Cake Texture. Textural properties of a food are important
characteristics affecting consumer acceptance. In this study,
these properties including hardness, cohesiveness, chewiness,
springiness and gumminess were determined using
TPA and presented in Table 2. Hardness is a measure of
maximum force necessary to compress a food by a specific
length at a specific rate. Based on the results, the hardness of
the cakes increased significantly from 0.430 to 0.526 kg as
the level of the SPI increased. Brewer et al. (1992) also
found that higher soy protein content resulted in higher
bread toughness. Cohesiveness refers to the rate at which
food disintegrates under mechanical action; it can be also
defined as the resistance of food to traction. Addition of SPI
significantly reduced the cohesiveness of the cakes from
0.800 to 0.728. Springiness is defined as food shape recovery
between the end of the first bite and the beginning of the
second one. This value decreased from 0.958 to 0.886 as the
level of SPI went up. Chewiness is related to the energy
required to masticate the cake. Gumminess indicates the
energy required for disintegration the cake to a state of
readiness for swallowing. These changes, involve the sensations
a consumer perceive during chewing. Addition of SPI
decreased the chewiness from 0.263 to 0.247 kg while
increased the gumminess of the samples from 0.345 to
0.383 kg.
Different factors may affect cake texture including cake
composition, water content and cake volume. Nevertheless,
the interaction of all these parameters is a determining
factor affecting the textural properties of the final product.
According to Wilderjans et al. (2008) starch gel influences
crumb firmness and that the protein aggregation in cake
crumb is related to springiness. McWatters et al. (2003)
attributed the harder texture of the cookies to the increased
protein content and its interaction during dough development
and baking. The presence of SPI with high waterbinding
capacity can reduce the free water and hence
decrease cake softness.