THESIS

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