Changes in Polyphenols and Antioxidant Activities of Yingshan Yunwu Tea during Digestion in Vitro

[Objectives]To explore the change rule of polyphenol content and antioxidant activity of coarse old leaves of Yingshan Yunwu Tea in the process of human digestion.[Methods]The coarse and old leaves of Yunwu tea in Yingshan,Huanggang,Hubei Province were selected as the research object,and their digestion in vitro was simulated.The total polyphenol content was determined by Folin-phenol reagent colorimetric method,and the DPPH radical scavenging activity and total antioxidant activity were determined.[Results]After simulated gastrointestinal digestion in vitro,the polyphenol content and antioxidant activity of coarse old leaf tea soup showed a downward trend.After gastrointestinal digestion,the polyphenol content in tea infusion separately decreased by 31.8%and 8.5%;the scavenging rate of DPPH free radical was 97%before digestion,decreased to 92%after gastric digestion and 65%after intestinal digestion,which decreased by 5%and 27%,respectively;after gastrointestinal digestion,the total antioxidant capacity of tea soup decreased by 4.7%and 3.1%,respectively.[Conclusions]This study provided a reference for the development and application of coarse old leaves of Yingshan Yunwu tea,and provided a reference for the nutritional value evaluation and comprehensive utilization of coarse old leaves,so as to make the best use of coarse tea leaves and reduce the waste of resources.

Preparation and properties of waste tea leaves particleboard

Urea-formaldehyde （UF） adhesive is the main source of formaldehyde emission from UF-bonded boards. The components in waste tea leaves can react with formaldehyde to serve as a raw material in the production of low formaldehyde emission boards. In our study, waste tea leaves and UF adhesive were employed in the preparation of waste tea leaves particleboard （WTLB）. An orthogonal experimental method was applied to investigate the effects of process parameters on formaldehyde emission and mechanical properties of WTLB. The results indicated that： 1） waste tea leaves had the ability to abate formaldehyde emission from boards; and 2） density of the WTLB was a significant factor affecting its modulus of rupture （MOR）, modulus of elasticity （MOE） and internal bonding （IB）.

Development and validation of an analytical method for detecting chlorantraniliprole residues in fresh tea leaves

An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troublesome matrix containing abundant pigments,via gas chromatography with an electron capture detector.Acetonitrile was used as the extraction solvent,with sodium chloride enhancing the analyte partition in the organic phase.The optimal mixture of MWCNTs and primary secondary amine(PSA)was based on the distribution of the target analyte recovery and on the clean-up efficiency;while matrix-matched calibration was recommended to combat the matrix effect.Mean recoveries of 95.2%–108.8%were obtained with intraday and interday precisions of less than 7.9%and 10.3%,respectively.Good linearity was observed for concentrations of 0.02–1.0 mg/kg with a correlation coefficient of 0.9984.The limits of detection and quantification were 0.005 mg/kg and 0.02 mg/kg,respectively.The method was employed to investigate the dissipation dynamics of chlorantraniliprole in fresh tea leaves with real field samples.Consequently,the dissipation rates of chlorantraniliprole in fresh tea leaves followed pseudo-first-order kinetics with a half-life of 1.9 d,and the average chlorantraniliprole residue content was below 0.02 mg/kg with a harvest withholding period of 14 d.

Determination of Vitamin B₁₂in Chinese Black Tea Leaves

We determined vitamin B12 content of Chinese black tea leaves using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.25 - 0.69 μg/100g dry weight) of vitamin B12 were detected in Pu’er, Fu, and Brick tea leaves. However, vitamin B12 content (0.06 - 1.37 μg/100g dry weight) of Ryubao tea leaves significantly varied. To determine whether Chinese black tea leaves contain vitamin B12 or other corrinoid compounds that are inactive in humans, corrinoid compounds were purified from Ryubao tea by an immunoaffinity column chromatography and vitamin B12 was identified by liquid chromatography-electrospray ionization/tandem mass spectrometry. Vitamin B12 content in the tea drink prepared from Ryubao tea leaves was very low (0.8 ng/100mL). Our results indicate that Chinese black tea is usually not a good source of B12, although Ryubao tea leaves with the highest B12 content may be utilized as a source of this vitamin for vegerarians.

