Abstract
Both the leaching of potassium and chlorophyll from broccoli and changes in color were examined during soaking in hot water at four temperatures ranging from 70°C to 100°C. To describe the leaching of potassium quantitatively, the measured data were fitted to the sphere diffusion model using a non-linear least squares method. Changes in color and chlorophyll based on the measured data were determined quantitatively by the zero-order and the first-order reaction, respectively. Therefore, the measured results were in approximate agreement with the calculated results. The applicability of microwaving for blanching broccoli was examined. Changes in enzyme (peroxidase) activity, weight, ascorbic acid and color were compared between two blanching methods (microwave radiation and immersion in boiling water). The time required for enzyme inactivation was 50 s in microwave blanching and 90 s in boiling water blanching. Weight loss increased with microwave blanching compared with boiling water blanching, whereas drip and ascorbic acid loss increased in boiling water blanching compared with microwave blanching. Chroma of broccoli showed little difference between microwave blanching and boiling water blanching. These results suggested that microwaving is useful for the blanching of broccoli.
