Questions About Storage and Safety of Home Canned Foods

How do I care for jars once they come out of the canner?

• When removing jars from the canner, place on wire rack, terry towel, or wooden board. Do not place on cold countertops, which increases the risk of breaking the jar.

• Cool jars 24 hours. Then check for seals. Remove screwband so that it will not rust.

• Label jars with day, and canner batch and style of pack

• Store in a cool dry place. Use within one year.

Why do lids buckle? Lids may buckle when screwbands are tightened too tightly, or jars are overfilled. Lids may also buckle when the canner is cooled with water, placed where cool air blows on it, or the canner vent was opened before the pressure returned to zero.

What causes food to darken at the top of home canned foods? Food may darken if not covered with liquid or if there is too much headspace. When the headspace is too large, the processing time is not long enough to drive out all the extra air from the top of the jar. This means a tight vacuum may not be formed, and the air left in the jar causes food to discolor.
If the jar is filled too full (leaving too little head space), the contents may boil out during processing. Seeds or solids caught under the flat can prevent the jar from sealing.
For the correct headspace for each food, follow processing directions exactly.

What causes canned foods to spoil? There are several types of spoilage:

Fermentation usually occurs in food that was not processed in a boiling water bath canner or pressure canner, since yeast is easily killed at temperatures of 155o F. Foods high in sugar are most likely to ferment – fruits and fruit juices. Prevent fermentation by hot filling jars of fruit juice, using sterilized jars, and process for 10 minutes or more.

Flat sour occurs if canned food is allowed to cool in the canner overnight, if food is packed too tightly in the jar, or not cooled properly. Flat sour has a very sour smell or unpleasant odor. No gas is present, but the liquid is very cloudy. Foods affected are tomatoes, beans, peas, corn, pumpkin, and greens.

# 1 Rule of Food Safety
When in Doubt,
Throw it Out!

Putrification is a very foul odor that intensifies with heating. The food is soft and slimy with gas bubbles present. Pressure canned foods are at risk if done improperly – fat, meats, greens, corn, beans, and peas.

Botulism is most frequently found in improperly canned protein foods, like meat, fish, poultry and vegetables. May have a rancid or rotten odor, or no odor at all. Gas may be present, the food may be slimy, and the liquid may be discolored, but not always.

Mold is a fuzzy, gray or white growth on the surface. I t may have a musty odor and the food may be slimy. Mold affects fruits, vegetables, and meats.

Other August  2005 Articles:
Missouri Grapes Serve Many Purposes
Canning, Freezing and Drying Grapes
Making Jams & Jellies with Added Pectin