Chapter 5: Pasteurized Fish and Fishery Products

• Potential Food Safety Hazard
• Control Measures
• Guidelines
• FDA Guidelines
• State Guidelines
• South Carolina: Blue crab (Callinectes sapidus)
• Texas: Blue crab (Callinectes sapidus)
• ECFF Guidelines
• Process Establishment
• Critical Aspects of Processes
• Analytical Procedures
• Thermometer calibration
• Microscopic examination of foods and care and use of the microscope (USFDA)
• Examination of canned foods (USFDA)
• Modification of headspace gas analysis methodology, using the SP4270 integrator (USFDA)
• Examination of metal containers for integrity (USFDA)
• Examination of glass containers for integrity (USFDA)
• Examination of flexible and semirigid food containers for integrity (USFDA)
• Examination of containers for integrity: Glossary and references (USFDA)
• Determination of commercial sterility and the presence of viable microorganisms in canned foods (HC)
• Other analytical procedures
• Pasteurizing Processes
• Blue Crab
• Caviar
• Dungeness crab
• Smoked salmon
• Surimi-based imitation crabmeat
• References

Selection of the target pathogen is critical. If a target pathogen other than C. botulinum type E and nonproteolytic types B and F is selected, you must consider the potential that C. botulinum type E or nonproteolytic types B and F will survive the pasteurization process and grow under normal storage conditions or moderate abuse conditions. Ordinarily, the potential exists if the product is reduced oxygen packaged (e.g. vacuum packaged, modified atmosphere packaged), does not contain other barriers that are sufficient to prevent growth and toxin formation by this pathogen, and is stored or distributed refrigerated (not frozen). For example, vacuum packaged lobster meat that is pasteurized to kill L. monocytogenes but not C. botulinum type E or nonproteolytic types B and F must be frozen to prevent growth and toxin formation by C. botulinum type E and nonproteolytic types B and F. Surveys of retail display cases and home refrigerators indicate that temperatures above the minimum growth temperature of C. botulinum type E and nonproteolytic types B and F (38°F [3.3°C]) are not uncommon. Therefore, refrigeration alone cannot be relied upon for control of the C. botulinum hazard.

For pasteurization processes that target nonproteolytic C. botulinum, generally a reduction of six orders of magnitude (six logarithms, e.g. from 10³ to 10^-3) in the level of contamination is suitable. This is called a "6D" process. However, lower degrees of destruction may be acceptable if supported by a scientific study of the normal inoculums in the food. It is also possible that higher levels of destruction may be necessary in some foods, if there is an especially high normal inoculums. Table A-4 provides 6D process times for a range of cooking temperatures, with C. botulinum type B (the most heat resistant form of nonproteolytic C. botulinum) as the target pathogen. The lethal rates and process times provided in the table may not be sufficient for the destruction of nonproteolytic C. botulinum in Dungeness crabmeat, because of the potential that naturally occurring substances, such as lysozyme, may enable the pathogen to more easily recover after heat damage.

Examples of properly pasteurized products are: blue crabmeat pasteurized to a cumulative lethality of F_185°F (F_85°C) = 31 min., z=16°F (9°C); surimi-based products pasteurized at an internal temperature of 194°F (90°C) for at least 10 minutes.

In some pasteurized surimi-based products, salt in combination with a milder pasteurization process in the finished product container work to prevent growth and toxin formation by C. botulinum type E and nonproteolytic types B and F. An example of a properly pasteurized surimi-based product in which 2.5% salt is present is one that has been pasteurized at an internal temperature of 185°F (85°C) for at least 15 minutes. This process may not be suitable for other types of products, because of the unique formulation and processing involved in the manufacture of surimi-based products.

Reduced oxygen packaged foods that are pasteurized to control nonproteolytic C. botulinum, but not proteolytic C. botulinum, and that do not contain barriers to its growth, must be refrigerated or frozen to control proteolytic C. botulinum. Control of refrigeration is critical to the safety of these products. Further information on C. botulinum and reduced oxygen packaging is contained in Chapter 13.

In cases where Listeria monocytogenes is selected, a 6D process is also generally suitable. FDA's draft L. monocytogenes risk assessment indicates that approximately 7% of raw fish are contaminated with from 1 to 10³ CFU/g, and that approximately 92% are contaminated at less than 1 CFU/g. Less than 1% of raw fish are contaminated at levels greater than 10³ CFU/g, and none at levels greater than 10⁶ CFU/g. FDA's action level for L. monocytogenes in ready-to-eat products, nondetectable, corresponds to a level of less than 1 CFU/25g. Table #A-3 provides 6D process times for a range of pasteurization temperatures, with L. monocytogenes as the target pathogen.

Lower degrees of destruction may be acceptable if supported by a scientific study of the normal inoculums in the food. It is also possible that higher levels of destruction may be necessary in some foods, if there is an especially high normal inoculums.

Products that are pasteurized in the finished product container are at risk for recontamination after pasteurization. Controls, such as container seal integrity and protection from contamination by cooling water, are critical to the safety of these products (FDA, 2001).

