Thermal Food Processing

Thermal Processing of Meat Products 171
of studies determining the survival and growth of C. perfringens spores during
thermal processing of meats is available. 37
6.5.2.5 Staphylococcus aureus
S. aureus is ubiquitous and is common in the mucous membranes and skin of most
warm-blooded animals, including food animals. S. aureus is an opportunistic pathogen,
cannot compete well with other food spoilage bacteria, and can grow and cause
illness in cooked foods that are cross-contaminated. Although staphylococci are
readily destroyed by the temperatures normally used for processing of meat and
poultry products, growth of the organisms to levels greater than 5.0 log CFU/g can
result in production of extremely heat stable enterotoxins, which can survive even
commercial sterilization processes. The organism is resistant to drying and may grow
and produce enterotoxins in products having a w as low as 0.85. It is very resistant
to freezing and thawing and survives well in frozen meat products. 20
The CDC estimates approximately 185,000 cases of staphylococcal illness
annually and 100% of the outbreaks are food-borne. 30 Although S. aureus is not
part of the lethality and stabilization performance standards for cooked ready-toeat
products, the ability of the organism to elaborate heat-stable toxins that can
survive subsequent cooking contribute to its importance during thermal processing
of meat products.
6.5.3 DESTRUCTION OF PARASITES
Trichinellosis is a parasitic disease caused by a roundworm of the Trichinella
genus that infects carnivorous and omnivorous animals, including domestic swine
and wild game (e.g., bears, cougars, and wild boars). While trichinellosis was
traditionally attributed to pork and pork products, recent surveillance by the CDC
indicates that wild game meat has emerged as the leading cause of the disease.
While Trichinella spiralis is more commonly associated with swine, other species,
Trichinella nativa, Trichinella pseudospiralis, and types Trichinella T-5 and
Trichinella T-6 are associated with other wildlife.
Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae)
of Trichinella. After exposure to gastric acid and pepsin, the larvae are released
from the cysts and invade the small bowel mucosa, where they develop into adult
worms. After 1 week, the females release larvae that migrate to the striated muscles,
where they encyst. Encystment is completed in 4 to 5 weeks and the encysted larvae
may remain viable for several years. Ingestion of the encysted larvae perpetuates
the cycle (Figure 6.6).
In the past, control measures for parasites were primarily postharvest treatments,
such as cooking, freezing, curing, and irradiation. Commercial preparation
of pork products by cooking requires that meat be heated to internal temperatures
that have been shown to inactivate trichinae (Table 6.4). Similar requirements for
freezing temperatures, times, and curing methods are prescribed in the Code of
Federal Regulations Title 9, Chapter III, §318.10. Treatment of fresh pork with