基于UPLC-MS/MS同时分析福建乌龙茶和白茶中的儿茶素类物质

目的:建立超高效液相色谱-串联质谱法(UPLC-MS/MS)快速分析茶叶中儿茶素类物质如儿茶素(Catechin,C)、表儿茶素(Epicatechin,EC)、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)等,对几种福建乌龙茶和白茶中的儿茶素类物质进行分析。方法:实验使用Waters T3 C₁₈色谱柱(250 mm×4.6 mm,5 μm),以0.1%(V/V)甲酸水溶液和甲醇为流动相对目标物进行梯度洗脱后,电喷雾正离子扫描方式下多反应监测(MRM)模式分析。结果:8 min内即可完成茶叶中8种儿茶素类物质的上机检测;儿茶素类物质的检出限为0.2~1.1 μg/L,线性方程的相关系数(r)为0.9966~0.9994。用建立的方法分析所采集的几种福建茶叶样品,表没食子儿茶素没食子酸酯(EGCG)相对于其它儿茶素类物质在茶叶中的含量最高,约占茶叶中儿茶素总量的60%。乌龙茶中儿茶素总量的含量范围为43.59~45.21 mg/g,白茶儿茶素总量的含量范围为50.52~70.71 mg/g。结论:建立的方法灵敏、准确、快速,研究结果可为福建茶叶产品的开发提供一定的科学依据。     

超高效液相色谱法测定糕点及饼干中儿茶素的含量

目的建立超高效液相色谱法(ultra performance liquid chromatography,UPLC)测定糕点及饼干中儿茶素含量的检测方法。方法使用UPLC完成糕点及饼干中儿茶素(catechin,C)、表儿茶素(epicatechin,EC)、没食子儿茶素(gallocatechin,GC)、表没食子儿茶素(epigallocatechin,EGC)、表儿茶素没食子酸酯(epicatechin gallate,ECG)、没食子儿茶素没食子酸酯(gallocatechin gallate,GCG)和表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)等7种儿茶素类化合物的测定。最佳色谱条件为以Phenomenex Kinetex-C_(18)(2.1 mm×100 mm,2.6μm)色谱柱,0.1%甲酸水和0.1%甲酸乙腈为流动相进行梯度洗脱,紫外检测波长278 nm。结果在1.0~100 mg/L范围内,儿茶素类化合物的校正曲线方程的线性良好(相关性系数0.9941~0.9998),检出限(limit of detection,LOD)为0.2 mg/L。糕点及饼干的加标回收率在82.2%~109%,相对标准偏差为2.3%~9.3%。结论该方法简单、快速、高效,且回收率较高,适用于糕点及饼干中茶多酚的检测。     

HPLC法同时测定茶叶中儿茶素类和咖啡因的含量

为了建立了一种等度洗脱茶叶中6种儿茶素类没食子儿茶素(GC)、表没食子儿茶素(EGC)、儿茶素(C)、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯(ECG)、表儿茶素(EC)及限量成分咖啡因(CAF)的高效液相色谱(HPLC)定量测定的方法,采用汉邦Benetnach TM C18(5μm×4.6mm×250mm)色谱柱,流动相为甲醇∶水∶磷酸(28∶72∶0.1,v/v/v),流速为0.8m L·min-1,UV检测波长为280nm,柱温为30℃。结果表明GC、EGC、C、EGCG、ECG、EC和CAF分别在0.10~1.00、0.16~1.00、0.10~1.00、0.05~0.50、0.10~1.50、0.10~2.00和0.02~1.00mg·m L-1内线性关系良好,相关系数在0.9984~0.9999间;平均加样回收率为100.89%(EGCG),99.07%(CAF);样品分析中,除GC的分离度RS1外,其他6个成分RS均2。该方法简单、快速、准确、重现性好,可用于儿茶素类和咖啡因的定量检测。     

儿茶素和表儿茶素异构体的高效逆流色谱分离制备

应用高效逆流色谱法(HPCCC)对茶叶中的儿茶素和表儿茶素两种同分异构体的分离制备方法进行研究。结果表明：以正己烷-乙酸乙酯-水(体积比1:20:20)为两相溶剂系统,上相为固定相,下相为流动相,可以实现儿茶素和表儿茶素的完全分离。采用138mL的分离柱、1g儿茶素粗提物,在120min内一次制备即可得到纯度在95%以上的表儿茶素约35mg,纯度在99%以上的儿茶素325mg,纯度90%～99%的儿茶素100mg。     

