Fate of postharvest-applied dichlorvos in stored and processed dates

The fate of dichlorvos (DDVP) on dates after storage and processing of post harvest-treated fruits has been investigated. Residues were determined usin g GC-ECD after extraction of the fruits. A postharvest application was made to fruits at different stages of maturity: khalal fruits (mature full colo red stage), rutab fruits (soft brown stage), and the mature tamer fruits (h ard raisin-like stage). The fate of the residues was followed during the st orage at refrigerated, room, and summer average temperatures (3, 22, and 43 degreesC). The amount of residues absorbed varied with the level of maturi ty. The rate of the loss of the residues was found to follow first-order ki netics. First-order rate constants were calculated for the different levels of maturity. The rate of the loss of DDVP increased as the temperature of storage increased. Also, it decreased with increasing maturation of the dat es, which was characterized by a decrease in moisture content as well as wa ter activity and an increase in sugar content. The period of storage study was limited by the time of maturation to the next stage. Most common home-c ooking methods, including dehydration, jam-making, and syrup-making, result ed in significant decreases in residue levels. Only 0-13% of initial DDVP r esidues was detected in final products.