flavan-3-ols

Flavan-3-ols are a group of polyphenols that include catechins, epicatechin, and related compounds found in cocoa. In a study combining quantification, reconstitution, and omission tests with human dose-response evaluation on roasted cocoa nibs, 7 flavan-3-ols were identified as contributors to both bitterness and astringency. However, the degree of contribution varies among individual compounds and depends on concentration.

A study in which food-grade epigallocatechin gallate (EGCG) derived from green tea was dissolved in water and evaluated by a trained panel (n=7) at concentrations of 0.2 to 0.8 mg/mL over 4 months found that EGCG exhibited clear, dose-dependent bitterness. Slight astringency was also perceived, but bitterness was the dominant characteristic. This result is from a system in which food-grade EGCG alone was dissolved in water and does not directly indicate the behavior when other components are co-present in tea leaf extract.

In the same study, when a cocoa-derived procyanidin-rich fraction (PRF, containing catechin, epicatechin, procyanidin B-2/B-5/C-1, cinnamtannin A-2, and others) was evaluated under the same conditions, it was perceived as bitter at all tested concentrations but lacked the clear dose-dependency observed with EGCG. The authors attribute this plateau to either the possibility that the mixture of oligomeric and monomeric catechins saturated bitter receptors even at low concentrations, or that astringency partially masked bitter perception at higher doses.