DNA Extraction and Molecular Identification of Green Tea

[Objective] The aim of this study was to provide reference for the quality identification of green tea.[Method] Green Tea was used as materials,and its total DNA was extracted through improved CTAB method.And the obtained DNA was used to carry out identification on 10 varieties of green tea through ISSR molecular markers.[Result] The high quality DNA from green tea could be obtained with new method,the DNA yield ranged from 101-498 μg/g tea sample for various green tea samples,and the average yield was 249 μg/g tea sample.The ISSR detection result showed that ISSR markers could effectively differentiate different varieties of green tea.[Conclusion] The result had provided reference for the further study on molecular identification of green tea.

Green tea extract:A potential cause of acute liver failure

The use of herbal products has increased significantly in recent years.Because these products are not subject to regulation by the Food and Drug Administration and are often used without supervision by a healthcare provider,the indication for and consumption of these supplements is quite variable.Moreover,their use is generally regarded as safe and natural by the lay-public.Unfortunately,there has been an increase in the number of reported adverse events occurring with the use of herbal products.We present a case of acute impending liver failure in an adolescent male using a weightloss product containing green tea extract.Our case adds to the growing concern surrounding the ingestion of green tea extract and serves to heighten healthcare provider awareness of a potential green tea extract hepatotoxicity.Despite the generally touted benefits of green tea as a whole,clinical concern regarding its use is emerging and has been linked to its concentration in multiple herbal supplements.Interestingly,the suspected harmful compounds are those previously proposed to be advantageous for weight-loss,cancer remedy,and anti-inflammatory purposes.Yet,we emphasize the need to be aware of not just green tea extract,but the importance of monitoring patient use of all dietary supplements and herbal products.

Effects of supplementation of green tea extract on the milk performance of peripartal dairy cows and the expression of stress response genes in the liver

Background: We hypothesised that supplementation of green tea extract(GTE) in dairy cows during the transition period can attenuate proinflammatory conditions and prevent endoplasmic reticulum(ER) stress in the liver of these cows. Thirty Holstein cows with an average parity of 3.06(± 1.31, SD) were divided into a control group and a group that received a daily amount of 10 g of GTE from d 7 before the calving day and a daily amount of 20 g of GTE from the day of calving until d 7 of lactation.Results: Cows supplemented with GTE did not show differences in energy intake or milk yield in weeks 2–7 of lactation. However, these cows had a lower milk fat concentration and a lower energy corrected milk yield than the control cows and showed a trend of improved energy balance. The relative m RNA concentrations of proinflammatory genes, genes involved in the acute phase reaction and antioxidant genes in the liver in weeks 1, 4 and 7 of lactation were not different between the two groups of cows. The concentrations of α-tocopherol and the Trolox equivalent antioxidant capacity in plasma were not different between the two groups. However, the group supplemented with GTE showed significant reductions of some genes of the unfolded protein response(UPR) in week 1 and a trend of lower liver triacylglycerol(TAG) concentrations in the liver compared to the control group.Conclusions: This study shows that supplementation of GTE in dairy cows lowers the fat concentration in the milk but overall has no effect on the expression of inflammatory genes and the antioxidative status in dairy cows during early lactation. The finding of reduced m RNA levels of genes involved in the UPR at week 1, however, supports other results showing that supplementation of polyphenols could prevent the development of ER stress in the liver of cows during early lactation. The finding of a tendency towards a reduced TAG concentration in the liver of cows supplemented with GTE might be due to an improved energy balance in these cows.

Inhibitory Effect of Green Tea Extract on the Carcinogenesis Induced by Asbestos Plus Benzo(a)pyrene in Rat

In this experiment lung carcinoma was induced by crocidolite plus benzo(a)pyrene in rat. From the cancer models, we observcd that the incidcnce (16.0%) of lung carcinomas was lowel, and the survival time (376 days) of the first case of carcinoma and the mean survival time (758 days) of the rats with carcinoma were higher in the group of rats drinking 2% green tea extract for life than in the positive group (without drinking green tea extract). The mortality ratio (0.5047) was smaller in the cxperimental group than in the positive control group, and the survival curve of the experimental group significantly raised up, in comparison with the positive group.

