Phenolic content and antioxidant properties of fermenting musts and fruit and vegetable fresh juices

DPPH, Folin-Ciocalteau (FC) and peroxidase catalysed methods have been used to determine the free radical scavenging activity and total phenolic content (TPC) of two fermenting musts and thirty-four fresh juice of fruits and vegetables. Generally, a good correlation between the phenolic content and the scavenging activity was found. The red must showed catechin equivalent (CE) values almost one magnitude higher than the white one, while the CE behaviours in the course of the fermentation process appeared similar for two musts and for all the measurement methods. The FC results showed TPC values generally higher than those obtained by the enzymatic method, while the scavenging activity, expressed as CE in order to better correlate the results, showed lower values with the exception of citrus fruit juices for which the enzymatic response was twice of that obtained by the FC test. Furthermore, generally it was found that fruits presented CE values 2-3 times higher than those found in the vegetables. Finally, the results obtained demonstrate the applicability of the peroxidase catalysed coupling method to the TPC and antioxidant properties determination in wine, tea, fruits and vegetables. © 2009 Akadémiai Kiadó, Budapest.