Objective Effect of Dendrobium huoshanense cultivation in greenhouse or under simulated wild conditions on bitter taste of the herbal material was analyzed.

Methods D. huoshanense plants from Huoshan and Tianzhushan producing areas in Anhui Province were sampled and tested on an e-tongue device for bitterness. In addition to the e-tongue bitterness measurement, untargeted metabolomics (LC-MS/MS) and targeted metabolomics (UHPLC-Q Exactive HFX) were employed to determine differential metabolites of the plants grown in a greenhouse (GC) and under simulated wild, tree-shaded conditions (UWC). Pearson correlation analysis was conducted on the sets of data to identify substances that contributed to the bitter taste of the medicinal material.

Results The bitterness signal response readings obtained by the e-tongue on the plants grown in GC were 17.92±0.59, and those in UWC 7.46±0.59. Of the 2,101 metabolites detected by the untargeted metabolomics, 795 differentiated significantly between the two groups and were largely flavonoids. The targeted metabolomics identified 87 flavonoids, of which, 8 differed significantly and were presumably bitter-tasting substances. Isoschaftoside, vitexin 2, kaempferol-3-neohesperidoside, lonicerin, and vitexin-4''-O-glucoside significantly correlated with the e-tongue bitterness reading (P＜0.001) and could conceivably serve as biomarkers for the sensory quality.

Conclusion By correlating the e-tongue readings with the non-targeted and targeted metabolomics determinations on isoschaftoside and lonicerin, the bitter taste of D. huoshanense grown under GC and UWC was distinctively differentiated to suggest superiority of the wild cultivation for the herbal plants.