高效液相色谱法对“黄金菊”茶中儿茶素和氨基酸组分含量的测定

为进一步研究江西特色茶树资源的生化成分,以“黄金菊”、安吉白茶、福鼎大白茶等茶树为试验材料,用高效液相色谱(high performance liquid chromatography,HPLC)法,对不同茶叶中儿茶素组分和氨基酸组分进行检测和对比分析。结果显示,“黄金菊”茶中儿茶素组分和氨基酸组分比较丰富,没食子酸酯儿茶素(gallate catechin,GC)、表没食子儿茶素(epigallocatechin,EGC)、儿茶素(catechin,C)、表儿茶素(epicatechin,EC)、表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、没食子儿茶素没食子酸酯(gallocatechin gallate,GCG)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、儿茶素没食子酸酯(catechin gallate,CG)含量分别为0.05%、1.21%、0.53%、0.99%、7.91%、0.23%、2.63%、0.01%;共检测出17种氨基酸组分,分别比安吉白茶、福鼎大白茶多检出1、3种氨基酸,检测出的成分含量与安吉白茶比较接近。试验结果说明,"黄金菊"茶树中儿茶素组分、氨基酸组分丰富,同时特征成分明显。     

不同保鲜处理过程中茶青品质成分含量的变化

本研究对采后茶鲜叶进行低温(5~8℃,10~13℃,15~18℃)和常温(21~23℃)处理,通过理化检测分析了茶青品质成分含量在不同保鲜处理过程中的变化情况。结果显示,相较于对照0 h,可溶性糖含量在低温和常温处理36 h中均未发生显著性变化;游离氨基酸含量在10~13℃组中维持着与对照相当的水平;儿茶素(catechin,C)、表儿茶素(epicatechin,EC)和表儿茶素没食子酸酯(epicatechin gallate,ECG)的含量在不同保鲜处理组中均出现了显著下降(p<0.05);表没食子儿茶素(epigallocatechin,EGC)、没食子儿茶素(gallocatechin,GC)和表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)的含量在5~8℃或10~13℃处理组中无显著性变化。此外,通过基于可溶糖、游离氨基酸、C、EC、ECG、GC、EGC和EGCG的主成分分析发现,在处理36 h后4组低温样品均能与常温样品进行区分,且较常温样品更接近0 h对照样品。综上所述,10~13℃处理能对茶青起到较好的保鲜作用。     

不同时期茶树鲜叶活性成分研究

为探明不同时期茶树活性成分的变化规律,采用高效液相色谱法(HPLC),对不同时间采摘的福鼎大白茶鲜叶氨基酸(amino acids,AA)、茶多酚(tea polyphenols,TP)、咖啡碱(caffeine,CAF)、没食子酸(gallic acid,GA)、表没食子儿茶素(epicatechin gallate,EGC)、表儿茶素没食子酸(epicatechin gallate,ECG)及表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)等生化成分含量进行分析比较。结果显示:福鼎大白茶鲜叶中儿茶素组分总含量在12.1 mg/g~18.7 mg/g之间,其中样品4 EGCG含量最高,3月份采摘一芽二叶鲜叶儿茶素品质指数最高为15.66,其儿茶素苦涩味指数也是样品中百分比最高的,儿茶素的品质指数与苦涩味指数、氨酚比呈正相关。     

不同闷黄工艺对蒙顶黄芽风味品质的影响

为缩短传统蒙顶黄芽加工时间，提出一种快速闷黄工艺，并结合感官审评、高效液相色谱(high performance liquid chromatography,HPLC)、气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)等分析方法，探讨不闷黄、传统闷黄、快速闷黄工艺对蒙顶黄芽风味品质的影响。结果表明，2种闷黄工艺的感官审评总分均比不闷黄工艺高，且快速闷黄工艺总分最高。闷黄工艺后，表没食子儿茶素(epigallocatechin,EGC)、儿茶素(catechin,C)、表儿茶素(epicatechin,EC)、咖啡碱、可溶性糖和谷氨酸含量均增加，EGC、可溶性糖和谷氨酸含量增加均达到显著水平(P<0.05)；表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、儿茶素总量均减少，快速闷黄工艺的EGCG、茶多酚、氨基酸总量、茶氨酸、叶绿素b和叶绿素总量的减少均达到显著水平(P<0.05)。3种工艺样品均鉴定出42种香气成分...     

