Transfer of heat and moisture during microwave baking of potatoes

Microwave baking of potatoes comprised two phases. In the first phase the internal temperature of the potatoes rose to approximately 100°C with little loss of water vapour. The uniformity of internal heating during this phase was assessed by identifying gelatinised starch. Starch gelatinisation began near the outer surface after 1.5min of cooking and was complete by 2.5min. During the second cooking phase the thermal energy absorbed was used to evaporate water. When immersion in boiling water was substituted for this second phase of microwave cooking, it took significantly longer for the internal texture to soften adequately for the potatoes to be considered cooked. This suggests that microwave cooking influences texture independently of the thermal profile of the cooking process. Damage by escaping steam is suggested as a mechanism. La cuisson par microonde des pommes de terre comprend deux phases. Dans la premiere phase, la temperature interne de la pomme de terre s'eleve jusqu'a environ 100°C s'accompagnant d'un legere perte en eau. La gelatinisation de l'amidon commence pres de la surface externe apres 1,5mn de cuisson et est complete a 2,5mn. Pendant la seconde phase, l'energie thermique absorbee est utilisee pour evaporer l'eau.