Can food be re-canned if the lid does not seal?
Canned food can safely be recanned if the unsealed jar is discovered within 24
hours. To re-can, remove the lid and check the jar sealing surface for tiny
nicks. Change the jar; if necessary, add a new treated lid and reprocess using
the same processing time.
If canned foods have been frozen during storage, are they
safe to eat?
Freezing does not cause food spoilage unless the seal is damaged or the jar is
broken. These often happen as the food expands during freezing. Frozen foods,
however, may be less palatable than properly stored canned food. In an unheated
storage place, protect canned foods by wrapping the jars in paper or covering
them with a blanket.
If my recipe doesn't call for processing, do I need to do
so?
Many recipes passed down through the years or found in older cookbooks do not
include instructions for processing. The foods are usually canned by the open
kettle method, sealed and stored. Foods prepared in this manner present a
serious health risk — particularly low acid foods. To minimize the risk of
food spoilage, all high acid foods should be processed in a water bath canner or
pressure canner and all low acid foods in a pressure canner.
Do I really need to leave a certain amount of headspace
in the jar?
Yes, leaving the specified amount of headspace in a jar is important to assure a
vacuum seal. If too little headspace is allowed the food may expand and bubble
out when air is being forced out from under the lid during processing. The
bubbling food may leave a deposit on the rim of the jar or the seal of the lid
and prevent the jar from sealing properly. If too much headspace is allowed, the
food at the top is likely to discolor. Also, the jar may not seal properly
because there will not be enough processing time to drive all the air out of the
jar.
How long will canned food keep?
Properly canned food stored in a cool, dry place will retain optimum eating
quality for at 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.
Is it necessary to sterilize jars before canning?
Jars do not need to be sterilized before canning if they will be filled with
food 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, once filled, need to be
sterilized first by boiling them in hot water for 10 minutes before they're
filled.
Is it safe to process food in the oven?
No. This can be dangerous because the temperature will vary according to the
accuracy of oven regulators and circulation of heat. Dry heat is very slow in
penetrating into jars of food. Also, jars explode easily in the oven.
Can two layers of jars be processed in a canner at one
time?
Yes, two layers can be processed at one time, in either the boiling water bath
or pressure canner. Place a small wire rack between the layers so water or steam
will circulate around each jar. Make certain that the water covers the tops of
all jars by 1 inch in a boiling water bath canner. The pressure canner should
have 2 to 3 inches of water in the bottom.
Is it necessary to exhaust a pressure canner?
Yes, it is very important to allow steam to escape for 10 minutes before closing
the valve, or placing the weight on the vent. If the canner is not exhausted,
the inside temperature may not correspond to the pressure on the gauge.
Should liquid lost during processing be replaced?
No. Loss of liquid does not cause food to spoil, though the food above the
liquid may darken. If, however, the loss is excessive (for example, if at least
half of the liquid is lost), refrigerate the jar(s) and use within 2 to 3 days.
Is it all right to reuse jar fittings (lids and bands)?
Lids should not be used a second time since the sealing compound becomes
indented by the first use, preventing another airtight seal. Screw bands may be
reused unless they are badly rusted or the top edge is pried up which would
prevent a proper seal.
Why is open kettle canning not recommended?
In open kettle canning, food is cooked in an ordinary kettle, then packed into
hot jars and sealed without processing. The temperatures obtained in open kettle
canning are not high enough to destroy all spoilage and food poisoning organisms
that may be in the food. Also, microorganisms can enter the food when it is
transferred from the kettle to jar and cause spoilage.
Why do the undersides of metal lids sometimes discolor?
Natural compounds in some foods, particularly acids, corrode metal and make a
dark deposit on the underside of jar lids. This deposit on lids of sealed,
properly processed canned foods is harmless.
What causes jars to break in a canner?
Breakage can occur for several reasons:
1. Using commercial food jars rather
than jars manufactured for home canning, 2. Using jars that have hairline
cracks, 3. Putting jars directly on bottom of canner instead of on a rack, 4.
