Impact of the drying mode and ageing time on sugar profiles and antioxidant capacity of electro-activated sweet whey

The effect of electro-activation (EA) on the properties of whey was investigated. During 60 min of EA treatment of whey, lactose isomerisation into lactulose was observed and paralleled pH evolution. Antioxidant capacity of EA-whey was investigated; EA time was the most significant parameter on the antioxidant capacity such as reducing power, Fe2+ chelating, and Trolox equivalent ABTS radical scavenging capacity. DPPH radical scavenging activity showed a significant increase up to a maximum value then gradually decreased. As a function of ageing treatment, the reducing power and DPPH radical scavenging activity were significantly increased, whereas Trolox equivalent ABTS radical scavenging activity was decreased; no effect on Fe2+ chelating activity was detected. All samples were stable in terms of their antioxidant activities during spray- and freeze-drying. Formation of protein hydrolysates was assessed by SDS-PAGE and formation of glycated compounds occurring during EA treatment was measured.