大宗茶鲜叶原料分级机的研制与实验

机采大宗茶鲜叶长短不一、老嫩不同,以此为原料制得的茶叶品质较低,为此研制了一种新型的抛掷式大宗茶鲜叶分级机,该机由分级槽体、传动机构、摇杆和机架等部分组成,通过抛掷的方式对茶鲜叶进行分级.结果表明,使用第二批次茶鲜叶进行分级,投叶量为5kg/min、振动频率为50Hz时,分级机的平均分净率最高,达79.04％,挂网率为3.60％.可见,该机能较好地实现机采大宗茶鲜叶的分级.     

不同嫩度鲜叶加工工夫红茶对品质和内含成分的影响

为研究不同嫩度鲜叶加工工夫红茶对品质和内含成分的影响,分别采摘一芽一二叶、一芽二三叶和一芽三四叶原料,按照萎凋、揉捻、发酵和干燥4道工序加工工夫红茶,探索不同嫩度鲜叶加工工夫红茶过程中茶多酚、儿茶素、茶黄素、氨基酸等含量的变化,以及对茶叶感官品质的影响。结果表明:感官品质总分表现为一芽一二叶一芽二三叶一芽三四叶,其中一芽三四叶各感官因子得分均为最差,一芽一二叶和一芽二三叶的汤色、香气和滋味内质评分相近;内含成分的变化表现为揉捻和发酵期间儿茶素含量迅速下降,水浸出物含量也有降低,茶黄素含量上升,红茶加工过程中咖啡碱含量变化不大,不同嫩度原料之间比较,红茶加工过程中EGCG的氧化率一芽一二叶最高为92.09%,一芽二三叶为85.29%,一芽三四叶为86.30%,生成的茶黄素为一芽二三叶最高,氨基酸含量为一芽一二叶一芽二三叶一芽三四叶。     

颗粒形绿茶的关键加工工艺参数优化

采用机采叶加工颗粒形绿茶,是实现绿茶机采机制的有效途径。通过研究机采鲜叶的采摘标准、杀青温度、二青时间和做形温度等对颗粒形绿茶品质的影响,筛选适宜的加工工艺参数。结果表明,颗粒形绿茶适制的机采叶标准为一芽二三叶,优化的关键工艺参数分别是杀青温度200~210℃、炒二青时间15 min、做形与定形温度160~170℃。此工艺加工的颗粒形绿茶外形品质较好,香气清高,滋味清醇,能达到优质绿茶的品质要求。     

不同工艺对丹桂秋季白茶品质的影响

为充分利用秋季茶树鲜叶资源、开发花香白茶产品,以丹桂品种秋季驻芽小开面三、四叶为原料,以传统白茶工艺为对照(CK),以萎凋中引入摇青工艺为处理(YQ),对比分析不同工艺对丹桂白茶生化成分、香气组分和感官品质的影响。结果表明,丹桂秋季茶树鲜叶内含物质较为丰富,组成较为合理,具有加工优质白茶的物质基础;白茶生化成分分析表明,YQ对主要生化成分的含量与组成影响显著,其中,茶多酚等9个生化成分在二者之间差异显著,YQ中茶氨酸、鲜味氨基酸、甜味氨基酸、必需氨基酸的含量均高于CK;香气成分分析发现,YQ中香气物质的种类较CK少,但在含量上却明显高于后者,尤其是花果香型的香气成分;感官审评结果表明,YQ感官品质及综合得分(90.70)均优于和高于CK(85.85)。综合分析认为,以丹桂秋季驻芽小开面三、四叶为原料,于萎凋中进行适度摇青处理可以增进白茶的香气和滋味品质,所制白茶品质优异。     

基于多元统计分析的不同品种和嫩度大叶种茶树新梢主要滋味物质的比较

为探究大叶种鲜叶原料的生化特性,本研究以云南大叶种（清水3号、香归银毫、云抗10号、云抗14号、云茶普蕊）的单芽、一芽一叶、一芽二叶、一芽三叶等不同嫩度的茶树新梢为研究对象,通过检测其主要滋味物质（茶多酚、黄酮苷、氨基酸及可溶性糖等）含量,探明不同品种云南大叶种鲜叶原料滋味品质随嫩度的变化规律,并运用多元统计方法研究不同嫩度鲜叶的分类,建立不同类别鲜叶的判别模型。结果表明,茶树新梢的成熟度越高,酚氨比、总简单儿茶素、黄酮苷、过氧化物酶等值越高（且一芽二叶和一芽三叶显著高于单芽和一芽一叶（P<0.05））,但没食子酸、氨基酸等值越低（且单芽和一芽一叶显著高于一芽二叶和一芽三叶（P<0.05））;茶多酚、总酯型儿茶素、咖啡碱等值随着嫩度的降低先升后降,与一芽三叶相比,一芽二叶的茶多酚、总酯型儿茶素、咖啡碱等值分别增加了7.67%、13.77%、10.22%;黄酮苷和可溶性糖中含量较高的组分分别为芦丁、蔗糖,质量分数范围分别为0.03%~0.93%、0.14%~1.14%;单芽的云抗14号、一芽二叶的清水3号分别为适制绿茶、适制红茶的较佳原料;多元统计分析可把不同嫩度鲜叶分为单芽和一芽一叶、一芽二叶和一芽三叶两类,总简单儿茶素、酚氨比、过氧化物酶、黄酮苷等可作为两类鲜叶中的关键差异指标;Fisher判别模型对鲜叶分类的验证正确率达85%。该研究为云南大叶种新梢的分级及标准化加工提供了理论参考。     