茶叶中多种功能成分含量测定与分析研究

目的 建立高效液相色谱法同时测定茶叶中20种功能成分(儿茶素、表儿茶素、没食子儿茶素、表没食子儿茶素、没食子儿茶素没食子酸酯、表儿茶素没食子酸酯、表没食子儿茶素没食子酸酯、芦丁、槲皮素、山奈酚、金丝桃苷、山奈酚-3-O-芸香糖苷、没食子酸、对羟基苯丙酸、咖啡碱、茶黄素、茶黄素-3-没食子酸酯、茶黄素-3’-没食子酸酯、茶黄素-3,3’-双没食子酸)含量, 并比较分析不同种类茶叶中功能成分差异情况。方法 茶叶样品经80%甲醇水溶液超声辅助提取后离心, 采用Waters C18 柱(4.6 mm×250 mm, 5.0 μm), 以乙腈-0.5%乙酸为流动相进行梯度洗脱, 流速0.7 mL/min, 紫外检测器于270 nm和360 nm双波长进行目标化合物的检测。并分析不同加工工艺茶叶中20种功能成分的差异。结果 20种分析化合物在0.05~200 mg/L浓度范围内线性关系良好(r>0.999), 加标回收率为82.29%~117.37%, 相对标准偏差均小于7.99%, 20种化合物的检出限为0.007~0.15 mg/L, 定量限为0.02~0.45 mg/L。茶叶实际样品分析结果表明不同加工工艺的茶叶中20种成分含量和总含量差异较大。结论 该方法分析快速简便、稳定和重复性好, 可用于茶叶中20种化合物同时测定和定量分析。本研究可为茶叶功能成分的开发利用和品质评价提供参考 依据。     

同时检测茶叶中5种儿茶素和咖啡因的QuEChERS-HPLC方法研究

建立了一种同时测定茶叶中5种儿茶素儿茶素(C)、表儿茶素(EC)、表没食子儿茶素(EGC)、表没食子儿茶素没食子酸酯(EGCG)以及表儿茶素没食子酸酯(ECG)和咖啡因的QuEChERS-HPLC方法。茶叶样品用70%甲醇水在70℃条件下水浴提取,混合使用25 mg乙二胺-N-丙基硅烷(PSA)、200 mg十八烷基硅烷(C_(18))作为吸附剂,净化2 min;净化液过膜后采用Thermo Fisher Syncronis C_(18)色谱柱(250 mm×4.6 mm,5μm)分离。以甲醇-1.25%乙酸水溶液为流动相,梯度洗脱,流速为1 mL/min,测定波长278 nm。结果表明,5种儿茶素和咖啡因在各自相应的浓度范围内具有良好的线性关系(相关系数0.999 0～0.999 8),样品加标回收率为93.87%～107.37%,相对标准偏差为1.45%～11.85%。该方法操作简便、快速、准确,可满足茶叶中儿茶素和咖啡因的分析要求。     

HPLC法同时测定茶叶中聚酯型儿茶素和茶黄素

为建立茶叶中3种聚酯型儿茶素(聚酯型儿茶素A、聚酯型儿茶素B、聚酯型儿茶素C)和4种茶黄素(茶黄素、茶黄素-3-没食子酸酯、茶黄素-3'-没食子酸酯和茶黄素双没食子酸酯)同时检测的高效液相色谱分析方法,采用日本cosmosil 5C18-AR-Ⅱ柱(4.6 mm×250 mm),2个流动相分别为50 mmol/L磷酸和100%乙腈,流速为0.8 mL/min,柱温35℃,检测波长280 nm,外标法定量。在该分析条件下,各组分获得了良好的分离。在一定的范围内,线性关系显著,R2均在0.9925以上。重复性试验、精密度试验、稳定性试验的相对标准偏差(RSD)分别在0.01%~0.72%,0.04%~0.28%,0.02%~0.32%。加标回收率试验结果显示:聚酯型儿茶素各组分平均回收率在95.50%~120.13%,相对标准偏差0.41%~4.24%;茶黄素各组分平均回收率在84.14%~105.31%,相对标准偏差1.59%~4.59%。该方法具有较好的重复性、精密性、稳定性,可同时测定茶叶中聚酯型儿茶素和茶黄素。     

