Correlation between leaf age,shade levels,and characteristic beneficial natural constituents of tea (Camellia sinensis) grown in Hawaii

This study showed the relationship between tea leaf age, bud and first two leaves, and shade levels, on the relative concentrations of six major compounds of tea leaf, namely l-theanine, caffeine, and the major tea catechins; (−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin (EC), and (−)-epicatechin gallate (ECG), all of which are reported to have positive effects on human health, as well as at the ferric reducing antioxidant power of bud and leaf extracts. The concentration of l-theanine and caffeine decreased as leaf age increased moving from bud to first and then second leaf, while the concentration of the four catechins increased from the bud to first and second leaves. In most cases this increase was generally relatively small but in the case of EGC it was 7 to 10-fold. Certain chemical components of freshly picked, minimally processed and essentially unoxidised tea may potentially be used as markers for age, quality, authenticity and area of growth.     

Effects of tea polyphenol coating combined with ozone water washing on the storage quality of black sea bream (Sparus macrocephalus)

The present research evaluated the effects of tea polyphenol (TP) combined with ozone water (O₃) on the quality of black sea bream (Sparus macrocephalus) over a period of 15 days storage at 4 °C. A solution of TP (0.2%, w/v) was used to coat the fish after washing with ozone water (1 mg/L). Fish physicochemical (pH, K value, peroxide value, thiobarbituric acid, total volatile basic nitrogen, trimethylamine, texture, and colour), sensory, and bacteriological characteristics were all analysed. TP + O₃ treatment effectively reduced nucleotide breakdown, lipid oxidation, protein decomposition, and microbial growth, and maintained better characteristics of texture, colour, and sensory compared with the control. The efficiency of TP + O₃ treatment was also better than that of TP treatment or O₃ treatment alone. Therefore, tea polyphenol coating combined with ozone water prewashing may be a promising method of maintaining the storage quality of black sea bream and of extending fish post-mortem shelf-life during 4 °C storage.     

泰山茶文化发展的历史、现状及建议

泰山茶文化早在唐代就已形成,目前正呈现出蓬勃发展的态势。要提高泰山茶的知名度,首先需要政府重视泰山茶文化的建设与宣传;其次,要进一步挖掘整理泰山茶文化,丰富泰山茶文化内容;然后,结合泰山旅游文化特色和茶行业特色,营造泰山茶文化氛围,多途径发展茶文化。     

Kinetics and equilibria of tea infusion: Rates of extraction of theaflavin,caffeine and theobromine from several whole teas and sieved fractions

The rates of infusion of theaflavin and caffeine into water at 80°C have been measured for Kapchorua Pekoe Fannings, Kapchorua Pekoe Dust, Betjan Flowery Broken Orange Pekoe and Rupai Flowery Orange Fannings whole teas and sieved fractions. For Kapchorua PF fractions the rates of theobromine infusion were also determined. Caffeine always infused faster than theobromine, and both infused faster than theaflavin. Rate constants were obtained from the slopes of first order kinetic plots which yielded straight lines with small intercepts. The rate constants for all three constituents increased by a factor of 2.2 as leaf size decreased from 850–1000μm to 500–600μm. The rates of extraction from whole teas varied more than fourfold. Kapchorua PD gave the most rapid rates and Betjan FBOP the slowest. Comparisons of similarly sized fractions of teas showed that leaf size distributions accounted for half these differences and the intrinsic properties of the leaf for the remaining factor of two. The Kenyan CTC teas gave higher rate constants than the Indian orthodox teas. From the rate constants, the effective diffusion coefficients for theaflavin and caffeine in Betjan FBOP leaf were calculated and found to be some 100 times smaller than in water. This shows the diffusion processes within the leaf to be complex ones.     

绿茶杀青叶浸提物理化特性研究

研究了提取温度对绿茶杀青叶提取物的物理和化学特性的影响。结果表明,茶汤固形物、茶多酚、咖啡因、氨基酸和主要儿茶素类化合物的提取率随提取温度上升而提高;茶汤明度和绿色程度随提取温度上升而下降;冷后浑和黄色程度随提取温度上升而提高。结论:在50℃提取的绿茶杀青叶提取物作为绿茶饮料的原料较理想。     

Antioxidant activities of crude tea polyphenols, polysaccharides and proteins of selenium-enriched tea and regular green tea

The crude tea polyphenols, polysaccharides and proteins of regular green tea and Se-enriched green tea were investigated in vitro for antioxidant activities by auto-oxidation test (AAPH) and α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging method. Results showed that crude tea polyphenols of Se-enriched green tea provided the highest antioxidant activity by DPPH assay and the antioxidant activity was decreased in the order: crude tea polyphenols > crude tea proteins > tea polysaccharides. The crude protein of Se-enriched green tea was found to exhibit the highest antioxidant activity by AAPH method and the antioxidant activity was decreased in the order: crude tea proteins > tea polyphenols > tea polysaccharides. Tea polyphenols and tea polysaccharides of Se-enriched green tea presented significantly higher antioxidant activities than that of regular green tea. No significant difference of antioxidant activities was found between crude tea proteins of Se-enriched green tea and regular green tea. The combinations of Se with tea polyphenols and tea polysaccharides were responsible for the higher antioxidant activities of Se-enriched green tea than regular green tea.     

Effects of tea polyphenols on the activities of α-amylase,pepsin, trypsin and lipase

Tea polyphenols (TP) possess many beneficial properties, such as reducing the risk of cancer and heart diseases, and acting as natural antioxidants for the food industry. At the same time, tea polyphenols might inhibit digestive enzymes and reduce food digestibility. To explore this possible antinutritional property, the effects of tea polyphenols on the activity of four typical digestive enzymes were investigated. HPLC analysis of the tea polyphenols extracted from Chinese green tea indicated that their catechin content was 93.6% (w/w), and that the content of ester bond-containing polyphenols was more than 82%. Measurement of the interaction of gelatin with tea polyphenols was first carried out, in order to model enzyme protein–TP interaction. It proved that tea polyphenols were capable of binding and precipitating protein, suggesting a potential ability of TP to denature digestive enzymes. In addition, the inhibitory effects of tea polyphenols on α-amylase, pepsin, trypsin and lipase were studied. In the presence of 0.05 mg/ml tea polyphenols, the inhibition ratios of α-amylase, pepsin, trypsin and lipase were, respectively, 61%, 32%, 38% and 54%, suggesting that TP might possess antinutritional properties.     

四川名茶矿质元素含量研究

分析了四川名茶矿质元素含量及特点。在所分析的１８种元素中，四川名茶Ｋ，Ｐ，Ｓ，Ｃａ，Ｍｇ元素含量较高（＞１５００ １０＾－６），Ｂａ，Ｃｒ，Ｖ，Ｃｏ，Ｓｅ含量较低（＜１０ １０＾－６）；与普通绿茶相比，四川名茶含有较高的Ｋ，Ｚｎ，Ｐ，Ｎａ，Ｎｉ，Ｃｕ，Ｓ，Ｓｅ，Ｃｏ元素，其高幅为０．３８％－１１５．６５％，而Ｍｇ，Ｍｎ，Ａｌ，Ｃａ，Ｂａ，Ｖ，Ｒｂ，Ｆｅ，Ｃｒ元素则为７．３２％－４６．６７％；红岩迎     

我国水溶性抗氧化剂研究概况

我国对水溶性抗氧化剂的研究近年来主要体现在天然抗氧化剂类的研究开发并利用。如对茶多酚，香辛料，中草药类及某些动物类抗氧化剂等抗氧化活性的研究等。