Effects of electric roasting and charcoal roasting and drying on tea quality

  Fuding White Tea is produced in Fuding City, Fujian Province, with a long history and high quality. It is divided into two steps: withering and drying, and is generally operated by tea processing machines. The drying process is used to remove excess water in leaves after withering, destroy activities such as polyphenol oxidase in leaves, and improve the aroma and taste of finished products. Drying is a key step in forming the quality of white tea, which is related to the appearance and inner quality of the finished tea.

At present, the commonly used drying methods for Fuding white tea are charcoal roasting and electric roasting. Charcoal grilling is more traditional, using lighted charcoal as the heat source. However, some researchers believe that the charcoal drying of tea leaves with a tea drying machine has certain advantages in terms of quality and storage, and is also the most commonly used drying method in the production of various types of tea.

Due to the importance of the drying process to the quality of white tea, choosing a suitable drying method is of great significance to the formation and control of the quality of white tea. Different drying methods have obvious effects on the aroma of finished white tea. “Fireworks” are generally the aroma produced by the sugar in tea leaves being fully coked under high temperature conditions, and are more common in Wuyi rock tea. In the study, the drying temperature of the low-temperature carbon roasting group was 55-65 °C, which was lower than that of the electric roasting group, but the finished tea had obvious pyrotechnic aroma compared with the latter. Combined with the charcoal roasting process, it can be speculated that the heating is prone to unevenness, resulting in higher temperature of some tea leaves near the heat source, resulting in uneven Maillard reaction, thus forming a pyrotechnic incense. This is also consistent with the sensory evaluation results of charcoal-fired dry tea with a more complex appearance. Similarly, uneven heating may also lead to large differences in aroma components between charcoal grilling groups, and there is no obvious correlation. It can be seen from this that the charcoal roasting process can indeed enhance the floral and fruity aroma of the finished tea, but it needs to test the relevant experience of tea processing personnel and the control of temperature changes during the drying process; tea dryer adopts the machine to set the temperature and adopts the air circulation device , to ensure the stability of the temperature in the machine, liberate manpower to a certain extent, and improve the yield of finished tea. Relevant enterprises can flexibly choose different drying methods or combinations to create products according to actual application scenarios and different customer needs.