Canning At Home

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					Canning At Home

  Rick Sloan
  FCS Agent
What will we learn?

   Principles of Canning
   Two Methods of Canning
   Packing Methods
   Canning Equipment
   Processing Time
   Boiling Water Processing
   Pressure Canning Processing

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Principles of Canning

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Canning Basics

 Food is placed in a canning jar and heated to a
  temperature that destroys targeted
 Heat also inactivates enzymes that cause
 Air is driven from the jar during heating. As
  the jar cools a vacuum seal is formed.

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Commercial Sterility

 All pathogens, spoilage bacteria, molds, and
  yeast are “killed.”
 Those that survive are thermophilic bacteria
  that cause spoilage but not illness.
   Some produce gases.
   Some produce bad odors.

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Vacuum Seal

 Holds the lid on the jar.
 Prevents recontamination of the food.
 Prevents air from drying out the food.

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Two Methods of Canning

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Two Methods of Canning

Boiling Water Canning
   Used for high-acid foods
Pressure Canning
   Used for low-acid foods.
   Can also be used for high-acid foods but might
    result in a soft texture.

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High-Acid Foods (pH < 4.6)

 All fruits, except for:
    figs
    tomatoes, and
    melons
 Rhubarb
 Fermented pickles, such as sauerkraut
 Acidified foods, such as pickles and tomatoes

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Low-acid Foods (pH > 4.6)

   All vegetables, except for rhubarb
   Meats
   Poultry
   Seafood
   Soups
   Mixed canned foods (low-acid + high-acid)

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Why Two Methods of Canning?

 Yeast, molds, and most bacteria are killed at boiling
  temperatures -- 212ºF at sea level.
 C. botulinum forms spores that require higher
  temperatures for destruction in a reasonable period
  of time -- usually 240ºF or above at sea level.

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Clostridium botulinum

 Clostridium botulinum bacteria are found naturally in
  soil and water.
 Seven known types, but only A, B, E and F cause
  illness in humans.
 This bacterium can produce heat-resistant spores.

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C. botulinum -- Growth

 To germinate, the spores need the following
       anaerobic environment (No Oxygen)
       low-acid food
       temperature between 40ºF and120ºF
       relatively high moisture

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C. botulinum -- Growth

Optimal conditions might be found in:
   Home canned foods
   Smoked fish and sausage
   Foil-wrapped baked potatoes sitting at room
   Packaged mushrooms
   Pot pies and other foods in gravy

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Botulinum Toxin

 The botulinum toxin, one of the deadliest known,
  causes botulism.
 1 mg can kill 655 tons of mice.
 Food can contain toxin without showing any signs.
 Antitoxin available, but slow recovery. Permanent
  nerve damage possible.

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Botulism -- Symptoms

Symptoms usually appear within 12 to 72 h after
eating contaminated food:
  •   Digestive upset (in some cases)
  •   Blurred, double vision
  •   Difficulty swallowing, speaking, and breathing
  •   Possible death from suffocation
  •   10-35% mortality rate

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Preventing Botulism

 Spores do not grow in high-acid foods.
 Spores killed when low-acid foods heated long
  enough at a specific temperature.
 Process low-acid foods in a pressure canner,
  which can reach a temperature of 240ºF.

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Preventing Botulism

 Prepare and process food according to
  instructions in a tested recipe.
 Canner gauge must be accurate and properly
 Use only high quality raw ingredients.
 If toxin is suspected, detoxify food before
  discarding. The toxin is destroyed by boiling
  even though the spores are not.

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Improperly Canned Foods

 Never consume improperly canned foods.
 Throw out – do not feed to animals.
 Boiling will not always adequately destroy
 When cleaning up surfaces contaminated by
  unsafe canned foods, prepare a 1:5 bleach to
  water solution.

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Packing Methods

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Raw Pack

 For foods that lose shape when cooked.
 Place raw food directly in jars. Pour boiling hot liquid
  over the food.
 Pack firmly, do not crush.
 Add jars carefully to warm canner to prevent jar
  breakage from heat shock.
 Preheat water to 140oF before putting raw-packed
  foods into boiling water bath.

