What Is Canning
Canning is a very popular, traditional method of preserving food, particularly garden produce. Scientists have learned that micro-organisms that spoil food and so the heat used in the canning process kills the micro-organisms. Improperly canned food can result in botulism and so the following “Canning Safety” section should be read before you start canning. Canning fresh produce will allow you to preserve important vitamins found in your produce. As well, it will allow you to prepare your food to your taste and health requirements which is particularly good for those that have a low salt diet or other dietary restrictions. Canned goods can last for several years though they’re best if eaten within one year since over time, canned goods do lose some of their nutritional value and crispness.
What Do I Need
Canning is a fairly simple procedure that requires a couple of inexpensive pieces of caning equipment, an extensive procedure and a few hours of time. The equipment needed depends upon the produce you are canning, refer to the “Canning Safety” section. A pressure canner is best for low acid foods, as this piece of equipment will have a pressure relief valve to ensure that the pot doesn’t explode under pressure. As well, it has a gauge to help control heat and pressure. A boiling water canner (or large deep pot with tight fitting lid) can be used for high acid foods. You will also need jars and lids which come in a variety of sizes and styles. Other pieces of equipment that are not necessary but help out with the process are: a blancher which is a basket that fits inside a large pot used to lower the food into the boiling water; a colander which is a strainer; a jar funnel which helps to pour food into the jars; a jar lifter which will make it easier and safer to remove jars from hot water; a long-handled slotted spoon; and a ladle. You will need a recipe for whichever produce you plan on canning.
Canning food improperly can result in the growth of micro-organisms or botulism. Eating such foods can cause serious illness and possibly death. Therefore you must ensure cleanliness and follow canning procedures strictly. Molds, viruses, bacteria and botulism that may grow in canned foods can be easily controlled by properly heating the jars and food within them as well as properly sealing the jars.
High acid foods can be canned under less restrictive conditions using a boiling water canner (or a large deep pot with a tight-fitting lid) as botulism prefers a low acid environment. These foods have a pH of 4.5 or less and include: apples, berries, jams, jellies, apricots, pears, peaches (fruit, fruit spreads and fruit juices), tomatoes, pickles, relishes, chutneys, vinegars, condiments, sauerkraut and more.
Low acid, high pH fruits and vegetables require a special device called a pressure canner. The pressure canner can also be used for canning the high acid foods. Low acid foods include: beans, asparagus, carrots, beets, corn, peas, mushrooms, squash, spinach, pumpkin, potatoes, soups, stews, seafood, vegetable mixtures and most meat.
It’s pretty easy to tell when a canning job has gone bad as there are numerous signs. One sign that food is no good is when the lid of the jar pops up (or bulges) and if there’s seeping around the seal. Another sign is when there is mold growing on the food. Also, abnormal colours in the brine of the food, cloudiness in the brine and a white coloured film on the surface of the food are all signs of contamination.
Never eat contaminated food as it will cause harm. Reheating the food and/or boiling it will not make the contaminated food safe to eat. Traditional methods such as open kettle canning, paraffin wax sealing, oven and microwave canning are not recommended.
Finally, it is best to store canned foods at a relatively low temperature. This will help prevent any activity by micro-organisms that may have survived the eating process. Keep your cans in a cool, dark place to help preserve vitamins and taste as well.
How Do I Do It
-High Acid Food
All High Acid Foods must be "heat processed" in a boiling water canner (or large deep pot with tight fitting lid). Use the best, top quality ingredients including produce at its peak of ripeness. As well, use only current, tested home canning recipes as older recipes may not incorporate our current knowledge of food safety.
1. Before you being, review your recipe and make sure you have all of your equipment and ingredients easily accessible.
2. Visually inspect all jars and lids for cracks, nicks, uneven rims, sharp edges or improperly fitting lids taht amy prevent sealing or cause breakage. Ensure SNAP Lids are scratch-free. Wash all jars and lids in hot, soapy water and rinse well.
3. Place the number of jars that will fit into the boiling water canner on a rack and place into the canner, cover with water and heat water to a simmer (180 degrees F/82 degrees C). Keep jars hot until ready to use.
4. Prepare your food as the recipe directs.
5. Set screw bands aside, heat SNAP Lids in hot NOT boiling water (180 degrees F/82 degrees C). Keep SNAP Lids hot until ready to use.
6. Ladle the prepared food into a hot jar leaving proper "heating space". This is the space at the top of the jar between the top of the food/liquid and the underside of the SNAP Lid. Under-filling or over-filling may result in the seal failing. Heat space is determined by the type of food.
- Jam, jelly, 1/4 inch (0.5cm)
- Fruit 1/2 inch (1cm)
- Pickles, tomatoes 1/2 inch (1cm)
- Relish, chutney, salsa 1/2 inch (1cm)
7. Remove air bubbles by sliding a non-metallic utensil such as a rubber spatula between jar and food. After this re-adjust heating space if need be.
8. Wipe jar to remove any stickiness. Centre SNAP Lid on jar.
9. Apply screw bands evenly and firmly until resistance is met (fingertip tight). Over tightening will prevent venting (air escaping during heating process) and can cause the seal to fail. The steam formed inside the jar during the heating process must be exhausted to allow for a strong seal to form.
