Food Preservation for Food Processors Part I

An interactive module about acidic foods

Module designed by Julie Garden-Robinson, Ph.D., L.R.D., Food and Nutrition Specialist, 2014

The following tips will help you navigate through each module. Click to go back and to move forward

in the module. Before you begin, you’ll take a pretest.

The pretest will open in a new window. When you are finished with the pretest, close

the window to return to the module. A symbolizes a question slide. You’ll

need to click forward to see the answer.

Click this button to return to your position in the module after reading the definition slide.

When you are finished with the module, you will take a post-test. The post-test will open in a new window. When you are finished with the post-test, close

the window to return to the module.

PretestBefore we begin, let’s take a

pretest to see how much you already know. Click here for the pretest.

Have a bright idea?Everyone loves my salsa and alwaysasks me to bring it to potlucks.Maybe I should start selling it. I bet Icould make a fortune. Maybe I canretire and buy a house in Arizona –no, Florida. Heck, maybe both!

Oh, no! There are regulations?

Hey, wait. Don’t give up. Go through this interactive module.It tells you what you need to knowabout processing acidified foods.Salsa is an acidified food.

Before we discuss the acidification process and regulations, let’s go over some basics about types of preservation and also what preserving means.

Food PreservationDefinition: The process of treating and handling food insuch a way that it stop or greatly slows spoilage to prevent foodborne illness while maintaining nutritional value, density, texture and flavor.

Factors that affect food spoilage Water availability (moisture) Oxygen pH Temperature

True or false: Oxygen is a factor affecting food spoilage.a. Trueb. False

Click the forward button to see the answer.

True or false: Oxygen is a factor affecting food spoilage.

a. Trueb. False

Oxygen is a factor affecting food spoilage.

Water Availability “Water availability” refers to the amount

of water available for microbial growth. It is shown on a scale from 0 to 1.

Bacteria grow in moist environments, so the higher the water availability, the greater the risk for microbial growth.

A solute such as salt or sugar added to water “soaks” up the water, making it unavailable for bacterial growth.

Water Availability Scale

0aW

Bone dry Pure

water

0.2aW

Very dry (instant coffee, milk powder, etc.)

0.99aW

Moist fresh food (meat/fish)

0.6aW

Dried fruit

0.8aW 1aW

Water Availability Bacteria, mold and yeast need a certain

amount of water available to grow. As the water availability decreases, bacteria, mold and then yeast cease to grow. Bacteria stop growing below 0.85aW Molds stop growing below 0.75aW Yeast stops growing below 0.6aW

Water availability of some common foods

Food Example Water Availability

Cheese spread 0.95

Soy sauce 0.80

Fudge sauce 0.83

Soft, moist pet food 0.83

Peanut butter 0.70

Dry milk 0.70

Liverwurst 0.96

Salami 0.82

*Water availabilities greater than 0.85 support bacterial growth.

True or false: High water availability supports bacterial growth.

a. Trueb. False

Click forward to see the answer.

True or false: High water availability supports bacterial growth.

a. Trueb. False

Most bacteria grow best in products with high water availabilities.

Oxygen Aerobic reactions need oxygen.

The browning of fruit is one example.

Anaerobic reactions do not require oxygen. Clostridium botulinum is a type of bacteria that

does not need oxygen to survive.

Fill in the blank: Bacteria that need oxygen to survive are ______.a. Aerobicb. Anaerobic

Click forward to see the answer.

Fill in the blank: Bacteria that need oxygen to survive are ______.a. Aerobicb. Anaerobic

Aerobic bacteria need oxygen to survive and grow.

pH Foods have different pH values. Chemical reactions are decreased at very

high and very low pH. A pH meter is used to determine the pH

level of foods.

Temperature Warm temperatures increase chemical

reactions. High temperatures can kill harmful

microorganisms. High temperatures are critical for certain

preservation methods: Pressure canning Boiling-water canning

Low temperatures can slow and eventually stop chemical reactions.

