This first step is essential to get the final result. The purpose of roasting is to kill those enzymes in the leaves that cause oxidation. In order to do this, the leaves are brutally heated to a temperature of around 100°C, either in large pans (the Chinese method) or by steam cooking (the Japanese way), for anything from 30 seconds to 5 minutes. The leaves thus become soft and easily bendable for the rolling process.
For this operation, the harvest is spread evenly over trellis-work trays placed above ducts carrying air blown by fans in a room kept at a constant temperature of between 20°C and 24°C. This phase generally lasts for about 18 to 20 hours, during which a certain number of biochemical reactions occur, releasing a characteristic floral scent.