U of I Extension
Freezing your summer harvest

 

[July 30, 2020] 

Freezing has many benefits. It maintains the fresh flavor, natural color, and nutritional value better than canning or dehydrating. Plus, it is easy, convenient and requires less time compared to other food preservation methods. Making it an excellent way to preserve the summer harvest.

To successfully freeze your summer harvest, it is important to acknowledge a few basic principles. First, freezing will stop the growth of harmful microorganisms. However, once thawed, microorganisms become active and begin multiplying rapidly. Therefore, it is important to safely thaw food in the refrigerator or microwave.

Second, natural chemical changes occur during the freezing process, due in part to enzyme activity. If enzymes are not inactivated, you may be very disappointed in your end-product. This is because enzyme activity effects the quality of your product, leading to changes in color, texture, and flavor. As well as loss of nutrients, such as Vitamin C in fruits.

The activity of enzymes is specific for the actual type of enzyme and is dependent on both pH and temperature, and this activity helps to speed up the deterioration or breakdown of food. It is important to understand that freezing does not stop enzyme activity; only blanching will inactivate enzymes in vegetables.

Blanching vegetables 101

Blanching vegetables is easy and will allow you to have a better-quality product when it comes time to enjoy your vegetables later in the year.

Blanching is the process of quickly exposing vegetables to boiling water or steam for a specified amount of time and then rapidly cooling. Blanching is needed to inactive enzymes which as shared earlier, can lead to loss of flavor, color, and texture.

For the record, blanching is not required from a food safety standpoint. However, it will affect the quality of frozen vegetables. And after all the hard work you have put in growing, harvesting, and preserving your garden, don’t you want a quality product when it comes time to enjoy it?

In addition to inactivating enzymes, blanching also destroys microorganisms on the surface of vegetables, brightens the color, slows the loss of vitamins, and softens the vegetable.

Steps for blanching vegetables

1. Use one gallon of water per pound of prepared vegetables.

2. Place vegetables in a blanching basket and lower into vigorously boiling water. Place a lid on the kettle. The water should return to boiling within 1 minute. If water does not return to a boil within 1 minute, too many vegetables are being used for boiling water.

3. Begin counting blanching time as soon as the water returns to a boil.

*Blanching times will vary depending upon the type and volume of vegetables being blanched. For more information about blanching times click here.

Finally, it is important to remember nothing will ever come out of the freezer in better condition than when it went in. Therefore, always select good quality produce. Fruits and vegetables should be free of disease, mold and not overripe.

Having a better understanding of the changes that occur during the freezing process and why they occur is a key factor in successfully freezing your garden harvest.

References:
Andress, Elizabeth L., and Judy A Harrison. Freezing. 2014, nchfp.uga.edu/how/freeze/blanching.html.
United States Department of Agriculture Food Safety and Inspection Service. (2013, June 15). Freezing and Food Safety.

https://www.fsis.usda.gov/wps/portal/
fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/safe-food-handling/freezing-and-food-safety/ct_index.

[WRITER: Diane Reinhold, MPH, MS, RDN, University of Illinois Extension, Educator, Nutrition and Wellness]