Processed Meats and Seafoods
103
Semidry sausages have a final pH around 4.7–5.0, and refrigeration is required. The final pH of dry
sausages is about the same as that for semidry but these products are shelf stable because of their lower
moisture content. The relative safety of these products is discussed below.
The common cured bacon in the United States is either dry or pickle cured, with the latter being
the more common. Following cure, it may be smoked. Canadian bacon is characterized by being quite
lean, since it comes from the large muscle of pork loins. Wiltshire bacon is prepared from the sides of
selected hogs, followed by pumping of cure ingredients and subsequent storage in pickle brines.
Most hams in commerce are of the pickle-cure variety and they are cured following injection of
the pickle cure by artery pumping, single-needle stitch, or multiple-needle stitch. For dry-cured or
country-cured hams, the dry curing salts are applied by rubbing followed by storage at refrigerator
temperatures for 28 to 50 days, depending on size and thickness.
All curing ingredients may be expected to contain microorganisms, and care should be taken to
ensure that undesirable ones are not introduced to products during ingredient application.
Smoking
This process is applied to many cured meats, and the primary purposes of smoking meat are (1) development of aroma and flavor, (2) preservation, (3) creation of new products, (4) development of color,
(5) formation of a protective skin on emulsion-type sausages, and (6) protection from oxidation.
73
Smoke, whether directly from wood or in liquid form, contains phenols, alcohol, organic acids, carbonyls, hydrocarbons, and gases. The antimicrobial properties of smoking result from the activities
of some of the smoke ingredients and the heat that is associated with wood smoking. Liquid smoke
contains all of the essential ingredients of wood smoke, but it is free of the carcinogen benzopyrene.
SAUSAGE, BACON, BOLOGNA, AND RELATED PRODUCTS
In addition to the meat components, sausages and frankfurters have additional sources of organisms
in the seasoning and formulation ingredients that are usually added in their production. Many spices
and condiments have high microbial counts. The lactic acid bacteria and yeasts in some composition
products are usually contributed by milk solids. In the case of pork sausage, natural casings have been
shown to contain large numbers of bacteria. In their study of salt-packaged casings, Riha and Solberg
76
found counts to range from log 10 4.48 to log 10 7.77 cfu/g and from log 10 5.26 to log 10 7.36 cfu/g for
wet-packaged casings. Over 60% of the isolates from these natural casings consisted of Bacillus spp.,
followed by clostridia and pseudomonads. Of the individual ingredients of fresh pork sausage, casings
have been shown to contribute the largest number of bacteria.
76,88
Processed meats such as bologna and salami may be expected to reflect the sum of their ingredient
makeup with regard to microbial numbers and types. The biota of frankfurters has been shown to consist
largely of Gram-positive organisms with micrococci, bacilli, lactobacilli, microbacteria, enterococci,
and leuconostocs along with yeast.
24 In a study of slime from frankfurters, these investigators found that
275 of 353 isolates were bacteria, and 78 were yeast. B. thermosphacta was the most conspicuous single
isolate. With regard to the incidence of C. botulinum spores in liver sausage, 3 of 276 heated (75
◦ C
for 20 minutes) and 2 of 276 unheated commercial preparations contained type A botulinal toxin.
43
The most probable number (MPN) of botulinal spores in this product was estimated to be 0.15/kg.
Wiltshire bacon has been reported to have a total count generally in the range of log 10 5–6/g,
53
whereas high-salt vacuum-packaged bacon has been reported to have a generally lower count—about
103
Semidry sausages have a final pH around 4.7–5.0, and refrigeration is required. The final pH of dry
sausages is about the same as that for semidry but these products are shelf stable because of their lower
moisture content. The relative safety of these products is discussed below.
The common cured bacon in the United States is either dry or pickle cured, with the latter being
the more common. Following cure, it may be smoked. Canadian bacon is characterized by being quite
lean, since it comes from the large muscle of pork loins. Wiltshire bacon is prepared from the sides of
selected hogs, followed by pumping of cure ingredients and subsequent storage in pickle brines.
Most hams in commerce are of the pickle-cure variety and they are cured following injection of
the pickle cure by artery pumping, single-needle stitch, or multiple-needle stitch. For dry-cured or
country-cured hams, the dry curing salts are applied by rubbing followed by storage at refrigerator
temperatures for 28 to 50 days, depending on size and thickness.
All curing ingredients may be expected to contain microorganisms, and care should be taken to
ensure that undesirable ones are not introduced to products during ingredient application.
Smoking
This process is applied to many cured meats, and the primary purposes of smoking meat are (1) development of aroma and flavor, (2) preservation, (3) creation of new products, (4) development of color,
(5) formation of a protective skin on emulsion-type sausages, and (6) protection from oxidation.
73
Smoke, whether directly from wood or in liquid form, contains phenols, alcohol, organic acids, carbonyls, hydrocarbons, and gases. The antimicrobial properties of smoking result from the activities
of some of the smoke ingredients and the heat that is associated with wood smoking. Liquid smoke
contains all of the essential ingredients of wood smoke, but it is free of the carcinogen benzopyrene.
SAUSAGE, BACON, BOLOGNA, AND RELATED PRODUCTS
In addition to the meat components, sausages and frankfurters have additional sources of organisms
in the seasoning and formulation ingredients that are usually added in their production. Many spices
and condiments have high microbial counts. The lactic acid bacteria and yeasts in some composition
products are usually contributed by milk solids. In the case of pork sausage, natural casings have been
shown to contain large numbers of bacteria. In their study of salt-packaged casings, Riha and Solberg
76
found counts to range from log 10 4.48 to log 10 7.77 cfu/g and from log 10 5.26 to log 10 7.36 cfu/g for
wet-packaged casings. Over 60% of the isolates from these natural casings consisted of Bacillus spp.,
followed by clostridia and pseudomonads. Of the individual ingredients of fresh pork sausage, casings
have been shown to contribute the largest number of bacteria.
76,88
Processed meats such as bologna and salami may be expected to reflect the sum of their ingredient
makeup with regard to microbial numbers and types. The biota of frankfurters has been shown to consist
largely of Gram-positive organisms with micrococci, bacilli, lactobacilli, microbacteria, enterococci,
and leuconostocs along with yeast.
24 In a study of slime from frankfurters, these investigators found that
275 of 353 isolates were bacteria, and 78 were yeast. B. thermosphacta was the most conspicuous single
isolate. With regard to the incidence of C. botulinum spores in liver sausage, 3 of 276 heated (75
◦ C
for 20 minutes) and 2 of 276 unheated commercial preparations contained type A botulinal toxin.
43
The most probable number (MPN) of botulinal spores in this product was estimated to be 0.15/kg.
Wiltshire bacon has been reported to have a total count generally in the range of log 10 5–6/g,
53
whereas high-salt vacuum-packaged bacon has been reported to have a generally lower count—about