THESIS
THESIS
THESIS
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125<br />
The decrease in volume of HFCS cakes seems to have two<br />
main causes. First is decrease in batter stability during the heating stage – related to<br />
batter viscosity decrease and foam bubble size increase. Second is changes in the<br />
thermosetting mechanism, due to different interactions among the HFCS- sucrose<br />
used and starch-proteins of the batter that affect starch gelatinization and protein<br />
denaturation temperatures. A decrease in any of these temperatures is expected to<br />
cause a premature thermosetting<br />
of protein or starch matrix, which will start at the<br />
crust due to direct contact with the heating medium. This, then, lowers the heat<br />
transfer rate, and produces a vapor pressure build-up, causing inadequate expansion of<br />
individual bubbles (Hicsasmaz et al. 2003).<br />
In general, butter cakes with higher volume showed higher<br />
central loaf height (Figure 29). The high values indicate<br />
that the cake has more height<br />
in the centre than in the sides. The 60% HFCS cakes showed the higher central loaf<br />
than the control. While when 100% HFCS was replaced, a marked decrease in the<br />
central height that agree with pervious studied by Murano and Johnson (1998).<br />
4) Texture profile analysis<br />
Several factors are known to affect the texture of cakes, such<br />
as the amount of fat, sucrose, manipulation and liquid. In fact, one of the most<br />
important functions of fat and sucrose is to tenderize baked products (Penfield and<br />
Campbell, 1990e). Texture profile analysis for fresh butter cake samples was<br />
presented in Table 20. The amount of HFCS replacement for sucrose was a significant<br />
factor (P≤ 0.05) in the texture values of the butter cakes. Significant changes occurred<br />
on HFCS<br />
butter cake in hardness and chewiness. However, the springiness,<br />
cohesiveness, gumminess and resilience were not significantly different (P≥0.05)<br />
among the control and HFCS butter cakes. With total sucrose replacement by HFCS,<br />
there was a general decrease<br />
in hardness of the cake samples, which was related to the<br />
low density of the HFCS cakes as suggested above on specific gravity of the cake<br />
batter.