Putting hot food in cold jars, or 5. Putting jars of raw or unheated food
directly into boiling water in the canner, rather than into hot water (sudden
change in temperature-too wide a margin between temperature of filled jars and
water in canner before processing).
If I find mold growing inside a jar of canned food, can
I just scrape it off and eat the food?
Mold growth in foods can raise the pH of the food. In home canned products, this
could mean that the high acid products could become low acid and therefore run
the risk of botulism or other bacterial spoilage. Thus, any home canned product
that shows signs of mold growth should be discarded. The exception to this is
jellied products. In these the high sugar content would prevent the growth of
Clostridium botulinum. In jellied products, remove any surface mold plus 1/2
inch of the good product underneath and then use the rest immediately. Jellied
products with extensive mold should be discarded.
How can I remove scale or hard-water film from canning
jars?
Soak jars for several hours in a solution containing 1 cup of vinegar and 1
gallon of water.
What can I process in half-gallon canning jars?
One or more canning jar manufacturers are selling half-gallon canning jars. One
manufacturer has a printed note on the top that says half-gallon jars are only
used for some highly acidic foods in a boiling water canner.
The only processes that USDA, the National Center for Home Food Preservation and the University of Georgia have to recommend for half-gallon jars are for very acidic fruit juices (and juice only): See more information on their web site here: Apple Juice (http://www.homefoodpreservation.com/how/can_02/apple_juice.html) and Grape Juice (http://www.homefoodpreservation.com/how/can_02/grape_juice.html). This process time is not to be used for tomato juice, for example.
There are no other research-tested processes for half-gallon jars. Boiling water processes for other foods for jars larger than those published with recipes (usually pints and/or quarts) cannot be extended by any formula to a larger jar.
We are aware that there are historical recommendations for canning foods in half-gallon jars. However, these are not currently accepted or endorsed by the USDA, Cooperative Extension System or U.S. manufacturers of home canning jars.
Is it safe to can food without salt?
Yes. Salt is used for flavor only and is not necessary to prevent spoilage.
Is it 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.
Can fruits and vegetables be canned without heating if
aspirin is used?
No. Aspirin should not be used in canning. It cannot be relied on to prevent
spoilage or to give satisfactory products. Adequate heat treatment is the only
safe procedure.
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).
Should all vegetables be precooked before canning?
For best quality, yes. However, some vegetables can be packed raw or cold into
jars before being processed in the pressure canner.
What vegetables expand instead of shrink during
processing?
Corn, peas and lima beans are starchy and expand during processing. They should
be packed loosely.
What causes corn to turn brown during processing?
This occurs most often when too high a temperature is used causing
caramelization of the sugar in the corn. It may also be caused by some minerals
in the water used in canning.
Why is canning summer squash or zucchini not
recommended?
Recommendations for canning summer squashes, including zucchini, that appeared
in former editions of So Easy to Preserve have been withdrawn due to uncertainty
about the determination of processing times. Squashes are low-acid vegetables
and require pressure canning for a known period of time that will destroy the
bacteria that cause botulism. Documentation for the previous processing times
cannot be found, and reports that are available do not support the old process.
Slices or cubes of cooked summer squash will get quite soft and pack tightly
into the jars. The amount of squash filled into a jar will affect the heating
pattern in that jar. It is best to freeze or pickle summer squashes, but they
may also be dried.
Can I can my own salsa recipe?
Salsas are usually mixtures of acid and low-acid ingredients; they are an
example of an acidified food. The specific recipe, and sometimes preparation
method, will determine if a salsa can be processed in a boiling water canner or
a pressure canner. A process must be scientifically determined for each recipe.
To can salsa at home, use our recipes for Hot Chile Salsa or Mexican Tomato
Sauce. Your County Extension agent may have additional tested recipes for
salsas.
Should giblets of chicken be canned in the same jar with
chicken?
