Effect of different blanching methods on peroxidase and lipoxygenase activity of broccoli and comparison of some nutritional values at enzymes inactivation levels

Peroxidase (POD) and lipoxygenase (LOX) inactivation temperature and time were investigated on broccoli florets at different blanching treatments. In addition, retention of nutritional components,which reduced POD and LOX activities, was compared. LOX inactivation required 14 min at 70 °C, 6 min at 80 °C, 11/2 min at 90 °C, 1 min at 100 °C water blanching and 1 min for steam blanching, 2 min in microwave without water and 6 min with microwave and water. The highest nutritional content of broccoli was evaluated in microwave blanching without water by comparison to all treatments. The decline of nitrate and nitrite value of broccoli was higher under longer time blanching than under higher temperature blanching.