Use of Reconstitued Yolk Systems To Study the Gelation Mechanism of Frozen–Thawed Hen Egg Yolk

Yolk gelation upon 5 week freezing-thawing was studied in four recombined yolk systems containing different plasma and granule proportions. Fractionation for mass distribution, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for protein distribution, and rheological properties were explored. Results indicate that both plasma and granule components, including low-density lipoprotein (LDL), high-density lipoprotein (HDL), and α-livetin proteins, contributed to gelation. Protein aggregation was reflected through a large mass increase in the granule fraction and appearance of a floating LDL layer upon fractionation of gelated yolk systems. A significant increase in gel strength (elastic modulus, G') was observed with the increase of the granule content. Overall, this study provides a better understanding of yolk gelation mechanism that may consequently lead to the design of innovative methods for preventing gelation. A schematic presentation of the yolk gelation mechanism is also proposed.