Chapter 6: Refrigerated Fish and Fishery Products

• Potential Food Safety Hazard
• Control Measures
• FDA Guidelines
• Labeling Guidelines
• Temperature Measurement
• Thermometers
• Temperature recorders
• Suppliers of temperature measurement equipment
• Thermometer calibration
• Time-Temperature measurement monitoring tags
• References

Pathogens can enter the process on raw materials. They can also be introduced into foods during processing from the air, unclean hands, insanitary utensils and equipment, unsafe water, and sewage, and through cross contamination between raw and cooked product. (FDA, 2001)

• Managing the amount of time that food is exposed to temperatures that are favorable for pathogen growth and toxin production;
• Killing pathogens by cooking, pasteurizing, or retorting;
• Controlling the amount of moisture that is available for pathogen growth, water activity, in the product by drying;
• Controlling the amount of moisture that is available for pathogen growth, water activity, in the product by formulation;
• Controlling the amount of salt or preservatives, such as sodium nitrite, in the product;
• Controlling the level of acidity, pH, in the product.

Note: The use of irradiation for fish or fishery products has not been approved by FDA. Irradiated fish and fishery products may not be distributed in the U.S. (FDA, 2001).

The time/temperature combinations that will ensure safety in your product are dependent upon a number of factors, including:

• The types of pathogens that are expected to be present and able to grow in your product. See information contained in Step #11.
• The infective or toxic dose of these pathogens or their toxins. The infective or toxic dose is the total number of a pathogen, or the total amount of a toxin, that is necessary to produce human illness. The dose often varies considerably for a single pathogen based on the health of the consumer and the virulence (infective capability) of the particular strain of the pathogen.

For many of the pathogens listed in Table A-1 the infective dose is known or suspected to be very low (from one to several hundred organisms). These include: Campylobacter jejuni, Escherichia coli, Salmonella spp., Shigella spp., and Yersinia enterocolitica. The infective dose for other pathogens, such as Vibrio vulnificus, Vibrio parahaemolyticus and Listeria monocytogenes is not known. In the case of both of these categories of pathogens it is advisable to prevent any significant growth. Stated another way, product temperatures should be maintained below the minimum growth temperature for the pathogen or should not be allowed to exceed that temperature for longer than the lag growth phase (i.e the slow growth phase during which pathogens are acclimating to their environment) of the pathogen at those temperatures.

Still other pathogens (e.g. Vibrio cholerae) require large numbers in order to cause disease or require large numbers in order to produce toxin (e.g. Staphylococcus aureus, Clostridium perfringens, Bacillus cereus). The infective dose of Vibrio cholerae is suspected to be 1,000,000 total cells. S. aureus toxin does not normally reach levels that will cause food poisoning until the numbers of the pathogen reach 100,000 to 1,000,000/gram. Clostridium perfringens does not produce toxin in the human gut unless at least 100,000,000 total bacteria are consumed. Limited growth of these pathogens may not compromise the safety of the product. However, time/temperature controls must be adequate to prevent growth before the stage of the infective or toxic dose is reached. For example, the prudent processor will design controls to ensure that the numbers of S. aureus do not exceed 10,000/gram.

• The numbers of these pathogens that are likely to be present. This is highly dependent upon the quality of the harvest water, how the raw material was handled before it was delivered to your plant, and the effectiveness of your sanitation control program. As a practical matter, the initial number of pathogens is of limited importance when you calculate critical limits for pathogens that have a low infective dose. Therefore, you will be designing a critical limit that prevents any significant growth.

On the other hand, for those pathogens that have a relatively high infective dose, the initial number of pathogens may be significant (FDA, 2001).

• All shellstock (in-shell molluscan shellfish) containers must bear a tag that discloses the date and place they were harvested (by State and site), type and quantity of shellfish, and by whom they were harvested (i.e., the identification number assigned to the harvester by the Shellfish Control Authority, where applicable or, if such identification numbers are not assigned, the name of the harvester or the name or registration number of the harvester's vessel). For bulk shipments of shellstock, where the shellstock is not containerized, accept shellstock only if it is accompanied by a bill of lading or other similar shipping document that contains the same information;

• All molluscan shellfish must have been harvested from waters authorized for harvesting by a Shellfish Control Authority. For U.S. Federal waters, no molluscan shellfish may be harvested from waters that are closed to harvesting by an agency of the federal government;

• All containers of shucked molluscan shellfish must bear a label that identifies the name, address, and certification number of the packer or repacker of the product;

• All molluscan shellfish must be from a harvester that is licensed as required (note that licensing may not be required in all jurisdictions) or from a processor that is certified by a Shellfish Control Authority.

• The following criteria is met for the maximum time from harvest to refrigeration: (Note: Average Monthly Maximum Air Temperature (AMMAT) is determined by the Shellfish Control Authority)

• For AMMAT of less than 66°F (less than 19°C): 36 hours;
• For AMMAT of 66 to 80°F (19 to 27°C): 24 hours;
• For AMMAT of greater than 80°F (greater than 27°C): 20 hours.

• All finished product shellstock intended for raw consumption must bear a tag that instructs retailers to inform their customers that consuming raw or undercooked shellfish may increase the risk of foodborne illness, especially for individuals with certain medical conditions (FDA, 2001).

