Nuno Mateus; Joana Oliveira; Mafalda Haettich-Motta; Victor de Freitas

“ Anthocyanins are the most important group of water-soluble plant pigments visible to the human eye. These pigments are responsible for a great variety of colours of several fruits, vegetables, and plants. The colour of red wine is manly due to the presence of these polyphenolic compounds extracted from grape berries during the wine-making process. ”

“ Sweet cherry, bilberry, red apple, plum, blackberry, and elderberry extracts were used as anthocyanin sources for the synthesis of anthocyanin-derived pigments. Following this, the formation of the anthocyanin-pyruvic-acid adduct was achieved through a reaction with pyruvic acid, as previously developed for grape malvidin 3-O-glucoside-pyruvic-acid adduct. The different anthocyanins from the red fruit extracts yielded pyruvic acid adducts with a λmax hypsochromically shifted from that of genuine anthocyanins, some of which are indicated in Table 3. ”

“ The glucosyl moiety linked at the 3-O position of ring C may also be acylated with acetic acid, coumaric acid, or caffeic acid.
These compounds undergo chemical transformations during wine ageing yielding new pigments that become responsible for the changing colour and its longevity [2] . These new pigments were first thought to result mainly from condensation reactions between anthocyanins and flavanols directly or mediated by acetaldehyde [3] , [4] , [5] , [6] , [7] , [8] , [9] . ”

“ The last step of their formation is thought to include decarboxylation, dehydration, and oxidation yielding a structure with extended conjugation of the π electrons, which is likely to confer a higher stability of the molecule and is probably at the origin of its blue color. ”

“ Picinelli, A & Bridle, P, “Model wine solutions: colour and composition changes during ageing”, Vitis 32: 111–118 ↑ Rivas-Gonzalo, J.C; Bravo-Haro, S & Santos-Buelga, C, “Detection of compounds formed through the reaction of malvidin-3-monoglucoside and catechin in the presence of acetaldehyde”, J Agric Food Chem 43: 1444–1449 ↑ Timberlake, C.F & Bridle, P, “Interactions between anthocyanins, phenolics compounds and acetaldehyde, and their significance in red wines”, Am J Enol Vitic 27: 97–105 ↑ Bakker, J ”