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Hot Pack

 Preferred method for most foods.
 Food is cooked in liquid before packing. Cooking liquid
  is then poured over food in jar.
 Less floating of food pieces in the jar.
 Better food color and flavor.
 Easier to pack, foods more pliable
 Heat in preparing kills some microorganisms.
 Preheat water to 180oF before putting into boiling water

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Canning Equipment

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Pressure Canners

 Flat rack in bottom
 Pressure regulator or indicator:
     Dial or weighted gauge
     Older models have petcocks
   Vent pipe for pressurizing
   Safety valves or overpressure plugs
   Safety locks when pressurized
   Rubber gaskets in lid (metal to metal seal)

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Replacement Parts

 Dial gauges, when inaccurate
 Gaskets (sealing rings)
   Every 2 years usually
 Rubber overpressure plugs
   Every 2 years
 Vent pipes if clogged
 Air vent/cover lock from lid
 Weighted gauges or dead weight if lost

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Processing Time

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Processing Schedules

Length of time at a specific temperature that a food
must be processed.
Affected by:
pH value of the food
Composition of the food
      - Viscosity
      - Tightness of pack
      - Convection vs. conduction transfer of heat
      - Starches, fats, bones

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Processing Schedules

Affected by:
   Preparation style of food
   Initial temperature of food as it is filled into jar
   Temperature of processing
   Size of jar
   Shape of jar

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Significance of Heat Penetration

 Processing time is affected by whether food heats
  by convection, conduction, or a combination of
 Heat penetration studies used to scientifically
  determine safe processing times.
 The “cold spot” in the food must reach the correct
  temperature for the correct length of time to
  destroy target pathogens.

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Heat Penetration

Follow recipe exactly.
   The following slows heat penetration:
      Extra sugar or fat
      Oversized food pieces
      Added thickeners
Use recommended canners.
   Heat-up and cool-down times in pressure canners
    are counted toward sterilizing value of the
    process. Do not rush them.

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Processing Time

 Each food and preparation style has its own
  processing time so always use a tested recipe.
 Time differs with size of jar.
 Too little = under processing  spoiled or
  unsafe food
 Too much = over processing  overcooked

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Pressure Increases Temperature

   Heat food to 240oF to destroy botulinum
    spores. Cannot achieve this in boiling water.
   The only safe way to can low-acid foods is
    with pressure.
   Temperature of 240ºF or above needed for
    reasonable processing times
      10 psig = 240ºF at sea level
      15 psig = 250ºF at sea level

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Boiling Water

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Boiling Water Bath

 Have water simmering (180oF) in canner,
  high enough to cover jars when filled (about
   six inches for most loads).
    Hot packed jars = simmering water
    Raw packed jars = warm to hot water
 Place jars on rack in canner.
 Add more hot water if necessary, once jars
  are in canner. (Never pour hot water directly onto
   raw-packed jars).

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Boiling Water Bath

 Start counting processing time after water
  returns to a full boil.
 Adjust processing time for altitudes over 1,000

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Boiling Water Bath

 If processing foods for more than 30 minutes,
  water should be two inches over jars when
  process begins.
 If water stops boiling at any time during
  process, bring the water to a boil and begin the
  process over.

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Pressure Canning

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Pressure Processing

 Have 2 to 3 inches of water simmering or hot in
    Hot packed jars = simmering water
    Raw packed jars = warm to hot water
 Place jars on rack in canner.
 Put lid on canner with weight off or petcock

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Pressure Processing

 Exhaust canner for 10 minutes.
 Close vent or petcock.
 Start counting processing times when correct
  pressure is reached.
 Adjust pressure for altitude, if needed.
 Turn off heat at end of processing.
 Let pressure drop to 0 psig naturally.

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Pressure Processing

 Wait two minutes after pressure drops to 0 psig.
  (For some canners, check that locks in handles are
 Remove weight or petcock.
 Open canner. Watch steam!
 Remove jars to padded surface or rack.
 Cool jars 2 to 24 hours, undisturbed.
 Check that the jars have sealed.

