Photochemical advanced oxidative process treatment effect on the pesticide residues reduction and quality changes in dried red peppers.

Pesticide residues in crops are widely monitored, and the residue reduction techniques at the post-harvest stage are important to maintain food safety. In dried crops, pesticide residues can be concentrated after dehydration, which increases concerns regarding residue risk. Therefore, the residue reduction effects of ultraviolet (UV), ozone, and photochemical advanced oxidative process (pAOP) were investigated for dried peppers at the post-harvest stage. UV254 treatment reduced 59.7% of the residue concentration on average, while UV360 showed a reduction of only 13.3% under 9.6 W m-2 of UV exposure for 24 h. Gaseous ozone treatments reduced the residue concentrations up to 57.9% on average. In contrast, the pAOP treatment reduced the concentration up to 97% and was superior to UV or ozone treatment alone. Increased drying temperature under pAOP condition resulted in higher reduction ratios at 40-80 °C. The pAOP conditions with 12 and 24 µmol/mol of ozone and UV254 irradiation for 24-48 h reduced the residue concentrations to 39-67%. Particularly, difenoconazole, fludioxonil, imidacloprid, and thiamethoxam residue concentrations were drastically reduced by over 50% under 12 µmol/mol ozone of the pAOP condition, while carbendazim, fluquinconazole, and pyrimethanil were relatively stable and their concentrations reduced below 50% under 24 µmol/mol ozone of the pAOP treatment. Various drying-related quality parameters of drying peppers such as water-soluble color, capsanthin, capsaicinoids, acid value, peroxide value, and thiobarbituric acid value were slightly altered, but not significantly, under 12 µmol/mol ozone of the pAOP condition, while the peroxide value was significantly altered under the higher ozone conditions. Therefore, pAOP treatment combined with gaseous ozone can be used for reducing residual pesticides in peppers without greatly reducing quality.

Chlorfenapyr Residue in Sweet Persimmon from Farm to Table.

The use of the pesticide chlorfenapyr has been increasing over time, with a consequent wider application to crops. However, there is limited information available on the amount and safety of the residues it leaves on crops. The amount of chlorfenapyr residues in sweet persimmon (Diospyros kaki L.) at both the pre- and postharvest stages were investigated in this study by calculating its biological half-life. The half-life at the preharvest stage was 8.8 days, shorter than that found during the storage periods at 4 and 20°C, when the half-lives were 11.0 and 23.9 days, respectively. In addition, peeling and washing after harvesting reduced residue content. The majority of the chlorfenapyr residues in sweet persimmon were found in the peel of the fruit, with the pulp containing less than 25% of the total. Thus, peeling effectively removed chlorfenapyr residues and diminished the residues below the limit of quantification in the pulp. In addition, washing with 1.0% alcohol and 0.2% Tween 20 solutions effectively removed 47.8 and 55.6% of the residues, respectively. Furthermore, a 1.0% alcohol solution showed high reduction efficiency for other hydrophobic pesticides, such as dimethomorph and fluquinconazole, up to 78.0%. Chlorfenapyr residues in sweet persimmon can be effectively reduced via storage or peeling and washing practices or a combination of them.