Electrophoretic patterns of microwaved and γ‐irradiated beef liver proteins

The effects of γ-irradiation treatments (2.5, 5 and 10 kGy) and microwaves generated from an oven at low and defrost power settings for 0.5, 1 and 2min on the total proteins and protein patterns of beef liver immediately after treatment and during frozen storage (-18°C) for different periods were studied. Chemical analyses indicated that the protein content of beef liver was reduced after exposure to γ-radiation or microwaves and also during frozen storage. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was used to illustrate the changes in protein bands of different molecular weights and their percentages before and after exposure to gamma and microwave radiation. The main effect of γ-radiation on the protein patterns of beef liver was the disappearance of some high-molecular-weight protein bands and the development of other bands characterised by moderate and low molecular weights. This finding indicates the degradation of beef liver proteins by γ-irradiation. In contrast, microwave treatment caused an increase in the levels of high-molecular-weight protein bands with a concomitant decrease in low-molecular-weight protein bands. This phenomenon demonstrates the polymerisation of low-molecular-weight proteins under the influence of microwaves. Les effets des rayonnements gamma (2,5 et 10 kGy) et des microondes produites par un four (puissance faible et decongelation pendant 0,5, 1 et 2 minutes) sur le profil electrophoretique (SDS-PAGE) des proteines de foie de boeuf immediatement apres traitement et apres un stockage a -18° (de duree variable) ont ete etudies. Les proteines de haut poids moleculaire sont degradees apres irradiation gamma. Par contre apres irradiation hyperfrequence, les proteines de haut PM augmentent, alors que celles de PM faible diminuent. Ce phenomene s'explique par une polymerisation des proteines de PM faible sous l'influence des microondes.