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Food Safety - Food Preservation
National Center for Home Food Preservation
Blanching Is Essential When Freezing Home Grown Vegetables
Freezing is an excellent and easy way to preserve fresh vegetables whether you pick from your garden or purchased at a local farmer’s market. To keep that fresh flavor taste, remember that blanching vegetables is an essential step when freezing vegetables.
Blanching stops enzyme action from destroying the fresh flavor of your vegetables. If vegetables are not blanched, they will loose their color and flavor after about four to six weeks of freezer storage.
Blanching cleanses the surface of dirt and organisms, brightens the color and helps retard loss of vitamins. It also wilts or softens vegetables and makes them easier to pack.
Blanching time is crucial and varies with the vegetable and size. Under blanching stimulates the activity of enzymes and is worse than no blanching. Over blanching causes loss of flavor, color, vitamins and minerals.
For home freezing, the most satisfactory way to heat all vegetables is in boiling water. Use a blancher which has a blanching basket and cover, or fit a wire basket into a large pot with a lid. Use one gallon water per pound of prepared vegetables. Put the vegetable in a blanching basket and lower into vigorously boiling water. Place a lid on the blancher. The water should return to boiling within 1 minute, or you are using too much vegetable for the amount of boiling water. Start counting blanching time as soon as the water returns to a boil. Keep heat high for the time given in the directions for the vegetable you are freezing.
Heating in steam is recommended for a few vegetables. For broccoli, pumpkin, sweet potatoes and winter squash, both steaming and boiling are satisfactory methods. Steam blanching takes about 1½ times longer than water blanching.
To steam, use a pot with a tight lid and a basket that holds the food at least three inches above the bottom of the pot. Put an inch or two of water in the pot and bring the water to a boil.
Put the vegetables in the basket in a single layer so that steam reaches all parts quickly. Cover the pot and keep heat high. Start counting steaming time as soon as the lid is on. See steam blanching times recommended for the vegetables listed below.
Microwave blanching may not be effective, since research shows that some enzymes may not be inactivated. This could result in off-flavors and loss of texture and color. Those choosing to run the risk of low quality vegetables by microwave blanching should be sure to work in small quantities, using the directions for their specific microwave oven. Microwave blanching will not save time or energy.
As soon as blanching is complete, vegetables should be cooled quickly and thoroughly to stop the cooking process. To cool, plunge the basket of vegetables immediately into a large quantity of cold water, 60ºF or below. Change water frequently or use cold running water or ice water. If ice is used, about one pound of ice for each pound of vegetable is needed. Cooling vegetables should take the same amount of time as blanching. Drain vegetables thoroughly after cooling. Extra moisture can cause a loss of quality when vegetables are frozen.
Just remember that blanching ensures that fresh vegetables stay fresh in the freezer. For more information on home food preservation contact the Ohio State Extension Office at 937-378-6716.
Here are recommended blanching times for some commonly frozen vegetables:
| Asparagus | |
| Small Stalk | 2 minutes |
| Medium Stalk | 3 minutes |
| Large Stalk | 4 minutes |
| Beans-Snap, Green, or Wax | 3 minutes |
| Broccoli flowerets | 3 minutes |
| Cabbage (shredded) | 1 ½ minutes |
| Corn-on-the-cob | |
| Small Ears | 7 minutes |
| Medium Ears | 9 minutes |
| Large Ears | 11 minutes |
|
Whole Kernel or Cream Style |
4 minutes |
| Cauliflower flowerets | 3 minutes |
| Peas | 2 minutes |
| Squash | 3 minutes |
Safe and Reliable Food Preservation Information Available from OSU Extension Office in Brown County
Whether you are canning green beans, freezing corn, or making blackberry jam, be sure that you are doing it correctly so that you will produce a safe and high quality food product for you and your family to enjoy. If you are going to can or freeze garden produce and fruit this summer, you need to be sure that you are using up-to-date and reliable food preservation information and safe processing methods. Where can you find this reliable information quickly, easily and free of charge? It is as easy as calling the Ohio State University Extension Office at 378-6716. You can also stop by our office located at 740 Mt. Orab Pike in Georgetown. We can provide you with the most current information available and also assist you with canning problems and questions.
Testing of Dial Gauge on Pressure Canners.
If you have a pressure canner with a dial gauge you need to have the gauge tested yearly for accuracy. This is the only way to know if you are processing your home canned foods at the proper poundage and temperature. If your gauge is reading incorrectly, you could be under processing which produces a food safety risk, or over processing foods, which will affect the quality of the food. To test your gauge, call and make an appointment with Kathy Jelley, FCS Extension Educator at 378-6716. The testing process takes about 10 minutes and is free of charge.
Green beans must be canned using a pressure canner.
Each year I receive several calls from people wanting to know the processing time to water bath green beans. No such processing time exists because water bathing is not recommended for canning green beans or any low acid vegetable or food. It is an unsafe canning method for low acid foods because the processing temperature in a boiling water bath can only reach 212 degrees F. This is not a high enough temperature to kill the spores that cause botulism which is a deadly type of food poisoning which can form in low acid canned vegetables. However, in a pressure canner a high enough temperature of 240 degrees F. can be reached which will kill the botulinum spores.
Green beans can be safely canned in a pressure canner using 11 pounds pressure in a dial gauge canner, and 10 pounds pressure in a weighted gauge canner, processing pints for 20 minutes and quarts for 25 minutes. If you do not have access to a pressure canner, you may want to consider freezing your green beans. This is a safe and quick method for preserving beans.
Call the OSU Extension at 378-6716 for information,
free fact sheets and assistance with home food preservation.
