Small deformation measurements of single and mixed gels of low cholesterolyolk and egg white

Isolates of reduced-cholesterol egg yolk were prepared by extracting choles terol from spray-dried yolk using the following solvents: (1) petroleum eth er, (2) petroleum ether/ethanol, (3) ethanol/water and (4) supercritical ca rbon dioxide. Differential scanning calorimetry demonstrated that the tempe rature of minimum heat flow of the denatured isolates was about 75C. Mechan ical properties of extracts were compared using small deformation oscillato ry rheology. Ethanol/water and petroleum ether treated yolk had the stronge st and weakest gelling characteristics respectively, following protein dena turation at 75C. When compared to egg white, yolk isolates formed stronger networks at 75C. Heating at higher temperatures denatured ovalbumin which p roduced slightly stronger gels than egg yolk. Binary mixtures of egg white and yolk formed phase separated gels. The best agreement between experiment al data and calculated composite moduli by using isostrain and isostress Ta kayanagi models, was obtained for egg white keeping 37% more water per unit concentration than the egg yolk.