Processing

• If the product is held at internal temperatures above 70°F (21.1°C) during processing, exposure time should ordinarily be limited to two hours (three hours if Staphylococcus aureus is the only pathogen of concern);

• If the product is held at internal temperatures above 50°F (10°C), but not above 70°F (21.1°C), exposure time should ordinarily be limited to six hours (twelve hours if Staphylococcus aureus is the only pathogen of concern);

• If the product is held at internal temperatures both above and below 70°F (21.1°C), exposure times above 50°F (10°C) should ordinarily be limited to 4 hours, as long as no more than 2 of those hours are above 70°F (21.1°C) (FDA, 2001).

Cooling after cooking

• If cooling after cooking is a critical control point (e.g., because of the potential for Clostridium perfringens or Bacillus cereus growth or toxin formation, the product should generally be cooled from 140°F (60°C) to 70°F (21.1°C) or below within two hours and to 40°F (4.4°C) or below within another four hours. The cooling rate critical limit is separate from the cumulative time/temperature critical limit (FDA, 2001).

Storage

• A maximum storage temperature of 40°F (4.4°C) is generally safe for most refrigerated, microbiologically sensitive products. 

• Where refrigeration is necessary to control the growth of nonproteolytic Clostridium botulinum, a maximum storage temperature of 38°F (3.3°C) is usually appropriate (FDA, 2001).

Group A foods

The appropriate label statement for Group A foods is:

 Group B foods

The appropriate label statement for Group B foods is:

Group C foods

The suggested optional label statement for Group C foods is:

or some other statement that explains to the consumer that the storage conditions are recommended to protect the quality of the product. To avoid confusion between refrigeration for safety purposes and refrigeration for quality reasons, Group A and Group B statements should not be used on Group C foods (FDA, 1997d).

Liquid-in-glass thermometer

Some liquid-in glass thermometers are NIST certified thermometers or thermometers calibrated to NIST-traceable standards.

Electrical resistance thermometer

Thermistor thermometer

Thermocouple thermometer

Radiometer thermometer

Bimetallic thermometer

Graphic recorders

Data loggers

Data logger systems are available with computer-generated call up services, either via e-mail, FAX, computer-generated voice messages or digital pager messages. When the data input shows a discrepancy from a normal or expected condition, the computer generates the telephone-based message to key personnel. The message type (FAX, voice, e-mail or pager) and destination telephone number are pre-determined by the user depending upon the location and type of discrepancy (Cox, 1999).

Cox Technologies
69 McAdenville Road
Belmont, NC 28012
Phone: 704-825-8146
Fax: 704-825-5128
Web: http://www.cx-en.com/cox.htm

Fisher Scientific
Pittsburgh, PA
Phone: 800-766-7000
Fax: 800-926-1166
Web: http://www.fishersci.com

The Foxboro Company
Phone: 888-369-2676
Web: http://www.foxboro.com/index1.htm

Hantover
700 Karnes Blvd.
Kansas City, MO 64108
Phone: 800-821-2227
Fax: 816-931-3272
Web: http://www.hantover.com/home.html

Taylor Precision Products, L.P.
2311 West 22nd Street
Oak Brook, IL 60523
Phone: 630-954-1250
Fax: 630-954-1275
Web: http://www.taylor-enviro.com/

Weber Scientific
2732 Kuser Road
Hamilton, NJ 08691
Phone:800-328-8378
Fax: 609-584-8388
Web: http://www.weberscientific.com

Anonymous. "Thermometers" EarthLab Digital Library, Ross Computational Resources, http://earthlab.meteor.wisc.edu/~grb/leveltxt/advanced/wxinst/thermom.htm (26 May 1999).

Cox. 1999. "What is RealTimeAlert™?" Cox Technologies, Belmont, NC. http://cx-en.com/RealTimeAlert.htm (27 May, 1999).

FDA. 1997. Guidance on labeling of foods that need refrigeration by consumers. Department of Health and Human Services, Public Health Service, Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Seafood, Washington, DC. Federal Register: February 24, 1997. 62(36):8248-8252.

FDA. 2001. Pathogen growth & toxin formation (other than Clostridium botulinum) as a result of time/temperature abuse. Ch. 12. In Fish and Fishery Products Hazards and Controls Guidance, 3^rd ed., p. 145-166. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Seafood, Washington, DC.

ISSC. 1997. Guide for the control of molluscan shellfish, 1997 Revision. Interstate Shellfish Sanitation Conference, U.S. Department of Health and Human Services, Public Health Service, Food and Drug Administration, Washington, DC.

Rippen, T.E. 1998. Personal communication. University of Maryland, Princess Anne, MD.

Ruscher, P. and Lusher, R. 1999. "Thermometers" http://www.met.fsu.edu/explores/thermometera.html (26 May 1999).

Ward, D., Bernard, D., Collette, R., Kraemer, D., Hart, K., Price, R., and Otwell, S. (Eds.) 1997. Hazards found in seafoods, Appendix III. In HACCP: Hazard Analysis and Critical Control Point Training Curriculum, 2^nd ed. p. 173-188. UNC-SG-96-02. North Carolina Sea Grant, Raleigh, NC.