Electrophoretic patterns of microwaved and γ‐irradiated beef liver proteins

Abstract

The effects of g-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 2 min on the total proteins and protein patterns of beef liver immediately after treatment and during frozen storage (À18°C) for different periods were studied. Chemical analyses indicated that the protein content of beef liver was reduced after exposure to g-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 g-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 ®nding indicates the degradation of beef liver proteins by girradiation. In contrast, microwave treatment caused an increase in the levels of high-molecularweight protein bands with a concomitant decrease in low-molecular-weight protein bands. This phenomenon demonstrates the polymerisation of low-molecular-weight proteins under the in¯uence of microwaves.

Alteration of Kafirin and Kafirin Film Structure by Heating with Microwave Energy and Tannin Complexation

“…The increase in oligomer band intensity after heating is consistent with the high oligomer band intensity reported in pepsin digestion residues of films made from heat-treated kafirin (3). Heatinduced protein polymerization has also been reported in rapeseed protein (11) and beef liver protein (12). Kafirin polymerization due to wet cooking has also been reported (13,14).…”