Effect of processing steps on pesticide residue reduction in bulgur wheat and rice

Pesticide residues in wheat and rice are of particular concern due to the widespread consumption of these staple foods and the associated potential health risks. This study examines how various processing steps, such as washing, soaking, cooking, and drying, affect pesticide residue levels in bulgur wheat (bulgur, processed wheat) and cooked white rice. A multiple linear regression analysis was employed to investigate the effects of these processing steps on pesticide residue levels. The processing parameters for bulgur wheat included: washing, soaking duration (0, 30, or 60 min), cooking time (15, 30, or 45 min), and drying time (0, 60, 120, or 180 min). The processing parameters for rice included: washing, soaking duration (0, 15, or 30 min), and cooking time (10, 15, or 20 min). Most processing methods resulted in some degree of reduction in pesticide residues in wheat, with processing factors (PFs) ranging from 0.10 for pirimicarb-desmethyl to 1.28 for difenoconazole. In contrast, all treatments led to at least some reduction in rice, with PFs ranging from 0.05 for azoxystrobin to 0.74 for metalaxyl. Cooking wheat was identified as an effective step in reducing pesticide residues. In contrast, drying led to an increase in residue levels due to the concentration effect, while washing and soaking had little influence on residue levels in wheat. The effectiveness of washing in removing pesticide residues is highly dependent on the nature and porosity of the grain. Rice processing showed that washing had the greatest impact on reducing pesticide residues, with soaking and cooking also contributing significantly, resulting in the lowest PFs observed for rice.