FTIR spectra, antioxidant capacity and degradation kinetics of maize anthocyanin extract under variable process conditions

Anthocyanin is highly sensitive pigment which loses its activity under adverse process and storage conditions of pH, temperature, and light. The evaluation of anthocyanin degradation in different pH of extracts kept in the dark was compared with extracts under solar light. It appears from t1/2 that extract under solar light were suffering 50 percent more degradation than those kept in the dark. Moreover, the rate of degradation kd under unfavorable alkaline pH was also higher (0.035) as compared to kd in acidic medium (0.009). The thermal degradation behavior of extract at temperature range 60 to 100 °C under dark showed first order kinetics with low activation energies. The z-value of degradation range from 3.8 to 10.3 whereas the d-value range from 12 to 255 min under defined experimental conditions. The enthalpy and entropy of activation were 19.87 kJ/mol and −235.30 J/mol·K, respectively.