Transcript Preserving Nature`s Bounty

Department of Family and Consumer Sciences
Preserving
Nature’s Bounty
Principles of Home
Canning
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Department of Family and Consumer Sciences
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Department of Family and Consumer Sciences
How Canning Preserves Foods
• Control growth of undesirable
microorganisms
– Bacteria
– Molds
– Yeasts
• Control activity of enzymes
• Control
– Reactions with oxygen
– Moisture Loss
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Department of Family and Consumer Sciences
Proper Canning Practices
• Carefully selecting and washing
fresh food
• Peeling some fresh foods
• Hot packing many foods
• Adding acids (lemon juice or
vinegar) to some foods
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Department of Family and Consumer Sciences
Proper Canning Practices
• Using acceptable jars and selfsealing lids
• Processing jars in a boilingwater or pressure canner for
the correct time
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Department of Family and Consumer Sciences
Not recommended
• Open-kettle
canning
• Microwave canning
• Dishwasher canning
• Oven canning
Open-kettle canning
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Department of Family and Consumer Sciences
Temperatures
• 2400 F – low acid foods
– Pressure canning
– Kills bacterial spores
• 2120 F – high acid foods
– Water-bath canning
– Kills molds, yeasts and some
bacteria
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Department of Family and Consumer Sciences
Temperatures
• 0o F
– Freezing
– Temporarily stops growth of microbes,
does not kill
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Department of Family and Consumer Sciences
How Canning Works
• Air is driven from the jar or can
• A vacuum seal is formed
• Prevents air (with
microorganisms) from getting
back into food
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Department of Family and Consumer Sciences
The Effect of Altitude
• Affects how long food is processed;
water boils at lower temperatures as
altitude increases
• For water-bath canning: Add time for
higher altitudes
• For pressure-canning: Add pressure for
higher altitudes
• Tennessee Valley varies from 20002500 feet
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Department of Family and Consumer Sciences
Use Mason Jars
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½ pint
Pint
Quart
½ gallon
(for high-acid juices only)
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Use Two-Piece Lids
• Rings
• Seals (cannot be reused)
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Jars to Avoid
• Old-style jars
– Wire bails and zinc lids
– Cannot be fitted and sealed
• Commercial jars
– Mayonnaise, peanut butter, etc.
– Narrower sealing surface
– Less tempered (will
break in pressure
canners)
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Department of Family and Consumer Sciences
Raw or Hot Pack
• Raw-Pack
– Pack jars with uncooked product
• Hot-Pack
– Pack jars with cooked product
– Maintains better color over time
– Removes more air
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Department of Family and Consumer Sciences
Control Headspace
• Space between product
and lid
– ¼ inch for jams and jellies
– ½ inch for fruits and tomatoes
– 1 to 1 ¼ inch for foods processed in pressure
canners
• Too much space, takes too
long to drive out air
• Too little space, may not seal
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Department of Family and Consumer Sciences
Filling Jars
• Fill clean jars with
food
• Remove excess air
• Wipe rims
• Apply lids and rings
• Tighten fingertip
tight
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Department of Family and Consumer Sciences
General Principles
• Follow tested recipes
• Do not alter ingredients
• Use water-bath canner for high acid
foods, pickles, jellies
• Use pressure canner for low acid
foods
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Department of Family and Consumer Sciences
For more information on
preserving foods safely, contact
Pat Whitaker,Extension Agent
Family & Consumer Sciences
Rutherford County
Developed by Janie Burney, PhD, RD
Professor, Family and Consumer Sciences
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