蔗汁酒精废液中的黄酮类物质含量及其抗氧化活性的分析

采用分光光度法测定了蔗汁酒精废液中的黄酮类物质含量,研究了蔗汁酒精废液中抗氧化物质的抗氧化活性及其对自由基的清除效果,并将其与茶多酚进行比较。结果表明,蔗汁酒精废液色素的抗氧化活性为茶多酚的87．8％,具有较好的应用前景。     

客家擂茶——中国茶文化的一朵奇葩

擂茶是中国最古老的饮茶方法,它是中华茶文化的重要组成部分,虽然随着社会的发展变革,饮茶的方式发生了很大的变化,但是擂茶这种具有深厚文化底蕴的文化习俗却在客属地区代代相传。探寻它的流传与存在,让我们能再次充分领略古老饮茶习俗的魅力,为我们研究客家饮茶习俗的发展提供了历史的证明。     

Determination of catechins in green tea infusions by reduced flow micellar electrokinetic chromatography

A sulfated-β-cyclodextrin (s-β-CD) modified reduced flow micellar electrokinetic chromatography (RF-MEKC) method was developed and validated for the determination of catechins in green tea. The optimal electrolyte consisted of 0.2% triethylamine, 50 mmol/L SDS and 0.8% s-β-CD (pH = 2.9), allowing baseline separation of five catechins in 4 min. The samples and standards were injected at 0.6 psi for 5 s under constant voltage of −30 kV. Sample preparation simply involved extraction of 2 g of tea with 200 mL water at 95 °C under constant stirring for 5 min. The method demonstrated excellent performance, with limits of detection (LOD) and quantification (LOQ) of 0.02–0.1 and 0.1–0.5 μg/mL, respectively, and recovery percentages of 94–101%. The method was applied to six samples of Brazilian green tea infusions. Epigallocatechin gallate (23.4–112.4 μg/mL) was the major component, followed by epigallocatechin (18.4–78.9 μg/mL), epicatechin gallate (5.6–29.6 μg/mL), epicatechin (4.6–14.5 μg/mL) and catechin (3.2–8.2 μg/mL).     

Characterisation of phenolic antioxidants in aqueous extract of Orthosiphon grandiflorus tea by LC–ESI-MS/MS coupled to DPPH assay

Aqueous extract from Orthosiphon grandiflorus tea was on-line screened for its antioxidant components based on their capacity to scavenge free DPPH (1,1-diphenyl-2-picrylhydrazyl) radical after separation by a LC gradient. The structural elucidation of the active compounds was achieved by negative ionisation LC–ESI-MS/MS. Based on their mass spectra and fragmentation patterns related to antioxidant activity trace, seven compounds showing strong DPPH scavenging were identified to be danshensu, caffeic acid, caftaric acid, rosmarinic acid, caffeic acid derivative, sagerinic acid and salvianolic acid B. It is noted that danshensu, caftaric acid, sagerinic acid and salvianolic acid B have been reported in O. grandiflorus for the first time. In addition, the quantification of antioxidant compounds was performed using LC–MS/MS in multiple reaction monitoring (MRM) mode. Rosmarinic acid was found as a major component responsible for the antioxidant activity of this plant extract.     

A stability study of green tea catechins during the biscuit making process

A green tea extract (GTE) was incorporated into biscuit as a source of tea catechins. The stability of tea catechins in the biscuit making process was studied. A method was developed for the separation and quantification of tea catechins in GTE, dough, and biscuit samples using a RP-HPLC system. GTEs at 150, 200, and 300 mg per 100 g of flour were formulated. The results obtained showed that green tea catechins were relatively stable in dough. The stability of (−)-EGCG and (−)-ECG was determined at an interval of every 2 min during baking. Their stability decreased as the baking progressed and increased as the concentration of GTE was increased in the biscuit dough. The stability of (−)-EGCG also increased as pH of the dough was reduced and made less alkaline.     

Determination of caffeine content in tea based on poly(safranine T) electroactive film modified electrode

Safranine T was electropolymerised on a glassy carbon electrode and then characterised by scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). This uniform electropolymerised film was crystallisable and showed a high electrocatalytic ability towards the oxidation of caffeine. To avoid the interferences of the anions, Nafion was covered on the surface of poly(safranine T) film modified glassy carbon electrode. As a new voltammetric sensor, this modified electrode is sensitive, selective and stable to determine caffeine content in tea. The peak current increased linearly with the concentration of caffeine in the range of 3 × 10⁻⁷–1 × 10⁻⁴ M, with a detection limit of 1 × 10⁻⁷ M. All of these make it a useful tool for determining caffeine content in tea. What’s more, it produces much less organic waste compared with other analytical techniques.     

