Study On New Processing Technique Of Congou Black Tea

Drying plays an important role on aroma and taste of black tea. Drying stage of the strip congou basically make use of drying, which has defects on the lower aroma and lighter taste. Frying process was introudeced in to the drying stage of black tea, and the combined drying parameters were discussed in this issue.The research on Congou-shaped craft has been done, but there are few studies on processing of flat congou. According to the problem of shaping and hardly fermented of flat congou, the influence of rolling and freezing technics on the quality of flat congou were discussed in this issue. The main results were as follows:1. Research on shaping technics of Congou Black teaInfluence of different shaping ways (Needle-shaped, curled, Strip, Flat) on the quality of black tea was studied. The results showed that the sensory quality of needle-shaped was best, which were fine and straight shape, black bloom, sweet smell, mellow flavor, red clear liquor colour and infused leaf, the worst was the flat congou, which were underfermentation, heterochromatic shape and infused leaf, orange yellow liquor colour, smother flavor. The results of quality components showed that the strip has the hightest content of tea polyphenol, the lowest content of soluble sugar, amino acid, theaflavins, thearubigins and theabrownin, suggestting that is underfermentation; the strip had the hightest content of theaflavins and thearubigins, the others components was no significant difference between the tea.2. Research on New Processing Technique of Strip Congou Black teaResearch on drying technics:Influence of different drying ways (all drying, drying-frying-drying, frying-drying-drying, drying-frying-roasting, all frying) on the quality of black tea was studied. The results showed that different drying ways had a significant effect on theaflavins, thearubigins, theabrownin and amino acid respectively. The tea has the highest content of theaflavins and thearubigins by frying-drying-drying, and indicated that is good for the quality of congou black tea. The results of organoleptic quality showed that the drying ways of all drying or all frying were bad for the quality of tea, and the combined dry process of frying-drying-drying and drying-frying-drying has the best sensory quality. Based on the results obtained, the suitable drying way was frying-drying-drying.Research on leaf water content of frying technics(40%,35%,30%,25%,20%)was done. The results showed that different water content had a significant effect on thearubigins, theabrownin respectively. With the leaf water content decreasing, the content of thearubigins increased first and then decreased. The water content, too high or too low, would induce adverse effects to sensory quality, the water content of 35% has the best sensory quality. Summarizing above results, the optimal water content was between 35 %-25%.Research on aroma-Enhancing:randomed trials were used to study the influence of two aroma-Enhancing factors which were temperature (80℃,90℃,100℃,110℃,120℃,130℃) and time (4 min,8 min,12 min,16 min,20 min) on the quality of congou. The results indicated that aroma-Enhancing technics had a significant effect on aroma and taste. The overlow temperature can’t be to remove the grass smell, and over high temperature could easily made the aroma and taste with high fire. With the temperature increasing, the content of theaflavins and thearubigins increased first and then decreased; with the time iecreasing, the content of theaflavins had a little decrease. Considered comprehensively, the best temperature of aroma-Enhancing was 100℃, and time was 8 min.3. Research on Processing Technique of Flat Congou Black teaResearch on rolling technics:influence of different rolling time (0 min,2.5 min,5 min, 7.5 min,10 min) on the quality of flat congou was studied. The results showed that rolling time had a significant effect on water extract, tea polyphenol, amino acid, soluble sugar, theaflavins, thearubigins and theabrownin respectively. With the time increasing, the content of theaflavins and thearubigins increased and tea polyphenol decreased significantly, which is helpful for decreasing the bitterness of tea infusion. The results of sensory quality showed that with the time increasing, the appearance of dry tea was adversely affected, but the color of dry tea was turned red. so the suitable rolling time was within 10 min.Research on freezing technics:randomed trials were used to study the influence of two freezing technics factors which were temperature (-5℃,-10℃,-20℃) and time (8 h,12 h, 16 h,20 h,24 h,28 h) on the quality of flat congou. The results showed that the influences of freezing temperature, freezing time and their interaction on water extract, tea polyphenol, amino acid, theaflavins, thearubigins and theabrownin respectively were significant. With the time iecreasing, the content of theaflavins and thearubigins increased; with the temperature decreasing, the content of theaflavins increased first and then decreased, reached the highest at-10℃, the content of thearubigins increased. The lower temperature of freezing, the longer time of freezing, the better for the color of dry tea and leaves turning red. Considering comprehensively, the best temperature of freezing was-10℃, and time was 12 h.