群体种茶树紫色芽叶的信阳红茶适制性研究

该文以信阳群体种紫色芽叶为原料,分析茶鲜叶主要生化成分,通过对紫色芽叶制品和对照组绿色芽叶制品的理化分析和感官审评,旨在对紫色芽叶的信阳红茶适制性及加工工艺进行研究。结果显示：紫色芽叶固定样的花青素显著高于对照组（P＜0.05）,茶多酚、氨基酸、咖啡碱和水浸出物与对照组相比差异不显著（P＞0.05）;紫色芽叶红茶样水浸出物含量显著高于对照组（P＜0.05）,茶多酚、氨基酸、茶黄素和茶红素与对照组相比差异不显著（P＞0.05）;紫色芽叶红茶样感官品质稍高于绿色芽叶红茶样,表现出良好的适制性。综上分析,夏季紫色芽叶表现出较好的红茶适制性。     

不同加工工艺对‘陕茶1号’绿茶品质的影响

选用‘陕茶1号’春季一芽二叶新梢为原料,分别按照扁形茶、卷曲形茶、针形茶、兰花形茶和炒青工艺加工成绿茶,所制茶样通过感官审评、内含成分分析、香气组分分析和抗氧化能力分析,以确定‘陕茶1号’春季鲜叶原料加工绿茶的最佳工艺。结果表明:兰花形茶各内含成分适中协调,水浸出物含量为46.24%,氨基酸含量最高达4.22%,咖啡碱含量为4.54%,茶多酚含量为21.52%,酚氨比最低,叶绿素含量最高达2.15 mg/g,绿茶主要香气物质含量最高达21.69%,感官品质最佳,其加工工艺是加工‘陕茶1号’春季一芽二叶新梢的最佳工艺;扁形茶感官品质及其主要香气物质含量仅次于兰花形茶,多酚类保留量最高,各内含成分也较协调,且抗氧化能力最强,其加工工艺也适合‘陕茶1号’春季一芽二叶新梢的加工。     

春季不同品种景宁白茶的适采期研究初报

为指导浙江景宁茶区景宁白茶的及时采摘,以当地的主栽品种——景白1号和景白2号为研究对象,一芽一二叶为标准芽叶,在春季3个不同时期分别对茶树冠面和采摘后鲜叶的机械组成以及茶树生长发育规律进行调查研究,并结合鲜叶的主要品质成分含量,综合判断景宁白茶的适采期。结果表明,景白1号的开采时间较景白2号晚3~5天,标准芽叶状态的持续时间约9天,大面积采摘主要集中在4月中旬。景白2号的开采时间早,标准芽叶状态的持续时间约12天,鲜叶在4月上旬采摘的鲜叶嫩度和内在品质最佳。4月20号之后,景白1号和景白2号鲜叶品质均较差,不适宜加工中高档名优绿茶。     

云南大叶种茶鲜叶原料的物化特性比较

鲜叶是制茶的基本原料,为探究大叶种鲜叶原料的物化特性,以春季和秋季的勐库大叶种、勐海大叶种、凤庆大叶种等茶树的单芽、一芽一叶、一芽二叶、一芽三叶共4个不同嫩度的新梢为研究对象,通过物理和化学指标的测定,分析嫩度、品种、季节间鲜叶品质的差异,并运用偏最小二乘判别分析（partial least squares discriminant analysis,PLS-DA）研究不同等级鲜叶的关键差异性指标。结果表明,鲜叶成熟度越高,叶长、节间长、百芽重、含水率、粗纤维等值越高,咖啡碱、全氮量、质量系数越低;秋季的叶长、百芽重、含水率、氨基酸等值大于春季;不同品种相同嫩度鲜叶的叶长、叶宽、叶面积差异不显著（P＞0.05）;勐海大叶种鲜叶春季的百叶重、秋季的质量系数值均高于相同季节的其他品种;春季单芽、秋季一芽一叶的茶多酚质量分数较高,均值分别为21.36%、22.73%;一芽二叶的氨基酸质量分数较高,春季和秋季的均值分别为3.51%、4.44%;春季和秋季的4个嫩度可分别分为2类和3类,氨基酸、茶多酚、叶长等为对差异贡献度较大的指标。该研究为云南大叶种新稍的分级及标准化加工提供理论参考。     

双龙银针茶机制技术规程(地方标准)

１适用范围本标准规定了双龙银针茶的品质特征与（鲜叶）采摘、摊放、杀青、理条整形、干燥等工序的技术规范。２品质特征２．１鲜叶特征一芽一叶初展或一芽一叶,大小均匀一致,不采夏茶、病虫叶、紫色芽叶、受污染芽叶。２．２外形和内质特征条索挺直,白毫显露,香高持...     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status