3.5.2. Cupcake characteristics
Mizukoshi, Maeda, and Amano (1980) proposed a model for
cake structural formation during baking. In the early stage of 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 rice flour (high starch fractions) could form
small sized air cells in the crumb of rice cupcake after baking.
Continued heating caused further coagulation of egg and flour
proteins, and strengthening of the cake structure continued until
the end of baking. The PSD of rice flour affected the cake volume
and the crumb structure. Because the ratio of starch granule
fraction (2e40 mm) 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 in Table 3. Specific
volume was ranged from 3.12 to 3.43 mL/g and was significantly
different (p < 0.05). The specific volume of rice cupcakes prepared
from HP-160 (