Thiabendazole uptake and storage performance of cactus pear [Opuntia ficus-indica (L.) Mill. cv Gialla] fruit following postharvest treatments with reduced doses of fungicide at 52 degrees C

摘要

The storage response of cactus pears [Opuntia ficus-indica Miller (L.) cv. Gialla] was investigated over 6 weeks at 6 degreesC, plus an additional week of simulated marketing period (SMP) at 20 degreesC, after a 3-min dip treatment with thiabendazole (TBZ) at 1000 mg/L at 20 degreesC or 150 mg/L TBZ at 52 1C. Untreated fruits were used as controls Following TBZ treatments at 20 and 52 degreesC, total residues were recovered from the peel of cactus pear, as the concentration of residues in the pulp was negligible. Treatments with 1000 mg/L TBZ at 20 degreesC resulted in a 2.82 mg/kg residue uptake (active ingredient, whole-fruit basis), whereas treatment at 150 mg/L TBZ left 1.09 mg/kg. TBZ showed great persistence over both storage and SMP: on average,, in the fruits treated at 20 and 52 degreesC, over 72 and 68%, respectively, of TBZ was still present after SMP. Postharvest treatments with 1000 mg/L TBZ at room temperature did not affect the expression of slight-to-mode rate chilling injury (CI), but reduced severe Cl by approximately 50% and decay development by 63.4% in comparison to those of untreated fruit after SMP. The effectiveness of TBZ was much higher with the treatment at 150 mg/L TBZ at 52 degreesC, providing 91% control of severe Cl and approximately 89% suppression of decay; no treatment damage occurred during storage and SMP., External appearance was better in fruit treated with 150 mg/L TBZ at 52 degreesC. Respiration rate, titratable acidity, soluble solids concentration, and acetaldehyde in the flesh were not significantly influenced by treatments. Ethylene production rate and ethanol levels in the flesh were significantly higher in the TBZ-treated fruit as opposed to those in the untreated control fruit.