Discovery of bitter masking compounds from Allspice (Pimenta dioica) using sensory guided isolation

Abstract

Bitter substances in functional foods and beverages can act as nutraceuticals, offering potential health benefits. However, their unpleasant sensory impact reduces the consumption of these foods. Consequently, the discovery of bitter masking compounds is crucial for enhancing the intake of bioactive compounds in functional foods and beverages. Bitter taste is mediated by TAS2Rs, a sub-family of G-protein-coupled receptors. TAS2R14 is especially pivotal in the perception of bitterness, as it is one of the most broadly tuned bitter receptors. In this study, allspice was extracted and purified to yield five single compounds based on sensory guided fractionation. The structures of each compound were determined based on nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HR-MS). In a sensory evaluation, compound 1 exhibited bitter masking activity against quinine. Molecular docking analysis revealed that compound 1 could act as an antagonist of the TAS2R14 bitter receptor.

Keywords: (2R)-3-(4-hydroxy-3-methoxy-phenyl) propane-1,2-diol (PubChem CID: 101154580); (4R)-R-terpineol 8-O-β-D-(6-O-galloyl) glucopyranoside (PubChem CID: 10695593); Bitter taste receptor; Bitterness; Food flavor; Pimentol (PubChem CID: 9917512), (4S)-R-terpineol 8-O-β-D-(6-O-galloyl) glucopyranoside (PubChem CID: 10552230); Sphalleroside A (PubChem CID: 101702475); TAS2R; Taste modulator.

Graphical abstract

Fig. 1

¹H NMR spectrum (methanol‑d₄, 600 MHz) of compound 1.

Fig. 2

¹³C NMR spectrum (methanol‑d₄, 150 MHz) of compound 1.

Fig. 3

Bitterness intensity of each fraction. On the left side, bar lengths correspond to three distinct values, representing different separation stages: 1. SP-70/C-18; 2. SP-70/C-18/LH-20; 3. SP-70/C-18/LH-20/LH-20. The right side displays the bitterness intensity of test solutions (Each fraction was added to standard solution and used as test solutions). Values are mean ± SD (n = 3).

Fig. 4

Bitterness intensity of standard and test solutions (6 ppm quinine was used as standard solution; compound 1 was added to standard solution at three different concentrations and used as test solutions). Statistical analyses were performed using ANOVA followed by Scheffe's post hoc test, and the criterion for statistical significance was set to p < 0.05. Values are mean ± SD (n = 3).

Fig. 5

Chemical structures of five compounds isolated from allspice based on sensory guided fractionation.

Fig. 6

Molecular docking analysis of the ligand-binding pocket of TAS2R14. a: 3D hydrogen bond surface plot at binding site. b: 2D representation showing interactions at binding site: hydrogen bond (green dashed line), π-alkyl hydrophobic bond (pink dashed line), and π-π bond (red dashed line). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)