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。     

云南普洱茶铜含量现况研究

目的了解云南普洱茶中铜含量的质量安全状况。方法采集云南普洱茶主产地的150份普洱茶样品,采用原子吸收光谱法进行检测。结果样品中铜含量为12.1～22.9mg/kgDW,普洱茶铜含量在各主产地区之间、在生熟茶工艺之间,差异有统计学意义(P0.05)。结论普洱生茶和熟茶不同的工艺特点确会引起终产品中铜含量的差异,但所有样品中铜含量均未超出国家最大限量标准60mg/kgDW,不会造成铜污染。     

云南不同地区生咖啡豆的风味前体物质研究

本文通过测定云南德宏、保山、临沧和普洱四个地区生咖啡豆中风味前体物质组成和含量,结合一元方差分析(ANOVA)和主成分分析(PCA)进行统计学分析,探索了不同地区生咖啡豆中风味前体物质的差异性。实验结果表明:氨基酸总量最高为德宏咖啡(10.31%),最低为保山咖啡(9.07%);蛋白质测定结果与氨基酸相类似;而德宏和临沧咖啡中脂肪和脂肪酸含量均小于普洱和保山咖啡;单糖总量最高为普洱咖啡(17.21%),最低为保山咖啡(15.95%)。PCA分析和方差分析表明,普洱咖啡中脂肪酸和其他地区均呈显著性差异(P0.05);保山咖啡中氨基酸同其他地区均呈显著性差异;而临沧咖啡中单糖、蛋白质、脂肪和保山咖啡均呈显著性差异;除少数样品外,大部分样品在PCA的二维得分投影图上按特性各自聚为一类。本研究可为云南咖啡的烘焙加工提供理论参考。     

晒青茶、普洱茶(生茶)紧压茶实物样研制及其品质特征分析

根据普洱茶(生茶)拼配规则及各普洱茶生产企业的产品质量生产情况,为进一步推动普洱茶(生茶)实物标准样的科学制备,规范普洱茶原料及普洱茶(生茶)产品,揭示影响云南大叶种晒青茶滋味品质的物质基础,并探讨影响因素间的相互作用。以临沧、普洱、大理、西双版纳的春、夏、秋三个季节的云南大叶种晒青茶为原料：(1)通过筛选可拼配单样、小样试拼及排序、大样拼堆及评定等程序,严格通过品质水平均匀性、稳定性检验,制备出二套实物标准样：晒青茶实物标准样、普洱茶(生茶)实物标准样。(2)通过理化分析及感官审评,通径分析表明,茶多酚与氨基酸、黄酮是影响晒青茶滋味品质的主要因素,其中,黄酮对晒青茶的滋味品质直接作用最明显,茶多酚通过其余变量对晒青茶滋味品质的间接作用综合影响最大。本研究不仅为普洱茶的质量标准信息化研究、茶饮料开发等方面提供分析方法参考,更为促进普洱茶的高质量、绿色化、品牌化发展提供科学依据。     

云南普洱茶产地及其历史变迁

云南省思茅、西双版纳两地州是普洱茶的主产区。历史上,唐代南诏时期的“银生茶”是明清以来“普洱茶”的前身,两者可统称为“云南普洱茶”。云南普洱茶的具体产地在两地州境内随历史发展而有所变迁。普洱茶也从最初的单一散茶发展成以散茶(晒青毛茶)为原料加工而成的各种规格的紧压茶为主体。几经兴衰,普洱茶至今依然是云南重要茶叶产品。     

不同仓储条件下普洱茶关键成分分析及品质评价

为进一步探究普洱茶品质与年份、贮藏地点之间的关系,选用分别贮藏于昆明和广州两地的,贮藏时间在2年～14年的7个普洱生茶和8个普洱熟茶样品,分析其在不同贮藏环境和时间下安全性、理化品质以及感官评价方面的差异性。结果表明,整体上普洱茶的贮藏环境安全。广州仓更利于生茶的转化,转化效率高,能够较快达到降低苦涩、提高醇和的效果且整体老茶陈香更为明显,而昆明仓更利于突出普洱生茶甘甜香或单一药香。仓储对普洱生茶香气的影响可能大于原料本身。对普洱熟茶而言,广州仓的转化更快,但若希望长期贮藏且追求老茶的木香、药香等陈香品质则建议贮藏在昆明仓。对于熟茶香气而言,原料比仓储条件的影响更大。贮藏14年内,普洱生茶和普洱熟茶的品质都有所提升。该文首次提出普洱茶的品质评价应分为3个维度,包括转化的安全因子、品质因子和转化强度因子,并针对普洱茶的不同的特性将理化指标与其进行初步的关联。     

