Emerging egg technology: egg protein improves yogurt
Egg white has several proteins with unique properties that may have interesting applications.
Presently, the only egg white protein that is separated by the egg products industry is lysozyme. Lysozyme is separated using ion exchange resins. Lysozyme has been used in cheese to inhibit gas production. It has also been found to be effective against viral and bacterial infections in pharmaceutical applications. If efficient economical methods for fractionating egg white proteins are developed, new value added uses of these proteins may be possible.
In a recent study, Paredes et al. 2006 (Journal of Food Process Engineering 29:36-52) developed a process to separate ovalbumin from egg white. The scientists utilized poly (glycidil methacrylate-co-ethylene dimethacrylate) resin to efficiently separate ovalbumin. Ovalbumin is the major protein in egg white, making up 60% of the total egg white complex. It contributes significant functional properties in various food applications.
These scientists obtained a theoretical 83% yield of ovalbumin using the resin in a chromatographic separation. SDS polyacrylamide gel electrophoresis indicated that the separated ovalbumin was relatively pure. The ovalbumin was dried using a vacuum drying apparatus. They added 1% of the pure dried ovalbumin to the standard yogurt mousse formulation. This was reported to be equivalent to 2% of dried egg white.
Ovalbumin increased the yield of the mousse. The mousse was also observed to have a higher viscosity. Organoleptic evaluation also indicated that the textural properties of the mousse with ovalbumin were superior as compared to the control.
The separation process using the resin was claimed to be simple and satisfactory. The cost of the separated ovalbumin was reported to be $40/Kg which, of course, is considerably more expensive than dried egg white.
It would have been interesting if these scientists would have also investigated the addition of egg white to the yogurt mousse. Previous research has investigated the utilization of egg albumen as a partial milk replacer in yogurt-type products including Essary et al., 1982 (Poultry Science 61:1461-1462) and Cunningham and Brant, 1984 (Poultry Tribune 90 no. 9:6, 8). Cunningham and Brant named their product "Eggurt". They indicated that 10% egg white was the optimum level. Eggurt was observed to have a superior taste and mouth feel as compared to yogurt prepared with milk alone.
The significance of this research is that fractionation procedures for egg white proteins may have potential applications in the future. Of course, the process must be economical and the fractionated proteins must have satisfactory functional properties.