Jasmine tisane is consumed in China, where it is called Jasmine tea. Jasminum sambac flowers are also used to make tea, which often has a base of green tea, but sometimes an Oolong base is used. The delicate Jasmine flower opens only at night and is plucked in the morning when the tiny petals are tightly closed. They are then stored in a cool place until night. Between six and eight in the evening, as the temperature cools, the petals begin to open. Flowers and tea are "mated" in machines that control temperature and humidity. It takes four hours or so for the tea to absorb the fragrance and flavour of the Jasmine blossoms, and for the highest grades, this process may be repeated as many as seven times. Because the tea has absorbed moisture from the flowers, it must be refired to prevent spoilage. The spent flowers may or may not be removed from the final product, as the flowers are completely dry and contain no aroma. Giant fans are used to blow away and remove the petals from the denser tea leaves. If present, they simply add visual appeal and are no indication of the quality of the tea.