葡萄酒香气化学研究进展

葡萄酒的整体香气主要取决于气味物质之间以及气味物质与非芳香基质成分的复杂反应。对葡萄与葡萄酒香气的化学研究,主要集中于对风味起作用的挥发性芳香物质的复杂性,以及不同葡萄品种、种植区和年份引起的变化。本文对葡萄酒中香气成分的种类、影响因素、分析方法及其应用进行综述。     

基于可见分光光度法的食用油过氧化值检测

为了构建食用油过氧化值快速检测分析方法,以食用油为试验材料,利用可见分光光度计测定碘与淀粉的显色变化,建立食用油过氧化值的检测模型,探讨测定波长、饱和碘化钾添加量、反应时间、淀粉指示剂添加量、溶剂混合比例和油脂种类等因素对测定结果的影响。通过模型建立和验证、盲样验证及精密度分析,结果表明:检测条件对测定结果影响均不显著;当取样质量为(0.100±0.010)g,入射光波长为535nm时,食用油过氧化值模型为:y=28.856x+0.1331(y为过氧化值,mmol/kg,x为溶液吸光度),R2=0.9985。模型预测值与国标法测定值高度线性相关,盲样验证相对误差均10%,检出限为0.79mmol/kg,符合国家标准的相关要求,基于可见分光光度法的食用油过氧化值检测方法是可行的。     

云南普洱茶砷和汞的含量分析

采集云南省5个地区13个普洱茶主产地的150个茶叶样本,对普洱茶中砷和汞的含量进行分析。样品中砷的含量为0.026～0.37mg/kg(md);汞的含量为0.0014～0.020mg/kg(md),并有85.9%的样品未检出汞,砷和汞的检测结果符合农业部质量标准。结果表明,云南西双版纳、思茅、临沧、保山、大理普洱茶中砷、汞富集存在地区性差异,生茶和熟茶这两种不同加工工艺可以影响产品砷和汞的终含量,但均未影响普洱茶的质量安全,以云南五地区为代表的中国普洱茶目前砷、汞质量安全状况良好。     

UPLC-MS/MS定性测定紫薯花青苷方法研究

目的:以紫薯1号和农林47为实验材料,建立超高效液相色谱-三重四级杆串联质谱(UPLC-MS/MS)法,研究紫薯提取液中花青苷定性的分析方法.方法:UPLC-MS/MS法,ACQUITY UPLC BEH C18(2.1mm×50mm,1.7 μm);柱温:40℃;流速:0.3mL/min;以6％甲酸水溶液和乙腈为流动相,采用电喷雾(ESI)正离子模式,用MRM模式监测.结果:紫薯1号和农林47提取液中花青苷组分分别为矢车菊素-3-葡萄糖苷和芍药素-3-葡萄糖苷.结论:该方法具有准确度高,重复性好、简单、快速等显著优点,可用于紫薯及其它作物中花青苷组分的测定.     

南方根结线虫1号小种对烟草抗病品种致病性变异研究

分别循环接种南方根结线虫1号小种虫卵于抗病烟草品种中烟14和感病烟草品种红花大金元幼苗,以探索该线虫对抗性烟草品种的致病性变异情况.结果显示,随着南方根结线虫1号小种繁殖世代的增加,其对中烟14的致病能力逐渐增强,连续繁殖5代后致病力差异显著,而该线虫对红花大金元的致病力变化不明显,表明南方根结线虫1号小种与其抗病品种连续互作可以导致其致病性增强.     

Nitrosating agents from the reaction between methyl oleate and dinitrogen trioxide: Identification and mutagenicity

Dinitrogen trioxide (N₂O₃) was reacted with methyl oleate and the residual N₂O₃ removed. The resulting products were capable of nitrosating 2,6-dimethylmorpholine above 80°C with a maximum yield of nitrosamine at 130°C. N-nitroso-2,6-dimethylmorpholine formation was first order in nitrosating agent. When the reaction products were added to ground uncured pork and fried, N-nitrosodimethylamine and N-nitrosopyrrolidine were formed in amounts similar to those formed in fried bacon. 2,3-Dimethyl-2-nitro-3-nitrosobutane also nitrosated amines in the presence of pork lipids. Individual products were separated by HPLC and identified by IR and MS as nitronitroso-, dinitro-, nitronitrate-, and nitro oxime additions to methyl oleate. The nitronitroso derivative, as previously predicted, occurred in the fraction with the greatest capacity to nitrosate the amine. The products of the reaction between oleic acid and N₂O₃ were mutagenic in Salmonella typhimurium strain TA1535 without S-9 activation showing a 5·5- to 66-fold increase in revertants at doses of 90 to 200 μg/plate. These findings support, but do not prove, the theory that nitrite reacts with unsaturated lipids in bacon to form compounds which are responsible for nitrosamine formation during frying.     