10. Place jar onto elevated rack in boiling water canner. Repeat jar filing/closing steps #6-9. When all jars are filled or canner is full, lower rack into water and place lid on canner. Make sure water covers jar by at least 1inch (2.5cm), add boiling water if needed.
11. Once the water returns to a full rolling boil, begin counting "heat processing time" which is indicated in your recipe. When time has elapsed, turn off heat and remove canner lid. Allow boil to subside then lift jars without tilting and place them upright on a towel to cool. DO NOT re-tighten screw bands. Cool jars undisturbed for 24 hours.
12. After jars have cooled, check jar seals by pressing on centre on each lid. If the lid centre is pulled down and does not move, remove the screw band and lift the jar by the lid. Lids that do not flex and cannot be easily lifted off the jars have a good seal. Refigerate or reprocess any unsealed jars.
13.Wipe jars with a damp cloth. Label and store jars in a cool, dark place. For best quality result use home canned foods within one year.-Low Acid Foods
All Low Acid Foods must be heat processed in a pressure canner. Use the best, top quality ingredients including produce at its peak of ripeness. As well, use only current, tested home canning recipes as older recipes may not incorporate our current knowledge of food safety.
1. Review the recipe and assemble all ingredients and equipment. Visually inspect all jars and lids for cracks, nicks, uneven rims, sharp edges or improperly fitting lids taht amy prevent sealing or cause breakage. Ensure SNAP Lids are scratch-free. Wash all jars and lids in hot, soapy water and rinse well.
2. Inspect pressure canner. Check the lid and gasket to ensure an airtight seal can be achieved. Have dial gauge checked regularly.
3. Place rack in pressure canner and add 2 to 3 inches (5 to 8 cm) of water. Place jars in canner, heat water to a gentle boil. Keep jars in canner until ready to fill.
4. Prepare food according to recipe.
5. Set screw bands aside. Heat SNAP Lids in hot water, NOT boiling *180 degrees F/82 degrees C). Keep SNAP Lids hot until ready to use.
6. Place food into a hot jar leaving 1-1/4 inch (3cm) of heating space. his is the space at the top of the jar between the top of the food/liquid and the underside of the SNAP Lid. Under-filling or over-filling may result in the seal failing. Heat space is determined by the type of food. Heat space is determined by the type of food.
7. Remove air bubbles by sliding a non-metallic utensil such as a rubber spatula between jar and food. After this re-adjust head space if required.
8. Wipe jar removing any stickiness. Centre SNAP Lid on jar.
9. Apply screw bands until fingertip tight. Fingertip tight is as snug as the band can be applied with your fingers. Fingertip tight allows some 'give' between the SNAP Lid and jar to allow rising stream to escape during the heat processing. The "rising steam" is created inside the jar during heat processing and must be exhausted to allow the formation of a strong airtight seal.
10. Place jar on rack in canner. Repeat jar filling/closing steps #6-9. When all jars are filled or canner is full, check that the water level in the canner is about 3 inches (8cm) or that recommended in manufacturer's manual.
11. Lock canner lid in place, leaving vent open. Place canner over high heat. Allow steam to escape steadily for 10 minutes (venting canner). Close the vent, using the weight or method described for your canner. Gradually reduce the heat to achieve and maintain the recommended pressure. Regulate heat only with gradual changes to heat level.
12. At altitudes up to 1,000 ft (305m) HEAT PROCESS at 10b (68kPa) pressure in a weighted gauge canner or 11 lb (75kPa) pressure in a dial gauge canner for the specified time for food and jar size. (At altitudes higher than 1,000 ft (305m) increase lb (kPa) pressure to that recommended for your elevation.
13. When processing time is complete, remove canner from heat. Let canner stand undisturbed until pressure drops to zero.
14. When dial gauge reaches zero or when no steam escapes when weighted gauge canner's weight is budged, wait 2 minutes then remove cover, tilting it away from yourself.
15. Lift jars without tilting from canner and place them upright on a towel to cool in a draft-free place. DO NOT RE-TIGHTEN screw bands.
16. After jars have cooled, check jar seals by pressing on centre of each lid. If the lid centre is pulled down and does not move, remove the screw band and lift the jar by the lid. Lids that do not flex and cannot be easily lifted off the jars have good seals. Refrigerate or reprocess any unsealed jars.
17. Wipe jars with damp cloth. Label and store jars in a cool, dark place. For best quality results use home canned foods within one year.
Storage of Canned Food
It is best to store canned foods at relatively low temperatures as this helps prevent any activity by micro-organisms that may have survived the heating process. Keep cans in a dark, cool place to help preserve vitamins and taste.
Where Can I Learn More
There are numerous books and websites available to help you including www.homecanning.com. Also, the Royal Botanical Gardens is hosting two canning workshops this year.
Early Harvest - Thursday May 29, 7-9p.m. at RBG Centre.
Members $28; Non-members $32.
During this session, Janet concentrates on early harvest jams and jellies and other fruits and vegetables that start the season off. Registration deadline May 20.
Late Harvest - Tuesday August 12, 7-9p.m. at RBG Centre.
Members $28; Non-members $32.
At this time of season the garden is in full swing and Janet features tomatoes, pickles and many of the other late harvest fruits and vegetables. Maximum 20. Registration deadline August 4.
Environment Hamilton will also be hosting canning workshops this Fall, check out our website for more details at www.environmenthamilton.org