尼勒克县新疆黑蜂蜂蜜游离氨基酸的测定及分析

为探究尼勒克县新疆黑蜂蜂蜜游离氨基酸含量组成特点,同时对蜂蜜产地进行区分分析。本研究采用行业标准方法测定尼勒克地区7个产区新疆黑蜂蜂蜜中游离氨基酸含量,对其必需氨基酸、药效氨基酸以及滋味氨基酸含量进行分析,并利用主成分分析和聚类分析探讨了尼勒克新疆黑蜂蜂蜜游离氨基酸特点。结果显示,7个产区新疆黑蜂蜂蜜总游离氨基酸含量在458.98~805.94 mg/kg之间,必需氨基酸占比为33.73%~51.84%,药效氨基酸占比为37.92%~57.94%,滋味氨基酸以芳香族氨基酸和甜味氨基酸为主。A3产区蜂蜜样品的游离氨基酸含量（805.94 mg/kg）远超其他6个产区（458.98~619.82 mg/kg）,且其苯丙氨酸、脯氨酸、丝氨酸、组氨酸、甘氨酸、丙氨酸、酪氨酸、缬氨酸和异亮氨酸均为7个产区最高,聚类分析显示A3产区蜂蜜可与其他产区蜂蜜较好分离。综上所述,尼勒克新疆黑蜂蜂蜜中游离氨基酸种类丰富,苯丙氨酸含量占比较高,药效氨基酸、滋味氨基酸含量高,且各产区蜂蜜可由游离氨基酸含量进行区分,具有开发成为口感独特的药用蜂蜜的潜力。     

Post-Northridge connections with slit dampers to enhance strength and ductility

In 1994 and 1995, Northridge and Kobe earthquakes caused unexpected damages to beam-to-column connections which were followed by extensive investigations on the connections' behavior to resolve problems in their performance and to improve their strength and ductility. During these years methods were proposed by researchers which were mainly based on reducing the beam section or strengthening the connection. Adding slit dampers at the top and bottom of the beam flanges plates is another way to improve the connection behavior. These dampers are able to absorb and dissipate a significant amount of energy. Slit dampers caused a remarkable reduction in the plastic strain at the column face area and consequently kept plastic hinge formation away from the column face. In this study a total of 8 small slit dampers were used at the column face area. To find out best configuration for slit dampers which can only be used for newly designed connections, a parametric study was carried on their geometry. Generally the slit damper yields in shear or in flexure. Hence, for two different yield mechanisms (shear yielding and flexural yielding) details for designing of slit dampers were proposed and connection's strength and ductility were compared.     

Effect of preincubation of sorghum flour with enzymes on the digestibility of sorghum gruel

A low-tannin sorghum cultivar M-35-1 was used in this study. Sorghum was germinated for 6 days and protease and amylase activities were measured every 24 h. Results showed that the 5th day germinated sorghum had a higher protease activity and a lower amylase activity. Sorghum flour was incubated for 30 min with the extract from germinated sorghum or with 0.01, 0.05 or 0.1 mg ml⁻¹ papain or trypsin prior to cooking in water. Results showed increase in in vitro protein digestibility (IVPD) with the 5th day germination extract. Pretreatment of sorghum flour with small amounts of papain or trypsin (0.01 mg ml⁻¹) improved the IVPD without affecting the paste viscosity, whereas the germinated sorghum extract led to very low paste viscosity. ©     

尼勒克县不同产区的新疆黑蜂蜂蜜理化性质与营养成分分析

为探明尼勒克县不同产区新疆黑蜂蜂蜜的理化性质及营养成分,本研究以尼勒克县7个不同产区的新疆黑蜂蜂蜜为研究对象,分析其理化性质以及14种维生素和10种矿物质的含量。结果表明:所有产区的蜂蜜样品中葡萄糖和果糖（≥1.14倍行业标准最低值）、淀粉酶活性（≥5.91倍行业标准最低值）、蔗糖（≤1.24%）和水分含量（≤18.5%）均优于中华全国供销合作总社行业推荐标准（GH/T 18796-2012）的相关规定。此外,脂溶性维生素中仅检出以δ-生育酚形式存在的维生素E（0.146~0.290 mg/100 g）;水溶性维生素中检出维生素B₂（0.061~0.159 mg/100 g）、维生素B₆（0.023~0.064 mg/100 g）、烟酸（0.263~1.909 mg/100 g）、泛酸（0.142~0.293 mg/100 g）和叶酸（2.185~14.564 μg/100 g）;矿物质检测呈现高钾低钠（钾钠比均值21.37）、高钙（均值40.634 mg/kg）以及富硒（0.047~0.243 mg/kg）。主成分分析和聚类分析显示,通过检测到的维生素和矿物质可以将7个不同产区的蜂蜜分为4大类,各大类蜂蜜间特色鲜明。尼勒克新疆黑蜂蜂蜜含有丰富的维生素和矿物质,具有发展成为地方特色蜂蜜的巨大潜力。     

