Experimental characterisation of the mechanical failure behaviour of whey protein gel treated with sodium hydroxide

• Published in: Food and bioproducts processing Vol. 129; pp. 94 - 104
• Main Authors: Liu, Jintian, Böl, Markus
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01.09.2021; Elsevier Science Ltd
• Subjects: biobased products; brittleness; Chemical damage; Chemical degradation; Chemical treatment; Failure; Gels; Hydroxides; Mechanical analysis; Mechanical failure; Mechanical properties; Proteins; Sodium; Sodium hydroxide; Sodium hydroxide (NaOH); Strain; Stress relaxation; Stress-strain relationships; Tensile strength; Tension experiment; Time dependence; Whey; Whey protein; Whey protein gel; Whey protein isolate; Sodium hydroxide (NaOH); Chemical degradation; Whey protein isolate; Whey protein gel; Tension experiment
• ISSN: 0960-3085; 1744-3571
• DOI: 10.1016/j.fbp.2021.07.007

•WPG was mechanically characterised by tension and tension relaxation experiments.•Untreated samples and those treated with sodium hydroxide (NaOH) were considered.•Stress–strain relations provide important data for the constitutive modelling of WPG damage behaviour.•Failure tensile strains are essential for the prediction of cohesive detachment of WPG. 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 0.5wt% 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 3.0min 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 WPG associated with the chemical damage of the protein network.