Effects of freezing and thawing treatment on the rheological and textural characteristics and micro-structure of heat-induced egg yolk gels

•Egg yolk can form heat-induced gels even after being frozen-thawed (FT).•FT egg yolk develops its network when frozen, then form crosslinking when heated.•Salt addition increases the texture of FT egg yolk gel, while sugar one does not.•FT egg yolk gel formed under heat treatment presented a relatively weaker crosslinking.

The objective of this study was to evaluate the rheological, textural characteristics and micro-structure of heat-induced gels obtained from frozen-thawed egg yolk. Results indicated that egg yolk kept its ability to form heat-induced gels after being frozen and thawed. The textural characteristics of frozen-thawed yolk gels decreased when yolk/water ratio was reduced. The network development of frozen-thawed egg yolk gels was different from that of fresh ones. The elastic (G′) and viscous (G″) modulus of frozen-thawed egg yolk started to increase at around 55 °C, and formed a stable network at about 90 °C. The addition of sugar did not affect the textural characteristics of the heat-induced gels from frozen-thawed egg yolk. However, the textural properties of gels improved significantly as the salt content was increased from 0 to 2% (w/w). In terms of the mechanical spectra and micro-structures, the crosslinking of heat-induced gels from frozen-thawed yolks was weaker than that of fresh egg yolk gels.