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.

These bacteria may include pathogens 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

High protein foods like meat promote growth of bacteria. Bacteria need food. High protein foods like meat promote growth of bacteria.

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 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 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!