Studies On Technology And Quality Of The White Tea Produced By Continuous And Cleaning Producing Line And The White Tea Withered By LED Lights

White tea processing is simple who divided into withering and drying process.But there are several difficult problems need to be solved.Such as how to control environmental parameters during the processing,how to achieve the demand of labor force and how to stabilize the quality of white tea.With the impetus of the market and the progress of the industry,white tea processing is required to achieve mechanized,continuous,automated and clean standards.So that,the first continuous cleaning production line of white tea was manufactured in Fuding City of Fujian Province,which was energy-efficient by withering with daylight.This topic studied the quality of white tea which produced in continuous production line and studied the light withering which was applied in the production line.Then did experiment about LED light withering in different lightwave and different lighting conditions.Contrast and analyze different quality between white tea producted from production line and traditional heating withering,explore the different effects on the withering speed,the activity of PPO and the quality between the white tea withered by different lightwave LED and different lighting conditions by Studying white tea’s leaf temperature,moisture content,chromaticity values,biochemical composition,the activity of polyphenol oxidase,aroma composition and sensory evaluation.The main results were as follows:1 The inpact on the quality of white teas withered by traditional heating method and continuous cleaning producing lineThe test samples were produced from four different processing methods in the same production base.The results showed that the withering speed of different withering ways was SJ(withering by heating on bamboo sieves)>WJ(withering by heating on bamboo curtain)>LJ(withering by heating in continuos production line)>LF(withering by more than one method in continuous production line),this trend was consistent with the trend of average leaf temperatur.Comparing the main biochemical composition,tea soup’s chromaticity values and sensory evaluation results comprehensively,in terms of quality,it finded that the white tea produced in the continuous production line was not worse than the white tea produced by traditional heating methods.Among them,LJ’s quality was the best.It embodyed as the highest content of amino acids,smallest of phenol ammonia ratio.Besides,Its shape was even and orderly,aroma smells fresh and pure,soup looked bright with apricot color and the value of L*(brightness of liquor color)was maximum.Study has shown that the production line had been achieved efficient,continuous and clean production,The quality of white tea produced by the production line was not worse than the white tea produced by traditional heating methods.So,the production line was worth to perfect and spread.2 The inpact on the quality of white teas withered by different LED lightIn the withering trials of different LED light,selected red,yellow,green,blue,white LED light and set natural withering as the comparison.The results showed that the withering speed of different LED light withering was blue light>white light>green light>yellow light>red light>CK.This trend was consistent with the trend of average leaf temperature.The light group lasted 48h to accomplish withering processes while the CK group need more 8h,and the average leaf temperature of blue group was higher than CK group 2.9℃.In the withering process,apart from white group had only one activity peak of PPO,other groups had two peaks,but CK group’s appear time of PPO activity peak was later 6h than light groups.The rank of mean values about PPO activity was red light>white light>blue light>yellow light>green light>CK.Among them,red group was higher 17.8%than CK group.Comparing the main biochemical composition,tea soup’s chromaticity values and sensory evaluation results comprehensively,the yellow group(the wavelength’s range is 586-592nm)was the best,and CK group(natural withering)was the worst.The different LED light withering had a significant impact to white tea’s appearance,aroma and taste.Firstly,white teas of yellow and blue group had pretty shape,dark green color,clean fresh aroma,mellow taste,especially yellow group’s aroma and taste contained pleasant flowery flavor.Secondly,white teas of green and white group had clean pure aroma,and green group’s taste was mellow.The red light was not benefit to the quality of white tea,and CK group contained grassy smell in aroma and taste and the shape was flat.The result of quality ingredients showed water extracts of red,blue and white group were higher than CK group;polyphenols of red,green and white group are higher than CK group;amino acid of light group were higher than CK group and yellow group was higher 9.85%than CK group;flavonoids of red,green and blue group were higher than CK group.It detected a total of 44 aroma components from six groups tea samples.Among them,red group had been detected 34,yellow 37,blue 31,green 23,white 24 and CK 24.Each group’s aroma ranked by total weight was blue light>white light>yellow light>red light>green light>CK.Blue group’s total aroma content was 1.84 times higher than CK group’s.The sensory evaluation results showed that yellow group appeared clean aroma with flowery flavor,and hexanal,1-nonanol,neroli,diluted(E)-2-hexenal may be conducive to the formation of flowery flavor.3 The inpact on the quality of white teas withered by different illumination timeIn the withering trials of differen illumination time,set natural withering as the control.The results showed that the withering speed of yellow light withering of different illumination time was C(lighting throughout)>B(lighting 36h)>A(lighting 18h)>CK(natural withering),this trend was consistent with the trend of average leaf temperature.The rank of mean values of PPO activity was A>CK>B>C.Comparing the main biochemical composition,tea soup’s chromaticity values and sensory evaluation results comprehensively,C group’s quality was best,CK group was worst.C group’s amino acid and flavonoids content was highest while CK group’s flavonoids content was lowest,and C group’s polyphenol and phenol ammonia ratio were smallest while CK group’s were highest.The sensory evaluation results showed that C group’s aroma was clean and brisk,taste was mellow,and both its aroma and taste contained pleasant flowery flavor.CK group’s soup color was little dark of apricot,b*was largest,aroma was low,taste was bland.4 The inpact on the quality of white teas withered by different illumination intensityIn the withering trials of differen illumination intensity,set natural withering as the control.The results showed that the withering speed of yellow light withering of different illumination intensity was Q(high illuminance,345Lux)>Z(Medium illuminance,245Lux)>R(low illuminance,145Lux)>CK(natural withering),this trend was consistent with the trend of average leaf temperature.The rank of mean values of PPO activity was R>CK>Z>Q.Comparing the main biochemical composition,tea soup’s chromaticity values and sensory evaluation results comprehensively,Z group’s quality was best while CK group was worst.Z group’s water extracts and flavonoids content was highest while CK group’s amino acid was lowest,and Z group’s phenol ammonia ratio was the smallest while CK group’s was highest.Besides,Z group’s soup was bright with apricot color,and its aroma was clean and brisk,taste was slightly mellow.CK group’s soup color was little dark of apricot,b*was largest,aroma was low.taste was bland.