Preserve foods by: Adding an acid Adding salt Drying to remove moisture Adding sugar Adding chemical preservatives Heating

=Vinegar (Acid)+

Now that we know what to control to prevent food from spoiling, let’s reviewsome methods of preservation.

Types of preservation:DryingCuring and smokingFreezing and refrigerationFermentationPressure canningMaking jam and jellyPickling/acidification

Which of the following is a preservation method?a. Dryingb. Freezingc. Smokingd. All of the above

Click the forward button to see the answer.

Which of the following is a preservation method?a. Dryingb. Freezingc. Smokingd. All of the above

“D” is the correct answer.

Drying One of the oldest methods of preservation Removes moisture to delay and prevent

bacterial growth Safe and easy-to-learn method of

preservation A food dehydrator

often is used Meats and fruits, such

as jerky, apples, bananas, mangos and tomatoes, arepopular items to dry

Fill in the blank: Drying preserves food by ______.a. adding an acidb. lowering the temperaturec. reducing the moisture content

Click the forward button to see the answer.

Fill in the blank: Drying preserves food by ______.a. adding an acidb. lowering the temperaturec. reducing the moisture content

“C” is the correct answer. A food dehydrator or oven on a low temperature is used to dry foods for preservation.

Curing and Smoking Meats must be cured before they are

smoked. Curing uses salt to reduce the moisture

available to microorganisms. Nitrates and nitrites are added to inhibit

the growth of Clostridium botulinum. Curing can take several hours to several

weeks.

Fill in the blank: Curing preserves food by ______.a. adding an acidb. lowering the temperaturec. reducing the moisture content

Click the forward button to see the answer.

Fill in the blank: Curing preserves food by ______.a. adding an acidb. lowering the temperaturec. reducing the moisture content

"C” is the correct answer. Salt is added to products being cured to reduce the moisture content.

Smoking After a product is cured, it can be smoked. Smoking usually is done in a smokehouse. The combination of heat and smoke dries

and preserves the food. Smoking adds flavor to the product. Meat, poultry, game and fish all can be

smoked.

Freezing and Refrigeration Are commonly used processes for

preserving Stops the growth of bacteria (freezing) or

slows the growth of bacteria (refrigeration) Slows most chemical reactions

Does freezing food kill bacteria?a. Yesb. No

Click the forward button to see the answer.

Does freezing food kill bacteria?a. Yesb. No

“B” is the correct answer. Bacteria is not killed by freezing foods, but the lower temperature slows the growth of bacteria.

Fermentation A microorganism such as yeast is added to

a product to convert carbohydrates into an acid or an alcohol. These microorganisms consume the food and

produce byproducts. Yogurt is one example.

Bacteria is added to milk. The bacteria eat the sugar and produce lactic acid.

Lactic acid reduces the pH of yogurt, which inhibits bacteria growth.

Which preservation method involves bacteria or yeast?a. Dryingb. Fermentingc. Picklingd. Freezing

Click the forward button to see the correct answer.

Which preservation method involves bacteria or yeast?a. Dryingb. Fermentingc. Picklingd. Freezing

“B” is the correct answer. Yogurt is an example of fermentation.

Pressure Canning Kills bacteria with high temperatures.

A temperature greater than 240 F must be reached.

Pressure canning is used when the product has a pH above 4.6.

Jams and Jellies Sugar reduces the amount of available

water. Jams and jellies normally have a pH lower

than 4.6. Jams and jellies cook during processing.

Post-test Now you have some basic knowledge

about why we preserve food and the methods of food preservation.

Before you move on to the next module, let’s take a post-test to see what you’ve already learned.

Click here to take the post-test

Learn more about food preservation with the following online resources National Center for Home Food Preservation

www.uga.edu/nchfp/ FDA - Acidified and Low Acid Canned Foods

www.fda.gov/food/guidanceregulation/guidancedocumentsregulatoryinformation/acidifiedlacf/default.htm

NDSU Extension Service Food Preservation and Storage www.ag.ndsu.edu/food