Rearch on quality preservation drying technology of Salvia leaves green tea

In order to develop Salvia leaf green tea products, the effects of different drying methods on effective components of Salvia leaves were studied in this paper. The optimum technology parameters for hot-air drying and vacuum-freeze drying were obtained by taking Salvianolic acid B and chlorophyll content as indexes, and comparing with the effective ingredients of Salvia leaves. The results showed that the optimal parameters were temperature 60°C, wind speed 0.6 m/s, and material thickness 2 layers for hot-air drying. The optimum processing for vacuum-freeze drying were pre-freezing for 2 h under -25°C, and kept on -25°C, 50 Pa sublimation for 22 h, then 20°C resolution for 14 h. Experiments showed that vacuum-freeze drying was the best quality preservation method, and the preservation for Salvianolic acid B and chlorophyll were 98.76% and 82.21% respectively under these optimal parameters.