THE INFLUENCE OF MICROWAVE EXPOSURE OF BOLETUS MUSHROOM-SOLVENT MIXTURES ON THE EXTRACTABILITY OF PHENOLICS AND ANTIOXIDANT ACTIVITY

Microwaves have been frequently applied for extraction of bioactive compounds of different origin, using systems operating at 200 -1000 W power, the efficiency being related to the heating of molecules. This study investigated the effects of non-thermal microwaves at 1.7 and 2.5 GHz for different exposure time, on the phenolic content and antioxidant activity of Boletus edulis extracts. The irradiated mixtures of fresh samples in ethanol solution showed increased phenolic content compared to control and in contrast to those of dried samples. The ATR-FTIR analysis indicates no structural changes after irradiation, confirming that the effect is due to the cell membrane disruption facilitating the compounds' release. The antioxidant activity of extracts from fresh samples significantly increased after MW exposure at 1.7 GHz for 3 h, 775 V?m-1. These results suggest that microwaves at investigated frequencies and electric field strengths can contribute to an efficient extraction of antioxidants from fresh mushrooms.