EFFECT OF HEATED SOLUTIONS ON DECAY CONTROL AND RESIDUES OF IMAZALIL IN LEMONS

Freshly harvested lemons [(Citrus limon (L.) Burm)] were dipped 3 min in water with and without imazalil (IMZ) at 50, 100, and 200 ppm at 50 degrees C and at 1000 ppm IMZ at 20 degrees C. Following treatments f ruit were kept at 9 degrees C and 90%-95% relative humidity (RH) for 1 3 weeks and an additional week at 21 degrees C and ca. 75% RH, to simu late a marketing period (SMP). No decay control was observed with frui t dipped in water at 50 degrees C. In contrast, IMZ treatments provide d 90%-96% control of Penicillium rots during cold storage and SMP. Fun gi other than Penicillium spp. were also found in all samples as diffe rences among treatments were negligible. IMZ treatment caused some ext ernal damage to the fruit (peel browning), and the percentage of damag ed fruit was related to the amount of active ingredient (AI) present i n it. Dipping in 200 or 1000 ppm IMZ promoted off-flavor development a fter 10 weeks of storage, and fruit were judged to be unacceptable for consumption after 13 weeks of cold storage. After 1000 ppm IMZ dippin g at 20 degrees C, residue concentration in fruit was 8.20 ppm; this v alue doubled that found in a previous investigation on lemons treated with comparable IMZ levels. Residue concentrations in fruit after trea tment at 50 degrees C was strictly related to the amount of fungicide employed. After 13 weeks Al residues in fruit decreased to average ca. 35% of the initial values. During the 1 week SMP, residue levels decr eased by a further ca. 25%. It was concluded that it is possible to ac hieve significant control of decay in lemons during longterm storage b y dipping fruit in 50 ppm IMZ mixtures at 50 degrees C. Such treatment should be advised to remarkably reduce potential pollution in the env ironment due to packinghouse wastewater disposal.