泥鳅脱腥技术比较研究

[目的]研究比较泥鳅加工中的不同脱腥方法的脱腥效果.[方法]确定用于即食泥鳅加工的香辛料腌制脱腥的最佳配方以及用于膨化泥鳅加工的柠檬酸盐混合液浸泡脱腥的最佳配方,并采用GC-MS法对脱腥前后泥鳅的挥发性成分及变化情况进行检测.[结果]用于即食泥鳅加工的香辛料腌制脱腥最佳配方为食盐3％,料酒8％,姜汁4％,五香粉1％;用于膨化泥鳅加工的柠檬酸盐混合液浸泡脱腥最佳配方为食盐2％,柠檬酸0.15％,鱼液质量比为1:4.未脱腥泥鳅肉中共检测出38种化合物,醛类、酮类是其主要腥味物质,经脱腥处理后,腥味物质含量明显减少.[结论]研究可为开发生产不同的泥鳅产品所需相应的脱腥工艺提供参考依据.     

水稻抗原特征次生物质与抗虫性的关系及其大田检验

应用苗期群体抗性测定方法,鉴定了华航1号、华航8号、胜巴丝苗等10个水稻品种对稻褐飞虱的抗性;应用高效液相色谱(HPLC)技术对其中6个品种的特征次生物质色谱峰进行了测定,并分析了主要抗性峰值与抗性级别之间的关系。结果表明：Mudgo为高抗,粳籼89、华航8号、胜巴丝苗为抗虫品种;小农占、籼小占、华航1号和粤香占呈中抗反应;双桂呈感虫反应,TN1为高感品种,这一鉴定级别与田间稻褐飞虱种群增长趋势指数变化相一致;稻褐飞虱在TN1上的种群趋势指数达28.079,中抗品种粤香占上为6.427 9,均表现增长趋势;在抗虫品种胜巴丝苗上种群趋势指数达1.513 8,高抗品种Mudgo上仅为0.862 8。其抗虫作用体现在抗虫品种天敌因子的作用远高于感虫品种。测定的水稻主要抗原特征次生物质色谱峰值表明,抗原色谱峰面积大小与抗性水平呈显著负相关性,可用线性回归方程(y=21.076 7–0.597 2x)拟合。     

苦瓜叶提取物及其活性物质防治农业害虫研究进展

对近几年国内外学者对苦瓜叶片提取物及其活性物质的研究进展进行了综述,介绍了苦瓜叶提取物中分离得到的化学物质,重点介绍了苦瓜叶提取物及活性物质对斑潜蝇和菜青虫的防治研究进展,以为运用苦瓜叶片提取物及活性物质来防治农业害虫提供参考,为进一步研究抗虫机理奠定基础。     

Activated carbon addition affects substrate pH and germination of six plant species

Activated carbon (AC) is widely used in ecological studies for neutralizing allelopathic compounds. However, it has been suggested that AC has direct effects on plants because it alters substrate parameters such as nutrient availability and pH. These side-effects of AC addition may interfere with allelopathic effects. In this study we analyzed three widely used commercial AC brands and analyzed their effect on pH, their ability to retain glucosinolates, and their effect on the germination of six plant species. AC brands differed significantly in their effect on pH values when added to different substrates. Glucosinolates were completely adsorbed by all brands, indicating that AC is suitable as adsorbent for this compound class. Finally, AC addition to substrates had differential effects on seed germination of Arabidopsis thaliana, Plantago lanceolata, Solidago canadensis, and Lotus corniculatus, whereas no effect was found on the germination of Lactuca sativa and Brassica oleracea. We suggest that scientists using AC should always include an experimental control to test for direct effects of AC addition on both substrate parameters and plant performance.     

