90
Modern Food Microbiology
from chicken carcasses,
104 pseudomonads were found to constitute 30.5%, Acinetobacter 22.7%,
Flavobacterium 13.9%, and Corynebacterium 12.7%, with yeasts, Enterobacteriaceae, and others
in lower numbers. Of the pseudomonads, these investigators found that 61.8% were fluorescent on
King’s medium and that 95.2% of all pseudomonads oxidized glucose. A previous characterization of
pseudomonads on poultry undergoing spoilage was made by Barnes and Impey,
11 who showed that the
pigmented pseudomonads decreased from 34% to 16% from initial storage to the development of strong
off-odors, whereas the nonpigmented actually increased from 11% to 58%. Acinetobacter and other
species of bacteria decreased along with the pseudomonads. A similar process occurs in spoiling fish.
Fungi are of considerably less importance in poultry spoilage except when antibiotics are employed
to suppress bacterial growth. When antibiotics are employed, however, molds become the primary
agents of spoilage. The genera Candida, Rhodotorula, Debaryomyces, and Yarrowia are the most
important yeasts found on poultry (Table 4–2). The essential feature of poultry spoilage is sliminess
at the outer surfaces of the carcass or cuts. The visceral cavity often displays sour odors or what is
commonly called visceral taint. This is especially true of the spoilage of New York-dressed poultry,
where the viscera are left inside. The causative organisms here are also bacteria of the type noted
above in addition to enterococci.
In a study of yeasts on fresh and spoiling poultry carcasses in South Africa, Candida and Debaryomyces spp. were the two most dominant genera on both fresh and spoiled carcasses, while Rhodotorula
was not found on spoiled carcasses.
180 Trichosporon spp. were not found on fresh poultry but they were
on 5% of spoiled while 3% of fresh and 11% of spoiled contained Yarrowia. The two most abundant
species found on fresh and spoiled were Candida zeylanoides and Debaryomyces hansenii.
180
S. putrefaciens grows well at 5
◦ C and produces potent off-odors in 7 days when growing on chicken
muscle.
124 Among odor producers in general, there is a selection of types that produce strong odors
among the varied biota that exists on fresh poultry.
122 The study noted was conducted with chicken
breast muscle, which spoils differently than leg muscles because the latter have a higher pH. With
chicken leg muscle stored at 2
◦ C for 16 days, 79% of the biota consisted of pseudomonads, 17% of
Acinetobacter-Moraxella, and 4% of S. putrefaciens.
123 All isolates of the latter produced sulfidelike odors and this organism produces H 2 S, methyl mercaptan, and dimethyl sulfide. It was not of
significance in the spoilage of chicken breast muscles.
When New York-dressed poultry undergoes microbial spoilage, the organisms make their way
through the gut walls and invade inner tissues of the intestinal cavity. The characteristic sharpness
associated with the spoilage of this type of poultry is referred to as “visceral taint.”
As poultry undergoes spoilage, off-odors are generally noted before sliminess, with the former being
first detected when log 10 numbers/cm
2 are about 7.2 to 8.0. Sliminess generally occurs shortly after the
appearance of off-odors, with the log 10 counts/cm
2 about 8.
6 Total aerobic plate counts/cm
2 of slimy
surface rarely go higher than log 10 9.5. With the initial growth first confined to poultry surfaces, the
tissue below the skin remains essentially free of bacteria for some time. Gradually, however, bacteria
begin to enter the deep tissues, bringing about increased hydration of muscle proteins, much as occurs
with beef. Whether autolysis plays an important role in the spoilage of inner poultry tissues is not clear.
The primary reasons that poultry spoilage is mainly restricted to the surfaces are as follows. The inner
portions of poultry tissue are generally sterile, or contain relatively few organisms, which generally
do not grow at low temperatures. The spoilage biota, therefore, is restricted to the surfaces and hide
where it is deposited from water, processing, and handling. The surfaces of fresh poultry stored in an
environment of high humidity are susceptible to the growth of aerobic bacteria such as pseudomonads.
These organisms grow well on the surfaces, where they form minute colonies that later coalesce to
produce the sliminess (biofilm) characteristic of spoiled poultry. May et al.
