Studies on Umami Taste of Tea

Umami is one of the five basic tastes and an important taste attribute of green tea.Amino acids are major components contributing to umami taste and the top three amino acids in tea are theanine,glutarnic acid and aspartic acid.Trace of umami taste components adenosine monophosphate （AMP） and guanosine monophosphate （GMP） were detected in tea.Levels of umami taste components varied with tea cultivar,environmental conditions,fertilizer and processing method.The taste threshold of amino acids differentiated greatly and its DOT （dose over threshold） is an important indicator evaluating its contribution to umami taste.     

Fluoride in Tea and Its Risk Assessment

Tea plant absorbs from soil a large amount of fluorine （F） which is accumulated in leaf,resulting in elevated F concentration in tea.It is a controversial topic whether the fluoride in tea is associated with fluorosis.The research advances in F variation of various kinds of tea,factors influencing F level in tea and the associated health risk assessment were reviewed in the present paper.The F level in tea increases with the maturity of the tea leaf.Brick tea had a high F content because it was prepared using mature shoots and old tea leaves as raw material.Some low grade UK supermarket economy teas contained elevated F comparable to the Chinese brick tea.Tea F level is also affected by tea cultivar,soil condition,tea processing method and tea infusion preparation method.     

Tea Seed and Its Bioactive Functions

Tea seed is a byproduct in tea production and also a source of nutritional and bioactive compounds.There have been studies showing that extracts of tea seeds offered many physiological functions including anti-inflammatory,anti-oxidant,anti-tumor,anti-obesity,hepatoprotective and gastroprotective effects.The tea seed oil is also an acceptable biodiesel and the saponin-rich tea seed meal can be used as vermicide to expel earthworms from the soil of golf courses and sports fields.The bioactive functions of tea seed extracts and their potential uses in agricultural and industrial sectors were reviewed in the present paper.     

Advances in Preparation of Theanine

Theanine is an important component affecting tea quality and it has many health benefits for human being.Chemical synthesis of theanine had high productivity,but its application needed efficient raceme resolution technique.Although only L-theanine will be synthesized through exogenous/endogenous enzymes or microbe fermentation,low yield is the main shortage of this technique.Extraction of theanine from tea leaves is a conventional and efficient preparation technique,and highly purified theanine can be achieved when extraction and separation procedures are suitable.     

A Study on Thought of Tea of Hanjae Yi-mok＇s Da-bu

The Da-bu of Hanjae Lee mok （1471-1498） is known as an original masterpiece,which is predominantly documented in Korean tea books.He had always spared no effort to put Confucianists＇ theories and thoughts into practice during his 28-year career.Da-bu tea magnificently reflected his concepts of Confucianism in conjunction with tea-drinking activities.The main contents of Da-bu have included written authors,tea species and production,landscape of tea cultivation,tea plants and leaves,ways of tea-drinking and three-grade tea,tea song of seven cups,5 merits and 6 moralities of tea,benefits of tea-drinking,tea comprehension,etc.According to the views of contents,tea of Hanjae Leemok is the only partner with which we can share life and it can also be beneficial to healthy diets.Not only does it have become part of our daily life,but also be a medicine for our physical and mental disease.He composed the tea song of seven cups,which sufficiently expressed a real practice of the pursued ideal state of Confucianism and Taoism.He also promoted a drinking tea for health enrichment of Confucianists.According to the analytical results of Da-bu,Hanjae＇s tea has recognizably become the personally real practice of Confucianism and state.He had reached the enlightenment for the state of birth and death.After consuming tea,his body and mind immediately changed to the state of joys and wonderland,and also he illustrated that this feeling is not a one-off state,it always comes out whenever drinking.Therefore,based on Hanjae Lee mok,tea drinking is not only the regiment for healthy benefits,but also it is a training method,＂ Dado in My Heart＂,for individuals to train their mind,body,and morality.     

Study on the Retention Rate of Green Tea Catechins Components and Tea Polyphenol by Different Processing Technology

The aim of this research was to explore the effect of fixation,rolling,and drying processing technology on the retention rate of green tea catechins components and tea polyphenol.Different fixation processes （rotary drum-firing,microwave,steam-blasting）,rolling process （weight of rolling,gently press rolling and traditional rolling）,drying process （stove drying,roasting dehydration,baked fried drying） were adopted.The effect of different tea processing technology on the retention rate of catechins component and tea polyphenol was analyzed.It showed that the microwave fixation process,gently press rolling process,baked fried dry process were beneficial to keep high levels of EGCG,C,EGC,EC,ECG.     

