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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. Home Food Preservation. 2. Principles of Canning. Home Food Preservation.

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canning at home

Canning At Home

Rick Sloan

FCS Agent

what will we learn
What will we learn?

Principles of Canning

Two Methods of Canning

Packing Methods

Canning Equipment

Processing Time

Boiling Water Processing

Pressure Canning Processing

Home Food Preservation

2

principles of canning

Principles of Canning

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canning basics
Canning Basics

Food is placed in a canning jar and heated to a temperature that destroys targeted microorganisms.

Heat also inactivates enzymes that cause spoilage.

Air is driven from the jar during heating. As the jar cools a vacuum seal is formed.

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commercial sterility
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
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

Two Methods of Canning

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two methods of canning8
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
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
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
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

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
C. botulinum -- Growth

To germinate, the spores need the following conditions:

anaerobic environment (No Oxygen)

low-acid food

temperature between 40ºF and120ºF

relatively high moisture

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c botulinum growth14
C. botulinum -- Growth

Optimal conditions might be found in:

Home canned foods

Smoked fish and sausage

Foil-wrapped baked potatoes sitting at room temperature

Packaged mushrooms

Pot pies and other foods in gravy

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botulinum toxin
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
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
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 botulism18
Preventing Botulism

Prepare and process food according to instructions in a tested recipe.

Canner gauge must be accurate and properly used.

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
Improperly Canned Foods

Never consume improperly canned foods.

Throw out – do not feed to animals.

Boiling will not always adequately destroy toxin.

When cleaning up surfaces contaminated by unsafe canned foods, prepare a 1:5 bleach to water solution.

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packing methods

Packing Methods

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raw pack
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
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 bath.

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canning equipment

Canning Equipment

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pressure canners
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
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

Processing Time

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processing schedules
Processing Schedules

Definition:

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 schedules28
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

Processing Schedules

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significance of heat penetration
Significance of Heat Penetration

Processing time is affected by whether food heats by convection, conduction, or a combination of both.

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
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 time31
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
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 processing

Boiling Water Processing

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boiling water bath
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 bath35
Boiling Water Bath

Start counting processing time after water returns to a full boil.

Adjust processing time for altitudes over 1,000 feet.

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boiling water bath36
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 processing

Pressure Canning Processing

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pressure processing
Pressure Processing

Have 2 to 3 inches of water simmering or hot in canner.

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 open.

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pressure processing39
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 processing40
Pressure Processing

Wait two minutes after pressure drops to 0 psig. (For some canners, check that locks in handles are released.)

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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module 3 canning high acid foods

MODULE 3Canning High-Acid Foods

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module 3 units
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

Definition of a High-Acid Food

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high acid foods ph 4 644
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 canning

Preparing Foods for Canning

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selecting fruits and tomatoes for canning
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
Washing Fruits and Tomatoes for Canning

Dirt contains many microorganisms hardest to kill.

Wash everything, even foods to be peeled.

Use several water changes.

Lift the food, do not soak.

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preventing fruit darkening
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 darkening49
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
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 safety

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 fruits51
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. Strain.

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canning liquids for fruits52
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

Acidifying Tomatoes

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acidifying tomatoes54
Acidifying Tomatoes

pH between 4.0 - 4.6 (borderline)

Even if pressure processing, tomatoes must be acidified.

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 tomatoes55
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 off.

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slide56
Salt

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

Canning High-Acid Foods

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canning high acid foods58
Canning High-Acid Foods

Heat canner with about six inches of water to simmering.

Treat new lids.

Wash jars.

Select and wash high quality raw product.

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canning high acid foods59
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 foods60
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 foods61
Canning High-Acid Foods

Check seals.

Remove screw bands.

Label.

Store.

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headspace
Headspace

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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headspace63
Headspace

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
Closing the Jars

Remove air bubbles.

Re-adjust headspace if necessary.

Wipe jar rims.

Adjust two-piece lids, fingertip-tight.

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