Research For Character Of Tea Catechins Enzymatic Oxidative Reaction And Mode Of Black Tea Fermentation With Saturated Oxygen

Black tea is a type of fermentation tea whose key process of quality formation is fermentation.Related researches about essence and mechanism of fermentation,as well as the effects and conditions of fermentation which are related to quality were always been the key research subjects in tea making and quality chemistry area.It is also the theoretical basis for the improvement of black tea processing technology.It was crucial for the tea polyphenols to fully contact with polyphenol oxidase during the fermentation process of black tea,and to maintainproper moisture,temperature,humidity,ventilation,pH value,etc..For the bar-type black tea,which has a maximum production and sale in China,the leaves were partially damaged at the rolling stage,which made tea polyphenols lack of enough contact with polyphenol oxidase.It also costs excessive labor and time for natural fermentation.Although covering could preserve heat and shorten hours,it causes badventilation and is prejudicial to quality of blacktea.The fermentation of bar-type black tea has become the technologicalbottleneck,which needs deeply researching and technological improvement.So this paper chooses the topic of ―The theoreticalstudy of fermentation-based black tea making technology‖.The principle of this study is based on oxygen as a majorsubstrate during the enzymatic reaction.The saturated oxygen supply could improve the concentration of oxygen and make full contact with enzyme and better for fermentationeventually.For a long time,ventilation was deemed as an essential condition offermentation and it supplied oxygen throughair flow in fact which means increasedthe concentration of enzymatic oligomer.Due to the limitation of that oxygen can be engaged in the fermentationof black tea,the studies of the significance of oxygen infermentation were finiteand lack of relateddocument literatures,so it was eager to launch relevantresearches.This study is aimed toprovide atechnologicaltheory about black tea fermentation with saturated oxygen supply.In this study,we used the principle of tea science and tea making to solve basic problems.Enzymatic oxidation test systemis used to take the experiment of enzymatic oxidation of tea catechin by saturated oxygen.This paper designs a device for black tea fermentation and through this device it takes the experiment of black tea fermentation with saturated oxygen supply.The tea samples of black tea which fermented under saturated oxygen supplywere analyzed by high performance liquid chromatography(HPLC)and gas chromatography–mass spectrometry(GC–MS)for its amino acids and volatile aroma components.The main research resultsare as follow:(1)The classical in vitro enzymatic oxidation test showed that both catechins EGCG and EC were enzymatically oxidized and the representative components of black tea were produced.The contents of teasafine(TFs)were 0.085 mg / ml(EC),0.066 mg / ml(EGCG,POD),0.111 mg / ml(EC,PPO)and 0.066 mg / ml(EC,POD)(EGCG,PPO),0.006 mg / ml(EGCG,POD),0.014 mg / ml(EC,PPO)and 0.006 mg / ml(EC,POD).(2)The high efficiency of enzymatic oxidation of catechins in vitro is consistent with that of black tea fermentation,which indicates that the simulation test is representative and can be used for reference.(EGCG,PPO),10-15 min(EGCG,POD),10-15 min(EC,PPO),and the time of EGCG <(EGCG,PPO),40 ± 2.5 ℃(EGCG,POD),35 ± 2.5 ℃(EC,PPO)and 40 ± 2.5 ℃(EC,POD),respectively.The optimum temperature was 35 ± 2.5 ℃(EGCG,PPO)ECO,POD),6.5 ± 0.20(EC,PPO)and 4.5 ± 0.20(EC,POD),respectively.The optimum pH values were 5.5 ± 0.20(EGCG,PPO),4.5 ± 0.20(EGCG,POD)(3)Catechins saturated oxygen enzymatic reaction test showed that the reaction to produce higher biological representative of the composition of black tea,the reaction of the balance of theaflavins(TFs)content were: TFs 0.117 ± 0.01 mg / mL(EGCG,PPO),0.183 ± 0.02 mg / mL(EC,PPO),0.23 times higher than that of the control,and 0.101 mg / mL(EGCG,POD),which was 1.12 times higher than the control,0.981 ± 0.02 mg / mL(EC,POD),11.41 times higher than the control.(4)caffeine saturated oxygen enzymatic reaction(compared with the control)has a higher reaction efficiency,the response time required for the balance: 4-5min(EGCG,PPO),speed up 2.0-2.25 times,8-9 min(EC,PPO),accelerated by 1.66-1.87 fold,12.5 min(EC,PPO),accelerated by about 2.0 times,27.5 min,(EC,POD),accelerated by about 1.5 times.(5)Black tea saturated oxygen fermentation(compared with the control)increased efficiency,theaflavin content increased significantly.The results showed that the fermentation efficiency of tea tea was increased by 8.20% and 3.28%,respectively,while the content of tea flavonoids(TFs)and tea montoxin(TRs)decreased by about 8 min 18.21%.(6)In the review of the quality of tea made of saturated tea,the results showed that the sensory score was 92.78 points(89.50 points);the color of the soup was 91.50 points(90.00 points),the taste was 92.50(control 85.00),92.50 leaf bottom(control 90.00 points).(7)The content of TFs and TRs in tea samples was 1.28-1.39%(control 1.24%),TRs content was 4.63-4.87%(control 4.62%),and the content of TBs was lower than that of CKs The control was 8.57-9.81%(control 11.37%);TRs / TFs ratio 3.60-4.81(control 3.57);TBs / TFs ratio 6.70-10.81(control 9.16);TBs / TRs ratio 1.85-2.25(control 2.56).(8)HPLC showed that there were 17 kinds of free amino acid components in the tea samples,including histidine(+ 3.22%),glycine(+ 7.17%),glutamic acid(+5.58(-23.23%),arginine(-92.70%),lysine(-24.32%),and the content of isoleucine(+ 7.16%)was higher than that of the control.Thionine(-78.95%)was lower than the control.(9)GC-MS showed that 48 samples were found in the tea samples of saturated tea,and 11 were proprietary components,accounting for 22.92%.The components with different relative contents were: ?-camphor(16.01),3-methyl-7-methylbicyclo [3.3.1] nonan-3-ol 5.43(24.03)trans-geraniol 10.98(19.51),methyl salicylate 13.62(20.02),Hexanoic acid-4-hexenyl ester 0.26(0.17),p-propenyl anisole 0.47(0.26);indicating that the difference with the control aroma from the composition and its content ratio is different.