The taste of color: how grape anthocyanin fractions affect in-mouth perceptions

Abstract

Anthocyanins are responsible for the red wine color and their ability to condense with tannins is considered as a contributor in astringency reduction. However, recent studies showed the possibility of anthocyanins to influence directly the in-mouth perception of wines.

In this study, grape anthocyanin extracts (TA) were fractionated using Centrifugal Partition Chromatography (CPC) and preparative HPLC in three fractions: glucoside (GF), acetylated (AF) and cinnamoylated (CF) anthocyanins. Sensory properties of these fractions were investigated by chemical analysis as reactivity towards salivary proteins and by tasting sessions as best estimated thresholds (BET) in wine-like solutions.

Anthocyanins reacted with salivary proteins in different extent depending on their acylation, with CF being the most reactive fraction. The BETs obtained were 297, 68, and 58 mg/L for GF, AF, and CF, respectively, while the unfractionated extract (TA) resulted in a BET of 255 mg/L.

In the next step, different sensory approaches (triangle test, check-all-that apply, descriptive analysis) were attempted to compare TA and fractions to polyphenols extracted from grape skins and seeds. The investigated sensations were bitterness, overall astringency and its sub-qualities, which were divided in sensation during (particulates) and after (surface smoothness) expectoration. TA and GF were described at wine range concentration as “velvety” and “chalky”. The addition of GF to skin and seed extract modified in-mouth perceptions differently: enriched seed extract was perceived more astringent, whereas enriched skin extract showed lower surface smoothness. Therefore, the presence of anthocyanins may be able to modify in-mouth sensations, influencing astringency and its sub-qualities.