Rheological properties and protein quality of UV-C processed liquid egg products

Rheological properties define the functionality and consequently, the technological quality, of food proteins. This study deals with the effects of short-wave ultraviolet treatments (dynamic or static UV-C) on the dynamic viscosity, flow behaviour, temperature-dependent viscosity, thermal properties and electrophoretic patterns of liquid egg products. Remarkably, none of the investigated parameters have been significantly influenced by UV-C treatments, static or dynamic. Rheological data, and thermal and electrophoretic properties indicate that the flow behaviour of UV-C treated egg white, whole egg or egg yolk, has not varied, and relevant protein denaturation or aggregation could be discarded. On the contrary, heat pasteurizations caused an increase on the viscosity-shear rate dependency, and also a certain degree of coagulation could be observed in the flow behaviour diagrams. Pasteurization additionally caused a reduction on the denaturation enthalpy observed in temperature-dependence viscosity measurements, and in DSC thermograms. The electrophoretic profiles also confirmed a certain degree of denaturation after pasteurization, with a reduction in the amount and intensity of the observed proteins. These results indicate that UV-C treatments do not affect significantly the rheological properties and the protein profile of liquid egg fractions, and could be used as an alternative to pasteurization.

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► Rheological properties of UV-C treated liquid egg products preserved.
► Minimal protein denaturation observed after UV-C.
► Heat pasteurizations altered the flow behaviour and contributed to protein aggregation.
► Short-wave ultraviolet might be a feasible alternative to heat.