适宜口感下的绿茶品饮冲泡技术研究

目的 通过茶叶的耐泡性品质特征探究适宜口感下的绿茶冲泡上限及其技术参数。方法 试验以一芽二叶绿茶为原料,通过将感官审评方法制备的茶汤梯度稀释并由50名志愿者品饮确定适宜口感浓度的基础上,以适宜口感下的水浸出物、茶多酚、氨基酸浓度为考察指标,采用单因素+响应面法的试验设计,优化筛选了绿茶每次品饮冲泡的技术参数以及适宜口感下的冲泡次数。结果 绿茶茶汤中水浸出物、茶多酚、氨基酸的质量浓度分别为2.14、1.07、0.34 mg/mL时,具有适宜的品饮口感;采用茶水比1:60（即1 g茶叶用60 ml纯水冲泡）、100 ℃的纯水冲泡3 min的优化参数冲泡第1次以及茶水比1:50、100 ℃的纯水冲泡5 min的优化参数冲泡第2次,各次所得茶汤均具有适宜的品饮口感并达到适宜口感的水浸出物、氨基酸浓度;但采用茶水比1:33.21、90 ℃的纯水冲泡5.86 min的优化参数进行第3次冲泡,所得茶汤口感过淡,同时茶汤中水浸出物、茶多酚、氨基酸也未能达到适宜口感下的浓度要求。结论 适宜口感下的绿茶品饮冲泡以冲泡两次为宜。     

工夫红茶主要内含成分与品质的相关性分析

通过对11种工夫红茶的水浸出物、茶多酚、咖啡碱、氨基酸、茶黄素、茶红素和茶褐素的含量的测定,并作了感官审评,比较了这些对品质影响较大的内含成分含量与品质之间的相关关系。结果表明,工夫红茶的水浸出物含量与工夫红茶香气得分呈极显著正相关,与汤色呈极显著正相关,与总得分呈极显著正相关;茶褐素含量与茶汤色得分呈极显著负相关,与滋味呈显著性负相关,与茶汤总得分呈显著性负相关;茶红素与茶黄素的比值和茶汤汤色得分呈二次曲线关系;氨基酸的含量与茶汤滋味品质有极显著正相关关系,与香气得分呈显著性正相关。     

外源纤维素酶对江华苦茶红茶品质的影响

本文以江华苦茶鲜叶为原料,研究了不同纤维素酶浓度对江华苦茶红茶加工品质的影响,实验添加20 mL浓度分别为0.5、1、1.5 g/L的外源纤维素酶进行江华苦茶红茶的加工,经过茶叶感官审评、常规理化分析和茶叶挥发性物质分析等发现,添加20 mL浓度为1.5 g/L的纤维素酶与2.5 kg茶鲜叶发酵生产的红茶品质最佳,红茶中水浸出物总量、游离氨基酸、茶黄素和茶红素等物质含量增加,EGCG、咖啡碱等苦涩物质含量降低,滋味愈发醇厚,茶汤浓度和苦涩度明显降低,红茶口感得到良好改善。同时,外源纤维素酶能够促进红茶挥发性物质种类的增加,推动茶叶香气前体物质向芳香类化合物转化,使得苦茶红茶花香馥郁,高扬悠长,从而改善江华苦茶红茶的品质,以期为江华苦茶资源开发及利用提供借鉴。     

金荞叶茶的冲泡条件研究

金荞叶茶是由金荞麦(Fagopyrum cymosum complex)健康叶制作的一种特殊的保健茶。本研究对金荞叶茶的冲泡温度、冲泡时间、茶水比、冲泡次数、茶汤温度等冲泡条件对茶汤中黄酮类物质含量的影响进行了研究。结果表明:茶样茶汤中黄酮浸出物随冲泡温度的升高、冲泡时间的延长、茶水比的增大而增加,逐渐达到饱和。茶水比对黄酮浸提量影响最大,其次是冲泡温度,冲泡时间对其影响较小。最佳冲泡条件为茶水比8 g∶150 mL、水温100℃、冲泡时间10 min。同一份金荞叶茶按最佳冲泡条件冲泡,进行冲泡次数试验,结果发现第一泡茶黄酮含量最高为1.63%,第二泡茶黄酮含量为0.95%、第三泡茶黄酮含量为0.65%,直到第十泡茶黄酮含量仍能达到0.103%,说明饮用金荞叶茶时,多次重复冲泡仍有饮用的价值,至少可冲泡3次以上。茶汤温度对茶水黄酮含量有一定影响,茶汤温度的降低可导致茶水黄酮含量的下降。     

