量极显著提高了55.88%,氨基酸总量显著减少9.79%,粗蛋白显著减少8.86%,粗脂肪显著增加30.96%,粗淀粉显著增加5.87%。同时,提取成熟子粒醇溶蛋白进行比较,CAL58/o2子粒的α、β-醇溶蛋白含量明显降低,γ-醇溶蛋白含量增加。     

玉米醇溶蛋白膜的制备研究

[目的]研究用玉米醇溶蛋白制作的可食包装膜。[方法]以玉米醇溶蛋白为主要原料,一定浓度的乙醇作为溶液,甘油和油酸用作增塑剂,研究增塑剂用量、挤压力度、制备温度对玉米醇溶蛋白膜强度的影响,以质构仪膜穿刺数据为评价指标,比较了不同条件对玉米醇溶蛋白膜强度的影响。[结果]优化结果表明,乙醇溶液浓度80%、油酸20%(与醇溶蛋白的质量比),压力10 MPa,水浴温度70℃时制备的玉米醇溶蛋白膜柔韧性和强度较好。[结论]在优化条件下,玉米醇溶蛋白可作为一种可食材料制作包装膜。     

Characterization of zein modified with a mild cross-linking agent

Zein, a predominant corn protein, is an alcohol-soluble protein extracted from corn and is an excellent film former. The characteristic brittleness of zein diminishes its usefulness as a film. It is well known that zein has a propensity for forming aggregates in solution. When zein molecules were cross-linked with 1-[3-dimethylaminopropyl]-3-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), it was found that the film-forming property was improved and the aggregation phenomenon in solution was suppressed. At the air/water interface, native zein forms brittle film with rough surface, whereas cross-linked zein forms rigid film with very smooth and even surface. Tensile strengths of the films were shown to be greatly increased by cross-linking. Objectives of this study are to determine the cross-linking mechanism of zein, the optimum reaction conditions, characteristics of the reaction product, and mechanical properties of cross-linked zein film. Through viscosity and dynamic light scattering, the cross-linking reaction was monitored. Optimum amount of EDC and NHS was determined to be 30 mg each per gram of zein. The cross-linking of zein with EDC and NHS seemed to be self-terminating because the cross-linking reaction did not proceed to precipitation.     

Investigation of surface properties of physico-chemically modified natural fibres using inverse gas chromatography

Inverse gas chromatography (IGC) is a suitable method to determine surface energy of natural fibres when compared to wetting techniques. In the present study, the surface properties of raw and modified lignocellulosic fibres have been investigated by IGC. The fibres chosen for the study were flax, hemp, kenaf, agave, agave hybrid, sisal and pineapple. The treatments used were 4% NaOH and 2% zein. The uniqueness of zein treatment is that it is bio-based and therefore maintains the biodegradable character of the natural fibres. Fourier transform infrared spectroscopy (FTIR) and environmental scanning electron microscope (ESEM) were also performed to characterize the surface changes in fibres. The surface properties of fibres are influenced by the chemical composition, crystallinity and morphology of the fibres. Bast fibres exhibited higher surface dispersive energy than leaf fibres. The raw fibres have a predominant basic character, whereas the alkaline treatment makes the fibres more acidic. Both alkaline and zein treatments decrease the dispersive surface energy and the specific free energy of adsorption.     

Melt-processed blends of zein with polyvinylpyrrolidone

Melt-processed blends of zein and polyvinylpyrrolidone (PVP) of varying molecular weights (55K, 360K and 1.3M) were compared based on mechanical and thermal properties. Generally, all samples stored at 50% RH exhibited a slight improvement in tensile strength, with the PVP360K samples showing the greatest improvement. At the higher levels of PVP, samples stored at 70% RH showed a decrease in tensile strength. Elongation was also more significantly impacted at higher humidity, with the higher levels of PVP causing greater elongation increases. Differential scanning calorimetry data for the blends showed single T_g values intermediate between the zein and PVP controls. Kinetic thermogravimetric data suggested a multi-step degradation interaction for the zein/PVP blends. Scanning electron microscope imaging of compression molded samples showed homogeneous surface contours for even the 20% PVP1.3M blend. Melt-processed blends of zein with polyvinylpyrrolidone of various molecular weights appear to be compatible. This work represents the first melt-processed blend of zein with PVP to generate a compatible blend.