Microbiology-PTM-OMA_Modules_1-5

Food Preparation • Purchase sufficient amount of single lot for candidate method analyses, reference  method analyses, MPN determination (if applicable) and aerobic plate count. • Screen food item for natural contamination  • Recommend using both the candidate and reference methods. • Naturally contaminated matrices are preferred • Naturally contaminated food may be temperature abused to increase level of  contamination or diluted with uncontaminated matrix to decrease level of  contamination. • If naturally contaminated, test two lots of matrix, 20 replicates each. • One lot must meet fractional positive requirement • No 0 CFU level required. • If natural contamination not found, artificially inoculate each matrix with a  different target organism (strain, serovar, species).