4种茶叶水提物及茶多酚的体外抗氧化性能研究

采用水提法对红茶、乌龙茶、绿茶和茉莉花茶进行提取,并对抽提物中总酚含量和各个儿茶素单体含量进行测定,通过常见的3种抗氧化能力测试方法,即DPPH法、2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐[(2,2-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid)diammonium salt,ABTS)]法及铁离子还原/抗氧化能力(ferric ion reducing antioxidant power,FRAP)法对4种茶叶水提物的体外抗氧化能力进行评价,同时比较茶多酚和VC的抗氧化活性。结果表明:4种茶叶水提物均有很强的体外抗氧化活性,绿茶、茉莉花茶、乌龙茶的DPPH法及FRAP法抗氧化活性测试结果优于红茶,红茶的ABTS+·清除率略高于其他3种茶。相关性分析结果显示儿茶素总量、总酚含量、没食子儿茶素(gallocatechin,GC)、表没食子儿茶素(epigallocatechin,EGC)、表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、表儿茶素没食子酸酯(epicatechin gallate,ECG)含量和DPPH法、FRAP法结果呈现正相关,而与ABTS法结果呈现负相关。此外,试验结果表明茶多酚的抗氧化能力高于V_C。     

窨制对茉莉花茶抑制癌细胞增殖的影响

目的探究茉莉花茶窨制过程中茶叶主要活性成分及抑制肝癌和胃癌细胞增殖能力的变化。方法利用四极杆飞行时间液相色谱质谱联用法和高效液相色谱法、紫外分光光度法对茉莉花茶主要活性成分进行定性和定量分析;利用主成分分析方法对窨制过程的茉莉花茶样本进行分析;利用四唑盐比色法(methyl thiazolyl tetrazolim,MTT)测定茉莉花茶抑制肝癌和胃癌细胞增殖的活性。结果本研究从茉莉花茶中鉴定出8种酚酸类及其衍生物、7种儿茶素、2种原花青素二聚体和6种黄酮醇苷类化合物。茉莉花茶细毛尖在窨制花茶过程中,其含有的黄酮、总儿茶素、生物碱、咖啡碱、没食子酸、表没食子儿茶素(epigallocatechin, EGC)、没食子儿茶素没食子酸酯(gallocatechin gallate,GCG)和表儿茶素没食子酸酯(epicatechin gallate,ECG)的含量逐渐下降;茉莉花茶龙峰在窨制成花茶过程中,其总多酚、可可碱、EGC、表儿茶素(epicatechin,EC)、表没食子儿茶素没食子酸酯(epigallocatechin gallate, EGCG)、GCG和ECG的含量逐渐上升,茶碱、没食子酸、GC含量则下降。主成分分析结果显示,不同窨制次数的茉莉花茶各自聚为一类。MTT结果显示,茉莉花茶细毛尖和龙峰的水浸出物抑制肝癌细胞HepG2增殖的IC_(50)分别为264.81～272.69μg/mL和377.46～435.95μg/mL,抑制胃癌细胞细胞BGC823的IC_(50)分别为42.49～46.35μg/mL和24.85～57.57μg/mL。茉莉花茶抑制胃癌细胞增殖能力强于肝癌,细毛尖窨制后,抑制肝癌细胞增殖能力无显著变化,抑制胃癌细胞增殖能力先下降后上升;龙峰窨制后,抑制肝癌细胞增殖能力下降15.5%,抑制胃癌细胞增殖能力增强45.3%。结论本研究初步明确了茉莉花茶的抗癌功效,明晰了茉莉花茶窨制过程中的主要活性成分和抗癌功效的变化,为消费者正确认识茉莉花茶提供科学数据支撑。     