Determination of 18 Kinds of Amino Acids in Fresh Tea Leaves by HPLC Coupled with Pre-column Derivatization

A rapid and accurate quantitative method of high performance liquid chromatography( HPLC) with fluorescence detector has been developed for the analysis of 18 kinds of amino acids in fresh tea leaves. The samples were minced and mixed,and extracted with ultra pure water at 90℃ for 20 min. The 6-aminoquinolyl N-hydroxy-succinimidyl carbamate( AQC) was used as pre-column derivatization reagent. Gradient HPLC separation was performed on a C_(18) column( Symmetry C_(18),3. 9 mm × 15 cm,4 μm). Good linearity between concentrations and peak areas was achieved in the concentration range of 5. 0-250 μmol/L for 18 kinds of amino acids. The method was validated by the analysis of five replicates. The 18 kinds of amino acid standards were spiked in fresh tea leaf samples and the average recovery rate was 86. 25%-109. 05% with relative standard deviations( n = 5) ranging from 6. 03% to 10. 56%. The limit of detection( LOD) for the analytes was0. 05-1. 27 μmol/L. The method was successfully applied to the analysis of the 18 kinds of amino acids in fresh tea leaves from east Dongting and west Dongting mountains in Suzhou. The results indicate that the method is simple,rapid,precise and reliable.

Synthesis of activated carbon from spent tea leaves for aspirin removal

Adsorption capacity of activated carbon prepared from spent tea leaves(STL-AC) for the removal of aspirin from aqueous solution was investigated in this study. Preliminary studies have shown that treatment with phosphoric acid(H_3PO_4) increased removal efficiency of STL-AC. Characterizations on STL-AC revealed excellent textural properties(1200 m^2·g^(-1), 51% mesoporosity), as well as distinctive surface chemistry(1.08 mmol·g^(-1) and 0.54 mmol·g^(-1) for acidic and basic oxygenated groups, pH_(pzc)= 2.02). Maximum removal efficiency of aspirin observed was 94.28% after 60 min when the initial concentration was 100 mg·L^(-1), 0.5 g of adsorbent used,pH 3 and at a temperature of 30 ℃. The adsorption data were well fitted to the Freundlich isotherm model and obeyed the pseudo-second order kinetics model. The adsorption of aspirin onto STL-AC was exothermic in nature(ΔH~Θ=^(-1)3.808 k J·mol^(-1)) and had a negative entropy change, ΔS~Θ(-41.444 J·mol^(-1)). A negative Gibbs free energy, ΔG~Θ was obtained indicating feasibility and spontaneity of the adsorption process. The adsorption capacity of AC-STL(178.57 mg·g^(-1)) is considerably high compared to most adsorbents synthesized from various sources, due to the well-defined textural properties coupled with surface chemistry of STL-AC which favors aspirin adsorption. The results demonstrate the potential of STL-AC as aspirin adsorbent.

Utilization of Infused Tea Leaves (Camellia sinensis) for the Removal of Pb2+, Fe2+ and Cd2+ Ions from Aqueous Solution: Equilibrium and Kinetic Studies

In this study, infused tea leaves as a low-cost adsorbent have been used in the removal of the Pb2+, Fe2+ and Cd2+ ions from aqueous solution. The adsorption study was carried out in a batch process and the effects of parameters such as initial pH, adsorbent dose, contact time and initial metal ion concentration were investigated. Experimental results showed that the maximum adsorption of metal ions occurred at pH 5 for Pb2+ and Fe2+ and at pH 6 for Cd2+. Adsorption of metal ions increased with increasing adsorbent concentration and contact time. The isothermal data for the adsorption of metal ions by infused tea leaves were found to fit well with the Langmuir equations. Based on the experimental data of the Langmuir isotherm model, the maximum adsorption capacities of the metal ions onto the infused tea leaves were found in the order of Pb2+ > Cd2+ > Fe2+ with the adsorption capacities of 26.32 mg·gǃ, 14.29 mg·gǃ and 12.38 mg·gǃ respectively. The adsorption process followed the pseudo-second order reaction and the corresponding rate constant were found to be 4.30 × 10Dž g·mgǃ·minǃ, 1.75 × 10ǃ g·mgǃ·minǃ and 1.45 × 10DŽ g·mgǃ·minǃ for Pb2+, Fe2+ and Cd2+ ions respectively.

Aluminum Contents in Dry Leaves and Infusions of Commercial Black and Green Tea Leaves: Effects of Sucrose and Ascorbic Acid Added to Infusions

Tea consumption has increased due to its beneficial effects. Results from a lab study on the effect of sucrose (5 g per cup, 150 mL) and/or ascorbic acid (2 mL per cup, 150 mL) on dissolved aluminum compounds during the infusion of two commercial types of dry tea leaves (black, green) with boiling water (5, 15 min infusion time) are presented. Factors influencing the presence of dissolved aluminum in the infusions of both tea leaves were infusion time and sugar contents, as well as the interaction between ascorbic acid and sucrose (p < 0.05). Aluminum contents found after 15 min of infusion were 0.7 mg L–1 for black tea infusions added with sugar, and 0.69 mg L–1 for green tea added with both sugar and ascorbic acid. Both concentrations are higher than the level accepted in Mexico for drinking water (there is no act concerning tea infusions), that is 0.2 mg L–1.

