Canning At Home Rick Sloan FCS Agent. What will we learn? Principles of Canning Two Methods of Canning Packing Methods Canning Equipment Processing

Canning At Home

Rick SloanFCS Agent

What will we learn?

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

2Home Food Preservation

Principles of Canning


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.


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.


Vacuum Seal

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


Two Methods of Canning


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.


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


Low-acid Foods (pH > 4.6)

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


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.


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.


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


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


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.


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


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.


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.


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.


Packing Methods


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.


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.


Canning Equipment


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)


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


Processing Time


Processing Schedules

Definition:Length of time at a specific temperature that a food must be processed.

Affected by:pH value of the foodComposition of the food

- Viscosity- Tightness of pack- Convection vs. conduction transfer of heat- Starches, fats, bones


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


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.


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.


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


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


Boiling Water Processing


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).


Boiling Water Bath

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

Adjust processing time for altitudes over 1,000 feet.


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.


Pressure Canning 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.


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.


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.


MODULE 3

Canning High-Acid Foods


MODULE 3: Units

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


Definition of a High-Acid Food


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


Preparing Foods 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.


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.


Preventing Fruit Darkening

1 teaspoon (3000 mg) ascorbic acid added to one gallon of water

Commercial ascorbic acid mixture Heating the fruit


Preventing Fruit Darkening

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


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.)



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.



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


Acidifying Tomatoes


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


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.


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.





Heat canner with about six inches of water to simmering.

Treat new lids. Wash jars. Select and wash high quality raw product.



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.



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.



Check seals. Remove screw bands. Label. Store.


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


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.


Closing the Jars

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


Documents

Canning At Home Rick Sloan FCS Agent. What will we learn? Principles of Canning Two Methods of Canning Packing Methods Canning Equipment Processing