| The scented tea which consisting about 1/3 of the whole tea production is an important category in Chinese tea. It is a favorite drink due to it combination of the taste of tea and the fragrance of flower. Recently, with the increase of economic and living level, the single jasmine tea can not meet the demand of consumption; therefore more and more researchers concentrate on exploiting the characteristic scented tea.In this thesis, the research was directed by the theory of tea processing science, tea biochemistry, tea inspection and used the principles and methods of adsorption dynamics and food sensory evaluation, etc. Based on the studies of the aroma adsorption, we developed to the studies of technical optimization in order to explore the technical approach of scenting the characteristic scented tea.Firstly, the influence of four factors including the scenting time, the temperature, the water content of base tea and the flower dosage on the aroma adsorption was studied, in order to explore the aroma adsorption character of characteristic scented tea. We choose Maofeng green tea as the base tea and Osmanthus fragrans var. latifolius, Chimonanthus praecox, Banana shrub as the flower material. At the same time, the flower utilization percentage was studied by measuring the aroma adsorption capacity before drying and after drying. The results showed that: (1)The adsorption capacity order of base tea to the three kinds of flowers was: Osmanthus fragrans var. latifolius>Chimonanthus praecox>Banana shrub; (2)The adsorption equation time order was: Banana shrub (21h)< Osmanthus fragrans var. latifolius (24h)Chimonanthus praecox>Osmanthus fragrans var. latifolius, and all of them were about 70%. But the adsorption aroma lost 48.03%～51.36% in drying. The utilization percentage of three kinds of flowers were 33.70%,36.05% and 38.86%.Base on the research above and the basic adsorption theory, the aroma adsorption dynamics of characteristic scented teas was studied. The adsorption velocity and equilibrium was described and the adsorption mechanism was discussed according the fitting of two kinds of adsorption dynamics. The results showed that: (1) The dynamics data of the primary phase could fit the pseudo first order preferably, and the whole dynamics data could fit the pseudo second order. The order of adsorption velocity was Osmanthus fragrans var. latifolius > Banana shrub > Chimonanthus praecox, and the order of adsorption equilibrium and the primary adsorption velocity was Osmanthus fragrans var. latifolius > Chimonanthus praecox > Banana shrub.(2) Adsorption of tea aroma to the initial stage of mainly physical adsorption and chemical adsorption of the whole process of participation.(3) The aroma adsorption capacity and water adsorption was significantly distinct difference linearity positive correlation, that means when the aroma adsorption capacity increased, the water adsorption capacity also increased(R_O~2=0.95394; R_C~2=0.96723; R_B~2=0.97837).In order to optimize the scenting technological parameter, the Osmanthus fragrans var. latifoliuswas was employed to explore the best condition, and the Two Regression Orthogonal Combination model was used. The results showed that the best parameters were: the water content of tea base was 3.80%～14.28%, the flower dosage was 17.93%～32.46%, and scenting temperature was 14.80℃～38.20℃, and the scenting time was 31.67h～38.50h, the results also showed that there were interactions between the four factors.Based on the researches above, the green tea, black tea and Oolong tea were used as base tea, the Osmanthus fragrans var. latifolius and Osmanthus fragrans var. thunbergii were used as flower meterial, and scenting condition was according to the optimized technological parameters. Therefore, six kinds of scented tea were made, and their qualities were investigated. The results showed that: (1) Their water extract contents increased 8.21%～29.45%, the amino acid contents increased 2.97%～11.66%, the tea polyphenol contents decreased 0.48%～6.48%, and the caffeine contents had no remarkable change. The TFs contents of Osmanthus fragrans var. latifolius-black tea and Osmanthus fragrans var. thunbergii-black tea decreased 19.6% and 19.2%, respectively. The TRs contents of them decreased 0.36% and 0.33%, respectively. And the TBs increased 4.43% and 5.05%, respectively. (2) The Osmanthus fragrans var. latifolius was adapted to scent green tea, the Osmanthus fragrans var. thunbergii was adapted to black tea, and both of them were adapted to Oolong tea. However, the utilization percentage of Osmanthus fragrans var. latifolius by green tea and black tea is more than the Osmanthus fragrans var. thunbergii, the utilization percentage of the Osmanthus fragrans var by Oolong tea is more than Osmanthus fragrans var. latifolius. That means the quality of scented tea is not decided by the aroma adsorption capacity.The results of the study aimed at providing the theoretical basis for scenting characteristic scented teas, as well as a rich tea category, and promoting the development of flowers to provide resource support. |
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