Bioactive Compounds Offered in Microcapsules to Determine the Nutritional Value of Copepods’ Natural Diet

Experiments were performed, feeding Calanus pacificus seston and a food consisting of seston and microcapsules (μ-caps), i.e., protein and lipid μ-caps to test for potential biochemical limitation. Seston was collected off Scripps Pier (La Jolla, CA, USA). Whereas protein μ-caps were too small to be efficiently ingested, lipid μ-caps rich in ω3-highly-unsaturated fatty acids (ω3-HUFA) were ingested similarly to natural seston and lipids were assimilated. However, egg production experiments exhibited that animals fed with lipid μ-caps didn’t produce significantly more eggs than with seston of equal carbon concentration and egg production even declined when the diet consisted of 50% lipid μ-caps. Thus, the content of certain ω3-HUFA seemed to have been sufficiently high in seston to prevent limitation. Algal counts revealed that seston consisted mainly of plankton rich in those fatty acids, such as cryptophytes, dinoflagellates, diatoms, and ciliates in the edible size range. This might be characteristic for upwelling systems like the area off Southern California which are known for high trophic transfer efficiency.     

密闭小室测定建材有机挥发物散发特性的研究

为研究室内装修材料有机挥发物(VOCs)的散发情况,提出一种改进的测定建材VOCs散发特性(初始VOCs平均浓度、分离系数)和对流传质系数的模型及计算方法,并应用该方法得到几种常见建材(复合地板、大芯板、地板砖和地毯)的VOCs散发特性和对流传质系数.结果表明:当实验时间有限、密闭小室与测试建材体积比较大时,模型计算能...     

Effect of hydrostatic high pressure pretreatment on flavor volatile profile of cooked rice

The impact of high hydrostatic-pressure (HHP) processing on the volatile profile of cooked Japonica rice (Wuchang) and Jasmine rice (Complete Wheel) was investigated by SPME–GC/MS. Presoaked samples were treated at 200, 400 and 600 MPa for 10 min and then cooked for volatile compound analysis. Seventy-seven compounds were identified in two cooked rice varieties: 20 aldehydes, 16 alcohols, 14 ketones, 9 arenes, 7 esters, 5 alkanes, 3 olefins and 3 hetero-cycle compounds. Results showed that both pressure level (P < 0.01) and rice variety (0.01 < P < 0.05) significantly impact the volatile compounds in rice and there is also an interaction between pressure and rice variety (P < 0.01). Overall, HPP decreased the amount of aldehydes more obviously in Complete Wheel rice than that in Wuchang variety. Both 200 and 400 MPa increased the levels of alcohols, ketones, esters and olefins, but reduced those of heterocycles, alkanes and arenes. Similar volatile change trends were found at 600 MPa except the concentration of each component was closer to that of control group. Based on the changes in the three key flavor compounds in rice (aldehydes, alcohols and ketones), the HPP process could be a suitable alternative to traditional pretreatment for improving flavor in cooked rice.     

基于烟草中致香成分的人工神经网络分类模型

从烟叶化学成分和结合评吸结果确定的烟叶品质的关系入手,用遗传BP神经网络建立了基于烟草中致香物质含量的烟草模式识别模型.分析结果表明,使用该方法能全局优化基于烟草致香成分的神经网络结构,较之梯度下降法的神经网络的训练效率更高,得到的识别结果也更加准确.它可以作为一种新的判别烟草香味特征的识别手段.     

蒙山茶的香气成分研究进展

蒙山茶包括蒙顶甘露、蒙顶黄芽、蒙顶石花、蒙山毛峰等较多种类。香气是衡量茶叶品质的重要指标之一，蒙山茶中香气成分的种类繁多但含量少，在收集过程中不稳定，因此对其分析与鉴定比较困难。综述了同时蒸馏萃取法（SDE）、减压蒸馏法（VDE）、超临界CO2萃取法（SFE-CO2）、顶空分析法（HAS）、搅拌子萃取（SBSE）、Tenax TA 吸附管、溶剂辅助风味蒸发法（SAFE）等茶叶中香气成分的常用提取方法，对蒙山特色名茶香气成分的研究进展进行了总结，并对其发展作了展望。     

尾叶桉干燥过程中有机挥发物释放的研究

采用小型干燥机干燥木材,采用高效液相色谱仪和气相色谱仪对干燥过程中释放的有机挥发物进行分析。结果表明,尾叶桉干燥释放的主要物质是甲醇、乙酸,其次是甲酸、乙醛、甲醛、丙烯醛/丙酮,而萜烯类挥发物很少。尾叶桉高温干燥释放的挥发物比常规干燥明显增多,尾气中甲醇浓度超过标准限值。甲醛高温干燥时随含水率降低释放速率增大,其它物质在高温和常规干燥时的释放速率随含水率减少呈下降趋势。