121 showed that poultry skin
Modern Food Microbiology
from chicken carcasses,
104 pseudomonads were found to constitute 30.5%, Acinetobacter 22.7%,
Flavobacterium 13.9%, and Corynebacterium 12.7%, with yeasts, Enterobacteriaceae, and others
in lower numbers. Of the pseudomonads, these investigators found that 61.8% were fluorescent on
King’s medium and that 95.2% of all pseudomonads oxidized glucose. A previous characterization of
pseudomonads on poultry undergoing spoilage was made by Barnes and Impey,
11 who showed that the
pigmented pseudomonads decreased from 34% to 16% from initial storage to the development of strong
off-odors, whereas the nonpigmented actually increased from 11% to 58%. Acinetobacter and other
species of bacteria decreased along with the pseudomonads. A similar process occurs in spoiling fish.
Fungi are of considerably less importance in poultry spoilage except when antibiotics are employed
to suppress bacterial growth. When antibiotics are employed, however, molds become the primary
agents of spoilage. The genera Candida, Rhodotorula, Debaryomyces, and Yarrowia are the most
important yeasts found on poultry (Table 4–2). The essential feature of poultry spoilage is sliminess
at the outer surfaces of the carcass or cuts. The visceral cavity often displays sour odors or what is
commonly called visceral taint. This is especially true of the spoilage of New York-dressed poultry,
where the viscera are left inside. The causative organisms here are also bacteria of the type noted
above in addition to enterococci.
In a study of yeasts on fresh and spoiling poultry carcasses in South Africa, Candida and Debaryomyces spp. were the two most dominant genera on both fresh and spoiled carcasses, while Rhodotorula
was not found on spoiled carcasses.
180 Trichosporon spp. were not found on fresh poultry but they were
on 5% of spoiled while 3% of fresh and 11% of spoiled contained Yarrowia. The two most abundant
species found on fresh and spoiled were Candida zeylanoides and Debaryomyces hansenii.
180
S. putrefaciens grows well at 5
◦ C and produces potent off-odors in 7 days when growing on chicken
muscle.
124 Among odor producers in general, there is a selection of types that produce strong odors
among the varied biota that exists on fresh poultry.
122 The study noted was conducted with chicken
breast muscle, which spoils differently than leg muscles because the latter have a higher pH. With
chicken leg muscle stored at 2
◦ C for 16 days, 79% of the biota consisted of pseudomonads, 17% of
Acinetobacter-Moraxella, and 4% of S. putrefaciens.
123 All isolates of the latter produced sulfidelike odors and this organism produces H 2 S, methyl mercaptan, and dimethyl sulfide. It was not of
significance in the spoilage of chicken breast muscles.
When New York-dressed poultry undergoes microbial spoilage, the organisms make their way
through the gut walls and invade inner tissues of the intestinal cavity. The characteristic sharpness
associated with the spoilage of this type of poultry is referred to as “visceral taint.”
As poultry undergoes spoilage, off-odors are generally noted before sliminess, with the former being
first detected when log 10 numbers/cm
2 are about 7.2 to 8.0. Sliminess generally occurs shortly after the
appearance of off-odors, with the log 10 counts/cm
2 about 8.
6 Total aerobic plate counts/cm
2 of slimy
surface rarely go higher than log 10 9.5. With the initial growth first confined to poultry surfaces, the
tissue below the skin remains essentially free of bacteria for some time. Gradually, however, bacteria
begin to enter the deep tissues, bringing about increased hydration of muscle proteins, much as occurs
with beef. Whether autolysis plays an important role in the spoilage of inner poultry tissues is not clear.
The primary reasons that poultry spoilage is mainly restricted to the surfaces are as follows. The inner
portions of poultry tissue are generally sterile, or contain relatively few organisms, which generally
do not grow at low temperatures. The spoilage biota, therefore, is restricted to the surfaces and hide
where it is deposited from water, processing, and handling. The surfaces of fresh poultry stored in an
environment of high humidity are susceptible to the growth of aerobic bacteria such as pseudomonads.
These organisms grow well on the surfaces, where they form minute colonies that later coalesce to
produce the sliminess (biofilm) characteristic of spoiled poultry. May et al.
121 showed that poultry skin