Fracture properties of short-dough biscuits: Effect of composition

The mechanical properties of short-dough biscuits of various composition we re determined in three-point bending tests. In general, reduction of fat co ntent increased the modulus and the fracture stress of biscuits. The relati ve magnitude of this effect depended on the fat type. Sucrose syrup slightl y enhanced the brittle character of biscuits, compared with crystalline suc rose, indicating that sucrose crystals were not the fracture-inducing defec ts. Substituting search for part of the flour had relatively little effect on the mechanical properties. Sugar-free biscuits had a significantly lower modulus and fracture stress. Differential scanning calorimetry showed that , irrespective of composition, starch gelatinisation was slight, presumably due to the limited water content coupled with the low baking temperature. It is concluded that biscuits comprise a glassy matrix;; their mechanical p roperties are mainly determined by air and fat volume fraction as well as t he size of inhomogeneities. (C) 1999 Academic Press.