Thermal degradation kinetics of anthocyanin and visual colour of plum puree

Thermal degradation kinetics of anthocyanin and visual colour (tristimulus L, a and b values) of plum puree were studied at selected temperatures (50-90degreesC) for a residence time of 20 min. Results indicated that the thermal degradation of anthocyanin, tristimulus colour a value (representing redness) and Lxaxb value (representing total colour) followed first-order reaction kinetics. The activation energy values for anthocyanin, red colour and total colour were 37.48, 25.86 and 30.68 kJ/mol respectively. Higher activation energy signified higher thermal sensitivity of anthocyanin during heat processing of plum puree. A linear relationship described well the variation of total visual colour (Lxaxb) with anthocyanin content of plum puree during thermal processing.