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Canning High-Acid

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MODULE 3: Units

   Definition of a High-Acid Food
   Preparing Foods for Canning
   Acidifying Tomatoes
   Canning High-Acid Foods

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Definition of a
High-Acid Food

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High-Acid Foods (pH < 4.6)

 All fruits, except for:
    figs
    tomatoes, and
    melons
 Rhubarb
 Fermented pickles, such as sauerkraut
 Acidified foods, such as pickles and tomatoes

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Preparing Foods for

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Selecting Fruits and Tomatoes
for Canning

 Choose firm, ripe products.
 Do not use overripe fruits.
 Gather or purchase only what you are able to
  can within 2 to 3 hours.

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 Washing Fruits and Tomatoes
 for Canning

 Dirt contains many microorganisms hardest to
 Wash everything, even foods to be peeled.
 Use several water changes.
 Lift the food, do not soak.

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Preventing Fruit Darkening

 1 teaspoon (3000 mg) ascorbic acid added to
  one gallon of water
 Commercial ascorbic acid mixture
 Heating the fruit

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Preventing Fruit Darkening

The following do not work as well:
     Citric acid solution
     Lemon juice
     Sugar syrup
     Salt/vinegar solution

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Canning Liquids for Fruits

Sweet syrup, water or juice can be used.
Sweet syrup:
   Helps retain shape, color, and flavor of fruit. Not needed for
   Mix sugar with water or juice, heat to dissolve sugar.
   Proportions of sugar to liquid given in publications.
   Up to 1/2 the sugar can be replaced by corn syrup or mild
    flavored honey. (Use more corn syrup if bland.)

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Canning Liquids for Fruits

Juice Packs:
   Commercial unsweetened apple, pineapple, or
    white grape juice.
   Juice can also be extracted from fruit being canned
    or from the above fresh fruits.
   Extracting juice:
      Thoroughly crush ripe, sound fruit. Heat to simmering.

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Canning Liquids for Fruits

Artificial Sweeteners:
   Add just before serving
   Saccharin-based sweeteners turn bitter
   Aspartame-based sweeteners lose flavor

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Acidifying Tomatoes

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Acidifying Tomatoes

 pH between 4.0 - 4.6 (borderline)
 Even if pressure processing, tomatoes must be
 For Pints:
    1 tablespoon bottled lemon juice or 1/4 teaspoon citric acid
 For Quarts:
    2 tablespoon bottled lemon juice or 1/2 teaspoon. citric acid

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Acidifying Tomatoes

 Add directly to jar before filling.
 If too acid tasting, add sugar.
 Use 4 tablespoons vinegar per quart or 2
  tablespoons per pint. However, flavor might be

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 Salt is only used for flavor in canned tomatoes
  and vegetables.
 It can be omitted because does improve the
  safety of the final product.

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Canning High-Acid Foods

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Canning High-Acid Foods

 Heat canner with about six inches of water to
 Treat new lids.
 Wash jars.
 Select and wash high quality raw product.

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Canning High-Acid Foods

 Fill jars either hot pack or cold pack:
    hot pack (food and liquid heated before filling)
    cold pack (raw food put in jar and boiling liquid
     poured over it)
 Leave appropriate headspace.
 Remove air bubbles.

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Canning High-Acid Foods

 Wipe rim of jars.
 Adjust lids.
 Lower jars slowly into canner.
 Count processing time when the water
  returns to a boil.
 Remove jars to a padded surface.
 Cool away from drafts, 12 to 24 hours.

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Canning High-Acid Foods

   Check seals.
   Remove screw bands.
   Label.
   Store.

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 Space in the jar between the inside of the lid
  and the top of the food or its liquid.
 Check canning directions for that correct
  headspace for each food.
 Usually:
    1/4” for jellied fruit products
    1/2” for high-acid foods, such as fruits,
     tomatoes, and pickles
    1” to 1-1/4” for low-acid foods

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Too little:
   • Food may bubble out during processing.
   • Deposit on rim may prevent proper sealing.
Too much:
   • Food at the top is likely to discolor.
   • Jar may not seal properly, because processing
     time not long enough to drive all the air from
     inside the jar.

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Closing the Jars

   Remove air bubbles.
   Re-adjust headspace if necessary.
   Wipe jar rims.
   Adjust two-piece lids, fingertip-tight.

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