To investigate the influence of chemical degradation on the mechanical (failure) behaviour of whey protein gels (WPGs), tensile and tensile relaxation experiments were performed on untreated and chemically treated gels. From each treatment performed, the tensile stresses increase with the applied strain rates, varying from 0.5 %/s to 2.0 %/s, indicating the time-dependent mechanical property of WPGs. Using sodium hydroxide solution with a concentration of 0.5 wt% showed a clear chemical degradation effect at higher immersion time, resulting in reduced tensile strength due to softer mechanical response and increased stress relaxation, making the WPG more flowable. Comparing the failure behaviour between untreated and 3.0 min treated WPG, the untreated gels show a brittle failure behaviour and exhibit a lower failure strain than the adequately treated ones. The measured failure strain can be used to predict the cohesive failure of WPG subject to the same chemical degradation. The stress-strain relationships, responding to different experimental conditions, provide useful input data for modelling the mechanical behaviour of WPGassociated with the chemical damage of the protein network.
J. Liu, M. Böl
Experimental characterisation of the mechanical failure behaviour of whey protein gel treated with sodium hydroxide
Food and Bioproducts Processing, in press, (2021) [Link]