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COMMON MISCONCEPTIONS
3
You may notice that some of the
temperatures in this chapter are
rounded up or down. For example,
in an exact conversion, 130 °F =
54.4 °C, and 54 °C = 129.2 °C, but we
have quoted them together as 54 °C
/ 130 °F. Throughout this chapter
we often quote from the official
FDA 2009 Food Code, and when
we do we use exactly what it
specifies. Some parts of the Food
Code round temperatures to the
nearest whole degree, whereas
other parts round to a tenth of
a degree. A nitpicker might observe
that the requirements of U.S. law
thus depend on whether you read
your thermometer in Celsius or
Fahrenheit.
Once upon a time, some well-meaning officials
decided that food safety recommendations should
include only temperatures instead of time-andtemperature
combinations. This decision, perhaps
the worst oversimplification in all of food safety, has
led to years of confusion and mountains of ruined
food.
Scientifically speaking, you need the right
combination of both time and temperature to kill
pathogens. Why give temperature-only rules when
the science says otherwise? One can only guess at
the reasoning of regulators, but they most likely
thought that providing both temperatures and
times would be too complicated. If you don’t
understand the meaning of time, however, you’ve
got bigger problems in the kitchen than food safety.
Once you eliminate time from the standards,
the strong tendency is to choose a temperature so
hot that it can produce the required D level of
pathogen reduction nearly instantaneously. This
impractically high temperature invariably leads to
overcooked meat and vegetables while preventing
very few cases of foodborne infection in addition
to those that would be prevented by less extreme
heat. After all, once a pathogen is dead, heating it
further doesn’t make it any deader.
Unfortunately, the use of temperature alone in
standards is only one of several sources of the
confusion that pervades discussions of food safety.
Another is the routinely invoked admonition that
cooking temperature must be measured in the
core or center of food or that “all parts of the food”
must be brought to a recommended temperature
for a specified time. Recall from the preceding
chapter that virtually all food contamination is an
external phenomenon; the interior of unpunctured,
whole-muscle meat is normally considered
sterile. This revelation often comes as a shock, but
it’s been verified in many tests: foodborne pathogens
generally can’t get inside an intact muscle.
There are a few notable exceptions, such as the
flesh-dwelling parasites Trichinella and Anisakis
and the hen ovary- and egg-infecting Salmonella
bacteria. But these kinds of infections are relatively
rare. The vast majority of cases of contamination
can be linked to human or animal fecal matter
that comes in contact with a susceptible surface.
The FDA acknowledges as much in the 2009
Food Code, which has the following to say about
beef steaks:
(C) A raw or undercooked WHOLE-
MUSCLE, INTACT BEEF steak may be
served or offered for sale in a READY-TO-
EAT form if:
(1) The FOOD ESTABLISHMENT
serves a population that is not a HIGHLY
SUSCEPTIBLE POPULATION,
(2) The steak is labeled to indicate that
it meets the definition of “WHOLE-
MUSCLE, INTACT BEEF” as specified
under 3-201.11(E), and
(3) The steak is cooked on both the
top and bottom to a surface temperature of
63 °C (145 °F) or above and a cooked color
change is achieved on all external surfaces.
In effect, the FDA says it isn’t concerned about
the interior or core temperature of a beef steak; it
cares only about the exterior temperature. So why
doesn’t the FDA see fit to apply the same criteria
to all intact muscle foods? What is the difference,
for example, between a beef tenderloin roast and
a fillet cut from it, or between a thick rib-eye steak
and a thin rib roast? There is no scientific basis, in
fact, for treating beef roasts any differently than
steaks.
More generally, no valid reason exists for handling
other intact, cultivated meats like lamb or
poultry any differently than beef steaks. Nevertheless,
many laws and regulations still specify a core
temperature for these meatsand these overly
conservative rules are likely to remain in place until
somebody lobbies for rare lamb or duck breast.
European chefs have long served red-meat
poultry, including duck and squab breast, cooked
rare like steaks. Searing the outer surface of these
meats should be sufficient, just as it is for beef
steaks. There is no more compelling reason for an
interior temperature requirement for these meats
than there is for beef.
This brings us to another common quirk of food
safety rules: having completely different rules for
different foods. We have come to expect that
chicken, for example, must be cooked differently
than beef to make it safe. Why should there be any
difference in cooking recommendations if most
food contamination is external and most of that
contamination is human-derived? Thankfully, as
the rules have evolved, they have clearly trended
toward greater uniformity across food types. The
FDA 2009 Food Code, in fact, uses similar
time-and- temperature combinations for most
foods. But other codes still do not.
Poultry is an interesting case in point. Chickens,
turkey, and ducks are typically sold whole
with the skin intact. It’s true that the risk of fecal
contamination is higher if meat is sold with its
skin or if it includes the abdominal cavity, from
which fluids contaminated with fecal matter can
leak during slaughter and processing. And chickens
are notoriously prone to Salmonella infections.
Consequently, past specifications treated chicken
as high risk and urged cooking it to correspondingly
high temperatureshigher than those
recommended for beef, for example.
Research has since shown that Salmonella can be
killed by temperatures as low as 49 °C / 120 °F if
the heat is applied long enough. Some food safety
rules better reflect the science and have lower
time-and- temperature requirements for poultry.
But other official standards still treat chicken as
though nothing short of cremation will safeguard
the consumer. The result is that government
regulations end up contradicting one another (see
Misconceptions About Chicken, page 180).
The Danger Zone
Another commonly oversimplified and misleading
food safety standard concerns the “danger zone”
between the maximum temperature at which cold
food can be safely held and the minimum temperature
at which hot food can be safely held. The
typical “danger-zone” rule is that you can only
leave food out for four hours when its temperature
is between 4.4 °C and 60 °C / 40 °F and 140 °F
before it becomes too hazardous to eat. Some
so-called authorities reduce this even further, to
Ground beef, in which interior and exterior
parts are thoroughly mixed, is particularly
susceptible to contamination. During
grinding, pathogens on the food surface
can end up in the food interior, which
doesn’t get as hot as the surface does
during cooking.
The concept of the “danger zone” is
based on an oversimplification of
microbial growth patterns. Not all
temperatures within the danger
zone are equally dangerous. Most
pathogens grow slowly at temperatures
below 10 °C / 50 °F. Their
growth accelerates modestly with
increasing temperature and is
typically fastest near human body
temperature, 37 °C / 98.6 °F.
Beyond this optimum, higher
temperatures sharply curtail the
growth of most pathogens until
they stop growing completely and
start to die.
174 VOLUME 1 · HISTORY AND FUNDAMENTALS
FOOD SAFETY 175