纳豆激酶的质量与安全评价研究进展

纳豆激酶是纳豆芽孢杆菌在发酵纳豆过程中产生的一种丝氨酸蛋白酶,具有溶解血栓等生理功能。本文就纳豆激酶的溶栓功能及机制做了简要的总结,着重综述纳豆激酶活力测定方法等质量指标及其安全性评价研究进展,展望了纳豆激酶产品开发与质量安全研究方向,以期为纳豆及其制品（含纳豆激酶产品）标准化提供理论基础。     

基于感官分析技术的烤烟厚度参比样研制

  背景和目的  烟叶评级身份评价时,经常发生不同产区烤烟的身份被描述为同一档次,而其实际身份却不一致的现象。厚度作为身份指标的重要组成部分,其参比样的建立既有利于身份评价,也有助于评级人员统一认识。  方法  依据“感官特性参比样建立一般导则”国家标准,采集厚度范围很广的全国代表性烤烟样品,筛选并初步分为9个不同厚度档次,通过感官分析排序法结合Friedman检验、多重比较与分组、二项式分布等方法,科学调整为7个厚度档次。  结果  经外部评价小组验证,本套厚度参比样档次充足,相邻档次厚度差异合理。基于本参比样对照评价来自河南许昌、重庆黔江和贵州毕节的烤烟厚度,发现比《烤烟》国标更能准确区分不同产地间的厚度差异。结合物理厚度测量,发现本参比样档次间差异充分体现心理物理学定律,符合厚度的人类感知差异,具有可靠的参考依据与实用价值。  结论  所建立烤烟厚度参比样利于统一感官尺度,易于体现区域外观厚度特征差别,可以在烟叶评级工作中加强对厚度特性的感知和定位。      

基于品质衰变理论的食品货架期预测模型及其应用研究进展

食品货架期是厂商对产品质量的承诺,也是消费者关心的质量要求。针对目前研究中货架期预测模型使用的随意性与不规范性,本文剖析货架食品的品质影响因素,明确感官、化学、物理和微生物4个货架期食品品质评价途径,分析所对应的货架食品品质衰变机理和货架寿命终点检测方法,归纳与总结现有货架预测常用模型和算法,形成基于品质衰变原理的货架期预测模型建立体系,并对该技术未来发展方向进行展望。     

基于归类法和GC-MS的花椒精油香气特性及关键香气物质分析

该文采用归类法（Sorting）进行香气感官评价,气相色谱- 质谱联用（Gas Chromatography-Mass Spectrometry, GC-MS）鉴定香气挥发性物质,并通过香气活力值（Odor Activity Value, OAV）结合多维标度分析（Multidimensional Scaling, MDS）、对应分析（Correspondence Analysis, CA）、相关性分析等多元统计方法,探究花椒精油的香气差异及其挥发性物质基础。Sorting的结果显示,消费者认为青花椒精油相似性较高,其余红花椒精油香气相似,但红花椒精油内部之间的差异也较大。且产生了12个香气描述词来描述这些花椒精油,不同花椒精油的描述词间存在显著差异（P<0.05）。通过GC-MS在13种花椒精油中共鉴定出51种挥发性化合物,包括烯烃类（25种）、醇类（9种）、醛类（2种）、酮类（5种）、酯类（6种）和其他类（4种）。并计算出26个的香气活性物质（OAV>1）,各描述词与香气活性物质OAV值的相关性分析结果显示,不同花椒精油的香气差异与其关键香气物质有关（P<0.05）。关键香气物质的OAV值差异,是导致消费者对花椒精油香气感知差异的本质。     

美国食品企业检查员管理政策法规体系分析

以美国食品企业检查员为研究对象,从检查依据、检查员的构成及资质管理、检查员职责和任务、培训教育以及检查员的使用等方面,研究美国食品企业检查员的相关管理制度,分析其特点以及可供借鉴的经验,为探索建立我国食品企业检查员制度提供参考。     

