Modeling of enzyme inactivation and quality changes during blanching of green beans

Blanching is a critical step in the industrial production of frozen vegetables, primarily intended to inactivate enzymes and preserve quality during storage. Residual enzyme activity can cause undesirable changes in texture, flavor, and appearance. However, excessive blanching may also impair product quality. Therefore, understanding enzyme inactivation and its relation to quality deterioration under specific blanching conditions is essential. This study developed models for the inactivation of selected enzymes during blanching of green beans prior to freezing. Additionally, if combined a heat-transfer the model can link the enzyme activity to texture development. Model validation was fitted using literature data and validated by new blanching experiments, measuring the activities of pectin methylesterase (PME), lipoxygenase (LOX), and peroxidase (POD). Furthermore, it is shown that POD inactivation functions as a practical time-temperature integrator for blanching intensity, but LOX is even a more sensitive indicator of overall quality. Nevertheless, the equivalent-blanching-time correlated to POD activity, texture loss, and leaching metrics, suggesting it is a practical tool for blanching optimization.