Evaluation of Unsaturated Alkanoic Acid Amides as Maskers of Epigallocatechin Gallate Astringency

Some foods, beverages, and food ingredients show characteristic long-lasting aftertastes. The sweet, lingering taste of high intensity sweeteners or the astringency of tea catechins are typical examples. Epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea, causes a long-lasting astringency and bitterness. These sensations are mostly perceived as aversive and are only accepted in a few foods (e.g., tea and red wine). For the evaluation of the aftertaste of such constituents over a certain period of time, Intensity Variation Descriptive Methodology (IVDM) was used. The approach allows the measurement of different descriptors in parallel in one panel session. IVDM was evaluated concerning the inter- and intraindividual differences of panelists for bitterness and astringency of EGCG. Subsequently, the test method was used as a screening tool for the identification of potential modality-selective masking compounds. In particular, the intensity of the astringency of EGCG (750 mg kg^–1) could be significantly lowered by 18–33% during the time course by adding the trigeminal-active compound <i>trans</i>-pellitorine (2<i>E</i>,4<i>E</i>-decadienoic acid <i>N</i>-isobutyl amide <b>1</b>, 5 mg kg^–1) without significantly affecting bitterness perception. Further, structurally related compounds were evaluated on EGCG to gain evidence for possible structure–activity relationships. A more polar derivative of <b>1</b>, (2<i>S</i>)-2-[[(2<i>E</i>,4<i>E</i>)-deca-2,4-dienoyl]­amino]­propanoic acid <b>9</b>, was also able to reduce the astringency of EGCG similar to <i>trans</i>-pellitorine but without showing the strong tingling effect