Chapter 9: Aerobic Plate Count
Updated: 03/07/08- Potential Food Safety Hazard
- FDA Guidelines
- State Guidelines
- Recommended Microbiological Limits
- Analytical Procedures
- Food sampling and preparation of sample homogenate (USFDA)
- Definition of Terms; Collection of Samples; Supplement to all Methods in the HC Compendium (HC)
- Aerobic plate count (USFDA)
- Determination of the aerobic colony count in foods (HC)
- Enumeration of total aerobic bacteria in food products and food ingredients using 3MTM PetrifilmTM aerobic count plates (HC)
- Determination of aerobic colony count in foods by the hydrophobic grid-membrane filter (HGMF) method (HC)
- Calculation of the most probable number of growth units for HGMF methods (HC)
- Environmental sampling for the detection of microorganisms (HC)
- Environmental sampling, detection of microorganisms, preparation of sampling material (HC)
- Most probable number from serial dilutions (USFDA)
- Calculation of the most probable number (MPN) of Growth Units for HGMF Methods (HC)
- Calculation of the most probable number (MPN) (HC)
- Other APC methods
- Commercial Test Products
- References
| Potential Food Safety Hazard | Contents |
The plating medium (nutrient source) used in an APC can affect the number and types of bacteria isolated because of differences in nutrient and salt requirements of the various microorganisms. For many fish and fishery products, a plate incubation temperature of 25ºC (77ºF) produces significantly higher numbers of bacteria than incubation at 35ºC (95ºF) (Nickelson and Finne, 1992).
| FDA Guidelines | Contents |
| Product | Guideline | Reference |
| Raw breaded shrimp | Aerobic plate counts (35ºC [95ºF]) – The mean log of 16 units of finished product breaded shrimp collected prior to freezing is greater than 5.00 (i.e., geometric mean greater than 100,000/g) and exceeds the mean log of 16 units of stock shrimp by more than twice the standard error of their difference (2 SED) | FDA, 1996a |
Table #A-5. FDA & EPA safety levels in regulations and guidance.
| State Guidelines | Contents |
| State | Product | Maximum APC |
| Alabama | Oysters, fresh or frozen | 5 x 105/g |
| Alaska | Oysters, clams, and mussels | 5 x 105/g |
| Oysters, clams, and mussels: in shell or shucked, but not eviscerated | 5 x 105/g | |
| Oysters, clams, and mussels: eviscerated | 1 x 105/g | |
| Arizona | Clams, mussels, and oysters | 5 x 105/g |
| Arkansas |
- |
|
| California | Oysters, clams, and mussels | 5 x 105/g |
| Colorado | Oysters, clams, mussels, and scallops | 5 x 105/g |
| Connecticut | Oysters, clams, and mussels | 5 x 105/g |
| Delaware | Clams, mussels, or other mollusks, fresh or frozen | 5 x 105/g |
| Florida | Blue crab | 105/g |
| Shellfish | 5 x 105/g | |
| Georgia | Clams, mussels, and oysters - fresh or frozen | 5 x 105/g |
| Fried clams, frozen | 104/g | |
| Scallops, fried, frozen | 104/g | |
| Scallops, breaded, frozen | 104/g | |
| Crabmeat, fresh cooked | 104/g | |
| Deviled crab, frozen, cooked | 104/g | |
| Deviled crab, fresh, uncooked | 106/g | |
| Shrimp, peeled, cooked | 105/g | |
| Shrimp, breaded, frozen, raw | 106/g | |
| Fish, frozen, breaded, fried | 2.5 ´ 104/g | |
| Fish, frozen, breaded, raw | 105/g | |
| Fried fish cakes, frozen | 104/g | |
| Hawaii | Oysters, clams, mussels, fresh or frozen | 5 x 105/g |
| Idaho | - |
- |
| Illinois | - |
- |
| Indiana | - |
- |
| Iowa | - |
- |
| Kansas | - |
- |
| Kentucky | Oysters, clams, scallops, shrimp, fresh or frozen | 5 x 105/g |
| Louisiana | - |
- |
| Maine | - |
- |
| Maryland | Fresh crabmeat | 105/g |
| Pasteurized crabmeat | 2.5 x 104/g | |
| Oysters, clams, mussels, fresh or frozen | 5 x 105/g | |
| Massachusetts | Oysters, clams, mussels, fresh or frozen | 5 x 105/ml |
| Michigan | - |
- |
| Minnesota | - |
- |
| Mississippi | Oysters, clams, mussels, fresh or frozen | 5 x 105/g |
| Missouri | Oysters, clams, mussels, fresh or frozen | 5 x 105/100ml |
| Foods | 1.5 x 106/g | |
| Montana | - |
- |
| Nebraska | Oysters, clams, mussels, fresh or frozen | 5 x 105/g |
| Deli foods (shrimp salad, etc.) | 105/g | |
| Nevada | - |
- |
| New Hampshire | Oysters, softshell clams, fresh or frozen | 5 x 105/g |
