| Determinations were made on the moisture sorption isotherms (at 25, 45 C) and the nonenzymatic browning (at 45 C) of whole egg, egg white and egg yolk, with and without selected food humectants (glucose, sucrose, glycerol, propylene glycol, sodium chloride). In the pure egg systems, the water activity (a(,w)) lowering ability of egg white was the highest, followed in order by whole egg and egg yolk. However, the sorption pattern was reversed when the food humectants were employed as the a(,w) controlling agents. Of the five humectants, sodium chloride exhibited the highest a(,w) depressing effect in all the egg systems followed by glycerol, propylene glycol, glucose and sucrose in order of effectiveness. The egg systems added with various levels of egg solids, glucose, sucrose and sodium chloride showed lower a(,w) at 45 C than at 25 C whereas glycerol produced higher a(,w) at the higher temperature when its level in the egg samples exceeded 30%.An intermediate moisture egg product having a(,w) of 0.83, 0.85, 0.88 and 0.90 was developed in the subsequent study. All the samples were microbiologically stable and sensory attributes did not significantly change throughout the 30 weeks of storage at room temperature. In vitro digestibility of intermediate moisture egg products was comparable to that obtained from conventional egg products. Comparison of the data on Instron shear force, sensory test and L, a, b color stability indicated that the intermediate egg product with an a(,w) of 0.90 had the best overall chemical and physical performance.In the absence of humectants, egg white, whole egg and egg yolk exhibited, in that order, decreasing browning pigment formation, with maxima detected at a(,w) 0.65-0.75, 0.65 and 0.85, respectively. The addition of glucose reversed the order of nonenzymatic browning rate and extent. Glycerol, propylene glycol and sodium chloride inhibited the Maillard reaction at all the a(,w) levels investigated. |
