Effet chez le porcelet d'une exposition à un régime co-contaminé en ...

INTRODUCTIONI. PHYSICAL METHODS1) Removal from contaminated maizea) SortingSince the majority of mycotoxin contamination usually occurs in a relatively small number ofseeds or kernels, the segregation and sorting of damaged, discolored, crops containing visible mouldgrowth can lead to the removal of significant quantities of mycotoxins from these crops (Kabak et al.,2006). Sorting of the maize by fluorescence can achieve a partial removal of aflatoxins.Contamination can be observed by fluorescence following illumination with UV light (365 nmwavelenght). The Bright Greenish Yellow (BGY) fluorescence obtained, is not caused by aflatoxin itselfbut by a peroxydase transformation product of kojic acid, a metabolite of Aspergillus flavus and otherfungi (Scott, 1998). This test, known as the black light test, is considered as a presumptive indicatorof aflatoxin, but as mentioned by Bothast and Hesseltine (1975) both false positives (BGYfluorescence and no toxin detected) and false negatives (toxin detected and no BGY fluorescence)may occur during this evaluation, and results must be interpreted with caution.More recently, Pearson et al. (2004) proposed another sorting method, based on the fact thatmycotoxin-producing molds initially infect the oil-rich germ using grain lipids for their growth andmetabolism. Therefore, the free fatty acid content of grain has been proposed as a sensitive index ofincipient grain deterioration. Using optimal pair of filters (spectral absorbances at 750 and 1200 nm)the authors could distinguish kernels with aflatoxin contamination at >100 ppb from kernels with nodetectable aflatoxin, with >98% accuracy. When these two spectral bands were applied to sortingcorn at high speeds, reductions in aflatoxin averaged 82% for corn samples with an initial level ofaflatoxin >10 ppb and by removing ≈5% of the incoming grain (Pearson et al., 2004).In the same study, the method was applied for fumonisins-contaminated corn. The high-speeddual-wavelength sorter reduced fumonisin by an average of 88%, including those with low levels offumonisin.b) Sieving-cleaningCleaning grains removes kernels with extensive mold growth, broken kernels and fine materialssuch as dirt and debris, which helps to reduce mycotoxin concentrations. Murphy et al. (1993)reported the sieving of corn screenings (160 samples) into eight different particle sizes andconcluded that corn screenings or broken corn kernels usually contain fumonisins levels about 10fold higher than intact corn kernels. Similarly, fractionation of maize samples by sieving through a 353