Thermal Degradation of Black Raspberry Anthocyanin Pigments in Model Systems

SUMMARY— The thermal degradation of anthocyanin pigments of black raspberries as influenced by pH, oxygen, sugars and their degradation products were studied. The degradation of the major anthocyanin component (cyanidin-3-digluco-side), the total isolated pigments and the pigment in the natural berry juice was retarded as the pH decreased. Under the same conditions, cyanidin was much more unstable than any of the anthocyanin containing systems. In all cases studied, replacement of the oxygen atmosphere with nitrogen enhanced pigment stability. The rate constants for the thermal degradation of cyanidin-3-diglucoside at various pH levels under oxygen and nitrogen were determined. The sugars studied accelerated pigment destruction to the same extent. Sugar degradation products were more effective than sugars in accelerating anthocyanin breakdown.