Ulrichs, T., Drotleff, A.M. and W. Ternes. 2015. Food Chemistry 172:909-920.
Center for Food Sciences, Institute of Food Toxicology and Analytical Chemistry, Department of Analytical Chemistry, University of Veterinary Medicine Hannover Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany
Corresponding author. Tel.: +49 511 856 7365.
Both authors contributed equally to the manuscript.
This study characterized the impact of technological treatments on the protein secondary structure of a newly developed egg yolk livetin formulation and its components α-livetin, which is identical with chicken serum albumin, and γ-livetin, the bioactive antibody immunoglobulin Y. Fourier transform infrared (FTIR) spectroscopy at 25 °C revealed that the largest proportion of conformal elements comprised intramolecular (native) β-sheets (60–80%) in γ-livetin, and α-helices/random coils (60.59%) in α-livetin. In reconstituted freeze-dried livetins, the main protein conformations were also intramolecular (native) β-sheets (55.08%) and α-helices/random coils (30.51%), but upon heating from 25 to 95 °C, the former decreased sigmoidally at the onset-of-denaturation temperature (TOD (FTIR)) of 69.5 °C, concomitant with a sigmoidal increase in intermolecular (denatured) β-sheets at a TOD (FTIR) of 72.4 °C and a sigmoidal decrease in IgY activity atTOD (ELISA) of 67.5 °C. Reconstituted spray-dried livetins showed less native β-sheets and significantly lower TOD (FTIR) values than freeze-dried livetins.