The Influences of Chain Length of Amylopectin on Resistant Starch in Rice (Oryza sativa L.)

Amylopectin is the principle component of starch. To elucidate the relationships between amylopectin and resistant starch content, six rice mutants with altered fine structure of amylopectin were selected for comparative studies with the primary wild type and two types of amylose‐extender (ae) mutants. Significant differences in resistant starch content were observed among mutants with similarity or differences in amylose levels. Mutants high in resistant starch had significantly increased proportions of short amylopectin chains with DP≤12, decreased levels of intermediate chains with size of 13≤DP≤36, and decreased fractions of long chains with DP≥37. Additionally, there was a mutant different to ae, which was characterized by an increased level of short chains with 8≤DP≤12 and 13≤DP≤24, and a decreased proportion of long chains with DP≥37. The increased contents of short chains with 8≤DP≤12 and decreased of intermediate and long chains with 24≤DP were clearly associated with the increase of resistant starch in rice.     

Comparative Effects of Acetylated and Unmodified High‐amylose Maize Starch in Rats

Acetylated, propionylated or butyrylated starches raise the large bowel pools of these short chain fatty acids (SCFA) in rats but their resistant starch (RS) content in vivo is unknown. This content was determined for acetylated starch (Starch A, DS = 0.18) in colectomised rats and compared to a standard maize (control) or high‐amylose (HAMS) maize starch. Digestibilities were 99.8% (control), 47.5% (Starch A) and 58% (HAMS). The effects of Starch A and HAMS were compared also in intact rats, that were fed a fibre‐free diet in which either 200 g/kg of HAMS or 100, 200 or 300 g of Starch A/kg was substituted for the standard maize starch. Caecal SCFA pools were larger in rats fed either RS with the greatest increase being in acetate in rats fed Starch A. Other acids (succinate and formate) appeared with increasing incorporation of RS. However, when the experiment was performed with a commercial diet, feeding Starch A or HAMS did not lead to any great increase in these other acids but SCFA pools expanded. The greatest increase in acetate was in rats fed Starch A. This suggests that other factors were necessary for optimal RS fermentation but not for release of acetate from Starch A. Comparison of the effects of Starch A and HAMS on SCFA suggests that the former was at least 100% more effective than HAMS at equivalent dietary intakes, despite similarities in RS content. Incubation of Starch A with caecal bacterial enzymes confirmed that release of acetate was relatively slow, indicating a capacity of this modified starch for sustained SCFA delivery in vivo.     

若干物理因素对抗性淀粉制备的影响

抗性淀粉是一种新兴的食品添加剂,可作为食品的膳食纤维功能成分,广泛应用于碳水化合物、脂肪质食品如作为糖、面粉替代品,作为膳食纤维添加于焙烤食品、低热、低脂人造奶油、冷冻甜点等或作为一种单独的添加剂加入食品配方中。通过对制备过程中物理因素的研究,探讨了抗性淀粉的最佳制备物理条件,为工业开发应用提供一定的理论基础,抗性淀粉作为低热、高膳食纤维含量功能食品成分将具有重要的应用前景。     

葡萄对白粉病与霜霉病的抗性机制

本文结合作者近7年来对葡萄白粉病与霜霉病的抗性研究,对葡萄植物抗白粉病与霜霉病的机制从组织结构生物化学物质两方面进行了综述与探讨。     

一种新型的高耐热、高阻燃、低介电损耗的热固性树脂的开发

文章介绍了马来酰亚胺与三嗪环改性的酚醛树脂通过MICHAEL加成反应形成的新型热固性树脂。这种新型热固性树脂与环氧树脂一起形成了二元共混体系,这个二元共混体系应用于覆铜板,使得覆铜板具有高耐热、高阻燃、低介电损耗的特点,而且机械性能和吸湿后耐焊性有很好的平衡。     

丁腈橡胶在燃气介质中的老化性能测试研究

基于烘箱热空气老化试验方法,建立了一种能让试验样品处于流通气氛冲刷的闭合试验装置,对橡胶材料进行燃气环境中老化性能测试。选用丁腈橡胶为试样,测试其在不同温度、不同气氛下的老化性能,预测其使用时间。测试结果显示,采用空气气氛方法进行丁腈橡胶加速老化试验,预测的使用时间结果与实际使用时间的偏差在80%以上;燃气气氛冲刷环境下,丁腈橡胶在老化速率是热空气老化的2倍左右,且燃气气氛下的加速老化使用时间的预测结果与实际的偏差在±20%之内。     

铁磁物料用耐磨衬板的研究

介绍了磁性耐磨衬板的机理 ,对衬板的实验室及生产现场工业性试验进行了分析研究 ,并通过于计算机仿真结果对比 ,指出了提高磁性衬板耐磨性能的几种途径     

Low and high amylose maize starches acetylated by a commercial or a laboratory process both deliver acetate to the large bowel of rats

Short chain fatty acids (SCFA) produced by large bowel bacterial fermentation of carbohydrates promote normal colonic function and health. Previous studies in rats have shown that starches acylated with SCFA to a high degree of substitution (DS) resist small intestinal digestion and pass into the large bowel where the acids are released by bacterial enzyme activity. These studies were conducted with starches manufactured from low or high amylose starches manufactured in the laboratory or commercially. In this study, a direct comparison was made between acetylated low and high amylose maize starch manufactured in the laboratory and high amylose maize starch acetylated commercially. Compared to a standard maize starch, all acetylated starches raised large bowel pools of acetate (by as much as 10-fold) and total SCFA (by between 320% and 775%) when fed to rats. They also raised large bowel digesta mass by as much as 2-fold and lowered pH by up to 28%. These changes were observed when the background diet contained unmodified low or high amylose starch, although the changes were greatest with high amylose maize starch which is consistent with its resistance to digestion. The data confirm that acylated starches are a viable means of raising specific large bowel SCFA, independent of the manufacturing process.     

PE防老化保温功能性母料及其挤吹棚膜的研制

本文介绍了ＰＥ挤吹棚膜的防老化保温功能复合体系及其功能母料和挤吹棚膜的生产工艺，通过不同棚膜的田间应用试验对复合体系的功能性进行了比较与分析。研制结果表明：复合体系的功能性显著，具有广阔应用前景。研制膜经自然老化田间试验六个月后，机械力学性能未发生明显变化，膜的透光性良好，手感柔软，其使用寿命是普通膜的２￣２．５倍。研制膜在自然田间试验中，棚内室温高于普通膜３￣５℃，棚内地温高１￣３℃，同时白天升     

SiC颗粒增强铝基复合材料的显微组织与力学性能

采用压铸浸渗法制备了体积分数为50%的SiC/Al-5.3Cu-0.8Mg-0.6Ag-0.5Mn耐热铝基复合材料.通过拉伸测试与组织观察,研究了高体积分数SiC颗粒增强对基体合金的显微组织与力学性能影响.结果表明,在基体Al-5.3Cu-0.8Mg-0.6Ag-0.5Mn合金中掺入高体积分数的SiC颗粒后,复合材料的时效硬化与拉伸性能得到了大幅度的提高,185 ℃峰时效处理后的抗拉强度从356 MPa增大到520 MPa.SiC/Al-5.3Cu-0.8Mg-0.6Ag-0.5Mn复合材料的组织致密,分布均匀,其断裂方式包括界面脱开、基体韧断和增强体开裂.高体积分数SiC颗粒的增强并不改变基体合金的时效析出过程,析出相由Ω相和少量θ＇相组成,但SiC颗粒与基体之间发生了界面反应,生成了纳米级的Al4C3化合物.