卵黄の加熱によるテクスチャーと微細構造の変化

概要

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Intact egg yolk(IY) and mechanically treated yolk(MY), the internal structure of which had been destroyed, were cooked at five different temperatures between 65℃ and 98℃, and then examined by a creemeter, optical microscope, transmisson electron microscope and cryo-scanning electron microscope to investigate the relationship between the texture and microstructure of cooked egg yolks. The hardness of both IY and MY was increased as the temperature was raised, whereas the cohesiveness was decreased. The hardness, cohesiveness and gumminess of MY were each greater than those of IY. Although raw egg yolk consisted of tightly packed yolk spheres, no membrane-like structures surrounding the yolk spheres were apparent. When IY was cooked at a temperature higher than 75℃, the yolk spheres solidified into polyhedral shapes, and a pore-like structure was observed in the matrix of the yolk spheres. This pore-like structure was fused and became more swollen as the temperature was raised. Although MY, when cooked, indicated a homogenous structure composed of the destroyed yolk spheres, a pore-like structure was also observed in the matrix. The texture of the hard-cooked yolk was caused by the formation of a network structure surrounding the pores in the yolk spheres as a result of heat denaturation of the yolk proteins and separation of the yolk spheres.
社団法人日本家政学会の論文
1998-04-15