Changes in Ultrastructure of Egg Albumen Pasteurized With Additives Used to Minimize Heat Denaturation

Abstract

Macromolecular changes in albumen ultrastructure were observed with the electron microscope following pasteurization without and with various additives used commercially to minimize heat denaturation. Treatments included heating albumen from 5 and 60 day old refrigerated eggs for various times at 60° C. with (1) no additives, (2) aluminum sulfate plus lactic acid, (3) lactic acid alone, (4) aluminum sulfate alone, and heating at 54.5° C. with (5) hydrogen peroxide, (6) sodium hexameta phosphate, and (7) no additives.Heat denaturation was observed in treatments 1, 3 and 4 at 3.5 minutes and in treatments 5, 6 and 7 at 15 minutes. In treatments 1, 4, 5, 6 and 7, the denaturation was characterized by the formation of electron dense irregular clumps of approximately 0.1 μ. diameter which became more numerous and dense as heating time progressed. These clumps were denser in the center than at the periphery. In treatment 3, uniformly electron dense spheres of denatured protein approximately 0.3 μ. in diameter appeared after 3.5 minutes and their numbers increased with time. In treatment 2 heat denaturation appeared minimal and undenatured protein formed a light sandy image of near uniform electron dense material spotted frequently with only slightly more dense sandy zones of approximately 0.01 μ. diameter. The 5 and 60 day albumen gave similar overall results, except evidences of denaturation in the 60 day samples were slightly more pronounced.