Residue uptake and storage responses of tarocco blood oranges after preharvest thiabendazole spray and postharvest heat treatment

Tarocco blood oranges (Citrus sinensis Linn. Obsek) were slubjected to a single preharvest spray with thiabendazole (TBZ) at a concentration of 1% active ingredient (ai) in water and harvested 2 weeks after fungicide application or heated at 37 degreesC for 48 h under saturated humidity after harvest. The two treatments were also combined before cold quarantine (3 weeks at 2 degreesC), subsequent storage (3 weeks at 8 degreesC), and simulated marketing period (SMP) (1 week at 20 degreesC). Fruit not treated with TBZ and unheated were used as controls. The residue levels of TBZ (active ingredient, whole fruit basis) after spray were approximately 6.3 and 5.4 mg(.)kg(-1) before fruit storage respectively, a level close to the tolerance limit set by the European Community. TBZ showed a high persistence during quarantine, storage, and SMP. TBZ spray significantly reduced the incidence and severity of chilling injury (Cl) and decay during the postquarantine period and SMP. Heat treatment (HT) produced beneficial effects in controlling Cl, especially during SMP, when applied in combination with TBZ. However, HT remarkably promoted the development of secondary fungal infections such as Phytophthora rots and adversely affected fruit flavor and taste. The occurrence of off-flavor and off-taste was found to be perceptible after heating.