Stability of the dithiocarbamate pesticide maneb in tomato homogenates during cold storage and thermal processing

Abstract

The effect of storage at 5 degrees C and of thermal processing by cooking at 100 degrees C and sterilization at 121 degrees C for 15 min on maneb residues in tomato homogenates was investigated. Remaining maneb and its toxic metabolite ethylenethiourea (ETU) were measured after each treatment by headspace gas chromatography with flame-photometric detection and by high-performance liquid chromatography with photo-diode array detection, respectively. No significant loss of maneb was observed during cold storage for up to 6 weeks, taking into account analytical variability. Conversely, thermal treatment resulted in substantial degradation of maneb with extensive conversion to ETU. After cooking, only 26 +/- 1% (+/- SE, n = 8) of initial maneb residues remained in the samples, whilst the conversion to ETU was 28 +/- 1% (mol mol(-1)) (+/- SE, n = 4). Sterilization eliminated the residues of the parent compound giving rise to conversion to ETU up to 32 +/- 1% (mol mol(-1)) (+/- SE, n = 4).

The potency of Saccharomyces cerevisiae and Lactobacillus plantarum to dissipate organophosphorus pesticides in wheat during fermentation

“…However, recent studies reported that autoclaving, among other tested stabilization treatments of whole wheat flour, improved digestibility of proteins, phytate content, minerals and dietary fibres and intensify antioxidant activity of flour by increasing total phenolic content (Demir and Elgün 2014). As it was recorded that during thermal treatments involving pasteurization and/or sterilization (autoclaving) degradation of pesticides may occur at different rates (Lalah and Wandiga 2002;Kontou et al 2004), possibility that applied sterilization may affect residues of pirimiphos methyl and chlorpyrifos methyl in wheat was took in consideration in this study. As can be seen from obtained results presented in Table 2, the concentration of chlorpyrifos methyl in the samples after thermal processing for 15 min at 121°C (103 kPa) was drastically reduced at all fortification levels, reaching 77.6% for sample spiked with MRL, 75.8% for one spiked with 5MRL and 75.1% for sample fortified with 15MRL of pesticide.…”

Evaluation of the performance of a castor-oil based formulation in limiting pesticide residues in strawberry crops

“…26,27 Mancozeb residues were analyzed as carbon disulfide (CS 2 ) by gas-liquid chromatographic headspace.…”

Fate of Pesticide Residues on Raw Agricultural Crops after Postharvest Storage and Food Processing to Edible Portions

“…In particular, pesticides such as carbamates, amides, ureas, thiocarbonyl and those containing imino groups may be readily hydrolyzed in the presence of trace amounts of acid and/or base during heating or boiling. On this topic, a substantially amount of work (Chavarri et al, 2005;Kontou et al, 2004a;Kontou et al, 2004b;Knio et al, 2000) has been published on the fate of pesticide residues of dithiocarbamates and the more toxic ETU that during cooking concluding that during cooking dithiocarbamates may be conversed to ETU by a factor of 30-48%. Although, ETU residues during boiling may pass into the boiling water, a significant amount remains in the processed food.…”