Extrusion and chemical treatments for destruction of aflatoxin in naturally-contaminated corn

Abstract

Naturally-contaminated corn containing 500 ppb total aflatoxins (AF) was ground to pass through a 20 mesh screen. Initial moisture content was determined for each sample and then adjusted to 15-20%. The samples were treated with sodium bicarbonate (NaHCO₃), sodium bisulfite (NaHSO₃), hydrogen peroxide (H₂O₂), calcium hydroxide (Ca(OH)₂), sodium hydroxide (NaOH), azodicarbonamide (Maturox), benzoyl peroxide (Novadelox), ammonium hydroxide (NH₄OH), or ammonium bicarbonate (NH₄HCO₃) in varying concentrations, and then extruded through a Wenger single barrel extruder at a temperature of 105°C. Extrusion conditions were the same for all samples. Prior to analysis the extruded product was dried and ground. All samples were analyzed in triplicate. A second set of samples were analyzed under acidic conditions using a 0.1 N hydrochloric acid (HCl) soak prior to extraction. Protein and amino acid analyses were conducted on extruded samples in which NH₄OH or NH₄HCO₃ were used. The Salmonella microsome mutagenicity assay was used to determine mutagenic potential on both "as is" and acidified extracts of the above samples. Extrusion without chemical treatment of each meal reduced the AF by 40 to 70%. Ammonium hydroxide and NH₄HCO₃ were the only chemicals which reduced AF to below the United States Food and Drug Administration (FDA) action level of 20 ppb. Protein and amino acids were not significantly changed, and mutagenicity tests were inconclusive.