Study on the Preparation of"Oil-tea"Instant Tea from the Compound Extract of Green Tea and Ginger

[Objectives]This study was conducted to develop an"oil-tea"instant tea with traditional"oil-tea"flavor,easy preservation and transportation and good taste.[Methods]With green tea,ginger and peanuts as experimental materials,a compound extract was obtained by boiling,and the"oil-tea"instant tea was prepared by spray drying.The tea polyphenol content and soluble solid content of the extract(oil tea soup),the yield of finished solid product and sensory quality were comprehensively evaluated.[Results]The optimum instant tea technical parameters were determined as follows:the ratio of material to liquid 1∶15,the extraction time of boiling 60 min,the inlet air temperature of spray drying 180℃,the feeding speed 850 ml/h,the soluble solid content of the extract 13%,and the amount of maltodextrin added 12 mg/g.Under these conditions,the yield of the instant tea was high,and the instant tea had better sensory quality and good solubility.[Conclusions]This study provides a reference for the commercial development of"oil tea".

Applications of Green Tea Extract in Bakery Products

Green tea extract(GTE) is a rich source of tea catechins with antioxidative,anticarcinogenic and antiarteriosclerotic activities and it has been applied in food such as bakery products to provide health benefits and extend the shelf life.This review outlines the stability of green tea catechins during baking process of bakery products supplemented with GTE and the effects of GTE on the functional properties,sensory properties,physical characteristics and Maillard reaction of bakery products.

Oxidative Stability of Green Tea Extract-Enriched Rice Bran Oil During Storage

Adding green tea extract to rice bran oil was expected to improve its oxidative stability,so this study was conducted to investigate oxidative stability of green tea extract-enriched rice bran oil(RBOG) during storage at 60℃ for 15 days compared to rice bran oil(RBO),olive(OL),canola(CN),and grape-seed oil(GS).Acid values did not increase during storage,and the highest value was found for OL.The peroxide values of RBOG,RBO,CN,OL,and GS increased for up to 15 days.The highest average rate constant for the change in peroxide value was found for RBO(0.282).TBARS increased continually during storage of RBOG,RBO,CN,and OL;however,the value increased for up to 9 days and then decreased for GS.The highest average rate constant of change in TBARS was found for CN.Overall,the results suggest that green tea extract improves oxidative stability of rice bran oil.

Antifi brotic effects of green tea on in vitro and in vivo models of liver fibrosis

AIM: To examine the protective effect of green tea extract (GT) on hepatic fi brosis in vitro and in vivo in dimethylnitrosamine (DMN)-induced rats.METHODS: HSC-T6, a rat hepatic stellate cell line, was used as an in vitro assay system. Cell proliferation, collagen content, and type 1 collagen expression were examined in activated HSC-T6 cells. Collagen was determined by estimating the hydroxyproline content. In rats with DMN-induced hepatic fi brosis, serum aspartate aminotransferase and alanine aminotransferase concentrations, liver hydroxyproline and lipid peroxides were determined. Pathologic changes were examined by hematoxylin & eosin staining.RESULTS: GT administration prevented the development of hepatic fibrosis in the rat model of DMN-induced liver fi brosis. These results were confi rmed both by liver histology and by quantitative measurement of hepatic hydroxyproline content, a marker of liver collagen deposition. Accordingly, inhibition of proliferation, reduced collagen deposition, and type 1 collagen expression were observed in activated HSC-T6 cells following GT treatment. These results imply that GT reduced the proliferation of activated HSC and down regulated the collagen content and expression of collagen type 1, thereby ameliorating hepatic fibrosis.CONCLUSION: This study demonstrates that greentea administration can effectively improve liver fibrosis caused by DMN, and may be used as a therapeutic option and preventive measure against hepatic f ibrosis.

气相色谱-串联质谱法测定宝洪红茶、白茶和绿茶中的挥发性物质

目的以云南唯一小叶种茶宝洪茶鲜叶为原料,比较分析采用不同加工工艺生产的宝洪红茶、白茶和绿茶挥发性物质。方法同时采用蒸馏萃取(simultaneous distillation extraction,SDE)和顶空萃取(headspace,HS)两种方法提取,气相色谱-串联质谱法(gas chromatography-tandem mass spectrometry,GC-MS/MS)测定,分析比较不同宝洪茶挥发性物质种类和含量差异。结果从宝洪红茶、宝洪白茶、宝洪绿茶中分别提取鉴定挥发性物质65种、44种和49种,这些化合物包括醛类、醇类、酯类、酮类、酸类、酚类、碳氢化合物、杂氧化合物和含氮化合物。SDE法提取得到主要挥发性物质宝洪红茶为棕榈酸和香叶醇,宝洪白茶为棕榈酸和香叶邻苯二甲酸二丁酯醇,宝洪绿茶为植醇和邻苯二甲酸二丁酯;HS干法提取得到主要挥发性成分为咖啡因,相对含量宝洪红茶55.300%,宝洪白茶58.800%,宝洪绿茶84.350%,HS湿法提取主要挥发性物质宝洪红茶为己醛和甲酸芳樟醇,宝洪白茶为甲酸芳樟醇和己醛,宝红绿茶为甲酸芳樟醇和对氨基间甲酚。结论不同工艺生产的宝洪茶挥发性物质种类和含量差异显著,2种提取方法互补性大于重叠性,结合分析可获得不同宝洪茶更全面、更完整挥发性物质信息。该研究结果可为改进加工工艺提高宝洪茶品质提供理论基础。