Note: D-values and F-values are discussed in chapter 3.

• Defective container closures;
• Contaminated container cooling water;
• Recontamination between cooking and reduced oxygen packaging.

Poorly formed or defective container closures can increase the risk of pathogens entering the container, especially during container cooling performed in a water bath. Contaminated cooling water can enter through the container closure, especially when the closure is defective. Container closure can be controlled by adherence to seal guidelines that are provided by the container or sealing machine manufacturer. Control is accomplished through periodic seal inspection.

Contamination of cooling water can be controlled by ensuring that a measurable residual of chlorine, or other approved water treatment chemical, is present in the cooling water, or by ensuring that ultraviolet (UV) treatment systems are operating properly.

Recontamination between cooking and reduced oxygen packaging in continuous filling systems where the product is packaged directly from the kettle can be controlled by hot filling at temperatures at or above 185°F (85°C). FDA is interested in information on the value of adding a time component (e.g. 3 minutes) to this hot filling temperature recommendation, to provide limited lethality for any nonproteolytic C. botulinum spores present on the packaging material.

It may also be prudent to use packaging that has been manufactured or treated to inactivate spores of C. botulinum type E and nonproteolytic types B and F (e.g. gamma irradiation, hot extrusion). FDA is interested in comment on the utility of such measures (FDA, 2001)

• by a minimum heat process and strict limitation of chill shelf life or, for longer life products, by storage below 3°C,
• by heat treatment sufficient to deliver a 6 log reduction in numbers of spores of psychrotrophic strains of C. botulinum and storage below 10°C, or
• by intrinsic preservation factors shown to be effective in modeling or inoculated pack/challenge tests.

Because of the variability inherent in water bath pasteurization systems, process establishment studies are usually performed initially for each container size and shape, and when equipment or procedures are modified. Generally, a process authority will compare these results to published heat sensitivity values for C. botulinum and other relevant pathogens when setting minimum process schedules. If conditions change in the design or operation of the equipment, or if another product container is selected, verification studies must be performed.

Process authorities commonly establish minimum pasteurization processes by generating heating profiles at the slowest heating point (cold point) of the product. Monitored containers are positioned throughout the pasteurization tank/chamber. Specialized instrumentation is required for this. These heating profiles are then used to determine process lethality, or the calculated effect of all heat exposure on a target microorganism. Commonly, this is achieved by determining an F-value for the slowest heating container in the system (Hackney et al., 1991; Rippen, 1998).

Note: Heat Exposure Calculations are discussed in Chapter 3.

• Length of the pasteurization cycle (speed of the belt for a continuous pasteurizer);
• Temperature of the water bath;
• Water bath circulation;
• Product initial temperature (I.T.);
• Container size (e.g., can dimensions, pouch thickness);
• Product formulation;
• Container integrity;
• Microbial quality of cooling water;
• Accuracy of thermometers, recorder thermometer charts, high temperature alarms, maximum indicating thermometers, and/or digital data loggers; and
• Accuracy of other monitoring and timing instruments

• Evaluating can double seams (FPI, 1989)
• Flexible package integrity (NFPA, 1989)
• Container evaluation (Gavin and Weddig, 1995)
• Performance of food cans (Hotchner, 1995)
• Guidelines for evaluation and disposition of damaged canned food containers (NFPA, 1998)

Cook crabs for 10 min at 121.1ºC (250ºF) (15 psi, 103.4 kPa) Cool in the retort basket using air circulation or mechanical refrigeration. Refrigerate crab at temperatures below 4.4ºC (40ºF) if delays between cooking and picking occur. Pick crabmeat into 401 flat cans and seal the containers. The crabmeat should be about 26.7-18.3ºC (60-65ºF) when the containers are sealed. Pasteurize within 24 h following picking. Pasteurize containers of crab in a water bath until the geometric center of the containers reach at least 85ºC (185ºF) for at least 1 min. Process 401 flat cans in an 87.8-88.9ºC (190-192ºF) water bath for 110-115 min to give a min. Cool containers in an ice bath at a temperature below 7.2ºC (45ºF) until the temperature of the containers reaches 37.8ºC (100ºF) (about 45 min). Transfer containers to dry storage at 0-2.2ºC (32-36ºF) (Tatro, 1970; Rippen and Hackney, 1992).

Blue crab (Callinectes sapidus) II

Cook crabs as soon as possible after they are delivered to the plant. Refrigerate crabs not cooked within about 2-4 h after delivery at 4.4-10ºC (40-50ºF). Cool crabs in the same container in which they were cooked. If crabs are not picked within about 8 h after cooking, refrigerate them at 4.4ºC (40ºF) or below. Pasteurize within 36 h after picking. Pasteurize to achieve a thermal process of of at least 31 min (Table 5-14). Chill containers to about 12.8ºC (55ºF) or below within 180 min after pasteurization. Cool the containers further to reach 3.3ºC (38ºF) or colder within about 18 h (Rippen et al., 1993).

