Inhibition effect of papain enzymatic hydrolysis on frozen egg yolk gelation during freezing

Freezing can lead to irreversible changes in the flowability and viscosity of egg yolk. To mitigate this, egg yolk was treated with 0.1% papain for varying durations prior to freezing, to investigate the underlying mechanism. The results demonstrated that egg yolk retained excellent fluidity and low turbidity when subjected to enzymatic hydrolysis, achieving a degree of hydrolysis between 3.62% and 4.06%. This enzymatic treatment notably reduced the textural firmness of frozen egg yolk. Notably, the sample subjected to 15 min of enzymatic hydrolysis exhibited the lowest values across all textural parameters. Furthermore, low-field nuclear magnetic resonance spectroscopy and magnetic resonance imaging revealed an increase in moisture content in the frozen-thawed yolk following enzymatic treatment. Microstructural analysis further revealed that enzymatic hydrolysis promoted the release of fat fractions bound to proteins. By comparing the effects across various hydrolysis durations, this study offers valuable insights for both industrial applications and scientific understanding.