Study on the effect of low-temperature vacuum drying technology on the quality of Oolong tea

The problem that hot air drying of Oolong tea is that the aroma in it is easy to lose, frozen vacuum drying of Oolong tea needs long time and large energy consumption. Research useing low-temperature vacuum drying technology to olry Oolong tea was stadied in this paper. The Oolong tea was put into vacuum refrigerator non-frozen with the temperature at 55℃, and the vacuum at 100(±30)Pa.Low-temperature vacuum drying, hot air drying traditional method and vacuum freeze drying method were compared to study the impact of low-temperature vacuum drying on active ingredients such as active ingredients preservation degree, sensory quality and rehydration characteristics. The results show that, by comparing the three kinds of drying methods, the quality of Oolong tea presented green color and bright obvious smell and flavour spirit rich, the control of by low-temperature vacuum drying technology, and was better on energy consumption and time. So, the low-temperature vacuum drying technology is a kind of new drying method that can improve the quality of Oolong tea.