Frequently Asked Questions

Family and Consumer Sciences


How long will home canned food keep?

Properly canned food stored in a cool, dry place will retain optimum eating quality for a least 1 year. Canned food stored in a warm place near hot pipes, a range, a furnace, or in indirect sunlight may lose some of its eating quality in a few weeks or months, depending on the temperature. Dampness may corrode cans or metal lids and cause leakage so the food will spoil.

What is blanching?

Heating or scalding the vegetables in boiling water or steam for a short period of time.

It is necessary to sterilize jars before canning?

Jars do not need to be sterilized before canning if they will be filled with foods and processed in a boiling water bath canner for 10 minutes or more or if they will be processed in a pressure canner. Jars that will be processed in a boiling water bath canner for less than 10 minutes need to be sterilized by boiling them in hot water for 10 minutes before they are filled.

Is it safe to can food without salt?

Yes. Salt is used for flavor only and is not necessary to prevent spoilage.

It is safe to can fruits without sugar?

Yes. Sugar is added to improve flavor, help stabilize color, and retain the shape of the fruit. It is not added as a preservative.

Is it safe to can green beans in a boiling water bath if vinegar is used?

No. Recommended processing methods must be used to assure safety. Recommended processing times cannot be shortened if vinegar is used in canning fresh vegetables (this does not refer to pickled vegetables). For more information on canning green beans or questions about canning in general, read Preparing Beans, Snap and Italian -- Pieces: Green and Wax for Canning or visit the National Food Safety Database web page.

How long will food remain frozen if the power goes off?

Foods stay frozen longer if the freezer remains unopened, is full, is in a cool place and is well insulated. Usually food in a loaded freezer will stay frozen for two to four days, depending on its size. A half-filled freezer will keep food frozen only about 24 hours. Cover the freezer with blankets, keeping them away from the compressor, to help hold the cold.

Can food be refrozen if is has been thawed?

Foods which have only partially thawed and still have ice crystals in the package can be safely refrozen, though quality will be poorer. Meat, fish, poultry, prepared foods, vegetables and fruits can be refrozen if the freezer temperature is 40° or below and if color and odor are good. However, their quality will be lower.  If freezer temperature rises above 40° , food safety issues arise.  The safest action is to dispose of such food items.

Brenda Williams

Questions? E-Mail Brenda at

Food Preservation Publications (EDIS)