Sensory-guided isolation and identification of new sweet-tasting dammarane-type saponins from Jiaogulan (Gynostemma pentaphyllum) herbal tea

•Sweet-tasting constituents of Jiaogulan were investigated.•Fifteen new sweet and one bitter-tasting gypenosides were isolated and identified.•Their sweetness intensities are 20–100 times greater than that of sucrose.•Their contents were analyzed by UPLC-MS/MS using the MRM modes.•Sweetness intensity could be affected by oxidation, acetylation and glycosylation.