Research On Continuous Shaping Technology For Yongxi Huoqing Green Tea

Yongxi Huoqing Green Tea(hereinafter referred to as Huoqing)is produced in Yongxi Village and Huangtian Village of Jing County,Anhui Province,and is one of the typical representatives of granular green tea.At present,Huoqing tea is produced mainly by a single machine,with long processing time and low processing efficiency.At the same time,due to the long-term processing,the appearance and infsion of finished tea are yellow,the aroma is not good,which does not meet the current market requirements.The quality is difficult to stabilize,and often has problems such as appearance is yellow,the quality of infusion and aroma is bad.Establishing continuous production technology is an effective way to solve these series of problems.Based on the previous research,this study used the fresh leaves of the Liuye species with one bud and two leaves as raw materials,analyzed the processes(Erqing,shaped)that had a great influence on the color quality of Huoqing tea,and found the correlation with quality.High key technical factors(The moisture content of Erqing,the weight of shaping leaves,and the shaping temperature),studied the impact of these key process factors on the Huoqing tea color,aroma,taste,shape and other quality indicators,and then used orthogonal test to optimize the continuous production process,and finally compare the optimized process with the traditional process to verify the feasibility of the optimized process.The main findings are as follows:(1)Screen out the key shaping factors that affect the quality of Huoqing tea.In the process of spreading,fixation,rolling,Erqing and shaping,the influence of Erqing and shaping on Huoqing tea's color is the biggest.From the correlation between process technology factors and quality indicators,it can be seen that the degree of Erqing,the weight of shaping leaves,the first shaping temperature and the second shaping temperature have a high correlation with quality,and there are significant and extremely significant correlations.(2)The influence of key technical factors of shaping on quality is studied.Under the condition of low and medium water content,the level of Erqing is higher in L~*,a~*value and catechin content of dry tea and tea soup,and the phenol-ammonia ratio and bulk density value decrease significantly.The catechin content was the lowest under the condition of 3.5 kg of leaves,and the highest was 4.0 kg of leaves.At the same time,the a~*value of dry tea increased significantly,and the bulk density value increased significantly with the increase of the weight of shaping leaves.When the first shaping temperature increases,the phenol to ammonia ratio,the a~*and b~*values of the tea infusion increase,and the L~*value and bulk density decrease.The second shaping temperature increased,the dry tea L~*,a~*value and tea infusion a~*,b~*value all increased significantly,the total catechins and tea infusion L~*value decreased significantly.(3)The volatile components under different shaping process conditions were analyzed.A total of 39 common volatile compounds were detected in the samples produced under different process parameters,which can be summarized as alcohols(10),aldehydes(4),alkenes(6),ketones(6),esters(5)and other categories(8)account for 30.38%,18.97%,6.26%,5.02%,7.58%,and 31.79%of the total volatile matter,respectively.All of the volatiles are aromatic and most of them are significantly affected by the process.Especially Dimethyl sulfide,Hexyl alcohol,Hotrienol and nonanal are significantly affected by the four process factors.(4)The technical parameters of continuous shaping of Huoqing Tea were determined.Orthogonal experiments showed that the key technical parameters of continuous shaping are 40%of the degree of greening,3.5 kg of leaves,the first shaping temperature of 45?and the second shaping temperature of 55?.Through the analysis of quality and comparison of processing efficiency,it is concluded that the optimization of continuous shaping is more green than the traditional processing of dry tea and tea infusion,and the processing is also improved.