Degradation of Dye Wastewater by Pulsed High-Voltage Discharge Combined with Spent Tea Leaves

Degradation of methylene blue （MB） was performed using the pulsed discharge process （PDP） combined with spent tea leaves （STLs）. The effects of STL dosage, concentration of initial solution, and pH were analyzed in the combined treatment. Results showed that the combined treatment was effective for dye wastewater degradation; when the dosage of STLs was 3.2 g/L, the degradation efficiency reached 90% after 15 rain treatment, and STLs showed a good repeatability. The degradation rate decreased with increasing initial MB concentration but not related to the solution pH in the combined treatment. Fourier-transform infrared spectra and N2 adsorption suggested that the number of acidic and basic groups in the STL surface increased after the treatment, but the surface area and pore volume remained unchanged.

Elemental Analysis of Tea Leaves (Camellia Sinensis) and Their Own Soils at Eastern Black Sea Region in Turkey

People consume tea brewed from the leaves of the Camellia sinensis plant for about 50 centuries. Health benefits of the tea have been investigated for about three decades. Especially green tea shows antitoxic and lots of properties with its determined ingredients. Turkey is not only the one of the best consumer and but also good producer of the tea as being 5 th producer all over the world. It grows eastern region of the Turkey and high quality tea is imported and exported. To have quality tea, grooving soils are also crucial. In the current research, Tea leaves and their own grown soils were collected from 20 stations where the most tea producer cities as Trabzon, Rize and Artvin tea fields of the eastern of Black Sea Region in Turkey. The cultivated tea and their own grown soil samples were analysed by using EDXRF Spectrometry. In the soil samples, the elements Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, Pb on percent level and the elements Mg, Al, Si, P, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn and Sr in the tea leaves were detected by using SKRAY 3600-EDXRF.and also the obtained data were evaluated with the Kriging interpolation of geostatistical method. Element content were investigated in the soil and tea samples according to the geological situations and also the relation of elemental difference between the tea and the own grown soil. Pb/Zn ratio was also anaysed in the samples.

Adsorptive Removal of Heavy Metals from Aqueous Solution with Environmental Friendly Material—Exhausted Tea Leaves

In this study adsorptive removal of Pb(II) and Cu(II) from aqueous solution by using environmental friendly natural polymers present in exhausted tea leaves has been studied. The biosorbent was modified with dimethylamine to introduce N-functional groups on the surface of adsorbent. The modified adsorbent was characterized by elemental analysis, zeta potential analysis, SEM, DRFTIR, XRD and TG/DTA analysis to conform the modification. Adsorption capacity of the adsorbent was determined as the function of pH of the solution, initial concentration of the solution and contact time. The adsorption experiments were performed using batch experiments. The maximum adsorption capacities of the adsorbent were found to be 91.68 and 71.20 mg/g for Pb(II) and Cu(II), respectively. To minimize the process cost, regeneration of the biosorbent and recovery of metal ions was explored by desorption study. The results indicate that the adsorbent holds great potential for the sequestration of Pb(II) and Cu(II) from their aqueous solution. Hence the modified exhausted tea leaves (MTL) have been investigated as a new cost effective and efficient biosorbent for removal of Pb(II) and Cu(II) from their aqueous solution.

The Spectral Emission Characteristics of Laser Induced Plasma on Tea Samples

Laser induced breakdown spectroscopy （LIBS） provides a useful technique for food security as well as determining nutrition contents. In this paper, optical emission studies of laser induced plasma on commercial tea samples were carried out. The spectral intensities of Mg, Mn, Ca, A1, C and CN vibration bands varying with laser energy and the detection delay time of an intensified charge coupled device were studied. In addition, the relative concentrations of six microelements, i.e., Mg, Mn, Ca, Al, Na and K, were analyzed semi-quantitatively as well as H, for four kinds of tea samples. Moreover, the plasma parameters were explored, including electron temperature and electron number density. The electron temperature and electron number density were around 11000 K and 1017 cm-3, respectively. The results show that it is reasonable to consider the LIBS technique as a new method for analyzing the compositions of tea leaf samples.

