Small and large strain rheology of gluten and gluten-starch doughs containing wheat bran dietary fiber.

Abstract

The small and large strain rheology of gluten (G) and gluten-starch (G + S) doughs containing wheat bran dietary fiber (WBDF) were investigated. At the small strain stage, i.e. frequency and strain sweep tests, the doughs containing high WBDF concentration are more vulnerable and unstable, as indicated by the lower dough linear viscoelastic strain limit as well as the higher slope of elastic modulus. However, the elastic nature of doughs remarkably increased upon WBDF addition, indicating the reinforcement of the dough mechanical strength, which is also confirmed by the large strain test wherein the maximum strain significantly decreased from 4.37 to 1.82 for the G system and from 12.09 to 2.72 for the G + S system. The creep recovery test showed that WBDF induced the reduction in the strain of the doughs at a fixed stress, which may be related to the enhanced strain hardening capacity. The addition of WBDF resulted in more brittle and unstable doughs with undesirable higher mechanical strength. The presence of starch greatly weakened the dough strength and led to inferior resistance to both small and large deformations. These findings confirmed the impairment of dough viscoelasticity upon addition of WBDF. © 2019 Society of Chemical Industry.