One solution is a salt water dip which is made by adding six tablespoons of pickling salt to one gallon of water. Soak for two to three minutes, then drain. Another solution is two tablespoons of ascorbic acid powder to one quart of lukewarm water. Soak, drain, and dry as above. Commercial fruit preservatives can also be purchased for this purpose.
Fruits are dry when somewhere between leathery and brittle.
Drying times are affected by a number of factors, so experience and common sense are the best guides. After sun drying fruit it needs to be equalized. Remove from trays and place in a bowl inside the house. Several times per day, for one week, stir the fruit pieces. This will allow any moisture from pieces that are not totally dry to be transferred to those which are overly dry.