AOAC 2019 First Action Methods

i. The nature of food (high viscosity or presence of food dye) may affect test usage or results. In that case, the cause needs to be eliminated by dilution or other means. j. The used kit must be decontaminated by autoclaving or boiling and disposed of according to local regulations for waste. Safety Precautions After use, the diluents and MC-Media Pads may contain microorganisms that may be a potential biohazard. When testing is complete, follow current industry standards for the disposal of contaminated waste. Consult the Safety Data Sheet for additional information and comply with local regulations for disposal. To reduce the risks associated with bacterial infection and workplace contamination: Perform MC-Media Pad testing in a properly equipped laboratory under the control of a skilled microbiologist. D. Sample Preparation Samples are prepared depending on what reference method is being followed. Please see below for the validated reference methods the MC-Media Pad ® Rapid Aerobic Count test pad has been compared to: 1. MLG 3.02 – Place a 50 g test portion in a filtered laboratory blender bag and add 450 mL of BPB. Homogenize with a laboratory blender. 2. SMEDP Chapter 6 – Place an 11 g or 11 mL test portion into a filtered laboratory blender bag and add 99 mL of BPB. Homogenize with a laboratory blender. 3. OMA 966.23 – Parsley (50 g), Vegetable Juice (50 mL), Cooked Prawns (50 g), Tuna Pâté (50 g), Egg Salad Sandwich (50 g), Deli Pasta Salad (50 g). Place a 50 g test portion in a filtered laboratory blender bag and add 450 mL of BPB. Homogenize with a laboratory blender. 4. ISO 4833:2013 – Raw Chicken Breast (10 g), Raw Ground Pork (10 g), Cream Cheese (10 g), Yogurt Drink (10 mL), Parsley (10 g), Vegetable Juice (10 mL), Cooked Prawns (10 g), Tuna Pâté (10 g), Egg Salad Sandwich (10 g) and Deli Pasta Salad (10 g). Place a 10 g test portion in a filtered laboratory blender bag and add 90 mL of Maximum Recovery Diluent (MRD). Homogenize with a laboratory blender. For all products, if necessary, make 10-fold serial dilutions with BPB or MRD. 5. Open the aluminum bag and remove MC-Media Pad ® . 6. Lift the transparent cover film and pipette 1.0 mL of sample solution onto test pad. (It is recommended to lift the cover film diagonally for easy and secure re-sealing). 7. Close the cover film and lightly press the edges of the film to seal. 8. For preparation of samples according to the USDA and SMEDP methods, incubate the MC-Media Pad ® RAC test plate at 35 ± 1°C for 24-48 hours. 9. For preparation of samples according to the ISO method, incubate the MC-Media Pad ® RAC test plate at 30 ± 1°C for 72 ± 3 hours. 10. After incubation, count all reddish colored colonies. 11. If a large number of colonies is difficult to count, estimate by counting colonies in one grid square and multiplying by 20. If more than 10 4 microbes are grown, the entire test pad may appear stained and it may appear that no individual colonies were formed. If this occurs, dilute the sample further and re- test.