Withered tea leaves pass through the tumble-roaster in about 1-2 minutes. This tumble-roasting machine is designed to mimic the motion of tea leaves traditionally tossed in a hot pan. As the hot tumble-roaster spins, it carries the withered tea leaves up one side, toasting them along the way. As they reach the top of the spinning tumble-roaster, the tea leaves fall down, turning and landing on their other side as they hit the hot roaster below. The tumble-roaster carries the tea leaves along for about one minute, tossing them dozens of times along the way so they are evenly fired. This firing partially halts the natural tea leaf oxidation process that would otherwise allow the tea leaves to change color from green to yellow, red, or brown. After passing through the tumble-roaster, these tea leaves have the rich, sweet aroma of toasted chestnuts.