baking, batter volume is increased by the expansion of bubbles caused by an increase in vapor pressure of water and air. Then the starch granules in batters are almost gelatinized and protein coagulation is accelerated. The sol-like batter changes to the gellike structure of cake. When the formation of the continuous gel phase (network) depresses the expansion of bubbles, the increased pressure in the bubbles causes the gas to release. At this point, an expansion of the cake batters is stopped. In this process, rice starch in cake batters gelatinized at 70.4e72.5 C(Table 2) and egg protein coagulated at 82e96 C(Mizukoshi et al., 1979). Amylose leaching during starch gelatinization helped to form a network structure with foaming of egg white protein. Therefore, it is predicted that smaller particle sized riceflour (high starch fractions) could form small sized air cells in the crumb of rice cupcake after baking. Continued heating caused further coagulation of egg andflour proteins, and strengthening of the cake structure continued until the end of baking. The PSD of riceflour affected the cake volume and the crumb structure. Because the ratio of starch granule fraction (2e40mm) to the cell fraction was different from rice flour PSD (Fig. 1), the size of air cell and homogeneity in crumbs were not similar (Fig. 2). It had been found that the thermal stability of the foam structure in the starch cake batters had been very dependent on protein (Howard, Hughes, & Strobel, 1968). The specific volume of rice cup cakes are noted inTable 3.Specific
volume was ranged from 3.12 to 3.43 mL/g and was significantly different (p