Thermal inactivation of mushroom polyphenoloxidase employing 2450 MHz microwave radiation

Browning reactions in fruits and vegetables are a serious problem for the f ood industry. In mushrooms, the principal enzyme responsible for the browni ng reaction is polyphenoloxidase (PPO). A microwave applicator has been des igned and used for studying mushroom PPO inactivation. The effects of micro waves and conventional heating on the kinetics of the monophenolase and dip henolase activities of PPO were studied. Conventional and microwave treatme nts produce different enzyme intermediates with different stability and kin etic properties. We describe how considerable time can be saved during micr owave inactivation of the enzyme compared with the time needed when convent ional hot-water treatment is used, resulting in greater profitability and e nhanced quality. The short exposure time required for samples irradiated wi th microwaves is very important for maintaining the quality of mushrooms. T he fast microwave treatment used resulted in an increase in antioxidant con tent and a considerable decrease in browning.