Canning
is a great way to preserve vegetables and fruits for your own use or for gifts.
The basic principal is simple: during the canning process, food is heated to a
high enough temperature to stop the decaying action of enzymes and/or bacteria
and other microorganisms in the food. The food is then stored in sterile,
airtight containers to prevent contamination.
This
isn't a process you should treat carelessly. Contaminated food can cause
illness, and botulism and it isn't something you want to mess with. Always
remember these things:
- Choose
only perfect produce. Overripe or damaged fruits and vegetables are more
prone to spoilage.
- Your
jars, lids and sealing rings should be in good condition and sterile (washed
and scalded).
- Wash
your produce thoroughly before processing.
- Know
your produce. Be sure to use the correct time, temperature and method of
processing for the food you will be canning.
- After
canning, check the seal on every jar to make sure they are air tight - when
you push down on a self-sealing lid, it should stay down. Test porcelain
lids by turning the jars upside down. If you see a stream of tiny air
bubbles, the seal is not air-tight.
- Don't
use foods from any jar that has a foamy or discolored appearance. Watch for
bulging or misshapen lids and leaking rims. Throw those jars away.
- Home
canned vegetables should be boiled before they are served (with the
exception of tomatoes).
PREPARING
AND PACKING
Jars
vs. Cans
Generally canning with glass jars is best, simply because you can see the
produce. It's easy to check for damage, leaking, and discoloration. Glass jars
are also cheaper, easier to use, and you can reuse them over and over again! Tin
cans may not break like a glass jar, but if you use tin cans for canning, you'll
need to buy a sealing device.
Glass
jars commonly used today have either a porcelain-lined cap, which consists of a
screw top and rubber ring, or a self-sealing cap, which consists of a flat lid
with sealant around the rim and a screw-on band that holds the lid against the
lip of the jar. The band can be reused, but you should use a new lid for each
process. Old-fashioned clamp-type jars can still be found, but do not use
decorative replicas for canning. With this type, the glass lid and rubber ring
are held in place with a long clamp during processing, and then a short clamp is
snapped down for a tight seal.
Wash
all produce prior to packing into containers. Vegetables and large fruits can be
cut into pieces and pitted if necessary. Smaller fruits such as berries can be
left whole. Fruits can be dipped in ascorbic acid (vitamin C) and packed in
sugar syrup to preserve their color, texture and flavor.
There
are two ways to pack the produce into the jars before processing: raw or cooked.
Raw
Packed:
Pack clean produce tightly into containers and pour on boiling juice, water or
syrup. Wipe the rim and sealing ring to remove any food particles, then close
the jar and proceed with the canning process.
Hot
Packed:
Steam or heat vegetables or fruits to boiling in juice, water or syrup, then
immediately pack them into the jars.
If
you are using a porcelain-lined cap jar, wet the rubber ring and fit it against
the top/shoulder of the jar. Screw the cap on firmly, then back off one quarter
turn. After processing, immediately screw the cap tightly again.
If
you are using a self-sealing cap jar, tighten band before processing and don't
loosen it again.
PROCESSING
There
are two methods of canning fruits and vegetables: boiling water bath or pressure
canning. Low acid vegetables (everything except tomatoes) can harbor
heat-resistant bacteria, and should be heated to at least 240°F - a temperature
that can only be produced by pressure canning. High acid food, which includes
tomatoes, pickled vegetables and most fruits, can be processed at boiling water
temperature (212°F).
BOILING
WATER BATH.
You
will need:
Boiling water bath canner. This is basically a large, deep pan with a tight
fitting lid. It should be large enough to allow 4 or more inches of
"headroom" above the jars.
Wire basket or rack to fit inside the pan and hold your jars.
Tongs to lift jars out of boiling water.
Oven mitts to handle hot jars.
Cooling rack, or several towels.
Kitchen timer.
First:
Fill canner halfway with hot water and put the jars into it, either inside the
basket, or setting on a rack on the bottom of the pan. Add boiling water to 2
inches above the jars. Be careful not to pour boiling water directly onto the
jars.
Second:
Cover canner tightly and bring water to a rolling boil. Start the timer and
reduce heat just enough to maintain a rapid boil. Add boiling water throughout
if needed.
Third:
When time is up, remove jars immediately with the tongs. If necessary, tighten
the lids. Set the jars on a cooling rack or layer of towels to cool. Leave space
between cooling jars.
PRESSURE-COOKER CANNING.
You
will need:
Pressure
canner with an accurate dial or gauge.
Rack to fit inside the canner.
Tongs to lift jars out of boiling water.
Oven mitts to handle hot jars.
Cooling rack, or several towels.
Kitchen timer.
First:
Fill the pressure canner with 2-3 inches of hot water and put the jars on a rack
on the bottom of the pan. Jars should be spaced apart from each other.
Second:
Fasten the lid and place over a maximum heat. Let steam exhaust for 10 minutes.
When the first inch of the steam jet is nearly invisible, close the vent.
Third:
At 8 lb pressure, lower heat slightly. Let the pressure continue to rise to 10
lb. At 10 lb pressure, start timing. Hold at that pressure for the full canning
period. If pressure drops below 10 lbs at any time during the process, start
timing all over again.
Fourth:
Remove canner from heat and let it cool. (Don't pour cold water on it.) When the
pressure is zero, open the vent, then carefully open the lid, slanting it away
from you. Set the jars on a cooling rack or layer of towels to cool, leaving
spaces between the jars. Tighten lids if necessary.
After
canning, label the jars with their contents and the date they were canned. Store
jars in a cool, dark place. Light can cause discoloration and loss of nutrients.