Rheological properties of gluten plasticized with glycerol: dependence on temperature, glycerol content and mixing conditions

Abstract

International audienceThe rheological behaviour of a gluten plasticized with glycerol has been studied in oscillatory shear. The mixing operation in a Haake batch mixer leads to a maximum torque for a level of specific energy (500-600 kJ/kg) and temperature (50-60 degrees C) quite independent of mixing conditions (rotor speed, mixing time, filling ratio). The gluten/glycerol dough behaves as a classical gluten/water dough, with a storage modulus higher than the loss modulus over the frequency range under study. A temperature increase induces a decrease of moduli, but the material is not thermorheologically simple. Glycerol has a plasticizing effect, which can be classically described by an exponential dependence. Mixing conditions influence the viscoelastic properties of the material, mainly through the specific mechanical energy input (to 2000 kJ/kg) and temperature increase (to 80 degrees C). Above 50 degrees C, specific mechanical energy highly increases the complex modulus. The aggregation of proteins, as evidenced by size-exclusion chromatography measurements, occurs later as the dough temperature reaches 70 degrees C. The nature of network interactions and the respective influence of hydrophobic and disulphide contribution is discussed. A general expression is proposed for describing the viscous behaviour of a gluten/glycerol mix, which could seem simplistic for such a complex rheological behaviour, but would remain sufficient for modelling the flow behaviour in a twin screw extruder

State of the Art in the Development and Properties of Protein-Based Films and Coatings and Their Applicability to Cellulose Based Products: An Extensive Review

“…For example an investigation about extrusion of gluten/glycerol blends revealed that temperature and mechanical energy input strongly affected the structural characteristics of the final product. In particular, extensive gluten cross-linking was observed when high SME input was used during extrusion [99].…”

Injection-molded nanocomposites and materials based on wheat gluten

“…wheat gluten is high due to its high molar mass and aggregated structure. Nevertheless, it has been shown, by us and others, that plasticized wheat gluten can be compression molded and extruded into films, troughs and plates [3][4][5][6][7][8]. These methods, however, provide rather limited ways of shaping the material/product into more or less complicated three dimensional (3D) items.…”

PLA-OMMT nanocomposites manufactured by reactive extrusion

“… measurements were used to calculate the specific mechanical energy (SME) according to Eq. (1) [67]. The SME defines the mechanical energy transferred to the melted polymer by the rotor shaft:…”