EFFECTS OF HARVESTING TIME, DRYING, EXTRACTION AND PURIFICATION METHODS ON SWEETENERS EXTRACTED FROM Stevia rebaudiana Bertoni

Hassan,, Mona I.; Zeitoun, A. A.; Zeitoun, M. A.; Moussa, M. M.

doi:10.21608/jfds.2002.253010

EFFECTS OF HARVESTING TIME, DRYING, EXTRACTION AND PURIFICATION METHODS ON SWEETENERS EXTRACTED FROM Stevia rebaudiana Bertoni

Document Type : Original Article

Authors

¹ Sugar Crop Inst., Agric. Research Center (El-Sabahia), Alexandria

² Food Science Department, Fac. of Agric. (Saba Basha), Alexandria University.

³ Food Science and Technology Department, Fac. of Agric. (El Shatby), Alexandria University.

10.21608/jfds.2002.253010

Abstract

Stevia rebaudiana Bertoni plant was cultivated in pots at greenhouse and open field at farm near Alexandria, Egypt. Leaves of the plant were collected monthly during growth period (7 months) and dried with three different methods. Sweeteners in the leaves were first determined with IR. Proximate composition was also determined. Dried leaves were extracted and purified with different methods. Extraction and purification efficiency of each method were monitored with TLC and HPLC determination. The results obtained revealed that high level of carbohydrate obtained at 4 months of growth which seems to be the most proper harvesting time, drying in open air at 19-31°C for 24 hrs daily had adversely affected the carbohydrates content in leaves. Potassium was the highest content of mineral content in dry leaves. The highest concentration of stevia sweeteners in leaves obtained at 4 months age. The highest amount of stevioside and RA were obtained in MeoH extract. Purification of stevia extracts were achieved by using neutral alumina or active carbon which removed all coloured polar constituents. Finally purified stevia sweeteners component were separated and identified by TLC and HPLC.