Degradation kinetics of anthocyanins in blackberry pulp during ohmic and conventional heating
2019
Tessaro, I. C. | Jaeschke, D. P. | Marczak, L. D. F. | Sarkis, J. R. | Mercali, G. D.
Anthocyanin degradation kinetics in blackberry pulp during ohmic and conventional heating was evaluated at different temperature conditions (70, 75, 80, 90°C). Ohmic heating experiments were performed at 23 V and 125 V (60 Hz). The anthocyanin degradation rates were similar for both heating technologies for low voltage (23 V). Nevertheless, when high voltages were applied, anthocyanin degradation increased. This result can be attributed to the electrochemical reactions that might contribute to greater anthocyanins degradation during ohmic heating. The first order model provided a good description of the degradation kinetics for both heating technologies, and the k values ranged from 0.0155 to 0.0051 min-1. The activation energies were 67 and 56 kJ mol-1 for ohmic and conventional heating, respectively. ΔH≠ , ΔS≠ and ΔG≠values were similar for all conditions, varying between 53.6 to 64 kJ mol-1, 102.3 to 105.5 kJ mol-1 and -114 to 144 J mol-1 K-1, respectively.
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