Table 5-14. F-values achieved for pasteurized blue crab¹.

Heating Time (min)	(min)	Heating Time (min)	(min)
90	5.0	125	35.6
95	6.8	127.5	40.7
100	9.7	130	43.6
105	13.4	132.5	46.5
110	17.3	135	49.4
112.5	21.0	137.5	52.0
115	23.4	140	55.1
117.5	26.8	142.5	58.0
120	30.2	145	60.9
122.5	32.7

Cook crabs within 1-2 h after receipt or refrigerate at 7.2-10ºC (45-50ºF). Cook crabs under steam pressure of 15 psig (103.4 kPa) (121.1ºC [250ºF]) for 10 min until the internal temperature of the centermost crab reaches 115.6ºC (240ºF). Air cool crabs to room temperature in the same container in which they were cooked. If not picked within 12 h, refrigerate crabs at 1.7-4.4ºC (35-40ºF). Pick crabmeat into 401 flat cans and seal within 1 h after picking. Pasteurize in a water bath at 87.8-88.9ºC (190-192ºF) for 110-115 min (an internal temperature of 85ºC (185ºF) for 3 min). Cool containers in ice water to an internal can temperature of 32.2ºC (90ºF) (45 min). Transfer to dry storage at 3.3ºC (38ºF) or below (Duersch et al., 1981).

Split open sturgeon belly and remove roe. Rub roe through a metal sieve that has a mesh large enough to permit the eggs to pass through without breaking, but will retain membranes. Mix eggs with salt and place in a sieve as soon as the salt is dissolved. Pack immediately into 9 ounce (255 ml) enameled cans. Process cans for 90 min at 60-65 °C (140-149 °F). Cool for 5 min to 20-30 °C (68-86 °F) with a water spray. Hold for 24 h at 24 °C (73 °F). Repeat pasteurization for a second and third time. Wash and dry cans. Store at 10 °C (50 °F) or less (Jarvis, 1987).

Process Temp.		Process Time (min)	D value	(min)
(ºF)	(ºC)
192	88.9	90	12.9	247
193	89.4	77.6	11.1
194	90.0	66.8	9.5
195	90.6	57.6	8.2	243
196	91.1	49.6	7.1
197	91.7	42.8	6.1
198	92.2	36.9	5.3	240
199	92.8	31.8	4.5
200	93.3	27.4	3.9
201	93.9	23.6	3.4
202	94.4	20.3	2.9	235

Packages of smoked salmon were precooled to a uniform internal temperature of 1.1ºC (34ºF) in slush ice. Products were pasteurized in water baths. Pasteurization processes include "come-up" time and are given in Table 5-16. All processes prevented toxin formation by types B and E.

During cooling in slush ice following pasteurization, product internal temperatures dropped below 71.1ºC (160ºF) within 3 min and below 25ºC (77ºF) within 11 min (Eklund, et al., 1988; Pelroy et al., 1982).

Table 5-16. Pasteurization processes for vacuum packaged smoked salmon (Eklund et al., 1988).

Surimi-based imitation flaked crabmeat

Flaked artificial crab was vacuum-packed into 907 g (2 pound) packages and pasteurized for 25 min in a 91ºC (195.8ºF) water bath to achieve an internal temperature of 81-85ºC (177.8-185ºF) for at least 5 min (Hollingworth et al., 1990).

Surimi-based imitation crab meat

AOAC. 1990. Official Methods of Analysis, 15^th ed. Association of Official Analytical Chemists, Arlington, VA.

Duersch, J.W., Paparella, M.W., and Cockey, R.P. 1981. Processing recommendations for pasteurizing meat from the blue crab. Publication UM-SG-MAP-81-02, Marine Products Laboratory, Center for Environmental and Estuarine Studies, University of Maryland, Crisfield, MD.

ECFF. 1999. European Chilled Food Federation Guidelines. Appendix C. Lethal rates for psychrotrophic Clostridium botulinum Type B. (6/8/01).

Eklund, M.W., Peterson, M.E., Paranjpye, R., and Pelroy, G.A. 1988. Feasibility of a heat-pasteurization process for the inactivation of nonproteolytic Clostridium botulinum types B and E in vacuum-packaged, hot-process (smoked) fish. J. Food Protect. 51(9):720-726.

FDA. 1998a. Pathogen growth & toxin formation as a result of inadequate drying. Ch. 14. In Fish and Fishery Products Hazards and Controls Guide, 2^nd ed., p. 175-182. 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.

FDA. 1998b. Pathogen survival through pasteurization. Ch. 17. In Fish and Fishery Products Hazards and Controls Guide, 2^nd ed., p. 197-204. 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.

FDA. 1998c. Introduction of pathogens after pasteurization. Ch. 18. In Fish and Fishery Products Hazards and Controls Guide, 2^nd ed., p. 205-212. 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.

FDA. 2001. Pathogen survival through pasteurization. Ch. 17. In Fish and Fishery Products Hazards and Controls Guidance, 3^rd ed., p. 219-226. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Seafood, Washington, DC.