Abstract:

In this work, thermal stability and degradation kinetics of peony anthocyanins were investigated under various sucrose concentrations (11, 30, 45 or 62°Brix) during heating. Results indicated that thermal degradation kinetic model of peony anthocyanins was a first-order degradation kinetic process. The half-life of anthocyanin degradation was shortened due to increased temperature. During the degradation process of anthocyanin monomers in solution, the degradation rate exhibited a drop order of cyanidin-3-O-glucoside ＞ peonidin-3-O-glucoside ＞cyanidin-3,5-di-O-glucoside ＞ peonidin-3,5-di-O-glucoside. Degradation of anthocyanins exhibited a decrease trend with increasing sucrose concentration during heating. However, the thermal degradation of anthocyanins did not obey the first-order kinetic model. In addition, the browning index was increased with increasing temperature and heating time. However, the degradation of anthocyanins with sucrose revealed the lower browning index than the sample without sucrose. These results suggest that the presence of sucrose reduces anthocyanin degradation in time-, temperature- and concentration-dependent manners.

Key words: anthocyanin, thermal stability, browning, degradation kinetics, sucrose, peony