Abstract:
Factors affecting on functional properties of pasteurized egg white, in terms of foaming properties of pasteurized egg white were investigated. Three types of sugar (sucrose, glucose or fructose) were varied into 4 level: 10, 20, 30 and 40% (w/v), compared with control. The results showed that foaming capacity of egg white was decreased inversely with the amount of sugar. While, the stability of foam was increased directly with the amount of sugar (p≤0.05). At the sugar less than 40% (w/v), foaming properties of the pasteurized egg white were not significantly affected by types of sugar (p>0.05). The best foaming properties was obtained by 30% (w/v) sugar addition. The addition of sugar into egg white led to an increase in the viscosity of egg white and a decrease in the size of air bubble in egg white foam (p≤0.05). Availability of water was monitored using Nuclear magnetic resonance (NMR) technique. Increasing sugar content resulted in a decrease in NMR relaxation time. The results, during storage (1, 4 and 7 days), revealed that the foaming capacity, foaming stability and the viscosity of egg white with sugar and without sugar were not significantly affected by storage time (p>0.05). The effect of sugar on heat-induce egg white gelation was then investigated. The results showed that the presence of sugar significantly promoted an increase in gelation temperature of egg white (p≤0.05). Egg white gel containing fructose showed the highest value of color difference compared to non sugar treatment. The texture of egg white gel related to gelation temperature. An increase in the amount of sugar led to a significantly decrease in maximum force required to break the gel and NMR relaxation time. Finally, the effect of carboxymethylcellulose (CMC) on the emulsifying properties of egg white emulsion was studies. Two types of CMC (1800 and 3000 mPa.s) at the levels of 0.1, 0.3 and 0.5% (w/v) were used and emulsion without CMC was set as a control. The results showed the emulsion activity Index (EAI) value of emulsions containing 0.5% (w/v) CMC was constant and emulsion exhibited no sign of serum separation during aging time of 30 min. The EAI value of emulsion containing 0.5% (w/v) CMC was not significantly affected by type of CMC (p>0.05). While, EAI value of emulsions without CMC and emulsion containing 0.1 and 0.3% (w/v) CMC decreased and emulsions exhibited serum separation after 5 min. The viscosity of emulsion containing 0.5% (w/v) CMC was significantly higher than the emulsion containing 0.1 and 0.3% (w/v) CMC (p≤0.05). Moreover, the uniform distribution and uniform size of oil droplet was also observed in continuous phase of emulsion containing 0.5% (w/v) CMC.