Determination of the Minerals of the Herbal Tea and Tea Green from Lippia multiflora

This study aims to determine the mineral composition of green teas and herbal tea in the savannah tea plant. Samples of buds, young leaves and broadleaf stems were collected from wild plants of Lippia multiflora in three localities, including two from the Center (Yamoussoukro, Toumodi) and one from the northeast (Bondoukou) of C&#244;te d’Ivoire. The lipid and ash contents were carried out by the AOAC method. The total protein and sugar contents were determined by the Kjeldahl and Agbo methods, respectively. Nine minerals (potassium, calcium, magnesium, iron, sodium, manganese, zinc, copper and cadmium) were quantitated by Atomic Absorption Spectrophotometry (AAS) from green teas (buds and young leaves) and herbal tea of Lippia multiflora. The results showed that ash levels (7.05% - 13.94%) and protein (6.22% - 9.97%) were high, however the lipid contents (1.01% - 2.98%) and total sugars (1.43% - 4.51%) are low. Majority of the minerals are calcium (2320.91 to 36150.10 mg/kg), potassium (2110.71 to 12174.67 mg/kg) and magnesium (3620.87 - 5870.46 mg/kg). Iron (52.55 to 483.11 mg/kg), sodium (35.66 to 469.16 mg/kg) and manganese (15.25 to 76.86 mg/kg) are represented in average proportions. There are small amounts of zinc (9.61 - 47.50 mg/kg), copper (5.66 - 8.71 mg/kg), and cadmium (0.17 - 1.49 mg/kg). Lippia multiflora herbal teas and green teas are low in fat, high in ash and are good sources of protein and minerals.

Study on Dishes with Longjing Tea Leaves as Spice

As one of the top ten Chinese teas, Longjing Green Tea is famous for its green tea leaves, sweet taste, pleasant aroma and beautiful shape. Besides of using as drinks, Longjing tea leaves can be applied as spice in Chinese cuisine for its particular taste and function. Under the background of pursuing healthy cuisine, the development of organic Longjing tea and advocate of Chinese tea culture have great economic and culture significance.

Antioxidant Ability of Green Tea in Conjunction with Processing and Quality

First order interaction of antioxidant capability of epicatechin was investigated in vitro by methods of response surface and central composite general rotary design.The results indicated that based on molar concentration,the ability to scavenge free radicals were in the order:ECG > EC > EGCG > ECG × EGCG > EGC.This suggests that the antioxidant ability of individual catechin had positively interacted effects under physiological condition.The free radical scavenging ability changed during tea processing.As compared with the fresh tea leaves,the leaves after indoor-spreading and Yao-Qing had a higher IC50of for DPPH free radical scavenge,being increased by 11.01%.It is deduced that the process technology of indoor-spreading might improve the quality of manufactured green tea.

早青与晚青乌龙茶的挥发性成分差异

为探明鲜叶不同采摘时段对乌龙茶香气化学特征的影响,本研究将铁观音早青与晚青按传统工艺加工成乌龙茶,运用气相色谱-质谱法分析鲜叶和乌龙茶的挥发性成分,比较早青茶与晚青茶中挥发性成分的差异。结果表明,晚青茶所含挥发性组分总量比早青茶少28.3%,醇类化合物的含量及占比均处优势,尤其是异植醇和反-橙花叔醇。挥发性成分在鲜叶与乌龙茶中的组成特征差异较大,醇类和酸类化合物在鲜叶中的占比相近,但在乌龙茶中二者差异较大;早青与晚青包含56种共有挥发性成分,比其乌龙茶的共有成分多4种,但在鲜叶与乌龙茶共有42种成分中十六烷酸、二氢猕猴桃内酯、反-橙花叔醇、异植醇等受加工工艺的影响明显,且变化幅度较大。可见晚青与早青中挥发性成分的分布特征相异,晚青茶优于早青茶且清香突出。