Multiple Seasonal Modifications in Enzymatic Flavour Formation in Tea

Carotenoid cleavage enzymes isolated from Japanese Camellia sinensis leaves （cultivar Yabukita） were used for investigating the structural patterns of carotenoid cleavage enzymes.Fresh tea leaves were used for the isolation of active enzymes and purified to single band stage in SDS PAGE gels after isoelectric focusing.The specific activity of the carotenoid cleavage enzymes was tested and the active fractions selected for further analysis.The sugar content and the amount of phosphate present in the purified enzymes were elucidated by the following methods：Phosphates were detected by phosphatase assays,fluorescence marker kits and ammoniumheptamolybdate complex measurements after incineration of the samples.Sugars were detected in gels using PAS reagent （periodide acid/ Schiff reagent） staining and by GC-MS after hydrolysation of the proteins with trifluoric acid.Phosphorylations as well as glycosylations of the samples could be detected in all cases,thus giving evidence for an increasing phosphorylation level of proteins in Camellia sinensis from spring （1.84 g/mg） to autumn （2.39 g/rg） as well as the presence of at least four different sugars （arabinose,xylose,galactose and ribose）.These secondary modifications of the carotenoid cleavage enzymes and their dependency on the harvesting season may well correspond to the changes on the functional level which were detected between spring （Michaelis Constant （Km） =9.45 mol/1） and autumn （K =17.16 mol/l） harvests.     

Stability of Tea Catechins and Antioxidant Properties of Green Tea Extracts as Affected by Boiling-treatment

Stability of tea catechins and the antioxidant properties of green tea extracts as affected by boiling-treatment from 1 to 5h were studied.Green tea catechins were partially epimerized from epi-form to nonepi-form under boiling-treatment.Total phenolic compounds of the samples under the boiling-treatment for 1 to 4h showed the same statistically significant （P ＞ 0.05） comparing with the untreated samples and there was no significant reduction （P ＞ 0.05） of total catechins when the green tea extracts were boiling-treated for 1 h.There were no significant （P ＞ 0.05） reduction of the antioxidant capacity when the samples were boiling-treated for 1 h,no significant （P ＞ 0.05） reduction of the scavenging ability against DPPH and O2-when treated for 2h,and no difference on scavenging ability against OH when treated even for 5h.The results indicated that boiling-treatment for 1h had limited effect on total catehins and phenols content in green tea extracts.Green tea extracts still remained excellent in antioxidant properties and free radical scavenging activity after boiling-treated for 1 h.     

Studies on Bitter and Astringent Taste of Tea

Bitterness and astringency are important sensory properties for evaluating quality of tea.The research advances in the mechanism of tea astringency and bitterness,astringent and bitter tasting components and their evaluations were reviewed in the present paper.The astringency arises from the interaction of salivary proteins with polyphenols which depends on the structure of both the polyphenols and the proteins.Bitter and astringent compounds in tea include phenolic acids,catechins and their oxidized products,flavonol glycosides and proanthocyanidins.There are many factors influencing on astringency and bitterness including the interaction between taste substances,repeated ingestion,saliva flow and its composition and acidity.Sensory assessment and instrumental evaluation were used in the evaluation of astringency.     

A Study on Effects of Turn-over Technology on the Quality of Jinmudan Oolong Tea

This paper reported the effect of oolong tea processing procedure of turn-over on quality of the Jinmudan Oolong tea,including taste components and volatile compounds.The content of the water extractable solids was gradually increased,but the content of amino acid decreased and then increased,and the content of the soluble sugar and tea polyphenols increased after the first turn-over processing.The major volatiles of the three tested Jinmudan Oolong tea samples were nerolidolcistrans,α-farnesene,palmitic acid,indole and 9,12,15-octadecatrienoicacid and methyl ester.The sensory evaluation results showed that an appropriate increase in the number of turn-over was helpful to quality of the Jinmudan Oolong tea.     