| New Jersey | Oysters, clams, mussels, fresh or frozen | 5 x 105/g |
| "Potentially hazardous" (tuna, shrimp salad) | 104/g | |
| New Mexico | - |
- |
| New York | - |
- |
| North Carolina | Shellfish | 5 x 105/g |
| Crustacea, fresh | 104/g | |
| Crustacea, pasteurized | 3 x 103/g | |
| North Dakota | - |
- |
| Ohio | - |
- |
| Oklahoma | - |
- |
| Oregon | Oysters, clams, mussels, fresh or frozen | 5 x 105/100g |
| Pennsylvania | - |
- |
| Rhode Island | Oysters, clams, mussels, fresh or frozen | 5 x 105/g |
| Fresh seafood | 106/g | |
| Smoked fish | 105/g | |
| South Carolina | Fresh cooked blue crabmeat | 105/g |
| Pasteurized blue crabmeat | 2.5 x 104/g | |
| Oysters, clams, mussels, fresh or frozen | 5 x 105/g | |
| South Dakota | - |
- |
| Tennessee | - |
- |
| Texas | Crabmeat | 105/g |
| Oysters, clams, mussels, fresh or frozen | 5 x 105/g | |
| Utah | - |
- |
| Vermont | - |
- |
| Virginia | Fresh blue crabmeat | 105/g |
| Pasteurized blue crabmeat | 3 x 103/g | |
| Shellfish - shucked or in the shell | 5 x 105/g | |
| Washington | Molluscan shellfish (Oysters, clams, mussels, fresh or frozen) | 5 x 105/g |
| West Virginia | - | - |
| Wisconsin | - | - |
| Wyoming | - | - |
| Recommended Microbiological Limits | Contents |
| ICMSF | Contents |
| Product | n1 |
c2 |
Bacteria/g or cm2 |
|
m3 |
M 4 |
|||
| Fresh and frozen fish and cold-smoked fish | 5 |
3 |
5 x 105 |
107 |
| Precooked breaded fish | 5 |
2 |
5 x 105 |
107 |
| Frozen raw crustaceans | 5 |
3 |
106 |
107 |
| Frozen cooked crustaceans | 5 |
2 |
5 x 105 |
107 |
| Cooked, chilled, and frozen crabmeat | 5 |
2 |
105 |
106 |
| Fresh and frozen bivalve molluscs | 5 |
0 |
5 x 105 |
- |
2 Maximum number of acceptable sample units with bacterial counts between m and M.
3 Maximum recommended bacterial counts for good quality products.
4 Maximum recommended bacterial counts for marginally acceptable quality products.
Plate counts below "m" are considered good quality. Plate counts between "m" and "M" are considered marginally acceptable quality, but can be accepted if the number of samples does not exceed "c." Plate counts at or above "M" are considered unacceptable quality (ICMSF, 1986).
| Analytical Procedures | Contents |
| Food sampling and preparation of sample homogenate (USFDA) | Contents |
| Definition of Terms (HC Appendix A); Collection of samples (HC Appendix B); Supplement to All Methods in the HC Compendium: General Microbiological Guidance (HC Appendix I) General Microbiological guidance on Pre-warming of Broths in All Qualitative Methods in the [HC] Compendium (HC Supplement to Appendix I) | Contents |
| Aerobic plate count (USFDA) | Contents |
| Determination of the aerobic colony count in foods (HC MFHPB-18) | Contents |
| Enumeration of total aerobic bacteria in food products and food ingredients using 3MTM PetrifilmTM aerobic count plates (HC MFHPB-33) | Contents |
| Determination of aerobic colony count in foods by the hydrophobic grid-membrane filter (HGMF) method (HC MFLP-56) | Contents |
| Calculating the most probable number of growth units for HGMF methods (HC Appendix C) | Contents |
| Environmental sampling for the detection of microorganisms (HC MFLP-41A) | Contents |
| Environmental sampling, detection of microorganisms, preparation of sampling material (HC MFLP-41B) | Contents |
| Most probable number from serial dilutions (USFDA) | Contents |
| Calculation of the most probable number (MPN) of Growth Units for HGMF Methods (HC Appendix C) | Contents |
| Calculation of the Most Probable Number (MPN) (HC Appendix D) |
| Other APC Methods | Contents |
- Aerobic plate count in foods: Dry rehydratable film (AOAC, 1995a).
- Aerobic plate count in foods: Hydrophobic grid filter method (AOAC, 1995b).
- Aerobic plate count: Pectin gel method (AOAC, 1995c).
| Commercial Test Products | Contents |
AOAC
Research Institute Approved Performance Tested MethodsSM - Microbiology
| References | Contents |
Andrews, W.H., and June, G.A. 1998. Food sampling and preparation of sample homogenate, Ch. 1. In Food and Drug Administration Bacteriological Analytical Manual, 8th ed. (revision A), (CD-ROM version). R.L. Merker (Ed.). AOAC International, Gaithersburg, MD.
