Study of the dynamic changes in the non-volatile chemical constituents of black tea during fermentation processing by a non-targeted metabolomics approach

Fermentation is a critical manufacturing process to produce black tea, in which the chemical compositions are greatly changed. However, the dynamic changes of this sophisticated process are far from clear, and were often characterized by determining a small number of compounds. In this study, we applied a non-targeted metabolomics approach based on ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry to comprehensively profile the variations of metabolites in tea samples with various fermentation durations of 0, 1, 2, 4, 6, 8, 10, 12 and 14 h. Principal component analysis indicated obvious stepwise alterations of tea metabolome during the fermentation. Relative quantitation of 61 identified metabolites including catechins, dimeric catechins, flavonol glycosides, amino acids, phenolic acids, alkaloids, and nucleosides revealed distinct changes of phenol pathway. Dynamic changes of a part of these compounds were mapped for the first time. To the best of our knowledge, this study offered the most comprehensive profiles of metabolite changes during the tea fermentation process.     

2018年中国4省脱粒小麦中9种真菌毒素污染情况调查

目的 调查2018年湖北、安徽、江苏和河北4省脱粒小麦中5种镰刀菌毒素和4种黄曲霉毒素（aflatoxins,AFs）的污染情况。方法 从4省采集2018年5~6月收获的脱粒小麦371份,经乙腈-水（84:16,V:V）提取、Mycosep 226多功能净化柱净化后,采用高效液相色谱串联质谱同时测定样品中脱氧雪腐镰刀菌烯醇（deoxynivalenol,DON）、3-乙酰基-DON（3-acetyl-DON,3-Ac-DON）、15-乙酰基-DON（15-acetyl-DON,15-Ac-DON）、雪腐镰刀菌烯醇（nivalenol,NIV）、玉米赤霉烯酮（zearalenone,ZEN）和4种AF, 共9种毒素的含量。 结果 4省脱粒小麦受多种镰刀菌毒素, 尤其是DON的污染较为严重,而AF污染相对较轻。DON的检出率最高,为90.3%,阳性样品中DON平均污染水平为2706.3 μg/kg,45.3%样品DON的含量超过国家限量标准1000 μg/kg;4种AF的检出率和平均污染水平均较低,其中AFB1和AFB2的检出率最高,均为3.2%,2份样品AFB1含量超过国家限量标准5 μg/kg,仅1份样品检出AFG2,所有样品均未检出AFG1。从地区来看,湖北省脱粒小麦中各毒素污染最严重,尤其是DON、其检出率和平均污染水平分别为100%和6314.9 μg/kg;江苏省样品中ZEN的平均污染水平为1971.2 μg/kg,远高于其它省份。Spearman相关性分析表明,5种镰刀菌毒素的污染具有显著相关性,DON与已检出的3种AF及3种AF间的污染相关性均较弱或无显著相关性。 结论 4省脱粒小麦受5种镰刀菌毒素的污染较为严重且具有显著相关性。污染程度为湖北>安徽>江苏>河北。因此,有必要对4省脱粒小麦中多种毒素的协同污染情况进行持续监测。     

超高效液相色谱-串联质谱法同时测定小麦制品中4种交链孢霉毒素

目的建立测定4种小麦制品(挂面、馒头、面包和饼干)中4种交链孢霉毒素的超高效液相色谱-串联质谱法。方法 4种小麦制品加入NaCl后,经酸化乙腈提取,固相萃取柱(SPE)净化后,以HSS T3色谱柱(2.1 mm×100 mm,1.7μm)为分析柱,以0.15 mmol/L碳酸氢铵水溶液-甲醇为流动相进行梯度洗脱,以负离子电喷雾模式电离(ESI~-),多反应离子监测(MRM)方式进行定性及定量检测,外标法定量。结果在0.040～50μg/L的线性范围内,4种交链孢霉毒素的回归方程均呈良好的线性关系,相关系数(r)0.99。交链孢菌酮酸、交链孢酚、腾毒素和交链孢酚单甲醚的方法检出限分别为0.10、0.01、0.03和0.01μg/kg,3个加标水平的回收率为85.7%～102%,相对标准偏差(RSD)为0.8%～11.0%。应用该方法对流通环节的挂面、馒头、面包和饼干进行检测,4种交链孢霉毒素均有检出,其浓度为0.02～185.00μg/kg。结论该方法灵敏度高、简便,适用于小麦制品中多种交链孢霉毒素的同时测定。     

北京市朝阳区部分社区老年人的肺炎疫苗接种率及影响因素分析

目的分析北京市朝阳区部分社区老年人肺炎疫苗接种率及其影响因素,以提高老年人肺炎疫苗的接种率,降低社区老年人肺炎球菌感染的危害。方法通过整群抽样的方法,选取北京市朝阳区年龄≥60岁的部分社区老年人进行问卷调查,收集调查对象的基本信息、健康状况、就医行为及疫苗接种情况,分析社区老年人肺炎疫苗接种率的影响因素。结果调查数据显示社区老年人的肺炎疫苗接种率为2.1%,经多因素Logistic回归分析,年龄、受教育程度及健康状况是肺炎疫苗接种率的主要影响因素(P<0.05)。结论应通过多种措施提高老年人等优先人群肺炎疫苗的接种率;干预过程中应重视受教育程度较低、身体素质较好以及年龄相对较轻的老年人。     

The industrial robot in a flexible manufacturing system: State of the art and prospects

The actual situation of the industrial robots is described here. A comparison of the density in different countries gives an idea of the importance of these machines. The situation in Germany and especially in assembly automation is described more in detail. The results of a study of assembly automation are described as well as the necessity for assembly-oriented product design.     

