Properties of short-dough biscuits in relation to structure

The mechanical properties of short-dough biscuits of various composition were determined in three-point bending tests. The temperature during dough preparation and the dough water content affected the air volume fraction and the mechanical properties to an extent which depended on the fat content. These results suggest that the air volume fraction of the biscuits is likely to be related to the rheological properties of the doughs. The temperature at which measurements were made affected the mechanical properties of the biscuits, especially at higher fat contents. The diffusion of Sudan III into the biscuits also depended on the fat content. The mechanical properties were markedly influenced by water content; as a result of the plasticising effect of water, the matrix underwent a glass transition. The effect of sugar type on mechanical properties depended on the type of biscuit. Iris concluded that low-fat biscuits are fat-dispersed systems and that high-fat biscuits are bicontinuous. Whether biscuits are in a glassy or rubbery state cannot be predicted from their water contents in relation to the state diagrams of either gluten or sucrose. (C) 1999 Academic Press.