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.