Food Sample Procedure (1:10 or Greater Dilution of Food Sample)

Transcription

1 M Petrifilm Aerobic Count Plate For detailed WARNINGS, cautions, DISCLAIMER OF WARRANtIES / LIMIted REMEDY, LIMITATION OF 3M LIABILITY, StoRAGE AND DISPoSAL information, and Instructions FoR use see product s package insert. Reminders for use Food Sample Procedure (1:10 or Greater Dilution of Food Sample) Sample Preparation 1 Weigh or pipette food product into an appropriate container. 2 Add appropriate diluent. 3 Blend or homogenize sample per current procedure. Inoculation 4 Place 3M Petrifilm Aerobic Count Plate (AC) on level surface. Lift top film. 5 Using a diluting pipettor, combine 0.5mL of Aerobic Lactic Acid Bacteria Broth (MRS and Chlorophenol Red) with 0.5mL diluted food sample within the pipette tip. 6 With pipettor perpendicular to 3M Petrifilm AC Plate, place entire 1mL of sample onto center of bottom film. Inoculation Incubation 7 Release top film; allow it to drop. DO NOT roll top film down. 8 With ridge side down, place plastic spreader over inoculum. Gently apply pressure to evenly distribute sample. 9 Incubate 3M Petrifilm AC Plates and inspect plates. Additional Comments Note: Remember to inoculate and spread each Petrifilm count plate before going on to the next.

2 Environmental Monitoring Prodedures** Sample Preparation Sample Preparation 1 Select swab containing appropriate neutralizer. Hold the swab handle to make a 30 angle with the surface. Firmly rub the swab head slowly and thoroughly over the desired surface area. Rub the head of the swab three times over the surface, reversing direction between alternating strokes. Inoculation 2 After sampling is complete, securely insert the swab head back into the swab tube and transport to the lab for plating. Plate the swab solution as soon as possible. 3 Mix lactic broth plus swab solutions in equal volumes. 4 With pipettor perpendicular to 3M Petrifilm AC Plate, place entire 1mL of sample onto center of bottom film. 5 Release top film; allow it to drop. DO NOT roll top film down. 6 With ridge side down, place plastic spreader over inoculum. Gently apply pressure to evenly distribute sample. Incubation 9 Incubate 3M Petrifilm AC Plates and inspect plates. 3M Quick Swab and Swab Samplers with either DE Neutralizing Broth or Letheen Broth are available from 3M. 3M Food Safety offers a full line of products to accomplish a variety of your microbial testing needs. For more product information, visit us at Food Safety 3M Australia Pty Limited 1 Rivett Road, North Ryde NSW M New Zealand 3M 94 Apollo Drive, Rosedale Auckland M and Petrifi lm are trademarks of the 3M company.

3 3M Petrifilm Interpretation Guide 3M Petrifilm Lactic Acid Bacteria Aerobic Count Plates Lactic Acid Bacteria Count = 8 A red indicator dye reacts with growing bacteria allowing colony visualization. Acid-producing bacteria produce a yellow zone (halo) around the colony. Bacteria shown in Figure 1: Lactococcus Lactic Acid Bacteria Count = 0 Negative Control Plate containing 0.5mL Aerobic Lactic Acid Bacteria Broth plus 0.5mL diluent.

4 Interpretation Guide: Aerobic Procedure for Lactic Acid Bacteria with 3M Petrifilm Plates for Monitoring Food and Environment 3M Petrifilm Lactic Acid Bacteria Aerobic Count Plates Lactic Acid Bacteria Count = 15 Colony color can vary from faint to dark pink depending on organism, environmental stress and sample matrix. Bacteria shown in Figure 3: Lactobacillus Lactic Acid Bacteria Count = 11 Colony-associated bubbles, which may appear whiter than the background, can indicate gas production. Bacteria shown in Figure 4: Weisella Red colonies are sometimes fainter and smaller near the edge of the inoculated area. Bacteria shown in Figure 5: Streptococcus agglacati Lactic Acid Bacteria Count = 7 Some lactic acid bacteria produce yellow zones (halos) before colonies are visible. Bacteria shown in Figure 6: Streptococcus oralis User s Responsibilities: 3M Petrifilm Plate performance has not been evaluated with all combinations of microbial flora, incubation conditions and food matrixes. It is the user s responsibility to determine that any test methods and results meet the user s requirements.

5 3M Petrifilm Lactic Acid Bacteria Aerobic Count Plates The presence of high levels of acid, whether produced by lactic acid bacteria or associated with the sample matrix, can turn the inoculation area yellow. Incubation conditions (time and temperature) or additional dilution may make it easier to identify and enumerate lactic acid bacteria Backlighting can aid in enumerating faint colonies or colonies in a low ph (yellow) background. Ham Salad Food particles can be distinguished from colonies by their irregular shape and darker red color. User s Responsibilities: 3M Petrifilm Plate performance has not been evaluated with all combinations of microbial flora, incubation conditions and food matrixes. It is the user s responsibility to determine that any test methods and results meet the user s requirements.

6 3M Petrifilm Lactic Acid Bacteria Aerobic Count Plates Non-lactic acid producing bacteria typically appear as red colonies against a red background. Additional incubation may change the color of the background. Bacteria shown in Figure 11: Pseudomonas Non-lactic acid producing bacteria typically appear as red colonies against a red background. Additional incubation may change the color of the background. Bacteria shown in Figure 12: E. coli User s Responsibilities: 3M Petrifilm Plate performance has not been evaluated with all combinations of microbial flora, incubation conditions and food matrixes. It is the user s responsibility to determine that any test methods and results meet the user s requirements.