Mechanical comparison of milk and whey protein isolate fouling deposits using indentation testings

• Published in: Food and bioproducts processing Vol. 122; pp. 145 - 158
• Main Authors: Liu, Jintian, Wiese, Hanna, Augustin, Wolfgang, Scholl, Stephan, Böl, Markus
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01.07.2020; Elsevier Science Ltd
• Subjects: Chemical reactions; Cleaning; Constitutive modelling; Dairy products; Deposits; Experiments; Fouling; Indentation; Indentation experiments; Indentation relaxation experiments; Mechanical properties; Milk; Milk fouling deposit; Pasteurization; Proteins; Three dimensional models; Time dependence; Whey; Whey protein; WPI; WPI; Milk fouling deposit; Indentation experiments; Indentation relaxation experiments; Whey protein; Constitutive modelling
• ISSN: 0960-3085; 1744-3571
• DOI: 10.1016/j.fbp.2020.03.007

•Milk and WPI fouling were mechanically characterised by indentation experiments.•WPI powder concentration was determined, able to mechanically mimicking milk fouling.•A 3D model is presented to describe the time-dependent behaviour of milk fouling.•Material parameters were identified by the inverse finite element method. Whey protein products have been previously used as a surrogate to mimic fouling and cleaning processes of dairy production. The basic idea builds on the fact that the main components of milk fouling are whey proteins and that the process from the solution to the fouling deposit is guided by similar chemical reactions. However, it remains unknown whether the resulting mechanical behaviour reflects that of milk deposits. Therefore, the objective of the present study is threefold: In the first step, the mechanical characteristics of raw milk and whey protein fouling deposits were determined and compared with each other. In a second step, we aimed to quantify the amount of whey protein isolate needed to obtain a similar mechanical behaviour. For the determination of the time-dependent mechanical characteristics of milk and whey protein deposits, indentation and indentation relaxation experiments were performed. The outcomes of this study show that whey protein deposits, generated from a solution featuring a whey protein powder concentration of 0.1g/l, lead to comparable mechanical characteristics to that of raw milk deposits. Furthermore, a significant influence of the milk deposit thickness on the mechanical behaviour was identified, resulting from the fouling generation process. Finally, a three-dimensional material modelling approach is suggested that can predict the time-dependent mechanical behaviour of milk fouling deposits.