Transcript thermometer powerpoint #2 part_two_powerpoint_wsu

You Can’t Judge a Burger
by Its Color!
Today we will learn:
Why undercooked meat may be
associated with foodborne illness
Common pathogens associated with
undercooked meats
Food science behind the color of
ground beef
Why ground beef can turn brown
before reaching a safe temperature
Why ground beef can be pink after
reaching a safe temperature
Discussion Questions for
Homework Assignment
Why do you think most people do
not associate foodborne illness
with bacteria in food?
(Hint: Look at symptoms, onset)
Why do you think undercooked
meat is associated with
pathogens?
Raw meat may contain
harmful bacteria.
Even under ideal conditions, meat
from normal, healthy animals
contain a variety of bacteria
These bacteria may include
pathogens
A pathogen is any disease
causing microorganism.
A foodborne illness is a disease
carried or transmitted to people
by food.
If meats are not properly cooked,
held, cooled, and stored, the
pathogens can cause foodborne
illness if consumed.
Bacteria require specific
conditions for growth
Food
Acid
Temperature
Time
Oxygen
Moisture
FOOD
Bacteria need food.
High protein foods like
meat promote growth of
bacteria.
Acid
Bacteria like to grow in low
acid foods.
Meat is low in acid.
Temperature
Most bacteria can grow
between 40 F and 140 F.
Keeping food out of this
“danger zone” can prevent
growth.
Bacteria that cause
foodborne illness are
killed at 160°F.
If meat is not thoroughly
cooked, pathogens will
not be killed.
Inadequate cooking
frequently contributes to
foodborne illness
outbreaks associated with
meats.
Cooking meats to 160°F will kill
bacteria that can make you sick.
Time
Meat and other foods that
support bacterial growth should
not be in the “Danger Zone” for
more than 2 hours.
Oxygen
•Most bacteria need oxygen, others can
not grow in the presence of oxygen.
•Some foods are packaged in a low
oxygen environment to delay spoilage.
•Controlling oxygen is not practical for
control of pathogens in meats at home.
Moisture
Bacteria grow best in moist
foods.
Raw meat provides the optimal
amount of moisture for bacterial
growth.
Are we only concerned
about E. coli O157:H7 and
ground beef?
Pathogens associated with
undercooked meat
Campylobacter jejuni
Salmonella species
Yersinia enterocolitica
E. coli O157:H7
Discussion Questions for
Homework Assignment
Which pathogen had the highest frequency?
What foods were associated with these
pathogens?
Should we only be concerned about E. coli
O157:H7? Only ground beef?
Why are we concerned about E. coli
O157:H7 if the frequency is lower than some
other pathogens?
(Hint: look at infective dose, symptoms)
Why is undercooked ground
beef a concern?
E. Coli O157:H7 has been associated with
undercooked ground beef
E. Coli O157:H7 is a bacteria which can
cause:
• Kidney failure
• Brain damage
• Strokes and seizures
• And may lead to death
In young children and the elderly.
Thorough
cooking of
ground beef to
an internal
temperature of
160 º F
throughout kills
E. coli O157:H7.
Recent
research
show that
color and
texture are
not reliable
indicators of
doneness of
ground beef
Problems with using color as
test for doneness
Some ground beef may appear to have lost all
pink color before it is fully cooked
If raw ground beef is brown already, it may
look fully cooked before it reaches
a safe temperature
Some lean ground beef may remain pink at
temperatures well above 160 º F
Why does ground beef turn
brown before a safe
temperature is reached?
The pigment myoglobin gives
fresh beef its color
When beef is exposed to air, the
iron in its myoglobin pigment is
oxygenated to form an ironoxygen complex
Myoglobin is a purplish-red color
in its unoxygenated state.
Myoglobin becomes red when the
iron complexes with oxygen to
form oxymyoglobin.
BUT . . .
Met-myoglobin is brown in color
Met-myoglobin is formed when
fresh meat is:
•Stored for long periods of time
•Stored at too high a temperature
•Overexposed to air
Raw meat from old carcasses
can also be dark in color and
can appear to be cooked when
it is still not cooked to a safe
temperature
When beef is cooked, it changes
color from pink to brown.
BUT . . .
If the meat is already brown it will
not change color.
Why does meat stay pink
when cooked to a safe
temperature?
Meat may remain pink because of:
•Amount of acid in the meat
•Level of pigment in the meat
•Fat content of the meat
Meat with less acid can remain
pink after reaching a safe
temperature.
A high concentration of pigment
also makes meat cooked to a safe
temperature remain pink.
Meat coming from bulls can be
•Lower in acid
•Higher in pigment
Low-fat beef patties require longer cooking
times and higher cooking temperatures to
reach a safe temperature.
Low-fat beef patties can remain pink even
though they have reached an internal
temperature of 160 º F
What should we do?
To avoid foodborne illness
Meat and poultry should be cooked to an
internal temperature of 160 º F
Always use a thermometer to check doneness
of meat
Fresh or thawed ground meat should be used
within 1 day
Do not eat pink beef patties unless a food
thermometer is used to verify the temperature
To avoid foodborne illness
Using a food thermometer to ensure safe
internal temperature is especially important for
those who cook or serve ground beef patties to
people most at risk.
Those most at risk for foodborne illness
include:
•Young children
•Elderly
•Immunocompromised
The ONLY way
to be sure
when meat is
safe to eat is
by testing the
temperature
with a
thermometer!