Study On Vacuum Drying And Fragrance Recovery Technology For Production Of Tieguanyin With Low Temperature

In this paper, we mainly study a drying technology of Fen flavor oolong under low-temperature and vacuum conditions,and the methods to recycle fragrance overflowed during the drying process were also studied. Firstly, the machinery, equipment and technology of oolong tea process and their effect on Oolong tea qualitywere summarized. Secondly on the basis of previous study, an integrative set of tea processing machinery for low-temperature vacuum drying and fragrance recovery were developed. And then with the tea processing machinery the drying technology of low fragrance Tie Guanyin under low-temperature and vacuum conditions was developed and the methods to recycle flavours overflowed during the drying process were studied deeply. (1) We have studied the method and key points of operating the tea processing machinery. (2) The effects of vacuum temperature (35℃, 40℃,45℃,50℃), vacuum time (15min,30 min,45 min,60 min), and fragrance enhanced temperature (70℃,75℃,80℃,85℃,90℃) on the quality of low fragrance TieGuanyin, were evaluated with water extract and sensory evaluation. The technological parameters were obtained through orthogonal experiment:vacuum pressure ranges from -0.1 Mpa to 0.1 Mpa, drying temperature is 40℃, Via alternating drying rounds of 30min in vacuum and 10min at atmospheric pressure the moisture content of tea gets blow 12%, extracting temperature is 80℃, time for enhancing fragrance is 10min. (3) The effect of extractant on fragrance recovery and the operating process of fragrance recovery were explored. It was found n-hexane is an ideal aroma recovery extractant with gas chromatography mass spectrometry (GC-MS). with an electronic nose the drying technology didn’t affect the main aroma components. The main flavor compounds and fragrant compounds were shown up excellently.