The influence of the addition of ionic salts (NaCl, NaBr, Nal, NaClO 4) on anthocyanin equilibria is studied in this work. The effect of their addition is a colour enhancement through the formation of an ion-pair between the charged flavylium cation and the anion, which displaces the equilibria towards the coloured flavylium form. The ion-pair formation is an alternative model to that which suggests a preferable hydration of salt anions instead of the flavylium cation. Throughout this work two natural anthocyanins are studied (malvidin 3,5-diglucoside and malvidin 3-glucoside) as well as one anthocyanidin (malvidin). The thermal and photochemical stability of the ion-pairs formed is also examined. Experiments with a synthetic anthocyanin analogue (4′,7-dihydroxyflavylium chloride) which has photochromic properties are also described for comparison purposes.
|Number of pages||4|
|Journal||Journal of the Chemical Society, Perkin Transactions 2|
|Publication status||Published - 1 Dec 1994|