Studies On The Wuyi Rock Tea Continuous Production Line And Its Process Optimization

This thesis take the continuous production line of wuyi rock tea processing as the research object,and analyzed technical parameters and performance characteristics of six modules of continuous production line of wuyi rock tea,such as withering,green-making,fixation,rolling,drying and microwave tempering and so on.In order to research the product quality and production efficiency of continuous production line of wuyi rock tea,the research of rain leaves with rapid withering,PLC green-making control,the high temperature hot air fixation,the automatic rolling unit and the microwave tempering drying were carried on,and the results are as follows:1.The devices of continuous production line of wuyi rock teaWithering module uses dynamic rapid composite withering way;Green-making module uses comprehensive green-making machine which controlled by PLC technology,to reduce the labor intensity and labor cost;Fixation module adopts 6 CSF-80 high temperature hot air fixing machine,realizes continues fixation of rock tea,and high temperature hot air can kill enzymes in a short time(about 1.5 min);Rolling module adopts 6CRZ-55 automatic rolling machine,it can control six rollers to reduce labor cost and labor intensity;Microwave module uses 6CSW-60 microwave tempering machine,the microwave tempering time is about 1.0 min,it can realize continues drying;Drying module adopts intelligent temperature control system to save energy.2.The physical and chemical quality change of rain leaves with dynamic rapid withering(1)The moisture content of rain leaves with dynamic rapid withering declined from 79.30%to 76.28%,which achieve the moisture content of fresh leaves without rain,The leaf temperature increased from 19.8? t0 31.3?.(2)The rain leaves uses dynamic rapid composite withering,the rapid withering time was reduced by 75%than traditional roller withering.(3)Processing A with rapid composite withering is conducive to the tea water extract and tea polyphenols oxidation to reduce acerbity,caffeine,flavonoids and soluble sugar content of processing A was significantly higher than that of processing B without rapid withering..(4)The primary tea with processing A have 72 aroma,19 more than those without rapid withering,The geraniol,linalool,fragrance material and beta ionone content of processing A is higher,the primary tea without rapid withering contained more phenylacetonitrile and benzoic acid which have grass gas.(5)The sensory quality of primary tea of processing A is better than that of without rapid withering.3.The physical and chemical quality changes of rock tea with PLC green-making control(1)The environmental temperature changes in 22.0?27.0 ?,relative humidity is59.4%?59.4%,leaf temperature changes between 23.8?26.6 ?,the change trend of environment temperature and humidity with two kinds of control are the same.(2)The water content of PLC control is on the decline,and there is no difference between manual control,tea polyphenols,amino acid content is higher than that of manual control,The water extract,caffeine content is higher than that of manual control.(3)The sensory quality between PLC green-making control and artificial control have no qualitative differences,PLC green-making control can replace manual control.4.The optimization experiment of high temperature hot air fixation and its contrast test(1)The optimal combination of the high temperature hot air fixation are:the roller frequency is 36 Hz,conveyor belt frequency is 40 Hz and hot blast temperature is 300 ?.(2)The water extract,tea polyphenol,amino acid,flavonoid,soluble sugar content of high temperature fixing leaf are higher than traditional roller fixation,tea polyphenols,amino acids,soluble sugar,caffeine content of primary tea with high temperature fixation are higher than that of roller fixation,the moisture content difference is not obvious.(3)The primary tea with high temperature hot air fixation have 62 kinds of aroma components,12 less than kinds of roller fixation,relative content of alcohols,esters and ketones of high temperature hot air fixation more than that with roller fixation,and it contains high fragrance material,such as 6-methyl-5-heptene-2-ketone,alpha olefin,nerolidol,etc..(4)The sensory quality between them have no qualitative differences.Through further refinement process parameters control,the high temperature hot air fixation can be used for fixation of wuyi rock tea.6.The process parameters optimization of automatic rolling unit(1)Using the response surface method to optimize process parameters,it is concluded that:the first rolling time is 1.41min,the second rolling time is 6.00 min,and the rolling pressure(the percentage of pressure down stroke accounted for the total trip)is 96.14%,predictive value of rolling bar rate is 66.51%,(2)The actual process parameters is that:the first rolling time is 1.5 min,the second rolling time is 6.0 min,rolling pressure is 95%,the actual determination of the rate is 65.32%,and is relatively close to the theoretical value.7.The physical and chemical quality changes of wuyi rock tea with microwave tempering(1)Microwave tempering can reduce the moisture content of stalk and leaf,make tea inside and outside moisture gradient lower,it can be applied in the wuyi rock tea processing.(2)With the tempering time growing and the greater the leaf thickness,the moisture content of stalk,leaf,the total tip are reduced,On the contrary,it will be opposite,when microwave time was 1.5 min,leaf thickness is 10 mm,the moisture content difference between leaf and stalk is minimal.(3)The influence of microwave tempering time on water extract,tea polyphenols,caffeine and soluble sugar content are significant,leaf thickness have significant influence on water extract,tea polyphenols,caffeine,amino acid content.(4)The brightness of the first drying leaf is down after tempering,the leaf color slants red yellow.8.The energy saving effect and economic benefit of wuyi rock tea continuous production line(1)The withering module:coal saving rate of dynamic rapid withering is 34.36%,power saving rate is 17.88%,the energy cost savings rate is 24.83%;(2)Green-making module:PLC control can reduce labor intensity by70%,save labor cost by75%;(3)Fixation module:the ultra high temperature hot air fixation can save labour 50%,and labour cost 27.27%;(4)Rolling module:rolling unit can save about 66.67%labour costs;(5)Drying module:coal saving rate of PID technology control was 21.18%,coal cost saving rate is 19.74%;(6)The annual energy and labor cost saving of Yongsheng rock tea factory is about 159357.72 yuan.