Summary:
Angel food cake was made using egg albumen subjected to the pH-induced unfolded and refolded treatment. The effect of treatment on the rheological properties of angel food cake was investigated. Egg albumen solutions were prepared and pH was adjusted to 1.5, 4.5, 8.5 or 12.5 and then held 60 min to unfold the proteins. After holding, the solutions were readjusted to pH 4.5 or 8.5, and held for 45 min to partially refold the proteins. Egg white foam with sucrose was whipped and flour and the rest of sucrose were folded into the foam. The foam batter was heated in a TA Instrument AR 2000 controlled stress rheometer equipped in a parallel geometry. Samples were heated from 21 ° C to 150 ° C at a rate of 8.5 ° C per min and then cooled down to 21 ° C to bake the angel food cake. At 21 ° C, oscillatory stress sweep was performed. There was no relationship between the G ′ value of angel cake batter and its G ′ value at 150 ° C. Changes in rheological properties of batters and angel food cakes using different combinations of ingredients were studied. The pH unfolding and refolding procedure led to more rigid final products compared to the controls with egg albumen samples not subject to pH treatment. Adding sucrose to the flour increased the starch gelation temperature up to 82 ° C. Higher protein concentrations resulted in better foams in the cake batter, but the batter made with an intermediate protein concentration produced the most rigid angel food cake. Adding egg albumin did not change gelation temperature of the starch. It appears that incorporation of flour with the egg white foam, leads to about a ten times decrease in the strength of the foam, and a decrease in the gelatinization process of starch after adding sugar, are crucial in forming an angel food cake texture.