Characterisation of the Mechanical Properties of Heat-Induced Protein Deposits in Immersed Cleaning Systems

1 Introduction 1.1 Motivation  1.2 Aim of the present work 1.3 Outline 2 Background of cleaning in place 2.1 Heat treatment in the dairy production 2.2 Fouling and cleaning in the dairy production 2.2.1 Heat-induced formation of fouling deposits 2.2.2 The use of whey protein for experimental studies 2.2.3 Cleaning process for the fouled heating surface 2.3 The influence factors of cleaning in place 2.4 Cleaning mechanisms on the mechanical properties of protein deposits 3 Mechanical behaviour of heat-induced deposits 3.1 Mechanical behaviour of fouling deposits 3.1.1 Fouling experiments with raw milk and whey protein solution 3.1.2 Realisation of quasi-static and dynamic indentation experiments 3.1.3 Comparison of mechanical responses between milk and whey protein deposits 3.1.4 Influences of heat treatment on the mechanical behaviour of fouling deposits 3.2 Mechanical behaviour of whey protein gel 3.2.1 Gelation of whey protein solution with different heating conditions 3.2.2 Characterisation of fracture behaviour of WPG 3.2.3 Degradation of the WPG samples with NaOH solution 3.2.4 Characterisation of failure behaviour of WPG 4 Constitutive modelling and numerical simulation 69 4.1 Kinematics and balance equations 4.1.1 Kinematics of deformation 4.1.2 Stress tensors 4.1.3 Balance equations 4.2 Constitutive equations for protein deposits 4.2.1 One-dimensional generalised Maxwell model 4.2.2 Three-dimensional visco-hyperelastic model 4.2.3 Parameter identification through inverse finite element method 4.2.4 Application of modelling approaches 5 Conclusion and Outlook