以云南铁观音为原料的速溶茶加工研究

铁观音是云南近年来发展迅速的一种茶叶产品,随着种植面积与产量的增加,急需要进行精深加工研究开发。以云南腾冲产的铁观音为原料,通过单因素、正交设计优化浸提条件,以及浓缩和干燥工艺考查,建立料液比1∶10(g/mL)、60%乙醇浸提36 h、过滤后茶渣以料液比1∶5(g/mL)沸水浸提30 min、40℃减压浓缩、100℃喷雾干燥的铁观音速溶茶加工工艺。加工产品速溶性强、花香浓郁、滋味醇厚,得率为28.47%,茶多酚、儿茶素(catechins,C)、表儿茶素(epicatechin,EC)、表没食子酸儿茶素(epigallocatechin,EGC)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)含量分别为34.03%、0.45%、2.25%、9.49%、2.14%和14.16%。研究开发一种具有市场潜力的深加工茶叶产品,为云南铁观音茶叶发展提供技术支持。     

UPLC-MS-MS同时测定茶油中8种儿茶素类物质

利用超高效液相色谱-串联质谱建立了一种可以同时检测茶油8种儿茶素类物质的分析方法。使用Waters T3 C18色谱柱(250mm×4.6mm,5μm),以0.1%(V/V)甲酸水溶液和甲醇和为流动相进行梯度洗脱,正扫描方式下多反应监测(MRM)模式测定。在优化的条件下,8种儿茶素类物质线性关系良好(r~2=0.9966～0.9995),方法检出限为0.2～1.1μg/L。在不同浓度水平的添加平均加标回收率为76.4.%～93.4%之间,相对标准偏差3.0%～8.9%。应用本方法可以检测出茶油中儿茶素(C)、表儿茶素表儿茶素(EC)、表没食子儿茶素(EGC)、表儿茶素没食子酸酯(ECG)、表没食子儿茶素没食子酸酯(EGCG)等的含量。结果表明,茶油中表没食子儿茶素没食子酸酯(EGCG)、表没食子儿茶素(EGC)、表儿茶素没食子酸酯(ECG)的含量相对较高。本方法结果准确可靠,方法快速,简单易行,可为茶油中儿茶素类物质的检测提供参考。     

茶黄素双没食子酸酯的酶法合成条件优化与纯化

利用皇冠梨多酚氧化酶催化表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)和表儿茶素没食子酸酯(epicatechin gallate,ECG)合成茶黄素双没食子酸酯(theaflavin-3,3’-O-digallate,TFDG),首先单因素试验确定了酶促反应的底物EGCG/ECG物质的量比3∶1、pH 4.0、反应温度35℃,在此基础上采用Box-Behnken试验设计法进行3因素3水平响应面优化试验,确定了TFDG最优酶促反应条件为底物EGCG/ECG物质的量比3.1∶1、pH 4.1、反应温度37℃;在最优反应条件下进行TFDG的合成,并利用AB-8层析柱结合高速逆流色谱技术分离纯化反应液,结果表明TFDG的得率和纯度分别达到85.14%和97%。     

热加工处理对奶茶体系中茶多酚生物可及性的影响

实验采用体外模拟胃肠消化方法,结合高效液相色谱检测,探究热处理加工条件(80℃/20 min、100℃/5 min)和加热方式(蛋白与茶多酚混合加热、蛋白单独加热)对奶茶模拟体系中表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)、表没食子儿茶素(epigallocatechin,EGC)、表儿茶素没食子酸酯(epicatechin gallate,ECG)及表儿茶素(epicatechin,EC)生物可及性的影响。结果表明,消化前加入乳清蛋白会降低游离茶多酚的含量,其中EC降低12.76%最明显;乳清蛋白的单独加热处理更能降低游离茶多酚的含量,其中蛋白在100℃加热下游离茶多酚含量最少;80℃热处理体系消化前游离多酚含量均大于100℃热处理体系。热加工处理对奶茶体系中茶多酚的生物可及性存在不同程度的影响——除80℃蛋白单独加热外,其余热处理均降低EGCG的生物可及性,降低11.11%~18.38%;100℃蛋白混合加热有利于提高EGC的生物可及性,提高9.05%,且除80℃混合加热外,其余热处理方式可显著降低其生物可及性,降低24.86%~40.14%;100℃热处理方式可显著提高ECG的生物可及性,提高22.72%~28.05%;80℃加热条件可提高EC约7.24%的生物可及性,而100℃热处理方式可降低EC约47.14%的生物可及性。相同热处理下,添加乳清蛋白可提高儿茶素的生物可及性(除EGC 80℃蛋白单独加热组外)。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

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

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.