Microstructure change in whole egg protein aggregates upon freezing: Effects of freezing time and sucrose addition

Protein is not stable under freezing conditions, which may lead to changes in protein aggregates. In this study, liquid whole egg samples were frozen and thawed. The structural changes in the whole egg aggregates were then analyzed. After analyzing samples using tunable resistance pulse sensing, it was found that the number of protein aggregate samples increased nearly six-fold after freezing and thawing. The addition of sucrose reduced the enhancement of particle number. The surface characteristics of whole egg protein aggregates varied during the freezing process. By adding sucrose to the whole egg sample, the variation in aggregate surface characteristics was weakened. The same samples were also investigated using a small-angle X-ray scattering device. The results showed that the inner structure of whole egg protein aggregates became less packed during the freezing process. However, changes in protein aggregates caused by freezing were prevented by the addition of sucrose. In conclusion, freezing unfolded whole egg proteins and reduced protein solubility, which further increased the number of protein aggregates and changed the structure of the aggregates. Sucrose could be a cryoprotectant and inhibit the influence of freezing on whole egg protein aggregates.