مشخصات پژوهش

The Paraguayan herb Stevia rebaudiana (Bertoni), also known by natives as Kaa-Hee ´ o “hierba dulce”, has captured growing interest as a potential source of natural non-caloric sweeteners for use as a possible substitute for synthetic sweeteners. Its use has been approved in Brazil, Argentina, and Paraguay, as well as in China, Korea, and Japan [1]. Stevia rebaudiana contains six diterpene glycosides with an intense sweet taste, the most abundant and important being stevioside, with a sweetening power 300 times that of sucrose, and rebaudioside A, the second most abundant and 400 times sweeter than sucrose. The rest are of minor concern: rebaudioside C and dulcoside A, and at trace levels, rebaudioside E and D [2]. Due to increasing interest for natural sweeteners as safe alternatives for synthetic sweeteners such as aspartame or assesulfam K, extraction of steviol glycosides is important. Ultrasound is a key-technology in achieving the objective of sustainable ‘‘green” chemistry and extraction. Ultrasound is well known to have a significant effect on the rate of various processes in the chemical and food industry. Using ultrasound, full extractions can now be completed in minutes with high reproducibility, reducing the consumption of solvent, simplifying manipulation and work-up, giving higher purity of the final product, eliminating post-treatment of waste water and consuming only a fraction of the fossil energy normally needed for a conventional extraction method such as Soxhlet extraction, maceration or Clevenger distillation [3]. In this study a taguchi optimization method was applied for ultrasound assisted extraction of steviol glycosides from stevia leaves.