Evaluation of different cleaning and processing methods for reducing chlorpyrifos residues on rice

Chlorpyrifos is commonly used to control rice pests，but it will residue on rice and cause potential harm. Degradation dynamics study of chlorpyrifos residues on rice during processing could provide an instruction for removal efficiency of chlorpyrifos on rice during different processing methods. Rice processing methods such as cleaning， cooked，porridge，cooked and then fried were used to remove the chlorpyrifos residues on rice and their removal effects were evaluated. Tap water could effectively remove the chlorpyrifos residues on rice. With the increase of cleaning time， the removal effect was obvious. After washed for 3 times，the removal rate of chlorpyrifos residues was 70.29% and the processing factor was 0.2971. Home cooking could effectively remove the chlorpyrifos residues on rice. The removal rate of chlorpyrifos residues in boiled rice was 87.83% and the processing factor was 0.1217. The removal rate of the chlorpyrifos residues on porridge was 96.07% and the processing factor was 0.0395. The removal rate of chlorpyrif residues on fried rice was 98.35% and the processing factor was 0.0165. But the chlorpyrifos residues would degrade into 3,5,6-trichloro-2-hydroxy-pyridine.