Abstract
This investigation is planned to make clear the mechanism of Yakifu expansion. First of all, relationships between baking conditions and expanded specific volume of yakifu were studied. Yakifu expanded when baked at the temperatures of oven-floor higher than 150°C. Higher the temperature was, larger the volume was. If the temperature of ceiling is the same as or lower than that of floor, expanded yakifu shrinks at once when stopped baking. Therefore, the temperature of ceiling was always set at 30°C higher than that of floor. Heat from the floor was transferred to cuts of gluten-dough and moisture involved in them started to vapor, forming air cells surrounded by gluten walls. Air cells formed honeycomb structure in the cuts of gluten-dough, and finally a top layers of the cuts were built up. Heat from the ceiling is important to promote drying to fix the structure of yakifu. Watering the cuts just before starting baking largely increased expanded specific volume of yakifu with increasing the amount of water.
