Fresh Meats and Poultry
91
supports the growth of the poultry spoilage biota better than even the muscle tissue. In the advanced
stages of poultry spoilage, the surfaces will often fluoresce when illuminated with ultraviolet light
because of the presence of large numbers of fluorescent pseudomonads. Surface spoilage organisms
can be recovered directly from the slime for plating, or one can prepare slides for viewing by smearing
with portions of slime. Upon Gram staining, one may note the uniform appearance of organisms
indistinguishable from those listed. Tetrazolium (2,3,5-triphenyltetrazolium chloride) can be used
also to assess microbial activity on poultry surfaces. When an eviscerated carcass is sprayed with this
compound, a red pigment develops in areas of high microbial activity. These areas generally consist
of cut muscle surfaces and other damaged areas such as feather follicles.
140 When the skin is removed
from a fresh chicken carcass, leg muscles are more likely to spoil faster than breast muscles since the
pH of the former is typically in the pH range of 6.3–6.6 while the latter is lower, i.e., 5.7–5.9.
Pseudomonads are favored at the lowest growth temperature. When poultry was spoiled at 1
◦ C,
these organisms dominated while at 10
◦ C and 15
◦ C, enteric and other bacteria became significant.
12
More information on poultry spoilage can be found in reference 28. The spoilage of poultry and other
meats under vacuum and modified atmosphere packaging is covered in Chapter 14.
CARCASS SANITIZING/WASHING
Just prior to slaughter, the outer surfaces of meat animals are laden with dust, dirt, and fecal matter.
It is inevitable that some of the microorganisms from these sources will be found on the carcasses of
slaughtered animals, and although most are nonpathogens, pathogens may be present. In an effort to
reduce the number and types of pathogens on dressed carcasses and finished products, a number of
methods have emerged:
1. Trimming—the excising of skin or outer tissue
2. Washing—the use of plain water at varying temperatures and hose pressures
3. Organic acids—the addition to wash water of acetic, citric, or lactic acid at concentrations of 2%
to 5%
4. Other chemicals—the addition to wash water of hydrogen peroxide, chlorine dioxide, or
chlorhexidine
5. Steam vacuum treatments—the application of steam for 5 to 10 seconds at 80
◦ C or higher as the
final carcass preparation step
6. Combinations—the use of two or more of the above
In the USDA’s pathogen reduction program for beef carcasses, 1 out of every 300 carcasses is to
be examined by sponging 100-cm
2 sections from three carcass areas (rump, flank, and brisket) for E.
coli, which should be <5 cfu/cm
2 .
175 The sponging method is one of six that were compared for beef
carcasses.
37
Overall, a large number of studies have been conducted on most of the methods noted above for
removing microorganisms from slaughter carcasses, and reduction of APCs on the order of 1 to 3 log
cycles is common. Many studies have employed laboratory and genetically modified strains of certain
pathogens that were mixed with fresh animal feces and then rubbed onto meat cuts. The removal of
biota applied in this way may be expected to be different from that acquired naturally, but comparative
studies are wanting. The long-term effect of acid and steam treatments on meat biota is unknown
because these procedures are relatively new for commercial use. The emergence of acid-resistant
91
supports the growth of the poultry spoilage biota better than even the muscle tissue. In the advanced
stages of poultry spoilage, the surfaces will often fluoresce when illuminated with ultraviolet light
because of the presence of large numbers of fluorescent pseudomonads. Surface spoilage organisms
can be recovered directly from the slime for plating, or one can prepare slides for viewing by smearing
with portions of slime. Upon Gram staining, one may note the uniform appearance of organisms
indistinguishable from those listed. Tetrazolium (2,3,5-triphenyltetrazolium chloride) can be used
also to assess microbial activity on poultry surfaces. When an eviscerated carcass is sprayed with this
compound, a red pigment develops in areas of high microbial activity. These areas generally consist
of cut muscle surfaces and other damaged areas such as feather follicles.
140 When the skin is removed
from a fresh chicken carcass, leg muscles are more likely to spoil faster than breast muscles since the
pH of the former is typically in the pH range of 6.3–6.6 while the latter is lower, i.e., 5.7–5.9.
Pseudomonads are favored at the lowest growth temperature. When poultry was spoiled at 1
◦ C,
these organisms dominated while at 10
◦ C and 15
◦ C, enteric and other bacteria became significant.
12
More information on poultry spoilage can be found in reference 28. The spoilage of poultry and other
meats under vacuum and modified atmosphere packaging is covered in Chapter 14.
CARCASS SANITIZING/WASHING
Just prior to slaughter, the outer surfaces of meat animals are laden with dust, dirt, and fecal matter.
It is inevitable that some of the microorganisms from these sources will be found on the carcasses of
slaughtered animals, and although most are nonpathogens, pathogens may be present. In an effort to
reduce the number and types of pathogens on dressed carcasses and finished products, a number of
methods have emerged:
1. Trimming—the excising of skin or outer tissue
2. Washing—the use of plain water at varying temperatures and hose pressures
3. Organic acids—the addition to wash water of acetic, citric, or lactic acid at concentrations of 2%
to 5%
4. Other chemicals—the addition to wash water of hydrogen peroxide, chlorine dioxide, or
chlorhexidine
5. Steam vacuum treatments—the application of steam for 5 to 10 seconds at 80
◦ C or higher as the
final carcass preparation step
6. Combinations—the use of two or more of the above
In the USDA’s pathogen reduction program for beef carcasses, 1 out of every 300 carcasses is to
be examined by sponging 100-cm
2 sections from three carcass areas (rump, flank, and brisket) for E.
coli, which should be <5 cfu/cm
2 .
175 The sponging method is one of six that were compared for beef
carcasses.
37
Overall, a large number of studies have been conducted on most of the methods noted above for
removing microorganisms from slaughter carcasses, and reduction of APCs on the order of 1 to 3 log
cycles is common. Many studies have employed laboratory and genetically modified strains of certain
pathogens that were mixed with fresh animal feces and then rubbed onto meat cuts. The removal of
biota applied in this way may be expected to be different from that acquired naturally, but comparative
studies are wanting. The long-term effect of acid and steam treatments on meat biota is unknown
because these procedures are relatively new for commercial use. The emergence of acid-resistant