There are an estimated 1,000 or more kinds of alcoholic drinks in Korea. Most are made from rice, and are fermented with the aid of yeast and nuruk (a wheat-based source of the enzyme amylase). Fruits, flowers, herbs, and other natural ingredients have also been used to craft traditional Korean alcoholic drinks. There are six distinct flavors: sweet, sour, pungent, roasted, bitter, and spicy. When the flavors are balanced, the alcohol is considered of good quality.