存在於甜菊(Stevia rebaudiana Bertoni)葉中的甜菊糖，其甜度約為蔗糖甜度的三百倍，且甜味性質優良，極具開發價值。本研究之目的，在於探討不同條件對於甜菊糖萃取效果之影響，以求山最適之萃取操作條件，作為工業化生產之參考。在萃取過程中，使用內徑2.8cm，長度45 cm，具有保溫外套管的玻璃管柱慎裝乾燥甜菊葉，以水進行升流萃取，得到最適萃取溫度為50~55℃，最適溶劑流速為4.5ml/min。以多管柱升流方式萃取甜菊糖，可較單管柱方式減少大量溶劑，有利於隨後蒸發濃縮所需能源之節約，而且可在較短時間內得到較高濃度之甜菊楮萃取液。以二管柱萃取所得之甜菊楮萃取液，其stevioside之濃度為單管柱時(524mg/ml)的1.85倍(9.7 mg/ml)，而所需溶劑體積僅為單管柱時的55%，以三管柱萃取時，則分別為3.05倍(16.0mg/ml)與33%。 Steviosides, which exist mainly in the leaves of Stevia rebaudiana Bertoni are about 300 times as sweet as sucrose and have excellent taste properties, and therefore worth exploiting. The purpose of this study is to investigate the effccts of various conditions on the extraction of steviosides, and to find out the optimal operation conditions.For the extraction, water jacketed glass columns (45cm x 2.8cm I.D.) were used to extract steviosides from dry stevia leaves with water by an ascending-current method. The optimal extraction temperature and flow rate were found to be 50-55℃ and 4.5 ml/min respectively. Extraction with the use of a multi-column system can effectively reduce the quantity of solvent needed, resulting in extracts of higher steviosidcs concentrations obtained in a shorter time. It is beneficial for saving energy needed for the subsequent concentration of the extracts. By the use of 2-column and 3-column extraction systems, the stevioside coocentrations of the extracts thus obtained were found to be 1.85 times (9.7mg/ml) and 3.05 times (16.0mg/ml),respectively, as high as those obtained with a single column system (524mg/ml),and the solvent volumes needed were only 55% and 33%, respectively, those needed in a single column system.