HPLC法测定黑豆皮中原儿茶酸、表儿茶素的含量

建立HPLC波长切换法同时测定黑豆皮中原儿茶酸、表儿茶素含量的方法。固定相为shim-pack VP-ODS C18(250 mm×4.6 mm,5μm),流动相为乙腈-0.1%磷酸溶液,流速为1.0 m L/min,检测波长为260、280 nm,柱温35℃。原儿茶酸、表儿茶素分别在0.010 52 mg/m L~1.052 mg/m L(r=0.999 6)和0.012 24 mg/m L~1.224 mg/m L(r=0.998 9)浓度范围内与峰面积呈良好的线性关系,平均回收率分别为99.46%(RSD=1.08%,n=6)和99.06%(RSD=1.02%,n=6)。     

高速逆流色谱法分离制备柿子中儿茶素及表儿茶素

采用HP2MGL大孔树脂对柿子中的儿茶素类物质进行初步分离,用高速逆流色谱进一步分离纯化柿子中的(-)-儿茶素、(-)-表儿茶素。结果表明,在以正丁醇-乙酸乙酯-水(体积比为1:2:3)组成的溶剂体系,上相为固定相,下相为流动相,转速800r/min,流速1mL/min的条件下进行HSCCC制备,经高效液相法测定,从58mg样品中分离出7.25mg(-)-儿茶素和0.43mg(-)-表儿茶素,纯度分别为98.3%和97.9%。     

康砖茶中儿茶素、咖啡因、没食子酸HPLC-DAD分析

采用二极管阵列检测器(DAD)和Acclaim TM 120色谱柱,建立了一种简单、灵敏分析茶叶中儿茶素、咖啡因(CAF)、没食子酸(GA)的高效液相色谱法。色谱条件:流动相为KH2PO4-乙腈系统,梯度洗脱,流速1.0m L/min,柱温25℃,进样量10μL,检测器波长为278nm。结果表明,6种儿茶素、咖啡因、没食子酸在一定范围内线性良好,相关系数为0.9991~0.9998,具有较低的日内和日间偏差,平均加标回收率在92.49%~106.08%之间,RSD小于3.59%。应用该方法对康砖茶进行分析,其GA、EGC、CAF、C、EC、EGCG、EGCG3"Me、ECG含量分别在0.0717%~1.115%、0.280%~0.660%、2.728%~4.621%、0~0.0882%、0.157%~1.238%、0.343%~7.176%、0~0.172%及0.108%~1.654%。     

Common tea formulations modulate in vitro digestive recovery of green tea catechins

Epidemiological evidence suggests a role for tea catechins in reduction of chronic disease risk. However, stability of catechins under digestive conditions is poorly understood. The objective of this study was to characterize the effect of common food additives on digestive recovery of tea catechins. Green tea water extracts were formulated in beverages providing 4.5, 18, 23, and 3.5 mg per 100 mL epicatechin (EC), epigallocatechin (EGC), epigallocatechin-gallate (EGCG), and epicatechin-gallate (ECG), respectively. Common commercial beverage additives; citric acid (CA), BHT, EDTA, ascorbic acid (AA), milk (bovine, soy, and rice), and citrus juice (orange, grapefruit, lemon, and lime) were formulated into finished tea beverages at incremental dosages. Samples were then subjected to in vitro digestion simulating gastric and small intestinal conditions with pre- and post-digestion catechin profiles assessed by HPLC. Catechin stability in green tea was poor with <20% total catechins remaining post-digestion. EGC and EGCG were most sensitive with less, not double equals 10% recovery. Teas formulated with 50% bovine, soy, and rice milk increased total catechin recovery significantly to 52, 55, and 69% respectively. Including 30 mg AA in 250 mL of tea beverage significantly (p<0.05) increased catechin recovery of EGC, EGCG, EC, and ECG to 74, 54, 82, and 45% respectively. Juice preparation resulted in the highest recovery of any formulation for EGC (81-98%), EGCG (56-76%), EC (86-95%), and ECG (30-55%). These data provide evidence that tea consumption practices and formulation factors likely impact catechin digestive recovery and may result in diverse physiological profiles.     

