Quality Characteristics of Sponge Cake Added with Purple Sweet Potato Depending on Various Shelf-Life

The quality and characteristics of purple sweet potato sponge cake were studied with the addition of different proportions of purple sweet potato powder depending on storage period The pHs, heights, and weights of doughs were in the ranges of 6.3~6.5, 4.8~4.4 cm and 397~418 g, respectively. The sponge cake groups with the addition of different proportions of purple sweet potato powder showed significantly different characteristics in hardness, adhesiveness, cohesiveness, gumminess, and chewiness, according to texture profile analysis. The difference in colors of sponge cakes with addition with purple sweet potato revealed that L-value and b-value were significantly reduced but a-value especially increased according to the density. Using scanning electron microscopy (SEM), it was confirmed that the stoma size of purple sweet potato sponge cake become smaller and the stoma wall became thicker in proportion to the contents of purple sweet potato powder, which could result in an increased level of water content after a long period pf storage. According with the observations, water content remarkably increased after 4~6 days of storage and the ability to keep water content seemed to contribute to extention the shef-life of sponge cakes. In sensory evaluation, sponge cakes with high contents of purple sweet potato were preferred and cakes with the addition of 25% and 30% purple sweet potato powder was most preferred. It was expected that the shelf-life of purple sweet potato sponge cake was 4 days under the normal temperature.