Anthocyanin Degradation in the Presence of Furfural and 5‐Hydroxymethylfurfural

Abstract

ABSTRACTThe influence of furfural (F) and 5‐hydroxymethylfurfural (HMF) on degradation of cyanidin‐3‐glucoside (CG) was investigated in blackberry juice and in a citrate buffer model solution (pH 3,45) at 24°, 50° and 70°C. Presence of 0.012 M F or HMF accelerated pigment degradation. The acceleration was directly temperature‐dependent, more pronounced in fruit juice, and considerably decreased in nitrogen. CG and HMF disappearance – but not the interaction between these compounds – followed the first‐order reaction kinetics. The influence of formaldehyde (Fa) acetaldehyde (Aa) and benzaldehyde (Ba) on the stability of CG was investigated in blackberry juice. CG degradation effect of non‐furane aldehydes (0.012 M) was Fa < Aa < Ba. CG and cyanidine (C) reactivities were studied by condensation with F and examination of molecular electrone properties (cyanidine, keto‐pseudobase, anhydrobase, chalcone). Furfural did not react with CG but it did react with C. Electron charge distribution points to anhydrobase as the tautomeric form of C most reactive to F. Possible mechanisms of C decomposition in presence of F are proposed and discussed.