Various microbes compete with humans for the same sources of food. Science and Technology in Society – How do science and technology affect the quality of our lives? 7.4 - Technology allows us to improve food production and preservation, thus improving our ability to meet the nutritional needs of growing populations. Various microbes compete with humans for the same sources of food.

C21. Describe how freezing, dehydration, pickling and irradiation prevent food spoilage caused by microbes.

Food Production & Preservation Technology Improves Our Ability to Meet the Nutritional Needs of A Growing Population

Food Spoilage Caused by microbes A microbe is a micro- organism There are 3 main types of microorganisms – fungi, bacteria, and viruses

Bacteria Single celled organisms Some are helpful They help us digest food Grow in milk to produce yogurt and cheese What are the dark streaks in bleu cheese? Right! Mold!

Bacteria Bacteria turns apple cider into vinegar Bacteria changes the smell and taste of food

Bacteria A cut in your hand while you are making potato salad may get staphylococcus bacteria in the salad Left at room temperature too long, the bacteria produces a toxin that can make you sick

Bacteria Salmonella is found in meat, eggs, fish If not killed during food preparation, it can make you very sick Attaches to intestine wall & multiples rapidly Nausea, vomiting, diarrhea and fever

Turtles You can also get salmonella bacteria from handling turtles This is why they cannot be sold in pet stores in CT Always wash your hands after handling turtles!

Food Poisoning Can be caused by chemicals, heavy metals, fungi, viruses, and most commonly, bacteria Fever, diarrhea, cramps, death Poor hygiene, insufficient cooking, contamination of food, eating raw seafood

Prevention of Food Spoilage

Dehydration Removes water from the food No water means that fungi, viruses, bacteria cannot grow Dehydration is a very old process Raisins, dried fruit of all kinds

Pickling Preserves food by using salt and acid to stop bacteria growth Also an old process Salt pulls moisture out of food by osmosis or absorption; acid keeps bacteria from growing

Canning Food is sealed in glass or “tin” containers and The temperature in the containers is raised to very high temperatures to kill bacteria Vegetables & meats sold in CANS in stores Individuals still “can” vegetables and fruits with pressure cooker

Irradiation Process only about 100 years old Passes food through an irradiation field caused by radioactive materials Food does not become radioactive The official symbol on irradiated food.

Freezing Most bacteria can only live at temperatures between 400F (50C) and 1400F (600C) Freezing keeps food below the lower limit Most cooking heats food above the upper limit

Temperature Extremes Some bacteria have been found in ice in Antarctica Some have been found in near-boiling hot springs BUT both extremes require water Salmonella will die within 5 days if it does not have water

Food Poisoning Prevention Tips #1 Wash hands, surfaces, and utensils before and after food preparation Why do you think this sign is posted in restaurants & fast food places?

PREVENTION Tip #2 Keep raw and uncooked food below 400F (50C) That is the temperature of the inside of your refrigerator

PREVENTION Tip #3 Don’t leave food lying out. Store it properly. 820C = ? F 710C = ? F 650C = ? F

PREVENTION Tip #4 Keep cold food cold! Keep hot food hot!

PREVENTION Tip #5 Don’t share eating or drinking utensils. Don’t take a bite of a friend’s apple Don’t “double dip”

PREVENTION Tip #6 When in doubt, throw it out!