Environmental Engineering Reference
In-Depth Information
are under controlled laboratory conditions, which normally do not prevail in the
average restaurant. The higher time - temperatures should be used in practice to
prevent possible disease transmission and ensure heat penetration.
Adequate cooking of ground beef and other meats is essential to prevent
infection with
E. coli
O157. Consumption of ground beef, particularly “pink”
(indicating undercooked) meat, has been associated with both outbreaks and spo-
radic cases of
E. coli
infection.
68
,
69
USDA recommends cooking hamburgers
and ground beef to 160
◦
F on a meat thermometer.
63
Cooked beef roasts and
turkeys, because of their size, are rarely rapidly cooled to 45
◦
F(7
◦
C) or less. If
not consumed or sold immediately, they should be reheated as noted before use.
Cooked roasts that have been rolled or punctured should be reheated to 160
◦
F
(71.1
◦
C) (FDA recommends 165
◦
F (73.9
◦
C)). Cooked roasts that have been cut
up into small pieces should be reheated to 165
◦
F (73.9
◦
C) because the handling
introduces greater possibility of contamination. Cooked roasts that include solid
muscle should be reheated to assure pasteurization of the surface of the roast.
There is a danger of cooking large masses of raw meat on the outside
but leaving the interior of the food underdone, thereby permitting survival of
salmonellae
70
spores introduced in handling, or those intrinsically present that
can germinate and cause
C. perfringens
food poisoning. However, if the meat
is cooked as already noted and eaten immediately after cooking, there is usually
minimal risk of bacterial foodborne illness.
Incomplete cooking of stews, meats, gravies, and large cuts of meat that have
been rolled or penetrated with skewers and failure to provide prompt and thor-
ough refrigeration can lead to contamination with
C. perfringens. Clostridium
perfringens
vegetative cells in food are destroyed by heat and thorough cook-
ing, but spores are not completely destroyed by normal cooking. Therefore, foods
contaminated with spores that are cooked and not promptly cooled can permit the
germination of spores and the multiplication of vegetative cells with the danger
of food poisoning on consumption. Heating
C. perfringens
enterotoxin at 140
◦
F
(60
◦
C) in cooked turkey showed a gradual decrease in serologic activity with no
detectable toxin being present after 80 minutes.
71
Clostridium perfringens
type A food poisoning is caused by the ingestion
of foods containing large numbers of vegetative cells of enterotoxigenic strains.
Many (not all) of these cells pass through the human stomach into the intestines
where they are able to grow and eventually sporulate. During sporulation, the
enterotoxin responsible for food-poisoning symptoms is synthesized and released.
The toxin does not normally develop in the food, as in staphylococcus food poi-
soning and botulism, but rather, forms in the intestinal tract. Adequate cooking
alone will not always prevent
C. perfringens
food poisoning because the spores
are resistant to heat and may survive, multiply during slow cooling, and pro-
duce a toxin under anaerobic conditions, unless the food is eaten immediately or
promptly
cooled to 45
◦
F(7
◦
C) or less and reheated to 165
◦
F(74
◦
C) for safety
to destroy the vegetative cells in the food.
The enterotoxin is produced in the intestinal tract after ingestion or in food
under suitable temperatures 60
◦
to 120
◦
F(16
◦
to 49
◦
C), 110
◦
to 117
◦
F(43
◦
to
