Study on thermal degradation stability of purple sweet potato anthocyanins in different organic acid systems

In order to obtain experimental reference and theoretical basis to improve the stability of purple sweet potato anthocyanins (PSPA) , thermal degradation stability of PSPA was studied in different organic acid systems like lactic, tartaric, malic, acetic, and citric acid system. PSPA degradation kinetic model was established to analysis the degradation rate constant (k) , the half-life (t1/2) and the thermal degradation activation energy (Ea) of PSPA in different organic acid systems. The results showed that the degradation of PSPA conformed to the first-order reaction kinetic model and the degradation rate of PSPA accelerated obviously with the increase of temperature. Compared with the blank group, the t1/2and Ea of PSPA in organic acid systems were all improved, which indicated that the stability of PSPA had been enhanced. The Ea of PSPA in organic acid systems was increased 35.71% by tartaric acid%, 32.06% by lactic acid, 20.61% by malic acid, 12.60% by acetic acid and45.31% by citric acid. The copigmentation effect of citric acid, tartaric acid, lactic acid was better, thus they could be considered as auxiliary color agents.