Keeping food safe to eat worksheet

Food Safety Worksheet Answer Key

Read each of the following scenarios

Scenario 1:

1. Based on Scenario 1, what are the possible sources of food-borne illness?

a. Using the same knife to trim the raw steak and then cut up vegetables for the potato salad. It would be best to use completely separate utensils and cutting boards for raw meat and ready-to-eat foods. If this is not possible, it is very important that the utensils and cutting board be thoroughly washed with hot soapy water to prevent cross-contamination.

b. Leaving the potato salad and meat sitting out at room temperature on a hot day for an extended period of time. The combination of leaving the food out on the counter while Jeremiah got ready for the BBQ and then leaving it out at the actual event, this creates an environment that is ideal for growth of pathogenic bacteria.

c. Cooking the burgers to medium doneness. Ground meats need to be cooked thoroughly (no pink); not doing so poses potential for serious food-borne illness.

2. Although Jeremiah did not get sick, there were several areas throughout Jeremiah’s day that could have led him to a serious case of food-borne illness. Point out these areas and briefly explain why they are of concern and what Jeremiah could have done differently.

a. Leaving the groceries in the hot trunk. Even though only for a short period of time, it would be best to make the grocery store the last stop before heading home, especially on a hot summer day. If this is not possible, consider keeping a cooler in the car to help keep groceries cooler during transport home.

b. Placement of raw meat in the refrigerator. Raw meat should be placed on the bottom shelf of the refrigerator, or in the specialized meat drawer. Raw meat contains juices that could potentially leak out and drip down on foods below.

c. Using the same knife and cutting board for raw meat and ready-to-eat foods. This leads to cross-contamination. If it is not possible to use completely separate cutting boards and utensils in preparation of raw meat and ready-to-eat foods, it is necessary to wash the utensils and cutting board with hot soapy water in between (if the raw meat is prepared before the ready-to-eat foods).

d. Leaving the food sitting out for an extended period of time. Room temperature is within the temperature danger zone. Leaving food sitting out in the temperature danger zone poses significant concern for food-borne illness.

e. Not cooking the ground meat thoroughly. Ground meat must be cooked so that there is no pink in the middle. Unlike a steak that only needs the outer surfaces to be cooked to kill off any potentially pathogenic bacteria, ground meat may have pathogenic bacteria anywhere throughout the meat.

3. Why is it safe for steak to be pink in the middle, but potentially dangerous for a hamburger not to be cooked all the way through? A steak only needs the outer surfaces to be cooked to kill off any potentially pathogenic bacteria, while ground meat may have pathogenic bacteria anywhere throughout the meat.

Scenario 2:

1. How could this illness have been prevented?

a. Putting the lid on the hot lasagna while it was cooling. Leaving the lid on will hold in the heat and prolong the cooling process.

b. Leaving the lasagna out to cool for 4 hours. The lasagna should not sit out in the temperature danger zone any longer than 2 hours. To speed up the cooling process, (in addition to leaving the lid off), put the lasagna into a shallow dish.

2. Based on the incubation period and symptoms of the illness, what is the most likely microorganism responsible for this illness? Based on the incubation period and symptoms, it is most likely the Staphylococcus aureus bacterium that is responsible for this illness.

3. Describe the temperature danger zone. Temperature danger zone : 40 to 140 degress F. This is the temperature range where bacteria can thrive. The best chance of preventing food-borne illness is to keep cold food cold (below 40 degrees F) and hot foods hot (above 140 degrees F).

4. How could Martha have sped up the cooling process of the lasagna?

a. Leave the lid off

b. Put the food into shallow containers – thick, dense food will hold in the heat.

c. Put ice packs under the container

1. If the leftover lasagna was thoroughly reheated, (which it was), how did it still lead to food-borne illness? Staphylococcus aureus is a bacterium that produces toxins. Reheating the lasagna would kill the bacterium, but not the toxin, which is responsible for causing the actual illness.

Scenario 3:

1. What could be the cause of Sally and her family members’ illness?

a. Leaving the chicken out on the counter (in the temperature danger zone) for 3 hours to marinate.

b. Serving the marinade that contained raw meat.

2. How could this illness have been prevented?

a. Marinate the chicken in the refrigerator.

b. Bring the marinade to a boil to kill off any potentially pathogenic bacteria from the raw meat.