Food • Bacteria like protein-rich foods. • Meat • Milk • Cheese • Eggs • Fish
ACIDITY • Bacteria grow best in an environment that is neutral or slightly acidic. • Acidic foods, like vinegar and fresh fruits (especially citrus), seldom provide a favorable climate for pathogenic bacteria. • Most bacteria will not grow at pH levels below 4.6 because the environment is too acidic. • Microorganisms thrive in a pH range between 6.6 and 7.5.
Acidity of Certain Foods https://www.extension.iastate.edu/foodsafety/lesson/L4/L4p4.html
Time • Food may become dangerous if left out for 2 hours or more after the time it takes to prepare it to be eaten.
Temperature • Danger zone = 40-140 • About room temperature is ideal for bacterial growth
Oxygen • Most bacteria needs oxygen to grow. • If something needs oxygen to grow this is called Aerobic • If something does NOT need oxygen to grow, this is called Anaerobic • I.E. Botulism does not need oxygen to grow (canned goods) It is rare but deadly.
Moisture • Bacteria LOVE wet/moist foods! • Not foods such as crackers and breads at room temperature. • Things well preserved with salt and sugar deprive bacteria of water and limit its reproduction. • Examples of this are jams, jellies, and beef jerky.
Vocabulary • Everyone will say the term after Ms. Pilant goes over the pronunciation. • Each person will read a term (or part of a term). • You will need to know these terms/definitions.
Quick Practice Quiz • https://www.extension.iastate.edu/foodsafety/lesson/L4/L4test.html
1. Bacteria prefer _____-_____ foods • High-acid • Protein-rich • Moldy • All of the above
2. Most pathogenic bacteria prefer environmental conditions that are • Dry • Wet • Acidic • All of the above
3. Most types of bacteria cannot live in foods that are • Acidic • Neutral • Alkaline • Odorous
4. Cooked meats at room temperature are in the Temperature Danger Zone (TDZ), which is between ________? • Room temperature and freezing • 40°F to 140°F • 41°F to 180°F • 70°F to 140°F
5. Pathogenic bacteria require time to multiply in a warm, moist, high protein environment. Generally, they must be in the TDZ more than _____________ to reach dangerous numbers that can cause foodborne illness. • 8 hours • 4 hours • 2 hours • 6 hours
6. Improperly canned foods could cause which of the following foodborne illnesses? • Bulimia • Conjunctivitis • Botulism • Cancer
7. Bacteria wouldn't multiply very fast in a box of corn flakes because • Cereal is low in moisture • The box is too high in the cupboard • Corn flakes are high in protein • Corn flakes are too acidic
8. Is it safe to eat an orange that has been kept at room temperature for more than two hours? • Yes • No
9. Beef jerky is shelf stable and safe to eat because • It is low in moisture • It has low water activity • It has been preserved by salt • All of the above
10. A chicken salad sandwich left in the TDZ could have a growth of pathogenic bacteria because • It is a protein-rich food • It has neutral pH • It has a high water activity • All of the above
11. Each of the letters in FATTOM represent a condition necessary for microorganisms to grow and multiply. The letters "O" and "M" stand for which two conditions? • Oxygen and Minerals • Oxygen and Moisture • Oleo and Margarine • Old and Moldy
12. You bring a sack lunch to school, but find out the cafeteria is serving pizza, so you decide to have that instead and leave the lunch in your locker. After school, you open your lunch to eat as a snack. What do you decide to do with the chicken sandwich? • Throw it out because it's been in the TDZ for more than two hours. • Eat it before your mom picks you up so she doesn't get mad. • Microwave it so you can eat it hot. • Share it with your best friend.
13. You bought a hamburger on the way home from school and were about to eat it when a friend stopped by to go to a movie.When you came home four hours later, you noticed it sitting where you left it. You know it's been in the TDZ for more than two hours, but you are pretty hungry. You should • Reheat the burger in the microwave to kill all the bacteria • Throw the burger away because you don't want to get sick • Scrape off the toppings and just eat the beef • Cover the burger and save it for later.
14. Mom bought some steaks at the grocery store, but while unpacking the groceries, she received a phone call. After 20 minutes you notice the meat is still on the counter. You should • Put the meat in the refrigerator to keep the bacteria from multiplying • Tell your mom the steak has been in the Danger Zone too long and ask if you can throw it away • Stop worrying about it because no air can get to the meat through the plastic wrap • turn on the air conditioner and go play a video game