You Can’t Judge You Can’t Judge a Burger by Its a Burger by Its

Color!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 Problems with using color as test for donenesstest 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 temperatureSome 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 iron-oxygen 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 illnessUsing 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!