title: Determination of the Gelation Mechanism of Freeze-Thawed Hen Egg Yolk.
abstract: A study of yolks stored up to 168 d at -20 °C was conducted to determine the gelation behavior and mechanism of freeze-thawed yolk. Methods used were rheology, native and sodium dodecyl sulfate polyacrylamide gel electrophoresis (native- and SDS-PAGE), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), particle size analysis, and proton nuclear magnetic resonance ((1)H NMR) spectroscopy for matrix mobility. Results indicate that both constituents of plasma and granules contributed to gelation of yolk under freezing. PAGE analyses suggest that granular proteins participated in aggregation during freeze-thaw. Increasing gel strength and particle size and decreasing water and lipid-water mobility indicate that lipoproteins or apolipoproteins aggregated. At storage times ≥84 d, increased protein and lipid mobility, the detection of smaller particles, and secondarily increased gel strength suggest the liberation of protein or lipoprotein components from previously formed aggregates and further aggregation of these constituents. Disruption of the gelled yolk matrix observed with TEM supported that ice crystal formation was required for gelation to occur. A two-stage dynamic gelation model is thus proposed.
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Carmen
authors.initials: C
authors.lastname: Au
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Nuria C
authors.initials: NC
authors.lastname: Acevedo
authors.affiliation: Department of Genetics, Development and Cell Biology & Microscopy and NanoImaging Facility, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Harry T
authors.initials: HT
authors.lastname: Horner
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D002645:Chickens; D004530:Egg Yolk / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005615:Freezing; D005782:Gels / Q000737:chemistry*; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D010316:Particle Size; D012212:Rheology
chemical_list: D005782:Gels
keywords: egg yolk; frozen storage; gelation; lipoproteins