Research Note: Aggregation-depolymerization of chicken egg yolk granule under different food processing conditions

Chicken egg yolk granule is a natural micro-nano aggregate in egg yolk, and its assembly structure varies under different processing conditions. In this study, the effects of NaCl concentration, pH, temperature, and ultrasonic treatment on the properties and microstructure of yolk granule were determined. The results showed that ionic strength (above 0.15 mol/L), alkaline environment (pH 9.5 and 12.0), and ultrasonic treatment induced the depolymerization of egg yolk granule; while freezing-thawing, heat treatment (65°C, 80°C, and 100°C), and mild acidic pH (pH 4.5) induced the aggregation of yolk granule. Scanning electron microscopy observation showed the assembly structure of yolk granule varied with different treatment conditions and confirmed the aggregation-depolymerization of yolk granule under different conditions. Correlation analysis showed that turbidity and average particle size are the 2 most critical indicators that can reflect the aggregation structure of yolk granule in solution. The results are important for understanding the changing mechanism of yolk granule during processing, and provide important information for the applications of yolk granule.