Impact of endogenous constituents from different flour milling streams on dough rheology and semi-sweet biscuit making potential by partial substitution of a commercial soft wheat flour

A flour fractionation-reconstitution procedure was used to study the substitution of a commercial soft wheat flour with gluten, water extractables, prime starch and starch tailing fractions isolated from patent and clear flour streams on dough rheology and semi-sweet biscuit characteristics. Substitution of soft wheat flour with increasing levels of the native patent and clear flour streams raised the dough consistency, hardness and elastic properties as well as the biscuit textural attributes (density, hardness). The dough stickiness of the base flour was also reduced and the biscuits were free of cracks. Gluten isolated from the patent flour had a greater impact on dough consistency, hardness and elastic properties than gluten obtained from the clear flour, likely due to the superior protein quality of the former. Additionally, with increasing gluten levels in the fortified flour there were moderate increases in biscuit density, hardness, and lower crunchiness. The addition of starch tailings produced the largest impact on consistency and hardness of the dough. This fraction also exerted a pronounced effect on biscuit density and hardness, while it lowered crunchiness, presumably due to its higher pentosan content. Overall, the dough rheological properties and biscuit characteristics were controlled by the amount-nature of the fractions added; i.e., besides gluten (amount and quality), other constituents such as pentosans and the overall composition of the flour blends can largely affect the quality of the semi-sweet biscuits.