超微粉碎技术对油菜花粉中槲皮素和山奈素溶出率的影响

为了探讨超微粉碎技术对油菜花粉中有效成分(槲皮素和山奈素)溶出的影响,采用高效液相色谱法分析比较油菜花粉超微粉与普通粉(65～100 目)中槲皮素和山奈素的溶出差异。结果表明,油菜花粉超微粉中槲皮素和山奈素的溶出率比普通粉分别提高了45.16% 和27.86%,超微粉碎可显著提高油菜花粉有效成分的溶出率。     

Flavour formation in meat and meat products: a review

The characteristic flavour of cooked meat derives from thermally induced reactions occurring during heating, principally the Maillard reaction and the degradation of lipid. Both types of reaction involve complex reaction pathways leading to a wide range of products, which account for the large number of volatile compounds found in cooked meat. Heterocyclic compounds, especially those containing sulfur, are important flavour compounds produced in the Maillard reaction providing savoury, meaty, roast and boiled flavours. Lipid degradation provides compounds which give fatty aromas to cooked meat and compounds which determine some of the aroma differences between meats from different species. Compounds formed during the Maillard reaction may also react with other components of meat, adding to the complexity of the profile of aroma compounds. For example, aldehydes and other carbonyls formed during lipid oxidation have been shown to react readily with Maillard intermediates. Such interactions give rise to additional aroma compounds, but they also modify the overall profile of compounds contributing to meat flavour. In particular, such interactions may control the formation of sulfur compounds, and other Maillard-derived volatiles, at levels which give the optimum cooked meat flavour characteristics.     

蜂胶乙醇提取物对小鼠主动脉内皮细胞损伤的保护作用

目的:探究蜂胶乙醇提取物（ethanol extracts of propolis,EEP）对脂多糖（lipopolysaccharide,LPS）诱导的小鼠主动脉内皮细胞（mouse aortic endothelial cell,MAEC）炎症因子损伤的保护作用。方法:将细胞分为对照组,LPS模型组,蜂胶低（2.5 μg/mL）、中（5 μg/mL）、高（10 μg/mL）剂量组。采用CCK-8检测MAEC的细胞增殖率,ELISA酶联免疫吸附实验测定MAEC炎症细胞中TNF-α、IL-6的含量,Western Blot法测定MAEC炎症细胞中ICAM-1、VCAM-1、MCP-1的表达水平。结果:与对照组相比,LPS组MAEC的细胞增殖率极其显著降低（P<0.001）,ICAM-1、VCAM-1、MCP-1、TNF-α以及IL-6的水平极其显著升高（P<0.001）。经不同浓度EEP处理后,MAEC的细胞增殖率显著上升（P<0.05或P<0.01）,TNF-α、IL-6的含量以及ICAM-1、VCAM-1、MCP-1表达水平降低,各蜂胶组与LPS组相比均有显著性差异（P<0.01或P<0.001）。结论:EEP能够抑制LPS诱导的MAEC中炎症因子的表达,对血管内皮细胞具有保护作用。     

金黄色葡萄球菌标准物质的定值方法

对含鸡肉基质的金黄色葡萄球菌标准物质进行定值,包括金黄色葡萄球菌计数方式的选择,标准值的测定,以及不确定度的分析。总不确定度以扩展不确定度表示。结果显示,金黄色葡萄球菌3种计数方式,BP平板倾注法计数结果与PCA计数法测定一致,BP平板倾注法SD值BP平板涂布法SD值,表明采用BP平板倾注法计数金黄色葡萄球菌的结果精密度、再现性较好,有利于试验结果的复现。标准值测定结果为275 CFU/瓶;总不确定度为6。因此,标准物质定值结果为(275±6)CFU/瓶。     

多重 PCR 技术同时检测四种肠道致病菌方法的建立与初步应用

目的 建立同时检测4种食源性肠道致病菌的多重PCR方法。方法 分别依据沙门氏菌(Salmonella spp) 的fimA基因、弗氏枸橼酸杆菌(Citrobacter freundii) 的ldh基因、奇异变形杆菌(Proteus mirabilis) 的idsC基因、迟缓爱德华菌(Edwardsiella tarda) 的fimA基因设计4对特异性引物, 并对多重PCR反应条件进行优化。结果 建立的多重PCR方法具有结果可靠、灵敏度高、方便快捷的优点。结论 本研究为研发快速检测以上4种食源性肠道致病菌的试剂盒提供了重要技术保障。