桑蚕丝织物茶皂素脱胶工艺研究

为减轻桑蚕丝化学脱胶造成的环境污染,节能降耗,采用茶皂素冷轧堆工艺对桑蚕丝织物进行脱胶处理,通过正交试验分析了茶皂素质量浓度、氢氧化钠质量浓度、保险粉质量浓度、堆置时间对织物练减率及白度的影响,得出茶皂素冷轧堆脱胶最佳工艺为:氢氧化钠8 g/L,茶皂素7 g/L,保险粉3 g/L,堆置时间18 h。结果表明,织物经茶皂素冷轧堆脱胶后,可以达到与传统的皂碱煮沸脱胶法相近的白度、毛效和练减率,断裂强力略有降低,但是织物弹性提高。     

锡兰红茶产区及市场研究

斯里兰卡2010年生产约32 2万吨茶叶,其产量居世界第三,但其出口量位居世界第一.锡兰茶的种植基地仅限于岛国的中央高地和南部低地,茶叶按生长的海拔高度不同分为三类,即高地茶、中地茶和低地茶.锡兰红茶的6大产区包括乌瓦(Uva)、乌达普沙拉瓦( Uda Pussellawa)、努瓦纳艾利(Nuwara Eliya)、卢...     

Antioxidant Activities of Free and Liposome-Encapsulated Green tea extracts on canola oil oxidation stability

In the present study, green tea extract was encapsulated in liposomes based on the Mozafari method (with no organic solvents) and characterized for its physicochemical properties (encapsulation efficiency, particle size, and Z-potential). Encapsulation efficiency, particles size, and Z-potential were determined to be 51.34, 419 nm, and -57 mV, respectively. Total polyphenol content of the green tea by Folin-Ciocalteu's phenol reagent was measured as 164.2 mg gallic acid/g extract. Free radical scavenging activities of free and liposomal extracts were 90.6 and 93.4%, respectively, using the DPPH method. Antioxidant activity of the ethanolic extract of green tea in free and liposomal forms with concentrations of 200, 600, and 1000 mg L⁻¹ were assessed on oxidative stability of the canola oil at 60 °C for 0, 4, 8, 12, 16, 20, 24, 28, and 32 days. Results were compared to results of synthetic antioxidant butylated hydroxytoluene at 200 mg L⁻¹. To assess antioxidant activity on canola oil stability, peroxide, thiobarbitoric acid, and anisidine values were assessed as well as the total oxidation value and rancimat test. Results showed that the liposomal green tea extract was more effective than the free extract. Furthermore, a 600 mg L⁻¹ concentration of the green tea extract showed a significant antioxidant activity, compared to other extract concentrations. Increasing storage time and various concentrations of the ethanolic green tea extracts included significant effects on canola oil stability (P ≤ 0.05). Results demonstrated that the green tea extract could be used as an effective antioxidant. Free and liposomal extract (at 600 mg L⁻¹) resulted in stronger functionality than the synthetic antioxidant butylated hydroxytoluene.     

Rebranding Terroir: Ethnoecology and Tea Agro-Ecosystem Management in Response to Increased Market Integration in Southern Yunnan,China

Prompted by increased domestic and transnational demand for Pu’er tea, an emergence of agroecosystem intensification in Southern Yunnan, China has resulted in various agro-ecosystems including tea forests, mixed crop systems, and monocultural terrace tea gardens, in the tea production system. Plants of Camellia sinensis assamica often grow as trees in forests whilst C. sinensis sinensis grow as shrubs in terrace tea gardens. Inspired by the wine industry, the concept „Terroir” acts as a framework that analyzes both environmental and human factors yielding var ying botanic profiles, and hence quantifies values created by the cultivation process. The approach allows economic opportunities of place-based tea products to be driven by the origin in lieu of extrinsic qualities, which has resulted in to the fabricated reputation of terroir. In response to a common gap in terms of botanical and cultural values between tea cultivation and marketing trends, this artic le investigates an alternative scenario in which tea production and promotion model could minimize its environmental impacts and utilize its economic weight to advance land conservation efforts specific to cultural complexity at community scales.