Properties of short-dough biscuits in relation to structure

The mechanical properties of short-dough biscuits of various composition we re determined in three-point bending tests. The temperature during dough pr eparation and the dough water content affected the air volume fraction and the mechanical properties to an extent which depended on the fat content. T hese 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 int o 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 sug ar type on mechanical properties depended on the type of biscuit. Iris conc luded that low-fat biscuits are fat-dispersed systems and that high-fat bis cuits are bicontinuous. Whether biscuits are in a glassy or rubbery state c annot be predicted from their water contents in relation to the state diagr ams of either gluten or sucrose. (C) 1999 Academic Press.