Prediction of Peroxidase Inactivation During Broccoli Blanching

The objective of this study was to integrate decimal reduction time (D_T) and the thermal resistance parameter (z) with 3D FEM-predicted temperature histories, incorporating temperature-dependent thermophysical properties to predict and validate peroxidase inactivation during broccoli blanching. Validations were carried out during the blanching of broccoli cylinders and florets at 80°C for 2 min. Residual activity (a_res) of peroxidase was predicted using both experimental and FEM temperature histories (ETH and FEMTH) and compared to experimental results. For evaluating D_T, a completely randomized design was applied for a_res, using temperature (50°C, 55°C, 60°C, 65°C, and 70°C) and time (1.5, 2.0, 2.5, 3.0, and 3.5 min) as factors, and D_T was assessed for each temperature. For validation, two completely randomized designs were applied: one for broccoli cylinders and another for florets, both blanched at 80°C for 2 min. The response variable was a_res and the factor was the determination method (ETH and experimental determination). Results for D_T at 50°C, 55°C, 60°C, 65°C, and 70°C were 57.0, 13.2, 6.64, 2.73, and 2.00 min, respectively, while the z-parameter was 13.9°C. No differences were found in a_res between determination methods. Activation energy (E_a) and frequency factor (A) were 153 kJ mol^-1 and 5.25 × 10²¹ s^-1, respectively. Validation confirmed that integration of the thermokinetic parameters, ETH, and FEMTH accurately predict peroxidase inactivation under the blanching conditions. The study highlights the importance of using extracts from specific vegetables for reliable predictions, as enzyme distribution is unique to each type of produce. PRACTICAL APPLICATIONS: The use of the appropriate thermokinetic parameters for peroxidase allows for the design and optimization of thermal treatments to inactivate the enzyme, contributing to improving retention of nutritional and sensory attributes while extending the shelf life of vegetable-based products.