一种测定食用菌中总糖含量的新方法

总糖含量是食用菌的一项重要质量指标,国标方法中采用分光光度计比色法。本实验采用多微孔板检测仪检测食用菌中的总糖含量,并与国标方法进行比较。结果表明,采用多微孔板检测仪测得的结果与国标方法测得的结果相符,而且新方法消耗试剂少,检测速度快,结果重现性好。多微孔板检测仪可以在1min对90个样品进行检测。      

加工方法及提取因素对甘薯中可溶性糖含量影响的研究

通过蒸、烤、炸三种加工方式对甘薯中水分和可溶性糖含量的动态影响进行研究。蒸制、烤制过程中,甘薯中的可溶性糖含量先增加而后降低,在处理末期又呈上升趋势,油炸过程中可溶性糖含量呈下降趋势。蒸、烤对甘薯中的水分含量无较大的影响,而油炸过程中,甘薯中的水分随油炸时间延长持续降低。通过单因素和正交实验方法探讨了提取温度、时间、料液比对可溶性糖提取量的影响。结果表明:在蒸制24min的条件下,对可溶性糖提取影响最大的是料液比,其次是温度,时间的影响最小;水提取可溶性糖的最佳工艺条件是料液比1g∶200mL,提取时间为20min,提取温度为40℃,提取率为41.03%;在烤制40min的条件下,对可溶性糖提取最大的是料液比,其次是温度,时间的影响最小;水提取可溶性糖的最佳工艺条件是料液比1g∶250mL,提取时间为30min,提取温度为50℃,此时的提取率是51.31%。      

A Review of White Granulated Sugar Standard Development in China and Comparative Study on the Chinese White Granulated Sugar Standard with International Standard

The sugar standard implemented under specific historical conditions had played a positive role in standardizing the production of China's sugar industry, promoting the development of sugar industry and strengthening the quality management of sugar products. This paper systematically combs the development of national standard and industrial standard of white granulated sugar, and analyzes the technical requirements such as sensory indicators, physical and chemical indicators and health indicators. From the development of China's white granulated sugar product standard, the sucrose content of the same level of white granulated sugar has not been adjusted, while the standard for indexes other than sucrose content, have been improved to meet the needs of the development of China's sugar industry and the development of domestic and foreign trade. Through comparison with the international standard of white granulated sugar, it is concluded that China's national standard of white granulated sugar has kept pace with international standard.     

用预留子载波降低OFDM系统峰均比的方法

针对正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)所具有的高峰均比问题.提出了一种简单有效的降峰均比的预留子载波的方法.使用预留的子载波形成降低峰均比的信号,通过合理的选择预留载波上的值,从而使时域组合信号的峰均比达到最小,同时当同一小区的扇区数目大于一时,可提高显著带宽的利用率.首先,选择用于降峰均比的子载波;然后.根据选择降峰均比的子载波生成相应的子载波信息,并将生成的信息发给不同扇区的降峰均比模块;最后,在各扇区的降峰均比模块中,使用同一组预留的子载波分别进行本扇区的降峰均比处理.数据仿真验证了所提出方法的有效性.     

稀少糖家族新成员—L-木酮糖的生物制备研究进展

L-木酮糖是自然界罕见的L-型戊酮糖,具有糖苷酶抑制活性能够降低血糖,还可以用作医药中间体。L-木酮糖仅能通过人工合成来大量获得,常用的方法包括利用氧化还原酶催化木糖醇或L-阿拉伯糖醇等。近年来L-木酮糖的生物制备技术获得了较为广泛的研究,文章针对L-木酮糖制备关键酶挖掘、制备工艺探索等内容进行了综述,以期为该领域的研究提供理论借鉴。     

Cold Stress Response Mechanisms in Anther Development

Unlike animals that can escape threats, plants must endure and adapt to biotic and abiotic stresses in their surroundings. One such condition, cold stress, impairs the normal growth and development of plants, in which most phases of reproductive development are particularly susceptible to external low temperature. Exposed to uncomfortably low temperature at the reproductive stage, meiosis, tapetal programmed cell death (PCD), pollen viability, and fertilization are disrupted, resulting in plant sterility. Of them, cold-induced tapetal dysfunction is the main cause of pollen sterility by blocking nutrition supplements for microspore development and altering their timely PCD. Further evidence has indicated that the homeostatic imbalances of hormones, including abscisic acid (ABA) and gibberellic acid (GA), and sugars have occurred in the cold-treated anthers. Among them, cold stress gives rise to the accumulation of ABA and the decrease of active GA in anthers to affect tapetal development and represses the transport of sugar to microspores. Therefore, plants have evolved lots of mechanisms to alleviate the damage of external cold stress to reproductive development by mainly regulating phytohormone levels and sugar metabolism. Herein, we discuss the physiological and metabolic effects of low temperature on male reproductive development and the underlying mechanisms from the perspective of molecular biology. A deep understanding of cold stress response mechanisms in anther development will provide noteworthy references for cold-tolerant crop breeding and crop production under cold stress.     

离子液体中酶法催化合成糖酯的研究进展

离子液体作为一类极具有发展潜力的绿色溶剂,其用于酶催化反应介质有着传统有机溶剂和功能性离子液体无法超越的优势。综合对国内外近十几年公开发表的有关离子液体中酶法催化合成糖酯的文献,从常见离子液体分类,离子液体对酶活性、稳定性和选择性的影响,以及糖酯酶法催化合成的方法及研究现状进行了归纳与总结,同时指出了今后在离子液体中糖酯酶法催化合成领域值得研究的重要内容。      

大豆分离蛋白与甜菜果胶静电复合过程的研究

利用葡萄糖酸内酯(GDL)诱导大豆分离蛋白(SPI)与甜菜果胶(SBP)形成静电复合物。在不同SPI/SBP混合比例下,通过动态光散射和紫外可见分光光度计对pH酸化过程中的散射光强和浊度进行测定,跟踪复合物的生成及结构演变。实验结果表明,SPI与SBP可生成具有不同结构和不同稳定性的分子复合物,包括分子内可溶复合物、分子间可溶复合物以及分子间不可溶复合物。不同类型复合物的形成取决于溶液体系的pH和不同SPI/SBP混合比例。该研究系统地建立了SPI与SBP静电复合物的相图。      

高温预处理稻草秸秆条件的优化

对稻草秸秆高温预处理条件进行优化,以提高酶解还原糖得率为目的,探讨了高温预处理时固液比、pH、温度、时间对还原糖得率的影响。通过采用单因素多水平和正交实验方法得到最优预处理条件:固液比为1∶8,pH为12,温度为190℃,时间15min。在此最优条件下,酶解后的还原糖得率为88.97%。