干燥方式对绿碎茶多酚提取物体外抗氧化和抗糖尿病及乙酰胆碱酯酶抑制活性的影响

研究不同干燥方式处理的绿碎茶多酚提取物体外抗氧化和抗糖尿病活性及对乙酰胆碱酯酶抑制作用。以绿碎茶为试验材料,采用蒸干结合真空干燥与真空冷冻干燥2种干燥工艺对绿碎茶乙酸乙酯萃取相进行干燥处理,比较研究了2种提取物的色泽,DPPH自由基、ABTS阳离子自由基、羟自由基(·OH)清除能力和铁离子还原能力以及α-淀粉酶、α-葡萄糖苷酶、乙酰胆碱酯酶的抑制能力和抗糖基化能力。结果表明,真空冷冻干燥绿碎茶多酚提取物(BGTE-FD)较蒸干结合真空干燥绿碎茶多酚提取物(BGTE-SVD)颜色相对偏黄,具有较强的DPPH自由基、ABTS阳离子自由基、·OH清除能力和铁离子还原能力,其IC_(50)值分别为2.64、5.17、247.01、27.73 mg/L。同时,BGTE-FD具有较高的α-淀粉酶、乙酰胆碱酯酶和α-葡萄糖苷酶抑制作用,IC_(50)值分别为85.84、416.45、4.38 mg/L,且其对α-葡萄糖苷酶的抑制能力显著强于阿卡波糖(IC_(50)值为929.59 mg/L)。此外,BGTE-FD和BGTE-SVD对晚期糖基化终产物抑制率分别高达65.28%和63.66%,略低于氨基胍(71.81%)。因此,真空冷冻干燥绿碎茶多酚提取物具有较强的体外抗氧化和抗糖尿病活性及一定的乙酰胆碱酯酶抑制能力,绿碎茶可作为降血糖和抗痴呆产品的潜在资源。

磁固相萃取结合超高效液相色谱串联质谱法检测绿茶中19种有机磷农药残留

本文采用化学共沉淀法合成磁性石墨烯(Fe_(3)O_(4)@G),并将其作为一种磁固相萃取剂用于绿茶中有机磷农药的萃取富集,结合超高效液相色谱串联质谱技术,建立同时检测绿茶中19种有机磷农药残留的分析方法。本实验选择吸附剂用量为40 mg,萃取时间20 min,样品溶液pH为7,3.0 mL丙酮解吸,氯化钠用量为4 g。结果表明,在5~500μg/L范围内,线性相关系数大于0.999,制备的Fe_(3)O_(4)@G材料具有良好的稳定性和可重复利用性。检出限(LOD)在5.0~6.0μg/kg,定量限(LOQ)在15.0~20.0μg/kg。当样品加标水平为20.0、40.0、200.0μg/kg时,回收率在61.2%~94.9%之间,相对标准偏差(RSD,n=6)在2.6%~10.2%之间。本方法适用范围广,前处理易操控,有机溶剂用量少,经济,安全,材料可重复使用,该磁分散固相萃取技术在茶叶中农药的富集分离有很好的应用前景。

藜芦根茎提取物可溶液剂防治茶绿盲蝽田间药效试验

为确定藜芦根茎提取物可溶液剂(藜芦胺)对防治茶绿盲蝽的效果,进行了不同浓度田间药效试验。结果表明,药后3 d,各处理防效和对照药剂防效均达最高值,0.5%藜芦根茎提取物可溶液剂600倍液处理的防效最高,为80.43%,各处理与0.3%苦参碱水剂无显著差异。本试验结果总体来看,0.5%藜芦根茎提取物可溶液剂防治茶绿盲蝽速效性、持效性相对较好,对茶园主要害虫茶小绿叶蝉也有较好的兼治作用;同时,对茶园主要益虫无明显不良影响。

