Using the microwave will only work to help start the ripening process; it isn’t a case of putting the unripe peach into the microwave and having it come out ripe. To start the ripening process, place the peach on a microwave-suitable plate. Put into the microwave oven, set to medium heat and microwave it for 15 seconds. Remove the unripe and now heated peach and place into a paper bag, with a banana or an apple. The ethylene released from all the fruit in the bag will ripen the peach and it will work a little faster thanks to the zap in the microwave oven.