Final Examination for the Degree of MSc - April X. Xu

Date and Time

Location

Webex meeting (Invitation will be sent to email listservs)

Details

Examining Committee
Dr. Donald Mercer, Chair
Dr. Michael Rogers, Advisor
Dr. Maria Corradini, Advisory Committee Member
Dr. Loong-Tak Lim, Department Member

TITLE: SOUS VIDE COOKING CHANGES LIPID BIOACCESSIBILITY OF EGG YOLKS

ABSTRACT: Significant correlations exist between structure and lipid bioaccessibility in egg yolks. Structural changes of raw (20°C) and cooked egg yolks (65 – 85°C) were determined using rheology, thermal analysis, Fourier-transform infrared spectroscopy. A multicompartmental in vitro gastrointestinal digestion system, TIM-1, was used to elucidate the effects of cooking temperature on three bioaccessibility parameters – total bioaccessibility, induction time, and rate of lipolysis. Results showed significant differences in bioaccessibility parameters between treatments in cumulative bioaccessibility, such that it decreased from 25.08 – 29.43% in raw yolks to 19.77 –24.08% in 85°C yolks. Induction time also increased from 138.4 – 156.5 minutes in raw yolks to 158.3 – 184.2 minutes in 85°C yolks. Visualization and image analysis of raw and cooked yolk during digestion showed obvious differences in particle size. Lipid bioaccessibility had a negative relationship between storage modulus (G′) and intermolecular β-sheets content, whereas increases in peak enthalpy was positively related to increases in lipid bioaccessibility.

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