GREEN TEA CATECHINS AS INHIBITORS OF OXIDATION OF MEAT LIPIDS

Antioxidant activity of green tea catechins, namely, epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) was evaluated in a meat model system. The inhibitory effect on 2-thiobarbituric acid (TBA) values of catechins was concentration dependent, being highest at 200 mg/kg. At 200 mg/kg, the antioxidant activity of catechins as evaluated by TBA values was EGCG ≈ ECG > EGC > EC. The hexanal and pentanal contents in the headspace volatiles of meats treated with catechins at 200 mg/kg was also evaluated. These results indicated that EGCG was most active followed by ECG and EGC; EC was least effective. In comparison with α-tocopherol, catechins were generally more effective in controlling oxidation of meat lipids. Based on TBA results, butylated hydroxytoluene (BHT) was less effective, but exerted a better effect than catechins in prevention of oxidation as evidenced by the hexanal/pentanal data.     

远安黄茶啤酒抗氧化物质的分离与鉴定

以抗氧化活性为筛选导向,采用醇沉、溶剂萃取、大孔树脂分离和半制备型液相色谱联用技术从远安黄茶啤酒中分离出8 个具有抗氧化作用的关键组分。进一步结合超高效液相色谱-四极杆飞行时间质谱联用技术对抗氧化组分进行分析,共鉴定出8 种化合物,分别为表没食子儿茶素（(－)-epigallocatechin,EGC）、咖啡因、表没食子儿茶素没食子酸酯（(－)-epigallocatechin gallate,EGCG）、表儿茶素（epicatechin,EC）、1,2,6-三没食子酰-β-D-葡萄糖、表儿茶素没食子酸酯（(－)-epicatechin gallate,ECG）、柯里拉京（corilagin,Cor）和色氨酸（Trp）。抗氧化活性和定量研究发现,EGC、EGCG、EC、ECG和Cor是远安黄茶啤酒中的主要抗氧化物质,对酒体的抗氧化活性贡献可达54.61%。其中,EGCG的贡献值最大,其次为EGC、ECG、EC和Cor。本研究为鉴定茶啤酒中的关键抗氧化成分,实现高抗氧化啤酒产品的选择性研发提供了技术支撑。     

高速逆流色谱法分离绿茶中的化学成分

采用高速逆流色谱（high-speed countercurrent chromatography,HSCCC）法对绿茶化学成分进行分离。通 过对绿茶有效部位的分段萃取和多种溶剂系统的筛选,建立了绿茶化学成分HSCCC分离的方法。经HSCCC分离得 到咖啡碱、表没食子儿茶素、表儿茶素、儿茶素、表没食子儿茶素没食子酸酯、没食子儿茶素没食子酸酯、表儿茶 素没食子酸酯、没食子酸8 种单体化合物,其纯度分别为99.5%、97.2%、98.2%、97.6%、98.8%、99.1%、99.2%和 98.8%。该法分离效率高、操作简单,对绿茶在食品医药等领域的应用具有重要意义。     

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。     

Stability of Green Tea Catechins in Commercial Tea Leaves during Storage for 6 Months

ABSTRACT:  To help meet the needs of consumers, producers of dietary tea products, and researchers for information on health-promoting tea ingredients, we determined by HPLC 7 catechins [(−)-epigallocatechin (EGC), (−)-catechin (C), (+)-epicatechin (EC), (−)-epigallocatechin 3-gallate (EGCG), (−)-gallocatechin 3-gallate (GCG), (−)-epicatechin 3-gallate (ECG), and (−)-catechin 3-gallate (CG)] in samples of 8 commercial green tea leaves of unknown history sold as tea bags in the United States, Korea, and Japan. The samples were stored at 20 °C and sampled at 1 wk and 1, 2, 4, and 6 mo. The following ranges in the initial values (0 controls) were observed (in mg/g tea leaves): EGC and C, 0 to trace amounts; EC, 1.9 to 21.1; EGCG, 13.3 to 113.0; GCG, 0.2 to 1.6; ECG, 5.7 to 50.5; CG 0.5 to 3.7; total catechins 36.5 to 169.7. Statistical analysis of the results and plots of changes in individual and total catechin levels as a function of storage time indicate a progressive decrease in the content in the total levels, most of which is due to losses in the most abundant catechins, EGCG and ECG. Possible mechanisms of degradations of catechins during storage and the possible significance of the results to consumers of tea are discussed.     

