The influence of physical and chemical modification on rheological characteristics of biscuit doughs and biscuit quality was Studied. Mixing time influenced rheological characteristics by increasing compliance, elastic recovery, cohesiveness, adhesiveness and stickiness and reducing extrusion time, apparent biaxial extensional viscosity, consistency and hardness. Dough mixed for 180 s gave biscuits having superior quality as compared with those made from a dough either mixed for 90 s or 300 s. Amongst additives known to modify dough proteins, only the disulphide cleaving agents, cysteine and dithioerythritol, influenced rheological characteristics. Either of these additives in a dough mined and reducing extrusion time, elastic recovery, apparent biaxial extensional viscosity, consistency and hardness and increased compliance, cohesiveness. adhesiveness and stickiness. Incorporation of cysteine or dithioerythritol, particularly in doughs from medium strong wheat flour, resulted in biscuits with greater spread and crispness. (C) 1997 Academic Press Limited.
