Evaluation of Viscoelastic Properties of Rich Sponge Cake with Apples Powder

  Apple is a rich source of fiber and polyphenols. To investigate the effect of replacing apple powder with wheat flour on viscoelastic properties of sponge cake, stress relaxation test was performed. First apple was dried in optimal conditions and milled, and then apple powder was used for enrichment of sponge cake at five levels of 0, 5, 10, 15 and 20 % (w/w) as substitute of wheat flour in the cake formulation. After preparing the samples, stress relaxation test was carried out using a texture analyzer during storage time and coefficients of the Peleg-Normand and the extended Maxwell models were calculated. The results showed that by increasing the substitution of apple powder and storage time, the initial force and balance force values were increased. The parameters of Peleg-Normand model include k1 and k2 decreased with time that indicated a reduced elasticity of the cake with the time. The cakes showed solid viscoelastic behavior and by increasing the replacement, total reduced forces (F1+F2+F3) of generalized Maxwell model are increased which indicates that the elasticity is reduced. The results of stress relaxation modeling of experimental data with Peleg-Normand and the extended Maxwell models showed that the extended Maxwell model is more efficient to evaluate the viscoelastic properties of rich sponge cake with apples powder.