轻揉捻轻发酵条件下茶树品种‘湘波绿’与‘槠叶齐’红茶品质分析

采摘茶树品种‘湘波绿’‘槠叶齐’春梢一芽一叶及一芽二叶,采用轻揉捻轻发酵工艺分别制成红茶,对茶样进行感官审评与生化成分检测分析。感官审评结果表明,轻揉捻轻发酵条件下两品种红茶香气兰花香显(‘湘波绿’一芽一叶红茶)、有花香(‘湘波绿’一芽二叶红茶)、带花香(‘槠叶齐’一芽二叶红茶);条索分别较紧结(一芽一叶红茶)或尚紧结(一芽二叶红茶);汤色明亮,分别为橙红(一芽一叶红茶)或尚红(一芽二叶红茶);滋味均表现为鲜醇。一芽一叶红茶生化成分检测结果表明,‘湘波绿’红茶水浸出物略低于‘槠叶齐’红茶,氨基酸含量等则相当;两品种红茶的香气成分均以醇类含量最高,其次是酯类和醛类。‘湘波绿’红茶酯类、醇类和酸类香气化合物含量高于‘槠叶齐’红茶。‘湘波绿’一芽一叶红茶主要香气成分有香叶醇、芳樟醇、水杨酸甲酯、氧化芳樟醇Ⅱ(呋喃型)、顺-茉莉酮、氧化芳樟醇Ⅰ(呋喃型)、顺-己酸-3-己烯酯、反-柠檬醛和橙花醇,‘槠叶齐’一芽一叶红茶主要香气成分有香叶醇、芳樟醇、水杨酸甲酯、氧化芳樟醇Ⅱ(呋喃型)、顺-茉莉酮、氧化芳樟醇Ⅰ(呋喃型)、橙花醇、反-柠檬醛、顺-罗勒烯和顺-己酸-3-己烯酯;香叶醇、芳樟醇、水杨酸甲酯3种香气成分含量两品种均相当,氧化芳樟醇Ⅱ(呋喃型)和氧化芳樟醇Ⅰ(呋喃型)、顺-茉莉酮、顺-己酸-3-己烯酯、桃金娘烯醇、a-萜品醇、2,6-二甲基-5-庚烯醛、苯乙醛、反-3,7-二甲基-2,6-丁二烯酸等‘湘波绿’高于‘槠叶齐’,反-3-己烯醇、2-正戊基呋喃、苯甲醛、杜松烯、异戊酸叶醇酯、己醇、壬醛、反,反-2,4-庚二烯醛、反-2-己烯醇、1-辛烯-3-醇、紫罗酮、月桂烯等‘湘波绿’低于‘槠叶齐’。这些生化成分含量及其差异分别构成了轻揉捻轻发酵工艺条件下‘湘波绿’红茶和‘槠叶齐’红茶的品质特征。试验结果可为优质红、绿茶适制茶树品种‘湘波绿’及‘槠叶齐’的加工利用及提升红茶品质新工艺探索提供一定的启示与参考。

基于PLC的茶叶揉捻机压力动态调节方法

传统茶叶揉捻机在工作时,茶叶在揉捻筒内不停翻滚,导致茶叶受到的压力忽大忽小,变化剧烈,对压力无法量化和精准控制,为此,提出了一种揉捻压力实时动态调节的控制方法,对控制系统的硬件、算法和程序进行了详细阐述。该系统能将压力值量化,确保了揉捻压力控制的动态调节、实时性和精准控制,加装该系统的茶叶揉捻机在成条率、碎茶率和生产效率方面均达到了行业标准要求。

大型连续绿茶精制加工生产线研发

茶叶加工技术与装备是茶叶产业发展的基础,对行业发展起着举足轻重的作用。为实现绿茶加工机械自动化生产,设计了大型连续绿茶精制加工生产线,阐述了该生产线系统结构、主要生产环节及安装调试应用。基于PLC控制的大型连续绿茶精制加工生产线,主要由鲜叶上料输送机、大型滚筒杀青机、冷却回潮机、四机协同联动式揉捻机组、并列连续预烘干机组、储料仓、计量分料装置、茶叶炒干与抛光机组、筛分装置、风选装置及配套的测控系统等组成。针对绿茶加工工艺的各个环节,采用模块化设计,根据茶叶加工企业的厂房实际情况,灵活安装组线,满足企业个性化需求。基于模糊PID温度控制的大型滚筒杀青机双模糊控制技术,解决了传统杀青温度与时间无法实现精确控制的难点问题。采用链式刮板输送智能加料装置与多机联动协同连续揉捻控制技术,实现多机协同联动式自动加料连续揉捻,边进料边揉捻,揉捻均匀度高。生产线上杀青机、理条机和烘干机各环节温度采用模糊PID控制,解决了茶叶加工温度、投叶量与杀青、理条、烘干时间实时配合的问题,输入不同等级、不同重量的鲜叶可输出相适应的杀青温度和时间,实现对茶叶生产过程的精确控制,减少人为因素的干扰,实现绿茶的智能化生产。近年来,生产线用户遍布皖、苏、浙、云、贵、川、豫、湘、鄂和陕等10多个省份200余家茶叶生产企业。该生产线的推广应用,实现了茶叶规模化生产,保证了茶叶品质,对茶产业发展具有重要意义。