雅安藏茶对脂肪酶的抑制作用

从雅安藏茶中系统萃取分离出7个级分,使用酶标仪与96孔板酶反应体系,对雅安藏茶水浸出物及各个级分抑制脂肪酶的活性成分进行系统筛选及评价。结果表明:雅安藏茶水浸出物(0.018～0.360 mg/mL及其7个级分的添加质量浓度(0.011～0.216 mg/mL与其对脂肪酶活性的抑制作用之间均具有显著的量效关系;对脂肪酶活性的最大抑制率进行比较,雅安藏茶水浸出物为37.14、儿茶素(catechin,C)级分为44.67、茶黄素(tavin,TF)级分为39.46、茶褐素(theabromine,TB)级分为30.31、茶红素Ⅱ(thearubiginsⅡ,TRsⅡ)级分为29.53%,结合主要成分含量和回归分析,各级分所含活性成分抑制脂肪酶活性能力大小顺序为:儿茶素茶黄素茶红素。     

“冷泡茶”冲泡方式对红茶、绿茶、乌龙茶感官品质的影响

"冷泡茶"概念出于台湾,即该茶可直接通过常温水进行冲泡,其茶汁内容物和感官品质与在相同条件下用沸水冲饮时相差无几。目前国内对"冷泡茶"的报道集中在速溶茶的溶解特性方面,而对茶叶的冲泡时间、茶水比、冲泡次数研究较少。本文就冲泡时间、茶水比和冲泡次数对红茶、绿茶、乌龙茶感官品质的影响进行探索研究。冲泡时间0.5、1.0、1.5、2.0、3.0h,冲泡茶水比3∶300、4∶300、5∶300、6∶300,冲泡次数:1、2、3次,分别进行感官审评评分。通过实验得知:红茶的茶水比为5∶300~6∶300,冲泡时间1.5~2.0h,其感官品质最好;绿茶的茶水比为4∶300~5∶300,冲泡时间1.0~1.5h,其感官品质最好;乌龙茶的茶水比为5∶300~6∶300,冲泡时间1.5~2.0h,其感官品质最好。并且红茶、绿茶、乌龙茶的冲泡次数最多2次,多于两次,基本无茶味。     

水酶法提取樱桃籽油的工艺及理化性质

目的:优化水酶法提取樱桃籽油工艺,提高樱桃籽利用率。方法:在单因素试验基础上,运用混料设计对混合酶的混合比例进行优化,以确定最佳提取工艺条件,再对樱桃籽油的理化性质进行检测。结果:混合酶法提取樱桃籽油的最优酶解条件为：混合酶(m_维素酶∶m_果胶酶∶m_{酸性蛋白酶}为0.67∶0.10∶0.23)添加量2.0%,液料比(V_蒸馏水∶m_樱桃籽粉)10∶1 (mL/g),酶解温度45℃,pH 4.0,酶解4.0 h,樱桃籽油回收率达到93.18%,实际提取率为28.66%。所得樱桃籽油符合食用油安全标准。结论:混料设计辅助水酶法提取樱桃籽油的工艺具有可行性。     

冲泡条件对灵芝茯茶茶汤品质的影响

为探究冲泡条件对灵芝茯茶茶汤品质的影响,以灵芝茯茶为原料,利用单因素试验研究茶水比、冲泡温度、冲泡时间对茶汤风味的影响,设计三因素三水平正交试验,结合感官评价及茶汤内8种主要风味成分含量,对其进行主成分分析,筛选出灵芝茯茶的最佳冲泡条件。结果表明,茶水比、冲泡温度和冲泡时间均对灵芝茯茶茶汤的风味有明显影响。通过主成分分析将11个指标简化为2个主成分,其累积方差贡献率为86.939%,综合评价结果显示,在茶水比3∶150(g/mL)、冲泡温度100℃、冲泡时间3 min条件下,茶汤的综合得分最高,为灵芝茯茶的最佳冲泡条件。     

你了解新式茶饮吗(二)

正吉洺萩:邵老师,我们上期谈到新式茶饮与传统茶在品饮方式上有很大不同,这是两者的根本区别。我的理解是,传统茶无论是茶水分离(盖碗)还是茶水不分离(杯泡),在热饮中感受到的香气都与冷饮中有很大不同,很多香气在冷饮中无法感受到。此外,传统茶的冲泡与品饮几乎是同步的,就算是冲泡与品饮分离,出来的风味几乎都能够被完整地感知到,但茶汤一旦放置过久,香气就会散失,而新式茶饮是否要求茶汤必     

冲泡条件对玫瑰茄花青素及总黄酮溶出量的影响

为提高玫瑰茄活性成分的有效利用率,以玫瑰茄干花萼为原料,研究不同冲泡条件对其茶汤中花青素及总黄酮溶出的影响。分别以花青素和总黄酮溶出量为指标,结合单因素和正交试验,优化玫瑰茄花茶冲泡的工艺条件。结果显示,在冲泡时间30 min、冲泡温度70℃、茶水比1∶50(g/mL)时,玫瑰茄花茶中花青素的溶出量最高,可达7.94 mg/g;在冲泡时间为40 min、冲泡温度为80℃、茶水比为1∶50(g/mL)时玫瑰茄花茶中总黄酮溶出效果最佳,溶出量可达58.77 mg/g。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press