普洱茶生茶与熟茶对大鼠营养生理功能的影响

目的:观察普洱茶生茶与熟茶对大鼠营养生理功能的影响。方法:生长期SD大鼠30只,分为3组,每组10只,饲喂人工半合成饲料。普洱茶生茶组和普洱熟茶组的人工半合成饲料中分别添加6%的普洱茶生茶和熟茶粉。各组饲料的能量、蛋白质、脂肪和纤维素含量均保持一致。采用对喂法喂养30d,观察有关营养生理指标的变化。结果:两个普洱茶组大鼠体质量、食物转化率、血清和肝脏中甘油三酯以及游离脂肪酸水平均明显低于对照组(P<0.05),其中熟茶组和生茶组体质量分别比对照组降低9.6%和7.3%;血清甘油三酯水平分别比对照组降低47.1%和32.2%。熟茶组大鼠血清HDL-C水平显著高于对照组,血清LDL-C水平两个普洱茶组均有所升高(P<0.05)。血清谷胱甘肽过氧化物酶活性普洱茶生茶组比对照组升高2.5%,血清脂质过氧化物丙二醛含量生茶组和熟茶组分别比对照组降低27.0%和20.8%(P<0.05)。结论:普洱茶能够生理性控制正常大鼠的体质量增长,显著降低体内甘油三酯水平,有明显的减肥降脂功效,熟茶的减肥降脂效果优于生茶,对正常大鼠胆固醇代谢没有明显影响。普洱茶还能够降低血清脂质过氧化物丙二醛含量,提高谷胱甘肽过氧化物酶活性,有较强...     

普洱茶晒青样游离氨基酸和色泽差异研究

为探讨游离氨基酸和色值在普洱茶晒青样产地及古树茶和台地茶中的差异,分析了来自云南西双版纳州、临沧市普洱茶晒青样中18 种游离氨基酸组分含量,用色差仪测定茶汤色值（L*、a*、b*）,并进行方差分析、主成分分析。结果表明：晒青样中游离氨基酸组分含量在两地间有明显差异,西双版纳样品中茶氨酸、天冬氨酸、谷氨酸、精氨酸等主要鲜味氨基酸含量高于临沧样品。氨基酸主成分分析对西双版纳和临沧晒青样可以很好区分。台地茶游离氨基酸总量、天冬氨酸、谷氨酸、茶氨酸、组氨酸含量均比古树茶高,精氨酸含量比古树茶低,其中氨基酸总量、谷氨酸、精氨酸、组氨酸差异显著,二者也是在主要鲜味氨基酸上存在差异。两地晒青样汤色存在差异,西双版纳样品L*、b*值较临沧大,a*值较小。古树茶与台地茶汤色差异不明显。     

石墨炉原子吸收光谱法测定生熟茶叶中的铅元素含量及其安全评估

采用石墨炉原子吸收光谱法测定了勐海和勐腊两个地区的18份生茶及28份熟茶样品中重金属铅的含量,分析不同产地、不同加工方式茶叶的铅含量差异及特征;根据GB 2760-2017及靶标危害系数法评价茶叶的铅暴露风险,为保障消费者安全及茶叶的加工方式选择提供参考依据。结果显示,生茶的铅含量范围在0.038±0.002至0.255±0.005mg/kg,熟茶的铅含量在0.008±0.001至0.264±0.001 mg/kg,不同地区的茶叶样品铅元素含量存在差异;总体上生茶的铅含量低于熟茶,散装生茶低于饼装生茶,表明茶叶采后加工过程中接触的机械、发酵、渥堆等过程均有可能增加茶叶被重金属污染的风险。勐海及勐腊地区的生、熟茶样品中铅含量均低于GB 2760-2017的限量标准;两个产地生、熟茶的THQ均远低于1,没有明显的铅暴露风险。     

普洱生茶和普洱熟茶对小鼠减肥降脂作用的差异

普洱茶及其成分的减肥、降脂效果早已众所周知,然而对普洱茶不同品系的减肥、降脂效果研究较少。本实验采用两种差异比较明显的普洱茶,即普洱生茶和普洱熟茶,制备茶汤来饲喂高脂饮食的C57BL6/J小鼠,观察两种茶汤干预效果的差异。结果表明,两种茶叶不仅能够在血液中的脂肪指标、脏器组织变化、以及肠道菌群方面表现出有效的抗肥胖作用,而且两种茶叶之间的干预功效也有较大差异。用普洱生茶饲喂小鼠2周后可以降低其血液中TC和TG水平,而用普洱熟茶饲喂小鼠8周后才出现该效果。普洱生茶能够降低血液中LDL-C的水平,而普洱熟茶能够提高HDL-C的水平。在肝脏脂质代谢中,普洱生茶与普洱熟茶都能有效减少小鼠肝脏中脂肪液滴的生成。饲喂小鼠8周后,普洱生茶显著上调了其肠道菌群中的阿克曼氏菌属、norank＿f＿＿Muribaculaceae、拟杆菌属的丰度,显著下调了罗伯布茨菌属的丰度;普洱熟茶能够显著上调了肠道菌群中的乳酸杆菌属、norank＿f＿＿Muribaculaceae的丰度,显著下调了罗伯布茨菌属、Erysipelatoclostridium的丰度。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the