Canning Foods at Home Safely
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In this program…..
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Food safety issues
Things to think about when canning
Food safety concerns when canning
10 tips for canning food safely at Home
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Why preserve food?
• Store good quality food for later use
– May be an economic advantage
• Protect food from spoilage
– mold, yeast and bacteria
• Keep food safe so it does not cause a foodborne
illness
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Food Spoilage
• Caused by microbes (a.k.a. bugs or germs)
• Caused by physical changes (bruises or
punctures in a food)
• Caused by enzymes found in fruits and
vegetables (need to be inactivated so taste
and texture changes do not occur)
Food spoilage = money wa$ted
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Bacteria
• Can cause food to spoil
• Can cause foodborne illness
• Bacteria have different requirements for living
– Oxygen vs. No oxygen
– High pH (low acid foods like vegetables and meat are
liked best by bacteria
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How Canning Preserves Food
• Canning
– Heat destroys bacteria and inactivates enzymes
– The seal formed during canning keeps other germs
from re-contaminating the food
• Pickling
– Makes a food more acidic so
it is harder for bacteria to grow
– Canning (processing) destroys other
bacteria and seals the lids
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How Food Preservation Works
• Jams and Jellies
– Sugar binds the water; germs are not able to use
the water
– Canning, freezing or refrigeration helps prevent
surface contamination by yeast or mold
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Should I can? Things to Consider:
• Food
– What are the safest methods for preserving?
– Which methods yield the best results?
– What is your skill level? Do you have the time?
• Storage capacity
– Do you have shelf space in a pantry
• Cost
– What equipment do you have available?
– Cost of equipment (canner & tools)
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Basic Equipment for Canning
Lid lifter
Jar lifter
Jar wrench – NOT RECOMMENDED
Funnel
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Don’t get bugged by deadly germs
• Clostridium botulinum
– Commonly found in the soil; come in 2 forms
• Vegetative cells (active cells – produce a deadly toxin)
– Anaerobic (live without oxygen)
– Killed by boiling in water (212 degrees)
• Spores (often in the soil; inactive; in hibernation)
– Spores can only be killed if they are boiled at 240 degrees
(must be done with a pressure canner)
– This bacteria loves a low-acid environment (think
meat and vegetables!)
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How botulism can be a problem
Fresh green beans with
inactive spores.
These green beans were canned in a
waterbath canner instead of pressure
canner. The lids sealed, creating an
Anaerobic (no oxygen) environment.
This environment causes the spores to
wake up and become active. They
divide, become overpopulated and start
to die. When that happened, they
produced the botulism toxin.
The green beans are now
contaminated
with the botulism toxin.
You can’t see the toxin!
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The pH of a food determines which
canning method you can safely use
pH = < 4.6
High Acid Foods
Pickles
Apricots
Apples
Raspberries
Apricots
Strawberries
Oranges
Blueberries
Grapefruit
Blackberries
Peaches
Pineapple
Grapefruit
Kraut
Plums
Pears
Figs
WATER BATH CANNER
pH >4.6
Low Acid Foods
Okra
Squash
Pumpkins
Carrots
Turnips
Cabbage
Beets
Beans
Potatoes
Spinach
Asparagus
Green peppers
Poultry
Corn
Hominy
Olives
Shrimp
Clams
Meat
Peas
Onions
PRESSURE CANNER
Source: So Easy to Preserve, 5th edition, University of Georgia,
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Keep You and Your Family Safe!
Follow these food safety tips
when canning foods at home.
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Food Safety Tips for
Canning Food at Home
1. Always begin food preservation with clean hands,
a clean preparation area, clean equipment and
the freshest foods available. Jars will be
inspected for nicks, cracks and rough edges
before used.
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Food Safety Tips for
Canning Food at Home
2. Always use a pressure canner when canning lowacid foods (pH > 4.6).
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Food Safety Tips for
Canning Food at Home
3. Get the dial gauge on your pressure canner
checked and tested each year.
More than half of home canners
do not test their gauges
on a yearly basis!
Source: University of Georgia, 2002
More than 1/3 of gauges tested in Nebraska
over 25 years tested too high, too low or
were unable to be tested.
Source: University of Nebraska, 2006
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Food Safety Tips for
Canning Food at Home
4. Only use tested recipes with up-to-date
researched processing times.
5. Never alter tested recipes.
- Exception: if you live at a high altitude (> 1,000 feet),
you have to adjust processing times
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Why adjust processing times
for altitude?
• At high altitudes, water boils at a lower
temperature. Even though the water is boiling,
the heat is not high enough to kill bacteria.
• By boiling longer or raising the pressure, we can
assure that any bacteria will be killed.
• Use tested recipes and guidelines for canning at
higher altitudes.
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How high altitude changes
processing times
Food
Jar size
Usual time (< 1000 feet)
1001-3000 ft
3001 - 6000 ft
Water bath canning
Crushed
tomatoes
quart
45 minutes
50 minutes
55 minutes
Jelly
quart
varies
Add 1 minute of processing time
per 1,000 ft of altitude
Pressure canning
Green beans quart
25 minutes
Process (canning) time depends
on altitude and type of pressure
canner (dial vs. weighed gauge)
Source: So Easy to Preserve, 5th edition, University of Georgia,
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Where to get Tested Recipes
YES!
Current Extension
publications
USDA
Manufacturers of home
canning equipment &
ingredients.
NO!
Personal internet sites
Cookbooks (esp. old ones)
“Back to nature”
publications
Out-of-date Extension
publications
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Food Safety Tips for
Canning Food at Home
6. When filling jars, be sure to use the correct
headspace.
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Food Safety Tips for
Canning Food at Home
7. Check jars for sealed lids and reprocess those
that do not seal within 24 hours.
This jar of pears sealed
the first time it was
processed.
This jar of pears had to
be reprocessed (canned) a
second time.
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Food Safety Tips for
Canning Food at Home
8. Label lids with date and batch number.
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Food Safety Tips for
Canning Food at Home
9. Periodically check jars for signs of spoilage.
If spoilage is present, do not use them.
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Food Safety Tips for
Canning Food at Home
10. For best quality, use homecanned foods within one year.
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For more information:
• So Easy to Preserve (University of Georgia
Cooperative Extension)
– http://www.uga.edu/setp/
• National Center for Home Food Preservation
– http://www.uga.edu/nchfp/
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Questions?
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