Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination

Abstract

One of the most important concerns in the decontamination of aflatoxin-containing feed commodities is the safety of the products for food-producing animals and for human consumption of products derived from these animals. A new method, based on the use of florisil and C18 solid phase extraction columns, was developed for the preparation of extracts from decontaminated peanut meal, which allowed testing with in vitro genotoxicity assays without interference of the residual aflatoxin B1. Recovery of degradation products in the extracts was evaluated by the use of radiolabelled [14C]-aflatoxin B1 (AFB1) added to naturally-contaminated peanut meal (3.5 mg AFB1/kg). The meal was treated by a small-scale version of an industrial decontamination process based on ammoniation. Following decontamination, more than 90% of the label could not be extracted from the meal. AFB1 accounted for about 10% of the radiolabel present in the extractable fraction, indicating a total AFB1 reduction of more than 99%. Decontamination of the meal by a number of other small- and industrial-scale ammonia-based processes resulted in similar efficiencies. Application of the extraction procedure resulted in AFB1-rich and AFB1-poor fractions, the latter containing half of the extractable decontamination products but less than 1% of the residual AFB1. Testing in the Salmonella/microsome mutagenicity assay (TA 100, with S9-mix) of the original crude extracts and AFB1-rich fractions prepared from non-treated and decontaminated meal, showed the positive results expected from the AFB1 contents as determined by HPLC analysis. Analysis and testing of the AFB1-poor fractions showed that the various decontamination processes not only resulted in a successful degradation of AFB1 but also did not produce other potent mutagenic compounds. Slight positive results obtained with these extracts were similar for the untreated and treated meals and may be due to unknown compounds originally present in the meal. Results obtained with an unscheduled DNA synthesis (UDS) and Comet assay with rat hepatocytes supported this conclusion. Positive results obtained with the micronucleus assay, using immortalized mouse hepatocytes (GKB), did not clearly reflect the mycotoxin levels and require further examination. It is concluded that the newly developed extraction procedure yields highly reproducible fractions and hence is very suitable for examining the possible formation of less potent degradation products of aflatoxins in short-term genotoxicity tests.

Natural occurrence of mycotoxins in peanut cake from Nigeria

“…AFB 1 concentrations in the peanut cakes reached 2820 mg/ kg, a level that was capable of inducing severe acute forms of aflatoxicosis in the consumers (Ezekiel, Alabi, et al, 2011;Fapohunda, Awoyinka, Olajuyigbe, Ezekiel, & Esiaba, 2007;Fapohunda, Ezekiel, Alabi, Omole, & Chioma, 2008;Hoogenboom et al, 2001;Wild & Turner, 2002). We also detected AFG 1 and M 1 at concentrations reaching 477 mg/kg and 126 mg/kg respectively.…”

Assessment of an application on a detoxification process of groundnut press cake for aflatoxins by ammoniation

“…Hoogenboom et al. ( 2001b ) showed a strong reduction in the mutagenic response of extracts from peanut meal ammoniated by commercial processes, supported by results for unscheduled DNA synthesis and Comet assay with rat hepatocytes. When ammoniated AFB1‐contaminated feeding material was given to rats, mice, ducklings, swine, chickens, lambs, trout and dairy and beef cattle in acute and chronic trials, no toxic effects related to the ammoniation procedure were disclosed (Park et al., 1988 ).…”

Decontamination of Aflatoxin B1

“…But at lower temperature, for example, at 25°C, AF1B level could not be reduced very well. Their study revealed that the moisture level of the product and holding temperature were the crucial factors to have influence upon the efficacy of aflatoxin decontamination [26][27][28][29]. The degradation of AFB1 is ammonization of aflatoxin (AFD1), which has been shown to be far less mutagenic than AFB1.…”