Volatile Flavor Components and the Body Weights of Rats in the Green Tea Added Miner Ingredients

In order to change for the good flavor in green tea of middle or low grade,roast naked barley （miner ingredient） was added to it.To make tea having functional property,mixed roast naked barley-green tea with one medicinal herb （MH,miner ingredient）.This study was performed to investigate the effect of drinking extracts of naked barley-MH-green tea （A group） and adlay-Angelica gigas Nakai-green tea （B group） on the body weights of rats,and volatile flavor components of best effective extract on weight reduction.Forty-eight male Sprague-Dawley rats divided into six groups were fed five different green tea extracts for 8 weeks.The result obtained in the experiment indicated that the change of body weights of rats was affected by A group,B group and others.A group showed highest reduction rate of body weights （36.40％）.Reduction rate of body weights on the B group （10.10％） was much lower than A group （36.40％）.Aroma compounds were extracted by the SDE method.The concentrated aroma extracts were analyzed and identified by GC and GC-MS.The main aroma components of the green tea blended with naked barley and MH were 12 pyrazines having roasty note,methyl butanals having sweet note,hexanal having briskness greenish note,and nerolidol and3-ionone having floral note.     

Tea Breeding in Japan

Tea breeding in Japan started around 116 years ago,and to date,more than 110 cultivars have been developed and released.Seedling plants were uprooted and rapidly replaced with new clonal cultivars after 1970.At present,more than 95％ of the tea gardens in Japan grow improved clonal cultivars.Although the cultivation of the ＂Yabukita＂ variety had expanded and contributed to approximately 76％ of the tea grown,this excessive plantation resulted in some serious problems in the cultivation and management of the tea industry after 1990.Therefore,after 2000,new programs have been initiated to breed superior varieties through the use of various genetic resources and DNA markers.     

Molecular Characterization of Arbuscular mycorrhizal Symbiosis for Defense,Nutrient Absorption andSecondary Metabolism in Plants简

Arbscular mycorrhiza （AM）,a symbiosis between plants and members of fungi Glomeromycota,improves the resistance,nutrition and material metabolism of plant.Arbuscules generated by symbiotic development,is the main site of nutrient exchange and genetic material recombination,resulting in physiological changes and gene expression regulation.AM regulates pathogenesis-related protein （PRs） genes and antioxidant enzyme genes against biotic and abiotic stresses.Nutrient exchange induced by AM is directly involved in uptake,transformation and utilization of nutrient elements in plants.Importantly,transporter genes play an important role in phosphate,nitrogen and carbon acquisition.In AM interactions,phosphate transporter （PT） genes,from both arbuscular mycorrhizal fungi and plant root,are induced and there product promote phosphate acquisition; increasing expression of ammonium transporter （AMT） genes and arginine biosynthesis/degradation enzyme genes is in charge of nitrogen acquisition;and promotion mechanism of carbon acquisition is involved in up-regulation of sugar transporter genes.In addition,secondary metabolites,functioned as signal moleculars and defense compounds,are increased with development of AM symbiont by up-regulating related synthetic genes based on different promotion mechanism.Taken together,molecular regulation of plant and arbuscular mycorrhizal fungi,induced by infection process,stimulate plant nutrient acquisition and resist to biotic/abiotic stress.     

Effects of Brewing Conditions on Quality of Pu＇erh Tea Infusion

To brew tea correctly is very important to absorb the tea nutrition for people.The dynamic changes of the main compositions in brewing Pu＇erh tea processing with different conditions were studied.Three different temperatures and eight times were designed to study the effects on the tea infusion quality.The index t0.5 min （50％ concentration of compounds in tea infusion） was used to evaluate the extract speed of compound in this experiment.The results showed that caffeine solubility speed at 80℃ was the highest to compare with tea polyphenols,amino acid,caffeine,soluble sugar,theaflavins and theabrownine,t0.5min of caffeine was 4.8 min,amino acid 10.3min was the second,the third one was tea polyphenols,soluble sugar was the lowest.We also found in different infusion temperature the t0.5min of compounds was distinguishing.With increasing the temperature all t0.5min of six compounds were shorter.However,the change regulations of t0.5min for all compounds in 90℃ and 100℃ were similar to in 80℃.Total quality score （TQS） were applied to evaluate the quality of tea infusion.The results found the TQS score of infusion was higher with the temperature rising,and the temperature to brew best quality infusion was 100℃ for 4-5min.According to the multiple regression analysis between sensory assessments and chemical components of Pu＇erh tea we suggested the TQS was mainly affected by theaflavins,amino acid,soluble sugar and theabrowine four factors in 100℃.     

