title: Exploring the relationship between protein secondary structures, temperature-dependent viscosities, and technological treatments in egg yolk and LDL by FTIR and rheology.
abstract: Egg yolk and its main component, low-density lipoproteins (LDL), were consecutively pasteurised, optimally freeze-dried, and dispersed in various NaCl solutions (0-10%). Heat-induced changes in the protein secondary structures which accompanied viscosity-increasing aggregation processes were monitored using Fourier transform infrared spectroscopy (FTIR) to determine the intensities of intermolecular β-sheets (1622 cm(-1)) and results were compared with the temperature-dependent viscosities. Considerable changes in secondary structures observed after reconstitution of freeze-dried LDL had no detectable effect on the characteristic heat-induced viscosity curves but suggest that LDL plays a particular role in the unwanted gel formation of egg yolk after conventional freezing. For all egg yolk samples and all NaCl-containing LDL samples, the sigmoidal changes in the absorbance units vs. temperature curves corresponded with the first increase in heat-induced viscosity. Both analytical methods showed that the presence of ionic strength caused a shift in curve progressions towards higher temperatures, indicating increased thermal stability.
authors.affiliation: 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.
authors.forename: K
authors.initials: K
authors.lastname: Blume
authors.affiliation: 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.
authors.forename: K
authors.initials: K
authors.lastname: Dietrich
authors.affiliation: 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.
authors.forename: S
authors.initials: S
authors.lastname: Lilienthal
authors.affiliation: 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.
authors.forename: W
authors.initials: W
authors.lastname: Ternes
authors.affiliation: 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. Electronic address: astrid.drotleff@tiho-hannover.de.
authors.forename: A M
authors.initials: AM
authors.lastname: Drotleff
mesh_terms: D004527:Egg Proteins / Q000737:chemistry*; D004530:Egg Yolk / Q000737:chemistry*; D005612:Freeze Drying; D005615:Freezing; D006358:Hot Temperature; D008077:Lipoproteins, LDL / Q000737:chemistry*; D009994:Osmolar Concentration; D017433:Protein Structure, Secondary; D012212:Rheology; D012965:Sodium Chloride; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014783:Viscosity
chemical_list: D004527:Egg Proteins; D008077:Lipoproteins, LDL; D012996:Solutions; D012965:Sodium Chloride
keywords: FTIR; Hen’s egg yolk lipoproteins; Protein secondary structure; Rheology; Technological treatments