Optimization of preparation process of cold brew tea by explosion puffing drying at variable temperature and pressure difference

In order to optimize the explosion puffing drying preparation process of cold brew tea at variable temperature and pressure difference, the influence of the moisture content, freezing treatment times and puffing temperature on the cold brew tea was studied. Single factor experiments and orthogonal experiments were carried out, and the experimental results indicated that the importance of the affecting factors were in the order of the moisture content, freezing treatment times and puffing temperature. The optimum explosion puffing drying preparation process was designed as follows: 50% of moisture content, three times freezing treatments at -18℃, 24 h each time, puffing treatment at 115℃. Under this optimized process condition, the cold brew tea was obtained and then soaked for another 30min at room temperature. Finally, the determination of the biochemistry ingredients of cold brew tea solution suggested that the water extract mass fraction, caffine mass fraction, tea polyphenols mass fraction, free amino acid mass fraction, water-soluble saccharides mass fraction reached to 16.45%, 0.84%, 11.45%, 0.93%, 2.47%, respectively. Results showed that biochemistry ingredients of cold brew tea prepared by explosion puffing drying at variable temperature and pressure difference were easy to extract. This research provides technical support for industrialization production of the cold brew tea.