干湿豆制浆模式下自制豆浆营养与感官品质分析

目的分析比较不同家用豆浆机干豆和湿豆2种模式下所制豆浆品质的差异方法以黄豆为原料选用国内外4个主流品牌的4款家用豆浆机分别采用干豆和湿豆2种模式制作豆浆,从营养品质(可溶性固形物、可溶性蛋白质、脂肪、还原糖含量)、物理性质(粘度、粒径)以及感官品质3个方面对豆浆品质进行比较和评价,分析干湿豆制浆模式和不同品牌豆浆机之间豆浆营养和感官品质的差异,探讨了不同制浆工艺对豆浆品质的影响。结果湿豆模式下所制得的豆浆在营养和感官品质上均优于干豆模式,不同品牌的豆浆机所制豆浆品质之间也存在较大差异。结论豆子经过浸泡后磨碎得更彻底,豆浆粒径更小,总营养物质溶出得更多。湿豆模式豆香味较浓郁,豆腥味淡,涩感弱,口感更绵滑。     

感官评价小组及成员排序能力评估的一般导则

针对感官评价小组及成员排序能力的评估,提出重复性、再现性与一致性的评估指标。分析了排序实验样品种类、样品间差异程度及样品个数对感官分析仪器性能评估的重要性。确定了以样品间的排列秩次作为能力评估统计的基础数据形式。排序能力评估中,对于无理论顺序样品,通过剔除重复性与再现性异常评价员结果后,采用Friedman检验结合最小显著性差（least significant difference,LSD）确定实验样品的最优估计顺序。文章重点分析用于双变量的Spearman秩相关及用于多变量的Kendall和谐系数,在评价小组及评价员的重复性、再现性与一致性等性能评估中的具体技术应用方法与理论分析。为感官评价小组及成员排序能力评估提出了良好操作示范,也为不同感官实验室评价小组间比对提供了理论基础。既有利于评价小组及成员的长期监测,也有利于感官分析实验室的良好管理能力。     

New dimensionality reduction model (manifold learning) coupled with electronic tongue for green tea grade identification

Multivariate data analysis methods play a key role in extracting effective features to denote original tea samples. The most commonly used multivariate data analysis methods are principle component analysis and linear discriminant analysis. These methods are based on statistical learning theory and complete in mathematics. However, there is correlation and redundancy among multiple sensors of electronic tongue, and it cannot guarantee that the tea samples are linearly separable in the original data space. The aim of this study is to conduct new dimensionality reduction methods: manifold learning algorithms, to extract effective features from the responses of electronic tongue sensors, and the algorithm which gives the highest recognition accuracy is considered to be the best for tea quality gradation. Experimental results show that supervised nonlinear manifold learning algorithms outperform other methods and achieve the highest recognition accuracy for green tea with four quality grades.     

Identifying the geographical origin of protected sea cucumbers (<Emphasis Type="Italic">Apostichopus japonicus</Emphasis>) in China using random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR)

Dalian sea cucumber, Yantai sea cucumber, and Weihai sea cucumber, which belong to Apostichopus japonicus, are protected as geographical indications in China based on their high nutritional values and medical propertys. The 26 samples, including Dalian sea cucumbers (9 samples) in Liaoning province, Yantai sea cucumbers (9 samples), and Weihai sea cucumbers (8 samples) in Shandong province, were individually collected from the designated geographical sea areas and the genetic relationships and DNA polymorphisms were evaluated by random amplified polymorphic DNA technology and gene segments sequencing. The RAPD dendrogram showed that the genetic diversity of the three types of sea cucumbers was rich. The neighbor-joining tree shows that the genetic relationship of the samples from the adjacent sea areas is closer. It demonstrates that the gene characteristics of sea cucumbers from different sea areas were obvious and the genetic diversity analysis by RAPD-PCR can be used as a rapid method for geographical discrimination.     

Combined recovery of valuable metals from LiFePO4–LiCoO2 system without adding oxidant and reductant

Based on the oxidation of ferrous ions in lithium iron phosphate and reduction of trivalent cobalt ions in lithium cobaltate, an innovative combined recovery process of lithium iron phosphate and lithium cobaltate powders is proposed. The effects of leaching conditions on leaching performance are studied and the optimal leaching conditions are obtained. Under these conditions, the leaching efficiencies of lithium and cobalt ions reach up to 99.92% and 81.11%, respectively. After removing ferric ions from leachate, the cobalt and lithium ions are separately recovered from the leaching solution. The final precipitation rate of cobalt ions is up to 97.71% with the purity of cobalt oxalate as 99.94%. In addition, the precipitation rate of lithium ions is 78.54% and the purity of lithium carbonate reaches up to 99.94%. Finally, the reaction path and mechanism for the combined recovery of lithium iron phosphate–lithium cobaltate system are preliminary investigated.