Scaling relations in rheology of proteins present in meat analogs

Abstract

In this paper, we investigate whether the rheology of plant proteins is following similar scaling rules, as recently found for maltodextrins. The aim is to construct master curves of the rheology measurements, such that in combination with the scaling rules, the rheology can also be extrapolated to relevant practical conditions, that are not accessible with rheometers. We have analysed 4 different plant proteins, which are currently used in the manufacturing of meat analogs, on which we have performed frequency and amplitude sweeps for a wide range of temperatures and moisture contents. The frequency sweeps show that for all investigated temperatures and moisture contents the protein doughs show elastic behaviour for small strains and low frequencies, which maps on to a single master curve. Yet, the linear elastic modulus is governed by the ratio of the (moisture-dependent) glass transition temperature and the actual processing temperature ( T g / T ). Furthermore, we have constructed master curves for the strain sweeps, characterized by a critical strain that is independent of moisture content and temperature. Beyond the critical strain, the protein dough is showing strain thinning behaviour. Also with the use of literature data, we have found for pea a similar scaling exponent for shear thinning, strain thinning, and the moduli in the transition zone. This seems to confirm that plant protein doughs adhere to the Cox-Merz and Rutgers-Delaware rule, allowing translation to practical steady flow conditions as occurring during manufacturing. • For small strains all protein doughs show elastic behaviour for all investigated temperatures and moisture contents. • The linear elastic modulus is a function of T g /T. • Beyond a critical strain, which is temperature and moisture independent, doughs exhibit strain thinning. • An identical scaling exponent is found for transition zone, strain and shear thinning.