Study On Effect Of Drying Processing With Artificial Light On The Quality Of Sundried Green Tea

Sunlight is an indispensable factor in the traditional drying process of sundried green tea,but it is difficult to regulate its conditions artificially.Sunlight consists of short wave ultraviolet(UVC),medium wave ultraviolet(UVB),long wave ultraviolet(UVA),visible light and infrared.Among them,short wave ultraviolet(UVC)is easy to be absorbed by air and hard to reach the ground.In this study,yingshuang,Pujiang County,Jinhua City,Zhejiang Province,was used as the raw material to process green tea.The samples of 0h(kneading leaves),2 h,4 h,6 h and 8 h in the process of drying were sampled and their physical and chemical properties were analyzed.Different artificial light sources,such as UV,were used to dry the green tea.Combined with different initial drying temperature and moisture content tests,the effects of different artificial light sources,initial drying temperature and moisture content on the quality of tea were explored.The main results are as follows:(1)In the process of sun drying,the quality components of green tea samples changed significantly in each stage,and the change was the biggest in 4H.The color of tea soup in process showed yellow green in different degrees,and with the extension of drying time,the yellow color increased,while the green color decreased.In the aspect of flavor components,the content of catechin and theobromine first decreased and then increased;the content of gallic acid first increased and then decreased;the total amount of flavonoids gradually increased.In terms of aroma components,33 kinds,65 kinds,68 kinds,79 kinds,100 kinds and 41 kinds of volatile substances were detected respectively in fresh leaves,rolled leaves,2 hours of sunlight drying,4 hours of sunlight drying,6 hours of sunlight drying and 8 hours of sunlight drying,mainly alcohols and hydrocarbons.In the process of drying,the hydrocarbon species are gradually enriched,but the proportion of hydrocarbon content is decreased;the ketone,aldehyde and alcohol species are gradually enriched,and the proportion of hydrocarbon content is also gradually increased.(2)Nine kinds of artificial light sources(UVB,UVA,visible light,infrared,UVA combined with UVB,UVB combined with infrared,UVA combined with infrared,visible light combined with infrared,all-optical spectrum)have obvious differences in the quality of dried green tea.The results of sensory evaluation showed that UVA combined with infrared>UVB combined with infrared>full spectrum>UVA>UVA combined with UVB>UVB>infrared>visible>visible combined with infrared.However,the degree of insolation of the samples dried by different artificial light sources is weaker than that of the samples dried by sunlight.Comb,ined with the analysis of physical and chemical components,the drying quality of UVA combined with infrared treatment is similar to that of sunlight drying.(3)In the different initial drying temperature(35?,30?,25?,20?),the quality of the sample at the initial drying temperature of 35? is the most similar to that of the control sample of sundried green tea.It has a strong fragrance and a strong taste of sunshine.In different initial moisture content(55%,35%,15%)treatments,the quality of 55%initial moisture content samples is better than that of 35%and 15%initial moisture content samples.In order to improve the production efficiency and quality of sun cured green tea,a study on artificial light source simulating solar drying was carried out in this paper.The results show that under the conditions of 35? initial leaf temperature,55%initial moisture content,UVA combined with infrared drying,the quality of tea samples is better and the effect of the process is most similar to that of the sun drying.