冠突散囊菌固体发酵铁观音茶的主要活性成分及其抗氧化性分析

为提高铁观音茶青的利用率,采用冠突散囊菌固体发酵铁观音茶,检测发酵前后茶叶中化学成分和抗氧化性的变化。结果表明,铁观音茶叶经发酵后,与未发酵的对照组茶叶相比,多酚、表没食子儿茶素没食子酸酯（EGCG）、表儿茶素没食子酸酯（ECG）、茶黄素,游离氨基酸、麦芽糖、蔗糖和果糖等物质的含量显著性降低（P<0.05）,尤其EGCG和ECG分别下降了92.2%和88.1%,而总黄酮、表没食子儿茶素（EGC）、儿茶素（+C）、表儿茶素（EC）、总糖、葡萄糖、三萜类物质、茶红素和茶褐素等物质的含量显著性增加（P<0.05）,尤其茶褐素增加了68.4%。经过冠突散囊菌发酵过的茶叶与对照茶叶相比总还原力和Fe3+还原能力,清除DPPH自由基、ABTS+自由基、羟基自由基能力仍然很强。综上,冠突散囊菌的固体发酵降低了茶叶中具有苦涩味道的茶多酚,增加了总糖、茶红素、茶褐素、EGC、+C、EC等含量,研究为铁观音茶青的发酵利用提供了实验依据。     

Albumin causes a synergistic increase in the antioxidant activity of green tea catechins in oil-in-water emulsions

Model oil-in-water emulsions containing epicatechin (EC) and epigallocatechin gallate (EGCG) showed a synergistic increase in stability in emulsions containing added albumin. EGCG showed a stronger synergy (35%) with ovalbumin than did EC. Oxidation of the oil was monitored by determining peroxide values and hexanal contents. The effect of bovine serum albumin (BSA) on model oil-in-water emulsions containing each of the green tea catechins [epicatechin gallate (ECG), EGCG, EC and epigallocatechin (EGC)] was studied during storage at 30 °C. The green tea catechins showed moderate antioxidant activity in the emulsions with the order of activity being ECG ≈ EGCG > EC > EGC. Although BSA had very little antioxidant activity in the absence of phenolic antioxidants, the combination of BSA with each of the catechins showed strong antioxidant activity. BSA, in combination with EC, EGCG or EGC, showing the strongest antioxidant activity with good stability after 45 days storage. Model experiments with the catechins stored with BSA in aqueous solutions confirmed that protein–catechin adducts with antioxidant activity were formed between the catechins and protein. The antioxidant activity of the separated protein–catechin adducts increased strongly with storage time and was stronger for EGCG and ECG than for EC or EGC.     

ANTIOXIDANT PROPERTIES OF POLYPHENOLS EXTRACTED FROM GREEN AND BLACK TEAS

The catechins, including epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG), and the theaflavins, including theaflavin (TF), theaflavin monogallate (TF-1), and theaflavin digallate (TF-2), were extracted from green tea and black tea, respectively. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging ability, superoxide-scavenging efficiency, and lipid oxidation-inhibition ability of the pure compounds listed above as well as epicatechin (EC), carnosol, carnosic acid, and butylated hydroxytoluene (BHT) were investigated.
The DPPH radical-scavenging ability of the catechins was EGCG > ECG > EGC > EC and of the theaflavins was TF-2 > TF-1 > TF. EGCG, ECG, EGC, TF-2, TF-1, and TF showed higher DPPH radical- and superoxide-scavenging abilities than carnosol, carnosic acid, and BHT. EGCG, ECG, EGC, carnosol, and carnosic acid showed higher lipid oxidation-inhibition activity, as measured by the Rancimat method, than BHT and theaflavins.