No. Their flavor may permeate other pieces of chicken in the jar.
Is it safe to can meat and poultry without salt?
Yes. Salt is used for flavor only and is not necessary for safe processing.
Why is it necessary to remove as much fat from meats as
possible before canning?
Any fat that gets on the rim of the canning jar can prevent an airtight seal.
Excess fat in jars makes it easier for the fat to climb the sides of the jar and
contaminate the seal.
Can I get directions for canning my Brunswick stew at
home?
Recommendations for canning Brunswick stews at home have not been scientifically
determined. These are low-acid mixtures which could support the growth of
bacteria that cause botulism, so a process cannot be estimated or made up. It
must be a tested process known to kill these bacteria in this product. In
addition, the recipes for Brunswick stew vary and a process would have to be
developed through scientific testing for each variation. No directions for this
product are available at this time. It is best to freeze Brunswick stews.
Can I can bread or cake in a jar?
These products are not recommended for canning; choose recipes that you can
freeze. In fact, most of these products are not really "canned." The
directions call for baking in the jar and then closing with a canning lid. Many
recipes for quick breads and cakes are low-acid and have the potential for
supporting the growth of a bacteria like Clostridium botulinum if it is present
inside the closed jar. One university's research showed a high potential for
problems. You will see these products made commercially; however, additives,
preservatives and processing controls not available for home recipes are used.
Canning jar manufacturers also don't endorse baking in their canning jars.
How do I can oil with herbs? Can I can pesto?
Herbs and oils are both low-acid and together could support the growth of the
disease-causing Clostridium botulinum bacteria. Oils may be flavored with herbs
if they are made up for fresh use, stored in the refrigerator and used within 2
to 3 days. There are no canning recommendations. Fresh herbs must be washed well
and dried completely before storing in the oil. The very best sanitation and
personal hygiene practices must be used. Pesto is an uncooked seasoning mixture
of herbs, usually including fresh basil, and some oil. It may be frozen for long
term storage; there are no home canning recommendations.
 | Storing Home Canned Foods |
| Packaging and Storing Dry Foods |
| Food Storage for Safety and Quality (Colorado State University) pdf |
| Cupboard Approximate Storage Times (Kansas State University) pdf |
| Refrigerator/Freezer Approximate Storage Times (Kansas State University) pdf |
| Proper Care and Handling of Fruits and Vegetables From Purchase to Preparation (Penn State University) pdf |
| Storing Vegetables at Home (University of Wisconsin) pdf |
| Safe Home Food Storage (Texas A&M University) pdf |
Problems and troubleshooting jellied products
| What do I do if there's mold on my jellied fruit product? NCHFP |
| Why did my jellied fruit product ferment, and what do I do? NCHFP |
| What happens if my jam or jelly doesn't gel? NCHFP |
| Ingredient Problems in Jelly and Jam N. Dakota State Univ. |
| Common Problems in Jam and Jelly Making N. Dakota State Univ. |
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Canning booksCanning & Preserving for Dummies
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The Ball Blue Book of PreservingThis is THE book on canning! My grandmother used this book when I was a child. It tells you in simple instructions how to can almost anything; complete with recipes for jam, jellies, pickles, sauces, canning vegetables, meats, etc. If it can be canned, this book likely tells you how! Click on the link below for more information and / or to buy (no obligation to buy) Price $8.95 |
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Complete Water Bath Canner KitThis is the same type of standard canner that my grandmother
used to make everything from applesauce to jams and jellies to tomato and
spaghetti sauce!. This complete kit includes everything you need and
lasts for years:
the canner, jar rack, jar grabber tongs,
lid lifting wand, six pint jars with lids and rings, a plastic funnel,
labels, bubble freer, and the bible of canning, the Ball Blue Book. It's
much cheaper than buying the items separately. You'll
never need anything else except more jars and lids! Average Customer Review:
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Lids, Rings, Jars, mixes, pectin, etc.
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