Postharvest treatments for the reduction of mancozeb in fresh apples.

The objective of this study was to determine the effectiveness of chlorine, chlorine dioxide, ozone, and hydrogen peroxyacetic acid (HPA) treatments on the degradation of mancozeb and ethylenethiourea (ETU) in apples. This study was based on model experiments at neutral pH and temperature. Fresh apples were treated with two different levels of mancozeb (1 and 10 microg/mL). Several of the treatments were effective in reducing or removing mancozeb and ETU residues on spiked apples. Mancozeb residues decreased 56-99% with chlorine and 36-87% with chlorine dioxide treatments. ETU was completely degraded by 500 ppm of calcium hypochlorite and 10 ppm of chlorine dioxide at a 1 ppm spike level. However, at a 10 ppm spike level, the effectiveness of ETU degradation was lower than observed at 1 ppm level. Mancozeb residues decreased 56-97% with ozone treatment. At 1 and 3 ppm of ozone, no ETU residue was detected at 1 ppm of spiked mancozeb after both 3 and 30 min. HPA was also effective in degrading the mancozeb residues, with 44-99% reduction depending on treatment time and HPA concentrations. ETU was completely degraded at 500 ppm of HPA after 30 min of reaction time. These treatments indicated good potential for the removal of pesticide residues on fruit and in processed products.

Ozone and hydrogen peroxyacetic acid treatment to reduce or remove EBDCs and ETU residues in a solution.

Laboratory studies were conducted in a model system to determine the effects of ozone (1 and 3 ppm) and hydrogen peroxyacetic acid (HPA) (5 and 50 ppm) at pH 4.6, 7.0, and 10.7 and at 10 and 21 degrees C on the degradation of mancozeb in solution over a 30 min period. All samples were analyzed for residues by GLC and HPLC. Ozonation and HPA treatment were effective in degrading mancozeb in solution. Rate of mancozeb degradation was dependent on pH, with the fastest rate at pH 7.0. Ethylenethiourea (ETU) residue concentrations in the mancozeb solutions were monitored over 60 min. Under controlled conditions, the ETU residue concentrations increased during the 15 min reaction time and then decreased for all three pH values. At 3 ppm of ozone treatment, no ETU residues were detected at all three pH ranges after 15 min of reaction time. Degradation of ETU by HPA was greatest at pH 4.6, and no ETU residues remained after 5 min at either 5 or 50 ppm. The results showed that ozone and HPA gave excellent degradation of pesticide residues depending on pH and temperature. These experiments indicated the potential for the removal of pesticide residues on fruit and in processed products.

Reduction of azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues in processed apples.

McIntosh, Red Delicious, and Golden Delicious from two years of experimental spray programs using azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl were processed into frozen apple slices, applesauce, single-strength juice, and juice concentrate. Residue levels were expressed as micrograms per 150 g of apple or the equivalent amount of apple product to calculate the percentage change in these pesticides brought about by processing. Producing single-strength apple juice reduced azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues by 97.6, 100, 97.8, and 78.1%, respectively. Production of applesauce reduced all four compounds by >/=95%. Azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues were reduced in apple slices by 94.1, 85.7, 98.6, and 94.7%, respectively. Processing is shown to be very effective in reducing the levels of these pesticides.

Polychlorinated biphenyls, polybrominated biphenyls, and dioxin reduction during processing/cooking food.

This chapter presents information on the levels of environmental contaminants found in recent market basket surveys as well as the effect of processing and cooking on the reduction of these contaminants. Although consumers have expressed concern over the level of environmental contaminants in the food supply, market basket surveys involving over 8,000 analyses of foods ready-to-eat, found measurable amounts (ppb levels) of PCBs in only 24 foods. Processing/cooking has been shown to reduce PCBs by 20-100%. Although PBBs got into the food chain as the result of one incredible accident and thus are not expected to be found in foods today, cooking/processing was also effective in reducing PBBs. Dioxins are the result of combustion processes and chemical manufacturing processes. TCDD levels found in Great Lakes fish were in the low part per trillion level. Again, cooking and processing resulted in substantially less TCDD in fish as eaten.

Deposition of malathion and permethrin on sod grass after single, ultra-low volume applications in a suburban neighborhood in Michigan.

Deposition of malathion and permethrin onto grass surfaces, after ultra-low volume (ULV) application, was studied in a suburban neighborhood in Saginaw County, Michigan. Commercial concentrates of malathion (Cythion ULV) and permethrin (Biomist 4 + 12) were sprayed using a truck-mounted ULV aerosol generator. Sod-grass blocks (0.18 m2) were placed in the frontyard and backyard of homes in the neighborhood at 4 distances to 91.4 m from the road where applications were made. Grass samples were taken from the sod blocks before application and at 15 min, 12 h, 24 h, and 36 h after application. Samples were extracted with solvent, and extractions were subjected to gas-liquid chromatography for detection of malathion and permethrin. Ranges of detection for malathion were 0.0-16.6 mg/0.18 m2 and for permethrin were 0.0-25.9 mg/0.18 m2. Most detections were from samples taken nearest the road at 15 min after application. Detections declined as a logarithmic function of time after application and as an exponential function of distance from the road.