Tolerance of bitter stimuli and attenuation/accumulation of their bitterness in humans

Non-invasive anticipation of infusion taste in fine-manipulated green teas through hyperspectral appearance analysis guided by ECG content

The high catechin content in summer-to-autumn tea leaves often results in strong, unpleasant tastes, leading to significant resource waste and economic losses due to lignification of unpicked leaves. This study aims to improve the taste quality of summer-to-autumn green teas by combining fine manipulation techniques with hyperspectral observation. Fine manipulation notably enhanced infusion taste quality, particularly in astringency and its aftertaste (aftertasteA). Using Partial Least Squares Discriminant Analysis (PLSDA) on hyperspectral data, 100% prediction accuracy was achieved for dry tea appearance in the near-infrared spectrum. Astringency and aftertasteA correlated with hyperspectral data, allowing precise estimation with over 90% accuracy in both visible and near-infrared spectrums. Epicatechin gallate (ECG) emerged as a key taste compound, enabling non-invasive taste prediction. Practical applications in processing and quality control are demonstrated by the derived equations (Astringency = -0.88 × ECG + 45.401, AftertasteA = -0.353 × ECG + 18.609), highlighting ECG's role in shaping green tea taste profiles.

Plant polyphenols, chemoreception, taste receptors and taste management

PURPOSE OF REVIEW

Polyphenols display beneficial health effects through chemopreventive actions on numerous chronic diseases including cancers, metabolic disorders, reproductive disorders and eating behaviour disorders. According to the principle of chemoreception, polyphenols bind cellular targets capable of accepting their stereochemistry, namely metabolizing enzymes and protein receptors, including taste receptors. The extraoral expression of taste receptors and their pharmacological interest in terms of novel drug therapies open up new perspectives on the potential use of these compounds and their interactions with other chemicals in cells. These new perspectives suggest the need to examine these phytochemicals further. However, most polyphenols have a bitterness property that may disrupt the acceptability of healthy foods or dietary supplements.

RECENT FINDINGS

Polyphenols bind to oral and extraoral bitter type 2 taste receptors, which modulate the signalling pathways involved in anti-inflammatory processes and metabolic and dietary regulations. Depending on their chemical nature, polyphenols may act as activators or inhibitors of taste receptors, and combinations of polyphenols (or herbal mixtures) may be used to modulate the acceptability of bitterness.

SUMMARY

The current review summarizes recent findings on polyphenol chemoreception and highlights the evidence of healthy effects through type 2 taste receptor mediation in signalling pathways, such as new targets, with promising perspectives.