碎茶末制备速溶绿茶提取工艺研究

为提高碎茶末利用价值,优化速溶绿茶提取工艺,以安康绿茶加工过程中产生的碎茶末为原料,采用超声波提取技术制备速溶绿茶,考察浸提时间、浸提温度、茶水比对速溶绿茶品质及提取率的影响,通过单因素及正交试验确定速溶绿茶的最优提取工艺。结果表明,超声波提取时间20 min,提取温度30℃,茶水比1︰25为最佳提取条件。在此条件下,速溶绿茶得率为24.67%,茶多酚含量为13.78%、游离氨基酸含量为2.30%、咖啡碱含量为3.32%、可溶性糖总量为9.04%。所制得的速溶绿茶干茶色泽嫩绿,汤色黄绿尚亮,滋味醇厚鲜爽,溶解性良好。经优化后的速溶绿茶超声波提取工艺设计合理、稳定可行且重复性高,所制速溶绿茶品质较优。

三种广西不同地区绿茶中总黄酮的提取及其抗氧化活性研究

为研究广西不同地区绿茶的总黄酮提取工艺及其抗氧化活性,该试验以三种广西不同地区(桂北、桂中、桂南)绿茶为原料,采用微波辅助提取法提取总黄酮,在单因素试验的基础上,通过正交试验对三种绿茶总黄酮的微波辅助提取条件进行优化,并根据1,1-二苯基-2-三硝基苯肼(DPPH)、羟基自由基清除能力评价其抗氧化活性。结果表明,桂北地区绿茶最佳提取条件为乙醇体积分数为60%、料液比为1∶60(g∶mL)、微波功率为600 W;桂中地区绿茶最佳提取条件为乙醇体积分数为50%、料液比为1∶50(g∶mL)、微波功率为500 W;桂南地区绿茶最佳提取条件为乙醇体积分数为50%、料液比为1∶50(g∶mL)、微波功率为600 W。在此优化条件下,三种绿茶的总黄酮得率分别为(12.29±0.56)%、(12.51±0.39)%、(14.32±0.42)%。体外抗氧化试验结果表明,三种绿茶总黄酮清除DPPH自由基能力较强,对羟基自由基有一定的清除能力。

绿茶提取物作为酸洗缓蚀剂的性能研究

在众多金属防腐方法中,缓蚀剂具有用量少、效果明显、方便经济等优点,备受研究人员的关注,而近年来,植物提取物由于其来源广泛,绿色环保等优势更是研究热点。使用超声提取法从绿茶中提取活性物质作金属酸洗缓蚀剂,采用了失重法探究了其在1mol·L^(-1)HCl溶液中对碳钢片的缓蚀作用,并通过单因素实验和正交实验(L9(3~3))探究不同温度、不同时间和不同绿茶提取物浓度下对碳钢片的缓蚀效率,为后续工作提供一定的数据支撑。通过实验发现,在实验温度为30℃,作用时间为10h,缓蚀剂用量为0.16mg·mL^(-1)时,具有良好的缓蚀效率,可以达到88.60%。最后通过红外表征初步探讨了其缓蚀机理。

基于HS-SPME-GC-MS对不同等级双井绿茶香气物质的研究

为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一级和双井绿茶二级四个不同等级的双井绿茶的香气物质进行了检测分析。结果表明,从四个不同等级的双井绿茶中共鉴定出70种香气物质,主要包括醇类、烯烃类、烷烃类、酯类等化合物。不同等级的双井绿茶中香气物质组成及相对含量均有差异,通过主成分分析(Principal component analysis,PCA)和偏最小二乘法-判别分析(Partial least squares-discriminant analysis,PLS-DA),可以有效区分不同等级的双井绿茶。不同等级双井绿茶香气差异主要由反式-β-金合欢烯、香叶醇、水杨酸甲酯、茉莉酮、苯乙醇等14种关键化合物差异引起。在不同等级双井绿茶中关键香气物质表现出不同的分布规律,随着芽叶开展,α-椰油烯、石竹烯及己酸乙酯含量降低,而顺式-3-己烯醇、香叶醇及水杨酸甲酯含量呈增加趋势,芳樟醇、茉莉酮、反式-橙花叔醇含量从低到高,随后含量又迅速下降。本文研究了不同等级双井绿茶中香气物质的组成特征及关键香气物质的分布规律,为今后双井绿茶生产提供了理论依据。