Andrews, W.H., Hammack, T.S., and Amaguana, R.M. 1998. Salmonella. Ch. 5. In Food and Drug Administration Bacteriological Analytical Manual, 8th ed. (revision A), (CD-ROM version). R.L Merker (Ed.). AOAC International, Gaithersburg, MD.
AOAC. 1990. Official Methods of Analysis of AOAC International, 15th ed. AOAC International, Gaithersburg, MD.
AOAC. 1995a. Aerobic plate count in foods: Dry rehydratable film. Sec. 17.02.07, Method 990.12. In Official Methods of Analysis of AOAC International, 16th ed., P.A. Cunniff (Ed.), 10-11. AOAC International, Gaithersburg, MD.
AOAC. 1995b. Aerobic plate count in foods: Hydrophobic grid filter method. Sec. 17.2.05, Method 986.32. In Official Methods of Analysis of AOAC International, 16th ed., P.A. Cunniff (Ed.), 8-10. AOAC International, Gaithersburg, MD.
AOAC. 1995c. Aerobic plate count: Pectin gel method. Sec. 17.02.06, Method 988.18. In Official Methods of Analysis of AOAC International, 16th ed., P.A. Cunniff (Ed.), 10. AOAC International, Gaithersburg, MD.
AOAC. 1995d. Official Methods of Analysis of AOAC International, 16th ed., P.A. Cunniff (Ed.). AOAC International, Gaithersburg, MD.
APHA. 1984. Compendium of Methods for the Microbiological Examination of Foods, 2nd ed. American Public Health Association, Washington, DC.
APHA. 1985. Laboratory Procedures for the Examination of Seawater and Shellfish, 5th ed. American Public Health Association, Washington, DC.
APHA. 1993. Standard Methods for the Examination of Dairy Products, 16th ed. American Public Health Association, Washington, DC.
Donnelly, C.B., J.E. Gilchrist, J.T. Peeler, and J.E. Campbell. 1976. Spiral plate count method for the examination of raw and pasteurized milk. Appl. Environ. Microbiol. 32:21-27.
FDA. 1978. Product code: Human foods. In EDRO Data Codes Manual. Food and Drug Administration, Rockville, MD.
FDA. 1989. Laboratory Procedures Manual. Food and Drug Administration, Rockville, MD.
FDA. 1993. Investigations Operations Manual. Food and Drug Administration, Rockville, MD.
FDA. 1996a. Raw breaded shrimp – Microbiological criteria for evaluating compliance with current good manufacturing practice regulations (CPG 7108.25). Section 540.420. Compliance Policy Guides, (August 1996 ed.), updated through October 31, 1996. Department of Health and Human Services, Public Health Service, Food and Drug Administration.
Gilchrist, J.E., Donnelly, C.B., Peeler, J.T., and Campbell, J.E. 1977. Collaborative study comparing the spiral plate and aerobic plate count methods. J. Assoc. Off. Anal. Chem. 60:807-812.
ICMSF. 1986. Microorganisms in Foods. 2. Sampling For Microbiological Analysis: Principles and Specific Applications, 2nd ed. University of Toronto Press, Buffalo, NY.
IDF. 1987. Milk and milk products: Enumeration of microorganisms—Colony count at 3ºC. Provisional IDF Standard 100A. International Dairy Federation, Brussels, Belgium.
Jarvis, B., V.H. Lach, and J.M. Wood. 1977. Evaluation of the spiral plate maker for the enumeration of microorganisms in foods. J. Appl. Bacteriol. 43:149-157.
Maturin, L.J. and Peeler, J.T. 1998. Aerobic plate count. Ch. 3. In Food and Drug Administration Bacteriological Analytical Manual, 8th ed. (revision A), (CD-ROM version). R.L. Merker (Ed.). AOAC International, Gaithersburg, MD.
NAS. 1969. An evaluation of the Salmonella problem. National Academy of Sciences, Washington, DC.
Nickelson, R. and Finne, G. 1992. Fish, crustaceans, and precooked seafoods. Ch. 47. In Compendium of Methods for the Microbiological Examination of Foods, 3rd ed., C. Vanderzant and D. F. Splittstoesser (Ed.), p. 875-895. American Public Health Association, Washington, DC.
Niemela, S. 1983. Statistical evaluation of results from the quantitative microbiological examinations. Report No. 1, 2nd ed. Nordic Committee on Food Analysis, Uppsala, Sweden.
Tomasiewicz, M.R., Hotchkiss, D.K., Reinbold, G.W., Read, R.B. Jr., and Hartman, P.A. 1980. The most suitable number of colonies on plates for counting. J. Food Protect. 43:282-286.
Zipkes, M.R., J.E. Gilchrist, and J.T. Peeler. 1981. Comparison of yeast and mold counts by spiral, pour, and streak plate methods. J. Assoc. Off. Anal. Chem. 64:1465-1469.
Send comments or questions to rjprice@ucdavis.edu
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Updated: 03/07/08 Update Log |
Pamela D. Tom,
SeafoodNIC Director Sea Grant Extension Program |
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