Freezing Basics:
Terms & Concepts

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An assortment of frozen foods

Freezing Food is one of the simplest and most commonly used method of preserving food for long term storage. 

If you learn the freezing basics before you start, you are much more likely to have a successful, enjoyable and economical experience. You will also learn a valuable set of skill that will serve you well for a lifetime.

Here are some basic concepts and terms you need to know related to freezing food for long term storage.  Learn them before you start, and you could save yourself some time & expense in the long run.

Freezing Basics - Safety

Foods stored at a constant 0°f will always stay safe to eat, providing of course it was fresh & safe when it was first frozen.

Freezing doesn't destroy micro-organisms like bacteria, yeasts, and molds in food, it simply makes them go into a dormant state.

Once the food has been thawed out, if they were there originally, the micro-organisms will reactivate. Proper cooking (either before freezing of after thawing out) is the only way to make sure that microorganisms are destroyed.

Freezing Basics - Color Changes

Frozen foods (especially meats) often change color. Surfaces can oxidize, and meat can go from red to brown. You shouldn't worry too much about color changes in relation to safety or flavor.

Vacuum packaging prior to freezing can reduce the occurrence of color changes in frozen foods.

Vaccum packaging blanche broccoli for freezing

Enzymes in foods can also cause color changes, and enzymes do not stop working when frozen. They will slow down dramatically, but they are still active.

Meats and high acid foods like fruit and tomatoes aren't affected as much by enzyme activity. Low acid foods like most vegetables should be blanched prior to freezing to destroy enzymes and stop their activity.

Freezing Basics - Freezer Burn

Freezer burn can happen when air is in contact with the surface of the food being frozen. Moisture is drawn out of the food and forms ice crystals on the surface, causing a dry, discolored tough spot that usually has an off flavor and an unpleasant texture.

A puncture hole or tear in a bag of frozen food can happen due to rough handling in the freezer.  If a small spot of freezer burn occurs, you can cut it away when you thaw it out, and still use the food.

If freezer burn happens over the entire surface (or a large portion) of a package of food, you might as well throw it out. It would still be safe to eat, it just wouldn't  taste as good.  Meats with freezer burn can still be used in soups and stews.

The best protection against freezer burn is to avoid exposing the frozen food to air. Pack foods in water, or it's own natural juices, or vacuum package it.  Once in the freezer, don't handle frozen foods roughly and you are much less likely to puncture or tear the packaging.

Freezing Basics - Power Outages

Unless you have a reliable home generator or access to dry ice, frozen foods are at risk of thawing and spoilage during an extended power outage. That being said, foods in a freezer are usually OK for a surprisingly long period of time.

A freezer full of food will be safe for up to 48 hours without electricity, if the lid or door is kept closed.

A half full freezer is normally OK for 24 hours.

Addition of dry ice can roughly double the time food stays frozen without electricity. Use about 25 to 50 pounds in a 15-20 cubic foot freezer.

It's a good idea to research in advance to find out where you can purchase dry ice in case of an emergency.  It's easier than frantically trying to call around when things are thawing out...

Quick Freeze Please

Food that is frozen quickly will be of better quality than food that has frozen slowly. Quick frozen foods form very small ice crystals - which is good. Food that freezes slowly, forms larger ice crystals which can damage cell walls in food.

Fruits and vegetables become much softer and mushier if they are frozen slowly. Meats that were frozen slowly tend to leak juices after it thaws, due to the cell damage, and will cook up much drier.

Many fruits and berries benefit from flash freezing, then vacuum packaging once they are frozen hard.  The vaccum packaging will do less damage to them that way, and they are MUCH easier to handle.

Flash frozen blackberries ready to be vacuum packaged.

When freezing food, package it as thinly as reasonable. A half inch thick package will freeze through much faster than a 2 inch thick package. Spreading the packages out in your freezer during initial freezing will also promote quick freezing.

Stacking packages results in much slower freezing through to the center packages.

Once frozen, you can stack it all up neatly. We will often use cookie sheets to help keep packages flat during freezing.

An added benefit to keeping foods frozen flat, is that it will make them more compact and easier to stack and store in your freezer.  This also can give you more freezer capacity by less wasted air space.

Freezing Basics:
Labeling and Inventory Control

Packages of fish fillets - oldest in front, newest in back

Always label foods that you are packaging to freeze. Identify what is in the package and the date that it was frozen. It's not always easy to tell two different same colored foods apart just by looking at the package.

Here are a few things I've gotten mixed up in the past, that I thought for sure that I could tell apart so didn't bother labeling! Summer squash and sweet corn, green beans and okra, beef cubes and beef stew.

Knowing the freezing basics before you start, will prevent unnecessary loss and waste.  Use fresh clean food to avoid contamination, package and handle carefully to avoid damage & freezer burn, and use appropriate packaging for the food you will be freezing. 

Use the FIFO (first in - first out) inventory system. Package frozen foods in the freezer so that it is easy to use the oldest first.  Follow these basics and you will have success in freezing and increasing your family's food self sufficiency.

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