不同粒度花椒籽黑种皮粉理化特性

为探讨不同粒度花椒籽黑种皮粉加工利用的差异性,本研究利用粒径测定、显微特征分析、红外光谱 分析等方法,比较了不同粒度花椒籽黑种皮粉的粒径、色度、微观结构、中红外光谱、吸附特性、活性物质 及其抗氧化活性之间的差异。结果表明：花椒籽黑种皮粗粉经超微粉碎后,粒度显著减小、色泽明显增亮, 可引起细胞壁破碎,持水力和持油力显著提高,分别提高了33.33%和44.60%,对重金属离子的吸附性显著增 强,但花椒籽黑种皮超微粉的官能团结构并未发生改变。随着粉体粒度的减小,花椒籽黑种皮超微粉中多酚和 黄酮的溶出量分别提高了15.93%和11.24%,对1,1-二苯基-2-三硝基苯肼自由基和2,2’-联氨-双-3-乙基苯并噻唑 啉-6-磺酸自由基清除能力显著增强（P＜0.05）。因此,超微粉碎可有效增加花椒籽黑种皮活性物质的溶出并提高 其抗氧化能力,从而提高了花椒籽黑种皮的有效利用率。     

安徽芡实营养特性分析

以安徽产芡实为原料,分别对其中主要营养组分、氨基酸组成和矿物元素进行了分析.分析结果显示,芡实是一种淀粉基原料,其中淀粉含量为72.27%,粗蛋白质含量与大米接近,为9.72%,脂肪含量较低.芡实蛋白中必需氨基酸总量达39.9,远高于标准必需氨基酸模式27.0.矿物元素的分析结果显示,芡实中含有丰富的镁、钠、钙、钾、铁、锌、锰等矿物元素,其中镁含量高达367.10mg/kg,硒含量为0.032mg/kg,四种重金属含量均未超出食品卫生标准的限量规定.此外,芡实中还含有丰富的酚类物质(0.79mg/g).     

High-level expression of recombinant human nerve growth factor beta in milk of nontransgenic rabbits

The technology for the large-scale production of therapeutic recombinant proteins remains a challenge in the biopharmaceutical industry. In this study, we reported a nontransgenic approach to producing a large quantity of human nerve growth factor beta (hNGF-beta) in rabbit milk by employing a recombinant adenoviral expression system. After directly instilling hNGF-beta recombinant adenoviruses into rabbit mammary glands, a polypeptide with a molecular weight of 13.2 kDa was detected in rabbit milk. The maximal expression level of hNGF-beta reached 346 mug/ml. The biological activity of recombinant hNGF-beta was confirmed using PC12 cells and cultures of dorsal root ganglion neurons from chicken embryos. Our data suggest that instilling recombinant adenovirus directly into the mammary gland of mammals is an efficient approach to producing a large quantity of hNGF-beta.     

水产品中创伤弧菌检测方法建立与应用

目的建立一种水产品中创伤弧菌检测方法 ,并对北京市市售水产品中创伤弧菌污染情况进行监测。方法分别使用18株创伤弧菌菌株和水产品中常污染的背景杂菌,定量接种于检测创伤弧菌的选择性增菌液和4种选择性平板,优化出适合创伤弧菌检测的选择性培养基。采用聚合酶链式反应(PCR)法和增菌培养法分别检测样品中的创伤弧菌后进行方法对比,建立PCR和增菌培养法相结合的检测方法 ,并应用此方法研究北京市市售水产品中创伤弧菌污染状况。结果改良后的选择性增菌液适用于创伤弧菌的检测。北京市市售水产品中创伤弧菌检出率为15.7%(18/115),其中贝类、蟹类、鱼类和虾类样品的检出率分别为23.4%(15/64)、8.3%(1/12)、5.3%(1/19)和5.0%(1/20)。结论 PCR法与传统增菌培养法相结合,可有效提高创伤弧菌检测效率。北京市市售贝类等水产品中创伤弧菌污染率较高,需引起食品安全风险监测重点关注。