IntroductionStevia rebaudiana (Bertoni) Bertoni is a perennial plant of theAsteraceae family native to Paraguay. The species S. rebaudiana,commonly known as sweet leaf, sugar leaf, or simply stevia, iswidely grown for its sweet leaf. It is well known that the leaf of ste-via contains sweet-tasting diterpenoid steviol glycosides (Kinghornand Soejarto, 1986). Amongst the known steviol glycosides, stevio-side and rebaudioside-A dominate, and both are more than 300times sweeter than sucrose (Crammer and Ikan, 1986). Stevia hasbeen used as a low-calorie sweetener for years in South Amer-ica, Asia, Japan, and China, and in some countries of the EuropeanUnion. Currently, Japan and Korea are the largest markets for stevia