Effect of heated solutions on decay control and residues of imazalil in lemons.

摘要

Freshly harvested lemons (Citrus limon) were dipped for 3 min in water with 0, 50, 100 or 200 ppm imazalil (IMZ) at 50deg C or with 1000 ppm IMZ at 20degree C. After treatment, the fruits were kept at 9degree C and 90-95% RH for 13 weeks and an additional week at 21degree C and～75% RH, as a simulated marketing period (SMP). No control of decay was observed with fruit dipped in water at 50degree C. In contrast, IMZ treatments provided 90-96% control of Penicillium rots during cold storage and SMP. Fungi other than Penicillium spp. were found in all samples; differences among treatments were negligible. IMZ treatment caused some external damage to the fruit (peel browning), and the percentage of damaged fruit was related to the amount of active ingredient (AI) present in it. Dipping in 200 or 1000 ppm IMZ promoted off-flavour development after 10 weeks of storage, and fruit were judged to be unacceptable for consumption after 13 weeks of cold storage. After dipping in 1000 ppm IMZ at 20degree C, the residue concentration in fruit was8.2 ppm; this value doubled that found in a previous investigation on lemons treated with comparable IMZ levels. Residue concentrations in fruit after treatment at 50degree C was strictly related to the amount of fungicide employed. After 13 weeks, AI residuesin fruit decreased to average～35% of the initial values. During the 1 week SMP, residue levels decreased by a further～25%. It was concluded that it is possible to achieve significant control of decay in lemons during long-term storage by dipping the fruit in 50 ppm IMZ mixtures at 50degree C. Such treatment should be advised to remarkably reduce potential pollution in the environment due to packinghouse wastewater disposal.