Functional Components of Tea （Camellia Sinensis） Germplasms Collected in Korea

This study was carried out to obtain useful information and to search quality related components for breeding of tea by analysis of Korean local tea leaves at Sulloc-Cha R＆D center in Jeju Island,Korea.It was also conducted to measure the major agronomic characteristics of 300 local germplasms.These results allowed us to select some superior lines as genetic resources for green-tea breeding and research genotypes.     

Protective effects of EGCG on Bifenthrin-Induced Oxidative Stress in the Human Embryonic Lung Fibroblast Cell Line HFL-I

Bifenthrin （BF） is an important type I synthetic fluorinated pyrethroid insecticide and acaricide.Previous investigations have indicated that the metabolisms of BF in human cells were through oxidative processes,and cytotoxicity was induced by the oxidative stress.In this study,the protective effects of EGCG,which is a major individual of green tea polyphenols,on the human embryonic lung fibroblast cell line HFL-I exposed to BF were investigated.The results showed that BF could induce oxidative stress leading to cytotoxicity in HFL-I cells.The pretreatment of EGCG at low concentrations significantly recovered the cell viability and morphology,inhibited excess generation of ROS,enhanced antioxidant enzyme activities and avoided loss of mitochondrial membrane potential.The results suggested that EGCG might eliminate the BF-induced damage in HFL-I cells.     

Volatile Compounds in Two Camellia chrysantha （Hu） Tuyama Species

In the study,the volatile compounds in two Camellia chrysantha （Hu） Tuyama species were extracted and analysed by simultaneous steam distillation and extraction （SDE） and gas chromatography mass spectrometry （GC-MS）,respectively.The relative contents of the chemical constituents in the volatile components were quantified by peak area normalization and NIST database.A total of 60 volatile components were identified,45 for Camellia nitidissima and 26 for Camellia euphlebia.Aldehydes and acids were the most dominant volatiles in Camellia nitidissima,but for Camellia euphlebia there were hydrocarbons and ketones.Hexanoic acid,4-（2,6,6-trimethyl-1-cyclohexenyl）-3-buten-2-one,cis-2-decenal,4-[2,2,6-trimethyl-7-oxabicyclo [4.1.0] hept-1-yl]-3-buten-2-one,phenylacetaldehyde,eicosane,alpha-ionone,geranylacetone 2,6-di-tert-butyl-4-methylphenol,7,9-di-tert-butyl-1-oxaspiro[4,5] deca-6,9-diene-2,8-dioi and tetradecanal were both in two Camellia chrysantha （Hu）Tuyama species.     

Effect of Chelated Vanadium Spray on Concentration of Vanadium and Organic Compounds in Tea Shoots

The study aimed to develop vanadium tea products and evaluated the potential of chelated vanadium （V） absorption by tea shoots and effect of vanadium accumulation on tea quality during the first crop season.Chelated V application with three times foliar sprays at 5 days intervals starting from 15 days before plucking showed a significant increase in V content of new young shoots,which was much effective at higher concentration.However,one or two times sprays had no increase in V content regardless of spray concentration compared to non-treated.Despite V accumulation in the treated at 3 to 9 times higher that of than the non-treated plants,there were no significant changes in contents of total amino acids,theanine,caffeine,total polyphenols,crude fiber,and cathechins between the treated and the non-treated.     

Extraction of Tea Polysaccharides and Their Effect on Wheat Starch Retrogradation

Tea Polysaccharides （TPS） has been acknowledged of one of the most important components with various bioactivities in tea.The extraction of TPS from wide tea sources was the previous and determinant work before further studies done.While the extraction procedures of TPS would be different due to the later utilization.In this work,the extraction conditions of TPS were previously optimized by respond surface methodology.A quadric model was obtained as Y =3.16 ＋0.31X1-0.55X2-0.47X3-0.034X1X2 ＋0.022X1X3-0.041X2X3-0.90X12-0.40X22-0.73X32.The model was tested and proved through the ANOVA with F-value and p-value.Furthermore,the optimal condition was achieved as extraction temperature of 82℃,extraction time of 106 min and ratio of water to material of33∶1 （mL/g）,meanwhile the highest yield of TPS showed 3.39％ ±0.08％.The crude TPS was later refined to be of purity of 81.3％.The refined TPS was incorporated with starch as to state the role of TPS in the starch retrogradation of starch-based food.The results showed that TPS-wheat starch mixture has a relatively low degree of retrogradation,which indicated that TPS has a delayed or resistant effect on wheat starch retrogradation.This work may provide a practical evidence for the promising starch-based food incorporated tea.