Influence of Casein Hydrolysates and Yeast on the Rheological Properties of Wheat Dough

The influence of casein hydrolysates (CHs) and yeast on the viscoelasticity of wheat dough at 25 °C were analysed. Three wheat doughs were studied: the unyeasted dough (UYD), the unyeasted dough with CHs (UYD-C) and the yeasted dough (YD). The characteristic parameters in the linear viscoelastic range (LVER) were analysed by stress sweep at 6.3 rad/s: UYD-C dough exhibited higher values of stress (σ_max) and strain (γ_max) amplitudes, and softer gel network (lower complex modulus, G*) comparing with UYD dough. The oscillatory data suggest that CHs would work as (energy and time) stabilising-agents based on the greatest reticular energy (E parameter) and the lowest frequency dependence of phase angle (δ) at the low frequency range. The rotatory tests show that CHs may act as shear thinning agents in the gluten-starch network, facilitating the solid-fluid transition at the yield point (UYD-C dough). The yeasted dough (YD) exhibited a more shear sensitive structure, evidenced in the highest influence of frequency on the elastic (G') and viscous (G″) parameters, and gel to sol transition at 0.23 rad/s was observed.

Rheological characterisation of gluten from triticale (x Triticosecale Wittmack)

BACKGROUND

Triticale gluten still remains very poorly characterised rheologically. In this study the mechanical spectra of gluten isolated from four triticale cultivars were registered and fitted with Cole-Cole functions yielding the visco-elastic plateau parameters. Master spectra were calculated. A retardation test was performed and used to calculate the composite mechanical spectra and the width of visco-elastic plateau l. Protein fractional composition of triticale flour and gluten was studied using capillary zone electrophoresis.

RESULTS

Differentiated HMW-GS/SS compositions were identified in the triticale cultivars studied. The rheological parameters reached the following values: J_N⁰ 1.05·10^-3 to 2.69·10^-3 Pa^-1 , G_N⁰ 372 to 956 Pa, ω₀ 0.003 to 0.06 rad s^-1 , l 169 to 3121, J_e⁰ 1.57·10^-3 to 5.03·10^-3 Pa^-1 , G_e⁰ 199 to 637 Pa and η₀ 1.06·10⁷ to 3.93·10⁷ Pa s.

CONCLUSIONS

Visco-elastic properties of triticale gluten correspond to the lower end of medium visco-elasticity shown by common wheat gluten. Master spectra and the composite mechanical spectra prove that four triticale glutens exhibit practically an identical type of visco-elastic behaviour of a biopolymeric visco-elastic liquid similar to wheat gluten. The visco-elastic plateau parameters G_N⁰ , J_N⁰ , ω₀ and l appeared significantly correlated with the contents of prolamins and secaloglutenins in triticale flours and glutens. © 2017 Society of Chemical Industry.