206例鸡蛋过敏儿童接种麻疹风疹联合减毒活疫苗后的安全性观察

目的观察鸡蛋过敏儿童接种麻疹风疹联合减毒活疫苗的安全性。方法选取北京市朝阳区2013年2~3月期间8~17月龄接种麻疹风疹联合减毒活疫苗的206名鸡蛋过敏体质儿童及242名非鸡蛋过敏体质儿童,接种麻疹风疹联合减毒活疫苗。采用电话调查的方法对接种疫苗后的不良反应发生情况进行回顾性队列分析。结果本次电话调查的总应答率为87.3%。在拨通电话的391例研究对象中,鸡蛋过敏组184例,非鸡蛋过敏组207例。鸡蛋过敏组和非鸡蛋过敏组的不良反应发生率分别为10.3%和8.2%;局部反应发生率分别为1.6%和1.0%;生命体征异常率分别为6.0%和4.8%;全身反应发生率分别为3.8%和5.8%,差异均无统计学意义(P>0.05)。不良反应中,明确为偶合反应的3例(鸡蛋过敏组2例,非鸡蛋过敏组1例,临床诊断均为幼儿急疹)。结论鸡蛋过敏儿童接种麻疹风疹联合减毒活疫苗与非鸡蛋过敏儿童相比,不良反应发生率未增加。     

Occurrence of four mycotoxins in cereal and oil products in Yangtze Delta region of China and their food safety risks

A total of 76 cereal and oil products collected from Yangtze Delta region of China were analyzed for occurrences of aflatoxins (AFs), aflatoxin B₁ (AFB₁), ochratoxin A (OTA), deoxynivalenol (DON) and zearalenone (ZEN). The mycotoxins were determined by the standard detection procedures using immunoaffinity column clean-up coupled with fluorometer (or HPLC-UV). ZEN was the most prevalent toxin, with the incidence of 27.6% (range = 10.0–440.0 μg kg⁻¹), and 9.2% of the evaluated samples were contaminated with a concentration higher than that of the legislation limit of China (60 μg kg⁻¹). AFs and AFB₁ were detected in 14.5% of the samples analyzed, the concentrations ranging 1.1–35.0 μg kg⁻¹ for AFs, and 1.0–32.2 μg kg⁻¹ for AFB₁; 4.0% of the samples had the concentrations of AFs and AFB₁ higher than that of the corresponding legislation limits of China (5.0, 10.0 and 20.0 μg kg⁻¹ for different products). OTA was detected in 14.5% of the cereal and oil products collected; the concentrations ranged 0.51–16.2 μg kg⁻¹. Only 2 samples showed OTA levels higher than that of the legislation limit of China (5.0 μg kg⁻¹). DON was detected in 7.9% of the samples; the concentrations ranged 100–700 μg kg⁻¹, and none of the samples showed DON concentration higher than that of the legislation limit of China (1.0 mg kg⁻¹). A total of 15.8% cereal and oil products were contaminated with at least two mycotoxins (multiple contaminations with different combinations including AFs-ZEN, AFs-OTA-ZEN, OTA-ZEN, ZEN-DON, OTA-ZEN-DON). The dietary exposure assessment results indicated that AFs (AFB₁), OTA, DON and ZEN from cereal-based products represented a series health risk to both adults and children in Yangtze Delta region of China. This is the first report of safety evaluation associated with major mycotoxins for the area.     

北京市朝阳区单核细胞增生李斯特菌关键毒力基因缺失与致病性关联性研究

目的 了解北京市朝阳区2016-2018年81株单核细胞增生李斯特菌(单增李斯特菌)关键毒力基因缺失与菌株致病性和血清型的关联性.方法 聚合酶链反应(PCR)结合血清凝集法进行血清学分型;PCR法检测11种毒力基因;微量肉汤稀释法进行药敏实验;结合流行病学调查数据,研究单增李斯特菌关键毒力基因缺失与致病性、血清型的关联...     

2008年北京奥运会食品卫生安全分析与对策探讨

目的分析2008年北京奥运会食品卫生安全形势及其对策。方法运用文献法、专家咨询法等深入剖析奥运会食品卫生安全形势并研究其对策。结果奥运会的食品卫生安全面临着流动人口多,食品需求量大,历时时间长,并处于食源性疾病高发时期以及恐怖主义等多方面的问题。结论建议北京市建立起食品卫生污染物检测网络,完善食品安全检测技术,加强餐饮企业的管理,开展对奥运会建设项目的卫生学评价和检查,并做好食品卫生突发事件的反应和处置。     

柠檬酸杆菌属基质辅助激光解析电离飞行时间质谱图谱库的扩展及效果评价

目的 扩展基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)中柠檬酸杆菌属数据库。方法 PCR方法扩增并测序管家基因leuS进行系统发育分析鉴定菌种；平行对照试验优化菌株培养和样品制备条件；按照自建库方法手动采集优化培养后菌株谱图,构建实验室内部数据库,并进行灵敏度与特异度评价。结果 经系统发育分析,有7个种共66株柠檬酸杆菌。优化条件为哥伦比亚血平板做培养基、转种1次、培养24 h,甲酸溶液体积25 μl。新增沃克曼氏柠檬酸杆菌与C.pasteurii2个菌种谱图,补充中国株弗氏、布氏、吉氏、杨氏、无丙二酸柠檬酸杆菌等5个菌种本地区谱图；结论 leuS基因可以有效区分柠檬酸杆菌属菌种,MALDI-TOF 图谱库的扩展提升了质谱对本地区柠檬酸杆菌属菌种鉴定准确性。