Effect of solid fat content on the viscoelasticity of margarine and impact on the rheological properties of cookie dough and fracture property of cookie at various temperature and water activity conditions

Effect of solid fat content (SFC) on the storage modulus (G′) and loss modulus (G″) of margarines was investigated. The G′ and G″ increased linearly with SFC in a double-logarithmic plot, independent of the types of margarine. There was a minor effect of dehydration on the G′ of margarine. Secondly, effect of the margarines on the G′ and yield stress of cookie dough was investigated. They could be corresponded to the G′ of each margarine in a double-logarithmic plot, independent of the types of margarine. These results will be useful to predict the die cutting and kneading properties of cookie dough. Finally, effect of the margarines on the texture properties of cookie was investigated at various temperature and water activity (aw) conditions. It was expected that the cookie samples having aw = 0.328 and aw = 0.753 were glassy state and rubbery state, respectively. Fracture stress of the cookie samples decreased with increasing temperature, and this behavior could be described as a linear relationship between log fracture stress and log G′ of dehydrated margarines. From the result, it was found that the fracture stress increased gradually (glassy cookie) and remarkably (rubbery cookie) with the G′ of dehydrated margarines. The reason why there was a major effect of margarine on the texture of rubbery cookie will be that amorphous hydrophilic part of the cookie was enough soft to be affected by the margarine.