Dissertation

Protein Particles for Structuring in Very Low Fat Mayonnaise

Young, Peter William

2021

Overview

This thesis aims to further understanding of protein fluid gels and their potential for use in reduced fat products. Previous research on fluid gels has shown their potential for fat replacement in semi-solid foods, and protein fluid gels have been used for the stabilization of foams. This thesis will investigate processing methods for and the influence of pH on the production of protein fluid gels, determining how this influences the fluid gel properties. Initially, protein fluid gels produced from egg white were compared with those produced from WPI as protein fluid gels have been produced previously from WPI. These were produced through heating under shear. Rheology and soft tribology were used to investigate the properties of these fluid gels. As proteins have different net charges at different pH levels relative to the isoelectric point (pI), the influence of pH on fluid gel properties was investigated. Fluid gels produced at the pI were shown to produce aggregated particles of less than 1 μm diameter. These systems produced at the pI demonstrated greater friction values in the mixed and boundary regimes of lubrication. Egg fluid gels offer a new functional ingredient for food products, in particular products such as mayonnaises and dressings in which egg is already an ingredient. Following on from this, dry protein fluid gel particles were produced from WPI through spray drying, and the properties of suspensions for these particles were investigated. To further understand the potential of these systems for use in reduced fat products, properties of emulsions stabilized by these particles were investigated and compared with a full fat mayonnaise and an emulsion stabilized by commercially available SimplesseTM. The greatest loss of solubility through processing of WPI was observed at pH 3.5. At pH 3.5, particles with an average size of 22.9 ± 2.0 m upon dispersion were produced. Addition of salts after particle production showed no effect on suspension rheology, demonstrating the potential for use in reduced fat dressings or mayonnaises in which salt is an ingredient. Both the particles and soluble protein were shown to be surface active. Emulsions stabilized by 20% spray-dried WPI in the aqueous phase were stable and showed similar rheology with increasing oil contents with oil droplets shown to contribute to the structuring of suspensions. Protein particles are shown to contribute to the structure of reduced fat emulsions.

• Publisher: ProQuest Dissertations & Theses
• Subject: Rheology