Modification of egg albumen to improve thermal stability

Abstract

Eggs are an excellent source of high quality protein for consumers that can be economically produced. This dissertation focuses on improving the thermal stability of egg albumen or egg white protein. As consumers are demanding more protein in their diets, egg white proteins can provide the supply to meet those needs. A major barrier of egg white protein’s use as a mainstream protein in beverages, further food processing, or other consumer food is its sensitivity to heat (precipitating out of solution when heated). If this functional property can be resolved, it would not only add value to the egg processing industry, but also would have an expanded use in various other applications. Three specific types of modification to the egg albumen as a whole were studied for this dissertation research. A series of thermal stability evaluations was used to determine the improvement in stability of the protein at 75°C, 95°C, and 121°C. Since egg albumen contains a mixture of several different proteins, working on the protein dispersion, as a whole is a challenge. The mechanism of protein aggregation is caused by hydrophobic protein-protein interaction after the protein has partially unfolded due to heating. As the proteins aggregate, it can either form a linear soluble aggregate or insoluble coagulum, which can precipitate. Glycation with partially hydrolyzed carboxymethylcellulose (HCMC), succinylation with octenyl succinic anhydride (OSA), and combinations of physical treatment (ultrasound) and the addition of OSA were investigated to prevent these aggregations leading to improved thermal stability of the protein. The HCMC is an anionic polysaccharide that can increase the electrostatic repulsion between proteins, similar to what OSA can do. However, OSA contains a hydrophobic carbon chain that may further interact with the hydrophobic groups of the unfolded proteins