Potential sweetening agents of plant origin. III. Organoleptic evaluation of Stevia leaf herbarium samples for sweetness.

A total of 184 Stevia leaf samples taken from herbarium specimens, representing 110 species and 121 taxa, were screened organoleptically for their taste sensation. Fragments of a 62-year-old leaf of S. rebaudiana exhibited a potent and prolonged sensation of sweetness, thereby indicating the stability of its sweet ent-kaurene glycoside constituents to drying, preservation, mounting and storage. No other leaf samples exhibited an intensity of sweetness equivalent to that of S. rebaudiana, though 18 species and varieties were considered to exhibit a sweet taste. These taxa appear to be promising candidates for future phytochemical investigation for new and known ent-kaurene glycosides.