M.A. Thesis:

Effect of additional of potassium sorbate tp sponge roll cake shelf life and investigation of microbial and physicochemical properties of product during the storage

In this study effect of different dose of potassium sorbate (200, 400 and 600ppm) on physicochemical properties (moisture, aw, pH, volume and color), microbial properties (E.coli, molds and yeasts counts) and sensory properties (color, flavor, odor, texture and Total acceptance) of sponge cake was assessed. Samples stored at15?C and 30?C temperatures, then Microbial, physicochemical and sensory properties of samples was evaluated immediately after baking, and after the seventh, fourteenth and twenty-eighth day of baking. The results showed increasing storage temperature lead to no changes of cake volume but decreased a? and b? factors significantly (0.05>p). within 28 days cake moisture, aw, pH and volume decreased (0.05>p). The color parameter of L? decreased significantly but there is no changes in b? parameter. Different dose of potassium sorbate had no effect on cake moisture, aw and color. pH increased significantly when the potassium sorbate concentration was increased. There is no difference in cake volume between control sample and sample with 200 ppm potassium sorbate but there was a significant decrease in cake volume with 200 and 400 ppm potassium sorbate. assessment of microbial quality of cake within 28 days showed there is no increase from the initial calculated count. When 200 ppm potassium sorbate concentration under 15?C and 30?C storage temperatures was used, the molds and yeasts counts increased from 1×102 cfu/ml to 3×102 and 1×103, respectively. There is no growth of E.coli in cake samples. sensory evaluation results showed the lowest score for overall acceptability being given to samples which was stored at 30?C within 28 days. But different concentration of sorbate had no significant effect on cake samples.

Keywords: sponge cake, potassium sorbate, microbial, physicochemical and sensory properties.