Processed Meats and Seafoods
109
5 reduction in the number of pathogens, especially E. coli 0157:H7, in the manufacture of dry and
semidry fermented sausages. As a result, a number of studies have been conducted on the efficacy of
domestic and commercial processing to achieve the pathogen reduction goal.
An outbreak of E. coli 0157:H7 from dry-cured salami occurred in the states of California and
Washington in 1994, and there were 23 victims.
15 Following this outbreak, a series of studies were
conducted on the conditions of pepperoni manufacture that are needed to effect a log 5 reduction in
numbers of specific pathogens. Using a 5-strain cocktail of E. coli 0157:H7 at a level of ≥ 2 × 10
7 /g,
it was found that the traditional nonthermal process destroyed only about log 2 units/g and that in
order to effect a log 5–6 reduction, postfermentation heating to an internal temperature of 63
◦ C
instantaneous or 53
◦ C for 60 minutes was necessary.
46 In a more extensive study, pepperoni sticks
were fermented at 36
◦ C and 85% relative humidity (RH) to a pH ≤4.8 and then dried at 13
◦ C and
65% RH to a moisture/protein ratio of ≤1.6:1.
29 The five-strain pathogen mixture was reduced only
about log 2 units. To achieve a log 5 reduction, storage for at least 2 weeks at ambient temperature
in air was necessary for sliced pepperoni. In another study, a >log 5 decrease in E. coli 0157:H7
could be achieved by fermentation at 41
◦ C to a pH of 4.6 or 5.0 and postfermentative heating of
summer sausage chubs to an internal temperature of 54
◦ C for 30 minutes.
12 In a similar study of
pepperoni manufacture and storage with S. Typhimurium DT104, it was found that this pathogen is
more sensitive to destruction than E. coli 0157:H7 and thus methods that will reduce the latter by log 5
are more than adequate for the former.
52 The fate of S. aureus in country-cured hams was investigated
by the spraying of fresh hams with four strains at levels of log 10 8.57 and log 10 8.12 followed by
curing, cold smoking, and aging. After 4 months of aging, S. aureus was below detectable levels by
plating, although some cells were recovered by enrichment.
74 Sodium nitrite was employed in some
cures and a w was controlled with 4.45 or 3.37% NaCl. Forty percent of the inoculated and 50% of
controls contained enterotoxin following the aging period.
SEAFOODS
Fish and Shellfish
As used in this chapter, the term seafood covers fish, shellfish, and mollusks from all waters–fresh,
marine, warm, or cold. In general, the biota of a fresh seafood animal is reflective of the waters from
which it is taken. As is the case for meat animals, the inner tissues of a healthy fish are sterile. With
fish, the microbial biota is found generally in three places: the outer slime, gills, and the intestines
of feeding fish. Fresh or warm-water fish tend to have a biota that is composed of more mesophilic
Gram-positive bacteria than cold-water fish, which tends to be largely Gram negative (the indigenous
bacterial biota of marine water is Gram negative).
The organisms that make up the biota of seafoods are listed in Table 5–5, and what is known about
their interplay in bringing about the spoilage of these products is discussed in the section on spoilage
of fish and shellfish.
Microorganisms
As noted above, the overall sanitary quality of the waters from which these animals are taken is key
to the overall microbial quality of finished products. Beyond the water source, microbes are picked up
at various processing steps such as peeling, shucking, evisceration, breading, and the like.
109
5 reduction in the number of pathogens, especially E. coli 0157:H7, in the manufacture of dry and
semidry fermented sausages. As a result, a number of studies have been conducted on the efficacy of
domestic and commercial processing to achieve the pathogen reduction goal.
An outbreak of E. coli 0157:H7 from dry-cured salami occurred in the states of California and
Washington in 1994, and there were 23 victims.
15 Following this outbreak, a series of studies were
conducted on the conditions of pepperoni manufacture that are needed to effect a log 5 reduction in
numbers of specific pathogens. Using a 5-strain cocktail of E. coli 0157:H7 at a level of ≥ 2 × 10
7 /g,
it was found that the traditional nonthermal process destroyed only about log 2 units/g and that in
order to effect a log 5–6 reduction, postfermentation heating to an internal temperature of 63
◦ C
instantaneous or 53
◦ C for 60 minutes was necessary.
46 In a more extensive study, pepperoni sticks
were fermented at 36
◦ C and 85% relative humidity (RH) to a pH ≤4.8 and then dried at 13
◦ C and
65% RH to a moisture/protein ratio of ≤1.6:1.
29 The five-strain pathogen mixture was reduced only
about log 2 units. To achieve a log 5 reduction, storage for at least 2 weeks at ambient temperature
in air was necessary for sliced pepperoni. In another study, a >log 5 decrease in E. coli 0157:H7
could be achieved by fermentation at 41
◦ C to a pH of 4.6 or 5.0 and postfermentative heating of
summer sausage chubs to an internal temperature of 54
◦ C for 30 minutes.
12 In a similar study of
pepperoni manufacture and storage with S. Typhimurium DT104, it was found that this pathogen is
more sensitive to destruction than E. coli 0157:H7 and thus methods that will reduce the latter by log 5
are more than adequate for the former.
52 The fate of S. aureus in country-cured hams was investigated
by the spraying of fresh hams with four strains at levels of log 10 8.57 and log 10 8.12 followed by
curing, cold smoking, and aging. After 4 months of aging, S. aureus was below detectable levels by
plating, although some cells were recovered by enrichment.
74 Sodium nitrite was employed in some
cures and a w was controlled with 4.45 or 3.37% NaCl. Forty percent of the inoculated and 50% of
controls contained enterotoxin following the aging period.
SEAFOODS
Fish and Shellfish
As used in this chapter, the term seafood covers fish, shellfish, and mollusks from all waters–fresh,
marine, warm, or cold. In general, the biota of a fresh seafood animal is reflective of the waters from
which it is taken. As is the case for meat animals, the inner tissues of a healthy fish are sterile. With
fish, the microbial biota is found generally in three places: the outer slime, gills, and the intestines
of feeding fish. Fresh or warm-water fish tend to have a biota that is composed of more mesophilic
Gram-positive bacteria than cold-water fish, which tends to be largely Gram negative (the indigenous
bacterial biota of marine water is Gram negative).
The organisms that make up the biota of seafoods are listed in Table 5–5, and what is known about
their interplay in bringing about the spoilage of these products is discussed in the section on spoilage
of fish and shellfish.
Microorganisms
As noted above, the overall sanitary quality of the waters from which these animals are taken is key
to the overall microbial quality of finished products. Beyond the water source, microbes are picked up
at various processing steps such as peeling, shucking, evisceration, breading, and the like.