Effect of pH, ionic strength, and freezing treatment on a colloidal suspension of egg white aggregates

Abstract Characteristics of protein colloidal suspensions can be modified by freezing treatment. In this study, different colloidal suspensions of egg white aggregates (with different pH levels and ionic strengths) were frozen for several days, after which the colloidal suspensions were analyzed by a tunable resistive pulse sensing device to detect changes in particle characteristics. The average particle diameter in suspension increased with an enhancement in ionic strength. Particle number concentration decreased during five days of freezing treatment. The same colloidal suspensions were also analyzed using a small-angle X-ray scattering device. The results indicate that the inner structure was influenced by pH but did not change during the freezing process. The stability of foam made from frozen-thawed suspensions also increased with the enhancement of ionic strength. Based on these results, it appears that by controlling pH levels, ionic strength, and freezing time, the characteristics of egg white aggregates can be modified by freezing.