AOAC-RI ERP Micro June 2016

OMAMAN-29/OMAMAN-30 Combined Collaborative Study Protocol OMA ERP - June 2016 ERP Use Only

3M MDA 2 Listeria species and L. monocytogenes Collaborative Study OMA-2016-MONTH-XXX

3.0

Test Portion Preparation 3.1

Preparation of inoculum . Deli turkey should be inoculated with heat-stressed organisms (e.g. 50°C for 10 min). The degree of injury caused by heat-stressing should be demonstrated by plating the inoculum in triplicate on selective and non- selective agars. The degree of injury is calculated as: 100 ) 1( x n n nonselect select − where n select = mean number of colonies on selective agar and n nonselect = mean number of colonies on nonselective agar. Raw chicken breast should be inoculated with a fresh, overnight culture diluted to the appropriate concentration. 3.2 Products will be obtained from local retail outlets. All food types will be screened for the presence of Listeria using the reference method. Any lots that screen positive will be confirmed out to the species level as per the specified reference method for that food type. Naturally contaminated test portions will be used if available at sufficient levels. Alternatively, the test portions will be artificially inoculated to meet the targets of 0.2-2.0 cfu/test portion for the low and 2 – 5 cfu/test portion for the high with the appropriate concentration of a wet inoculum. 3.3 Preparation of test portions. Each food type will be chopped into small pieces or divided and a liquid inoculum will be added drop-wise to a bulk quantity of food for each inoculation level. The bulk quantity will then be mixed to achieve equal distribution of analyte throughout. The test portions will be stored at 2-8 ° C for 48-72 h prior to testing. 3.4 Shipment of test portions. Test portions will be packaged in leak-proof, insulated containers and shipped (according to the Dangerous Goods Regulations IATA for Infections Substances) refrigerated via overnight courier to the collaborators to arrive on a Friday. Test portion processing and analysis will begin on Monday . All refrigerated test portions will be packed with ice packs to maintain a temperature of <7 ° C during transport. A temperature control sample will be included with each shipment to verify temperature of sample upon receipt. Upon arrival, the test portions will be stored at 2-8 ° C until they are analyzed. 3.5 Microbiological analysis. Each collaborator will receive36 x 60g raw chicken breast test portions (to be divided) and 72 x 125g deli turkey test portions. They will be instructed to weigh 25g raw chicken breast for the 3MMDA2 methods and another 25g for the reference methods. For deli turkey, they will be instructed to test one 125g test portion for the 3M MDA2 - Listeria monocytogenes method and the other 125g test portion for the USDA/FSIS MLG 8.09 reference method. All test portions assayed by the 3M MDA2methods will be confirmed following the reference method for confirmation of Listeria monocytogenes . The reference method confirmation procedures following the USDA/FSIS MLG 8.09 should be

AOAC Research Institute Expert Review Panel Use Only

5/4/16