植物中药抗菌驱蚊功能棉纤维的制备及性能

为了赋予棉纤维抗菌、防蚊功能,将植物精油微胶囊、尼姆树果实、绿茶提取物配制成一定浓度的混合液,再放入经过预处理的棉纤维进行特殊处理,制得抗菌驱蚊棉纤维,并利用相关仪器或设备测试了该纤维的相关性能。结果表明:与未经处理的棉纤维相比,处理后的抗菌驱蚊棉纤维断裂强度降低了0.33 cN/dtex,断裂伸长率增加了1.04%,回潮率增加了1.51%。由抗菌驱蚊棉纤维洗前和水洗20次抗菌效果对比分析可知,功能棉纤维对3种菌的抑制率分别可以达到98.60%、97.22%、95.34%和95.42%、93.51%、90.46%;水洗0次和水洗20次的驱蚊率分别达到78.80%和47.80%。

市售冷泡绿茶主要品质成分冷泡浸出规律研究

“冷泡茶”(Cold-brewing tea)因其最大程度保留了茶叶的鲜爽味且兼具饮用便利性,已成为消费者追捧的新型茶饮。文章系统研究了7个市售冷泡绿茶以及1个自制冷泡龙井茶的主要品质成分及其冷水浸出规律。结果表明,冷泡茶的含水率在4.12%~12.95%之间,差异较大;水浸出物、茶多酚、游离氨基酸和咖啡碱含量范围分别在34.06%~45.32%、23.99%~32.04%、3.03%~4.22%和2.78%~3.21%。随着冷水浸泡时间延长,茶汤中主要品质成分含量均逐渐增加。冷水浸泡40 min,所有样品的茶汤中水浸出物溶出率为19.7%~51.4%、茶多酚溶出率5.3%~19.0%、氨基酸溶出率24.4%~93.1%、咖啡碱溶出率在18.4%~39.3%。冲泡方式显著影响茶叶中茶多酚、氨基酸和咖啡碱的溶出率,冲泡20 min后茶多酚冷/热水溶出比为0.30~0.60、咖啡碱冷/热水溶出比为0.18~0.34、游离氨基酸冷/热水溶出比超过0.70,冷水浸泡茶汤中游离氨基酸溶出率较茶多酚和咖啡碱高,是冷泡绿茶口感更加鲜爽的主要原因。本研究结果可为冷泡茶产品质量标准制定和新型冷泡茶产品开发提供理论依据。

绿茶籽水溶性提取物的物化性质研究

利用水提法提取绿茶籽水溶性物质(TSW),通过热凝胶法制备质量分数15%的TSW凝胶。使用DPPH法和试剂盒法,测定提取物自由基清除率和总抗氧化能力;利用乳析指数和显微观察判断其稳定乳液的能力,测定TSW凝胶的凝胶指数和凝胶保水性。结果表明:TSW质量分数为0.3%时,DPPH清除率最大,为17.53%,证实TSW质量分数越大,抗氧化能力越强;油相体积分数增加可提高TSW乳液的储存稳定性;质量分数15%的TSW溶液在90℃完全成胶,室温下凝胶保水性均大于98%。

绿茶在水醇复合体系中的浸提规律研究

为探究绿茶在水醇复合体系中的浸提规律,以绿碎片茶为原料,研究绿茶在酒精度45%vol的白酒和不同浓度乙醇溶液中浸提的总浸提率、浸提液中茶多酚和游离氨基酸含量,以及浸提液的色差值。结果表明,绿茶在酒精度45%vol的白酒中浸提50 min,料液比1∶20(g/mL)、1∶30(g/mL)和1∶40(g/mL)对应的总浸提率分别为29.29%、30.02%和32.19%;浸提液中茶多酚含量分别为9.72 mg/mL、6.43 mg/mL和5.07 mg/mL;浸提液中游离氨基酸含量分别为1.96 mg/mL、1.50 mg/mL和0.91 mg/mL;随着浸提时间延长,浸提液色差L^(*)值逐渐降低,a^(*)值和b^(*)值逐渐增大。绿茶在乙醇浓度为40%时总浸提率最大为29.93%;乙醇浓度为50%时浸提液中的茶多酚浓度最高为6.17 mg/mL;乙醇浓度为30%的浸提液中游离氨基酸浓度最大为1.53 mg/mL。结合产业分析,可以选择乙醇浓度50%左右的酒溶液浸提绿茶,料液比1∶30(g/mL),时间为50 min。