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 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.     

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.     

Effect of Different Drying Methods on the Volatile Compounds Jinmudan Oolong Tea

Jinmudan,a new tea variety from Fujian Province has an excellent quality with a unique aroma like magnolia frogrance.To monitor the changes in the tea volatile compounds during the Jinmudan Oolong tea manufacturing （drying） process,the volatiles of tea samples were extracted and analyzed.Characteristic volatile compounds in Jinmudan Oolong tea were nerolidol,α-famesene,linolenic acid,palmitic acid,indole,phenylacetaldehyde,cisjasmone,β-phenylethanol,etc.The content of nerolidol was the highest in four tested samples.The composition of the volatile compounds in microwave drying sample was simple,but its concentration was high,in which the main volatile compounds were alcohols and esters.The processing with combination of traditional drying craft and modem aroma-improvement technique could obviously improve the tea aroma,especially in level of epoxy linalool and jasmine lactone.     

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.     

Effect of Drinking Green Tea on Mental State of Humans

Tea is one of the most widely consumed beverages in the world,among which green tea is most common in China and Korea.Green tea constituents possess a great value to human health wherein lots of clinical studies and investigations were conducted by researchers and experts.However,there are still increasing demands and interest on the health properties of green tea,especially its effects on mental state of human brains.Based on the collated clinical studies,green tea was used to improve mental alertness and thinking.Thus,higher consumption of green tea was associated with a lower prevalence of cognitive impairment.This review summarizes the effects of drinking green tea on the mental state of human brains.Green tea contains a unique set of L-theanine and epigallocatechin gallate （EGCG） that possess biological activities in antioxidant,anti-memory loss,and antiproliferative assays potentially relevant to the prevention and treatment of various forms of brain damage.Theanine in green tea may play a role in reducing stress.The use of highly innovative method of reading and mental behavior of the human brain＇s response with the intake of green tea thru neuroimaging was also covered in this review.     

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 Consumption and Antihypertensive Effects

Tea consumption is a major source of flavanoids for a wide large population.Any physiological effects of tea,like antihypertension,could have a significant impact on population health.The effects of tea on blood pressure are less consistent.Results of population studies and long term controlled studies are consistent with a blood pressure-lowering effect of tea.However,some of the short-term intervention trials,mainly in normotensive individuals,have not demonstrated significant blood pressure reduction with tea.The focus of this review is on the mounting evidence from human studies that tea can lower blood pressure.     

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.     

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.     

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.     

Effects of Soil Characters on the Tea Quality in the Tea Region of Qin-Ba Mountain,Hubei Province,PR China

Based on the analysis of physical and chemical properties of soil,nutrient elements and biochemical compositions of tea leaves,the relationship between soil characters and tea quality was studied.The results showed that soil total phosphorus,potassium,available potassium,copper and zinc were the main factors which affected and limited the content of nutrient elements of tea leaves.Furthermore,soil pH,organic matter,total nitrogen,potassium,exchangeable calcium,magnesium,available copper and zinc were the main factors affecting and limiting the content of biochemical compositions in tea leaves.Tea quality could be improved by controlling these soil factors.     

Analysis of the Volatile Chemicals of Longjing Tea from Different Production Locations Using Electronic Nose

Electronic nose has been applied in analysis of food products by monitoring their flavours.But it gives an overall response to a mixture of volatile components.In this work,multianalysis and chemometrics technique were employed to analyse the E-nose and GC-MS data of Longjing tea produced in different locations in Zhejiang province,China.A good discrimination of Longjing tea samples was obtained by E-nose according to the producing area,and a total of 38 compounds were commonly identified from the GC-MS data.Each individual volatile component was related to E-nose response using PLSR and the significance of each component was evaluated by the coefficient R2.Results indicated that isoamyl isovalerate,cis-3-hexenyl hexanoate,cadinene,phenylethylalcohol and linalool played an important role in response on E-nose sensors.It was possible to give a complementary information concerning the individual chemicals interacts with the sensors of E-nose instead of the total volatile components.     

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.     

Yuexiang Longjing Tea and Its Quality Characteristics

Shengzhou is a major tea producing county in China and the major tea produced in Shengzhou is Yuexiang Longjing tea.Environment and tea cultivar are two important factors influencing tea quality.Chemical composition of tea samples prepared using materials from cultivars ‘Zhenong-117＇ and ‘ Baiye-1＇ were investigated.It showed that concentrations of total amino acids and catechins were more than 4.4％ and 129 mg/g respectively,suggesting that Yuexiang Longjing had a good quality potential.     

The Beauty of Elegance ‘Pungnyu＇ in the Tea Culture of Korea

‘Tea culture＇ broadly includes ‘providing tea＇,‘ the tea ceremony＇,‘ tea ritual＇,‘ tea artistry＇ and ‘ tea party＇.The concept of ‘Pungnyu＇ in Korea was proposed by Choi Chi-won （857 ～ 894？）,who pointed out that ＂there is a profound truth ‘ Tao＇ in Korea,which was considered to be ‘ Pungnyu＇ or the beauty of elegance.The origin of ‘Pungnyu＇ can be traced back to the history of hermits.‘Pungnyu＇ includes the teachings of Buddhism,Confucianism and Taoism.     

Tea Culture and Tea Consumption Trends in Australia

Tea is a large part of modem Australian culture with its British origins.Australians drink tea and have afternoon tea and morning tea much the way the British do.Tea was introduced to Australia through eolonisation by the British.In fact,tea was aboard the First Fleet in 1788.Tea was the staple drink and considered a necessity,even when other items were scarce.Much of the time tea drinking is not the delicate,refined cultural expression that the rest of the world imagines-like a more formal tea ceremony.Tea is usually black tea served with milk with or without sugar.Strong tea served with lots of milk and often two teaspoons of sugar.Even very slightly formal events can be a cause for cups and saucers to be used instead of mugs.For most people,a cup （or commonly a mug） of tea is something drink very often.     

Analysis of Volatile Compounds of Jinmudan Oolong Tea by Different Wrapping-Twisting

In this study,the volatile compounds in four kinds of Jinmudan Oolong tea were extracted and analyzed 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 93 volatile components were identified,46 for sample 1,56 for sample 2,45 for sample 3 and 30 for sample 4.Alcohols and esters were the most abundant volatiles in Jinmudan Oolong tea.Palmitic acid,nerolidol,2-phenylethanol,phytol,cis-5-ethenyltetrahydro-,α,α-5-trimethyl-2-furanmethanol,2,2,6-trimethyl-6-ethenyltetrahydro-2h-pyran-3-ol,a-farnesene,eicosane,hexadecane,indole,β-phenethyl hexanoate,β-phenethyl hexanoate,methyl palmitate,benzoic acid,2-phenylethyl ester,tetrahydro-6-（cis-2-pentenyl）-2h-pyran-2-one and cis-jasmone were in all of the samples.Nerolidol was shown to be the aroma components with the highest content in Jinmudan Oolong tea,which accounted for 26.61％,36.89％,36.89％ and 36.89％.