Effect Of Different Light Withering On The Quality Of Black Tea

Black tea has the largest production, consumption and trade volume in the world than any other kind of teas. As its unique flavor is loved by consumers around the world, it gradually becomes the indispensable necessity for millions of tea consumers. The researches on black tea processing in China and abroad both concentrated on impact factors on tea qualities such as tea varieties, temperature and humidity in withering, fermentation processes and so on. Some report shows that lights can affect the contents of sugars, amino acids, polyphenols, flavonoids and other ingredients in the plants respectively, and these ingredients are the main quality components in black tea. So effects of light quality, light intensity and raw materials on black teas’ qualities were studied with different light quality treatments on withering tea leaves.1. Effects of different light qualities on black teasIn experimental tea withering equipment, with different light withering process, the selected light source were:ultraviolet, yellow, blue, orange, white, purple, red, glaucoma, green, where white light as the control, seting a processing do not light treatment. The results show that different light quality withering has a significant impact to black tea, Organoleptic appreciation scores of each treatment followed:yellow, orange, red, blue, UV, violet, glaucoma, dark, white, green handle.The influence of different light to black tea is mainly reflected in two aspects of the tea aroma and taste.Yellow light, red light, orange light and so on processing the aroma is higher than contrast, sweet prominent. main biochemical compositions analysis results show that, according to the results of yellow light, red light, orange light treatment of amino acids, theaflavins, catechin contents are significantily higher than control, soluble sugar content is also higher than contrast, green processing is the worst in Organoleptic appreciation, which amino acid content declined significantly compared to control, soluble sugar, polyphenols have no significantly differents with control group.2. Effects of different light conditions on black teasThe single yellow light was used to withering tea leaves, and three light intensities of 9W、18W、27W were setted. The results showed 27W and 18W treatment is improved significantly on aroma and taste scores. And the chemical test showed that, the contents of amino acids, catechins in teas under27W were significant larger than 9W.The single yellow light was used to withering tea leaves, and three light illumination time of 3h、6h、9h were setted. Based on organoleptic evaluations, the tea which was long time light withered had the best qualities, especially in aroma and taste scores. The chemical test showed that, Enhance illumination time significant promoted the content of tea polyphenols, amino acids, but soluble sugar content is not significant affected.the longer the illumination time, the more obvious light influence on the quality of black tea.The result of different leaf thickness test showed that, leaf thickness play an important role in light effect tea quality. The tea was fragrance and sweet tasting which the leaf thickness was 5 cm and 10 cm. The chemical test showed that the amino acids content is significant rised which the leaf thickness is 5cm, there is no significant effect on polyphenols, soluble sugar contents.3.Impact of material to black teas in light withingDifferent tenderness of one bud with one leave, one bud with two leaves and one bud with three or four leaves were taken as raw materials to withering under yellow light with no light treatment as the control. The organoleptic evaluation showed that the more tenderness the raw materials were the more fresh and brisk black tea tasted and smelled. Based on chemical analysis, tea polyphenol content had no significant differences with the control while the amino acid content was remarkable larger. And the content of soluble sugars between one bud with one leave and one bud with two leaves had no differences while the content in one bud with three or four leaves had a prominent increase.Different varieties of Yingshuang, Fuyunliuhao and Wulong were taken as raw materials to withering under yellow light. The organoleptic evaluation showed that the quality of each varieties leaves was improved with light withering. Effect followed,Wulong>Yingshuang>Fuyunliuhao. Based on physical and chemical analysis, tea polyphenol content had no significant differences with the control while the amino acid content was remarkable larger than control. To Fyunliuhao variety, the soluble sugar contents was significanty improved while it was not significanty on Wulong and Yingshuang varieties.