外文文献-外文翻译-英文文献-用电位计流动注射器判断茶叶发酵程度.doc

Effects of pulsed electric fields on bioactive components, colour and flavour of green tea infusionAuthor :Zhao, Wei ；Yang, Ruijin ；Wang, Mo ；Lu, RongrongAbstract: Green tea is an unfermented tea containing a higher quantity of bioactive components. In this paper, the effects of pulsed electric field (PEF) treatments on the bioactive components (polyphenols, catechins and free amino acids), colour and flavour of green tea infusions were studied. PEF as a promising non-thermal sterilisation technology could efficiently retain polyphenols, catechins and original colour of green tea infusions with electric field strength from 20 to 40 kV cm(-1) for 200 mu s. PEF treatments caused a significant increase in the total free amino acids of green tea infusions. The total free amino acids increased by 7.5% after PEF treatment at 40 kV cm(-1). The increase in total amino acids induced by PEF treatment, especially to theanine, is beneficial for the quality of commercial ready-to-drink green tea infusion products. There was no significant effect of PEF treatment at 20 or 30 kV cm(-1) on flavour compounds of green tea infusions. However, PEF treatment caused losses of volatiles in green tea infusions to different extents when PEF dosage was higher than a critical level. The total concentration of volatiles lost was approximately 10% after PEF treatment at 40 kV cm(-1) for 200 mu s.Keywords :green tea infusion green tea color green tea flavor高压脉冲电场对绿茶提取液的生物活性成分、颜色及其香味的影响摘要：绿茶是一类未发酵的茶，内含大量的生物活性成分。本文讲述用高压脉冲电场对绿茶提取液进行处理，来研究其对绿茶生物活性成分(多酚类、儿茶素、游离氨基酸)、绿茶的颜色及香味成分的影响。PEF是一种有发展前景的的非热能的灭菌技术，它能够有效地保留用20到 40 kV cm(-1)高压脉冲电场中处理200分钟的绿茶提取液中的多酚类、儿茶素及绿茶色素。PEF处理后的绿茶提取液中的整体的游离氨基酸含量增加。在40 kV cm(-1)高压脉冲电场处理下的游离氨基酸含量增加7.5%，整体氨基酸含量的增加是由于PEF处理导致的，这种处理技术对于提高商业中的绿茶饮料产品中的质量有益，尤其对于茶氨酸。而将绿茶提取液置于20 或30 kV cm(-1)条件下用PEF处理对绿茶香味成分没有什么影响。然而，当用超于临界的剂量的PEF处理绿茶提取液会使得绿茶提取液挥发物不同程度地减少。经过用PEF在40 kV cm(-1)条件下处理200分钟的绿茶提取液的挥发物大约减少10%关键词：绿茶提取液 ：绿茶颜色：绿茶香味Potentiometric flow-injection estimation of tea fermentation degreeAuthor :Nieh, CH ；Hsieh, BC ；Chen, PC ；Hsiao, HY ；Cheng, TJ ；Chen, RLCAbstract: A potentiometric flow-injection (FI) system was developed for estimating tea fermentation degrees; the method is based on the redox potentials or tea infusions. The infusions were extracted with phosphate buffer (10 mM, pH7.0), and injected (200 mu L) into the FI system (1 mLmin(-1). The redox potentials (vs. Ag/AgCl) of carrier stream were monitored with a home-made electrochemical flow cell equipped with a platinum indicating electrode. Flow-injection strategy Successfully decreased the problem of electrode fouling with increased reproducibility (S.D.20determination h(-1). During indoor withering process (0-24 h) for making pouching tea, the redox potential of tea infusions rose (110-130mV) along with the depletion of tea catechins. The system can also be used to estimate the fermentation degrees of commercial tea samples. For commercialization, the platinum electrode can be replaced with a screen-printed carbon-paste disposable electrode with similar performance. Keywords:potentiometric,flow-injection,tea-fermatationdegree,Redox-potential,Tea-catechins用电位计流动注射器判断茶叶发酵程度摘要：电位计流动注射系统的发展是为用来判断茶叶发酵程度的。这种方法是基于氧化还原电位或茶叶浸出液，这种浸出液是用磷酸盐缓冲液在（10 mM, pH7.0）条件下用流动注射器以1 mLmin(-1)的速度注射(200 mu L)提取出来的。这种氧化还原电位的载流是用国产的以铂为电极的电化学流动细胞设备监测的。这种流动注射方法成功地降低了电极污染，增加了可再利用性(S.D.1.5 mV)，增加了试样的生产率，在室内萎凋（0-24 h）为了制成包种茶。茶叶浸出液的氧化还原电位随着儿茶素的消耗而上升。这种系统也能用来测定样茶的发酵程度，在商业市场上，用铂作为的电极会被有相似作用的以碳作为材料的电极所取代。关键词：电位计流动注射；茶叶发酵程度：氧化还原电位；儿茶素Aspergillus acidus from Puerh tea and black tea does not produce ochratoxin A and fumonisin B2.Author : Mogensen, J. M. ；Varga, J. ；Thrane, U. ；Frisvad, J. C.Abstract : Puerh tea is a unique Chinese fermented tea. Unlike other teas it is stored for a long period of time. Aspergillus niger is claimed to be the dominant microorganism in the Puerh tea manufacturing process and also to be common on tea in general. A. niger sensu stricto is known to produce the mycotoxins ochratoxin A, fumonisins B2 and B4. With this in mind, we performed a preliminary study to determine if production of these mycotoxins by black Aspergilli isolated from Puerh and black tea can occur. An examination of 47 isolates from Puerh tea and black tea showed that none of these was A. niger. A part of the calmodulin gene in 17 isolates were sequenced, and these 17 isolates were all identified as Aspergillus acidus (= A. foetidus var. acidus). The rest of the 47 isolates were also identified as A. acidus from their metabolite profile. Neither production of ochratoxin A nor fumonisins B2 and B4 by any of the 47 isolates were observedKeywords: Aspergillus Niger，Black Tea，Puer Tea，CropsFood ，Safety Beverages，Mycotoxins，Plants Foods 普洱茶和红茶中的曲霉不会产生赭曲霉毒素A和烟曲霉毒素B2.摘要:普洱茶是中国唯一一种后发酵的茶类，不像其他茶，它需要储存很长一段时间。黑曲霉被称为是普洱茶制作过程中存在的主要的微生物，也普遍存在于茶叶当中。黑曲霉严格意义上是能够产生真菌毒素赭曲霉毒素A和烟曲霉毒素B2和B4.。以这种思路，我们开始了初步研究是否与普洱茶和红茶隔离开来的真菌会产生黑曲霉毒素。一个对从普洱茶和红茶提取的47菌株的实验研究表明当中没有曲霉A,对17菌株里面的一部分钙调素基因进行了测定，而这17菌株都被认定有曲霉菌，47菌株中其余的也被认为有代谢产物的曲霉菌。被47菌株隔离的赭曲霉毒素A和烟曲霉毒素B2.和B4的产物没有观察到。关键词：黑曲霉菌；红茶；普洱茶；农作物；安全食用饮料；真菌毒素；植物食品