Abstract
By measuring the polyphenol oxidase activities, studies were made on the progress of cooking the potatoes by microwaves.
The results were as follows :
1. In case of direct cooking in the range microwaves penetrated into the certain parts of potatoes at the beginning, and then heated through. On the other hand, the outer layer of peeled potatoes did not gelatinized perfectly because the surface was in contact with the air that could not be heated by microwaves.
2. In the case of cooking potatoes in liquid (plain water, 10% sugar solution, or 10% vinegar solution), microwaves penetrated into the potatoes. Heat distribution and the time required for complete cooking of potatoes were similar in each case. On the contrary, microwaves were prevented from penetrating into potatoes, when they were cooked in a salt solution; only the temperature of the solution was raised, following the gradual heating of potatoes by heat conduction. The latter process of heating was similar to the cooking potatoes by an electric range. These results indicate that the seasoning with salt should be done after the cooking, when the foods require longer heating such as potatoes cooked by an electronic range.
