Microbes, Foodborne Illness, and Food

Preservation

•Food Spoilage•Foodborne Illness

How do Microbes Affect Us?

What is Food Spoilage?• Microbes in food can cause the

food to spoil (rot)• Microbes cause millions of

dollars of food to spoil each year

What is Foodborne Illness?

What is it?• A disease caused by consuming contaminated

foods or beverages• Contamination caused by bacteria or virus

– Pathogen-• harmful bacteria that can cause disease

What’s the Problem?

Some microbes make us sick when we eat them. You can’t see these microbes!!!!!!

The greatest dangers are microbes that produce toxins and causes human illness!

Is Foodborne Illness a Big Problem?

• Over 76 million Americans get sick from foodborne microbes each year!

• About 5,000 Americans die from foodborne illness each year.

What Happens?• Microbes pass from stomach to intestines

– Microbes attach to intestine wall and prevent water from being absorbed, or nutrients from being absorbed

– Certain microbes release a toxin that will enter the bloodstream and travel through the entire body

• Up to 5000 people die every year

Symptoms• Range from mild stomach &

intestine problems to DEATH, including

• Upset Stomach• Abdominal Cramps• Nausea and vomiting• Diarrhea• Fever• Dehydration

How Does Food get Contaminated?

• Food is exposed to pathogens-When grown or raised

1. animals have pathogens in intestines already2. vegetables grown in dirty soil, or watered with contaminated water

-In factory or Slaughter House1. meat exposed to pathogens from other meats

Example of Bacteria in Food

Bacteria naturally living in milk will spoil milk in two or three hours if left at room temperature.

Putting milk in the refrigerator doesn’t kill bacteria already there, but it slows down the bacteria enough that the milk will stay fresh for a week or two.

How does Food get Contaminated?

By humans in their own kitchen1. Poor hygiene 2. Using used dirty utensils3. Using an old cutting board4. Not washing your counters5. Leaving food out of refrigerator6. Not washing food

How can we Prevent Foodborne Illnesses?

1. Proper Hygiene and Handling of Food to keep pathogens away

2. Food Preservation Methods to keep food from spoiling

Why Does Preserving Food Help?

The basic idea - food preservation either: – Slows down the activity of disease-

causing bacteria – Kills the bacteria altogether

Is Food Preservation New?

• Food preservation is one of the oldest technologies used by human beings.

• Some food preservation methods have been around for thousands of years (e.g. pickling and sun-drying), while others are more modern (e.g. pasteurization and irradiation).

What is “sterile”?

• A food that is sterile contains no bacteria.

• Unless sterilized and sealed, all food contains bacteria.

How Does This Work?

• We preserve food by changing the environment that the food is in (e.g. changing the temperature, oxygen, pH or by removing water).

Can you think of the different ways that food is

preserved?

Common Food Preservation Methods Include:

• Refrigeration and freezing• Canning• Dehydration (Drying Food)• Freeze-Drying• Salting• Pickling• Pasteurization• Fermentation• Chemical Preservation• Irradiation

Food Preservation Methods: The Details

Food Preservation

• Physical Methods

Refrigeration and Freezing

• Refrigeration and freezing are the most popular forms of food preservation in use today.

• Refrigeration = 32 ° F to 40 ° F • Freezing = below 32° F

Refrigeration and Freezing

a. Refrigeration slows the growth of bacteria1. bacteria is less active,

but they are not killed2. Food will still eventually

spoil in time

b. Freezing kills bacteria or cause it to become completely inactive

Canning Food

-Used since 1825=Food can be stored for long periods of timeb. Process

1. Food is heated to a temperature that kills all bacteria2. Container is sealed to prevent new bacteria from getting to food

c. Can be in any sealable container1. Milk cartons, fruits in jars, vegetables in cans

Canning

• Once you open the can, bacteria enter and begin attacking the food, so you have to "refrigerate the contents after opening"

Drying

• Evidence shows that Middle East and oriental cultures actively dried foods in the hot sun as early as 12,000 B.C..

• Drying removes water from the food. Since most bacteria die or become inactive when dried, dried foods kept in air-tight containers can last quite a long time.

Drying (Dehydration)a. Food can be stored for long periods of timeb. Drying removes water from food

1. Bacteria grown in moist environmentsc. Process uses fans and high temperatures to

dry the foodd. Examples

1. beef jerky, powdered milk, pasta, instant rice, fruit chips

Sun-Dried Raisins

Salting

a. salt causes the moisture to come out of the food

b. Eliminates water so bacteria can’t liv

b. one of oldest preservation method

Pasteurization

a. Food is heated to high temperature for a short time at 145-165°F to kill all microbes

b. Used on milk and juicesc. Food must be refrigerated

after pasteurization

Food Irradiation

a. Food is sterilized by using energy in the form of radiation1. Does NOT make food radioactive

b. Microbes are killed by radiationc. Used on fruit and vegetables

1. Kills insects, fungi, and bacteria

2. Delays ripening so food can be shipped

Irradiation

• Irradiation DOES NOT make food radioactive. The food never touches a radioactive substance. Irradiation destroys insects, fungi, and bacteria.

Vacuum Packing

a. Air is removed from package before it is sealedb. Without oxygen, bacteria and mold can not grow

Food Preservation

Chemical Methods

Pickling

a. Acidic environments prevent the growth of bacteria.

b. Usually uses vinegar, salt water, or an alcohol to preserve food

c. Will drastically change the flavor of food so is not good for all types of food

Pickling or Fermentation

• These leave food with a higher level of acid, making it an inhospitable environment for spoilage bacteria.

2. Fermentation

a. encourages growth of “good” bacteria and prevent growth of “bad” bacteria

b. Examples of fermented food:1. bread, yogurt, wine, cheese, soy sauce

c. Foods must be refrigerated

Fermentation

• Fermentation refers to the activity of bacteria and fungi.

• These microbes break food molecules into simple substances.

Smoked Foods

• Smoking adds chemicals from smoke to food that help destroy potential spoilage organisms.

3. Smoking

a. Used to preserve meats1. Heat Kills bacteria2. chemicals from smoke kill microbes3. Outer surface of meat is dried removing moisture

Food Preservatives

• If you look at the ingredient labels of different foods, you will see different types of chemicals used.

• All of these chemicals either prevent the activity of bacteria or kill the bacteria.

• Pancake syrup can sit out because of the ingredients it contains.

Chemical Preservation

• There are three classes of chemical preservatives commonly used in foods: – Benzoates (such as sodium benzoate)– Nitrites (such as sodium nitrite) – Sulphites (such as sulphur dioxide)

The End