Date of this Version
Kar, A. (2021). Effect of radiofrequency assisted thermal processing on the structural, functional and biological properties of egg white powder. M.S. Thesis, University of Nebraska-Lincoln
Radiofrequency (RF) assisted thermal processing is a novel and energy-efficient method used for pasteurization, which heats the product volumetrically as opposed to traditional hot room (HR) pasteurization. RF-assisted thermal processing accelerates the heating rate of egg white powder (EWP), which has a low thermal conductivity and further affect its gelling properties. The effect of processing methods (RF and HR) due to pH and treatment temperature combination was monitored by subjecting neutral EWP (6.4 pH) to 70 and 80 ℃ and alkaline EWP (pH 9.9) samples to 70 ℃ over 0, 5, 10, 15 and 20 d. At 80 ℃ and 0 d, the gel firmness was 48.6% higher than HR, indicating RF could potentially improve the functionality as well as reduce the come-up time to less than a day as opposed to the traditional hot room processing used in the industry which takes 5-6 days. With increased treatment severity, the gel firmness substantially increased without changing the soluble protein contents, and insoluble contents. The secondary protein conformations evaluated using surface hydrophobicity, CD spectroscopy and Raman spectroscopy for EWP processed at 80 ℃ and 0 d, exhibited no significant effect of RF assisted thermal processing over HR processing. An in-vitro digestion model on egg white gels demonstrated that the accessibility of pepsin and trypsin to egg white peptides was not compromised despite a stronger gel network in RF assisted thermal processing at 80 ℃ and 0d. An in-silico analysis of the peptides in the egg white gel hydrolysates demonstrated that Ovalbumin and Ovotransferrin were the parent protein of most of the unique peptides generated, and minor structural differences were accounted for these peptides. The transport of soluble egg white gel hydrolysates, the cell viability, and tight junction proteins in the Caco-2 cells were not affected by RF assisted thermal processing.
Advisors: Kaustav Majumder & Jeyamkondan Subbiah