Mechanism of heat-induced thinning of thick egg white in weak alkaline condition: molecular aggregation, functional and structure properties analysis

The thinning of thick egg white (KEW) was simulated by weak alkaline (pH 10.0) combined with mild heat (50 degrees C) treatment. The molecular aggregation, functional and structural characteristics changes in simulated KEW thinning process were comprehensively studied. It was found that KEW molecule entered "molten pellet (MG)" state with decline of apparent viscosity of KEW. At this time, particle size increased by 40.9%, surface hydrophobicity and solubility declined 11.3% and 8.9%, respectively. However, with more mild heating time, KEW structure gradually unfolded, ovomucin (OVM) degraded, particle size diminished significantly. Surface hydrophobicity and solubility increased 6.6% and 19.7%, respectively. Functional properties indicated that thermal gel of KEW gradually became soft and tough, water holding capacity (WHC) advanced by 10%, emulsifying property significantly improved by 40%. Moreover, correlation analysis indicated that tertiary structure was correlated with particle size (P < 0.01), secondary structure related to hardness and WHC (P < 0.05). Through the results of SDS-PAGE and comparison with KEW simple mild heating, it was concluded that rise of pH was intrinsic driving force of KEW thinning. Therefore, this study provided a new insight for revealing the thinning mechanism of KEW and a scientific basis for its industrial application.