Behavior of 11 Organonitrogen Pesticides during the Refinement of Edible Oils

Abstract

Eleven organonitrogen pesticides (EPTC, chlorpropham, alachlor, metolachlor, thiobencarb, diethofencarb, pendimethalin, flutolanil, lenacil, fenarimol and bitertanol) were added to crude soybean oil, which was refined through degumming, alkali refining, bleaching and deodorization. The amounts of residual pesticides in the treated oils were determined immediately after each process. DEGUMMING : Bitertanol and fenarimol were significantly decreased by H3PO4 treatment, but the other pesticides were not. With hot water treatment, all the pesticides remained at a level of 85% or more. ALKALI REFINING : About 50% of lenacil was removed by both the 125% NaOH and 200% NaOH treatments. Removal rates of the other pesticides ranged from 15 to 20% for 125% NaOH and from 20 to 30% for 200% NaOH treatments, respectively. BLEACHING : More than 90% of bitertanol and fenarimol were efficiently removed by both the activated clay and activated clay containing activated charcoal. On the contrary, chlorpropham, thiobencarb and pendimetharin were decreased by less than 10%. DEODORIZATION : About half of fenarimol and bitertanol, and more than 80% of lenacil and flutolanil remaind after treatment at 260°C while the other pesticides decreased to below quantification limits. We found that while each pesticide was decreased at a different rate, and each process decreased these pesticides differently, they could all ultimately be decreased through the 4 refining processes. © 2005, Japan Oil Chemists' Society. All rights reserved.