Abstract

The effect of different drying conditions (based on hot air convective drying and vacuum drying with or without microwave pretreatment) on residual behavior of abamectin, buprofezin, imazalil, and thiophanate-methyl in orange slices was investigated. Processing factors ranged between 1.55 and 3.41, indicating concentration of the residue levels in dried orange slices due to the moisture losses. However, based on the normalized residue concentration with dry matter content of the slices, pesticide residue levels in fresh orange slices reduced by 40.8%–73.2% after drying processes. Hot air drying caused more reduction in residue levels compared to vacuum drying. It was observed that decrease in absolute pressure of vacuum drying from 30 kPa to 15 kPa, increase in drying temperature from 60 °C to 80 °C, and application of microwave pretreatment increased the degradation rate. Moreover, the Pearson analysis revealed that degradation rate in the residue levels during drying was negatively proportional to the octanol-water coefficient of pesticides. Therefore, the highest degradation rate was obtained for buprofezin and thiophanate-methyl during hot air drying (at 80 °C) with application of microwave pretreatment and the lowest degradation rate was obtained for abamectin during vacuum drying (at 60 °C and 30 kPa).

摘要

研究了不同干燥条件（基于热风对流干燥和真空干燥，有或没有微波预处理）对橙片中阿维菌素、丁苯丙嗪、抑霉唑和甲基硫菌灵残留行为的影响。加工系数介于 1.55 和 3.41 之间，表明由于水分损失，干橙片中的残留水平集中。然而，根据切片干物质含量归一化的残留浓度，干燥处理后鲜橙切片的农药残留水平降低了 40.8%–73.2%。与真空干燥相比，热风干燥使残留物水平降低更多。观察到真空干燥的绝对压力从 30 kPa 降低到 15 kPa，干燥温度从 60 °C 升高到 80 °C，微波预处理的应用提高了降解率。此外，Pearson 分析表明，干燥过程中残留水平的降解率与农药的辛醇-水系数成负比。因此，在应用微波预处理的热风干燥（80°C）过程中，buprofezin和甲基硫菌灵的降解率最高，而阿维菌素在真空干燥（60°C和30 kPa）过程中的降解率最低。 .