14C-dimethoate residues in olive oil during oil processing

Area of Science:

• Agricultural Chemistry
• Food Science
• Environmental Science

Background:

• Pesticide residues in food crops are a significant concern for consumer safety and regulatory compliance.
• Dimethoate is an organophosphate insecticide used on various crops, including olives.
• Understanding the fate of pesticide residues during food processing is crucial for risk assessment.

Purpose of the Study:

• To quantify the reduction of 14C-dimethoate residues in olive oil throughout the industrial refining process.
• To investigate the nature of the terminal 14C residues in refined olive oil.
• To compare residue levels in field-treated versus artificially fortified olive oil.

Main Methods:

• Olive trees were treated with 14C-dimethoate, and residues were analyzed in fruits at harvest.
• Olive oil was extracted and subjected to industrial refining steps: neutralization, bleaching, and deodorization.
• Crude oil was artificially fortified with 14C-dimethoate and processed similarly for comparison.

Main Results:

• Crude oil contained 14.1% of total 14C from fruits; refining reduced this to 4.4% in the final product.
• Neutralization, bleaching, and deodorization significantly decreased 14C residues.
• Fortified oil showed a 7.3% residue in refined oil, suggesting different residue forms in field-aged vs. fortified oil.

Conclusions:

• Industrial olive oil refining effectively reduces dimethoate residues.
• The terminal 14C residue in refined oil from field experiments was not dimethoate or its oxon.
• Residue behavior differs between field-aged and artificially fortified oils, indicating complex degradation pathways.