For Boiling Water canning refer to our section on Water Bathing.
Pressure CANNERS and Pressure COOKERS are TWO ENTIRELY DIFFERENT THINGS!,kb
You cannot pressure can in pressure cooker. You can cook in a pressure canner. A canner works at a sustained high temperature with a great deal mor accuracy.
Safe canning
Pressure canning is a method for safely preserving low acid foods such as tomatoes, figs, vegetables such as potatoes adn carrots as well as meats, vgetables, poultry, seafood, soups and meal blends such as spagetti sauces, stew etc.
Pressure canning heats the food to a temperature that will destroy microorganisms and inactivates enzymes that will change the colour, flavour and texture of food. The process, similar to waterbathing or overflow method will vacuum seal the contents of your ‘can’ (jar) to prevent recontamination and spoilage.
Acid foods are foods with a pH of less than 4.6 Saurkraut, most fruits, pickles (made with vinegar)
Low acid foods have a pH greater than 4.6.
One of the biggers dangers for canning is Clostridium botulinum.
This forms protective heat resistant spores which standard canning methods witll not destroy. The higher temperature of a pressure canner (around 116 degrees are required to destroy the c. Botulinum spores. Spores will germinate in a moist and airless envirionment so just vacuum sealing is not enough.
Syptoms include Digestive upset, nausea, blurred vision, paralysis, death.
Spore will not germinate in an acid environment so pickles and relishes are safe.
MUST for canning:
Food properly prepared and proceed to the correct time with the correct altitude adjestment. Directions followed according ot your specific canner
Process tim is determined by the length of time to heat the coldes part of the jar contents. Size of the jar, consistency of contents all have an effect on canning times.
FOllow your canners directions and take your time. Take into account warm up and more importantly cool down time required when canner. Always leave your canner to cool properly before opening – steam burns HURT
Methods of Packing food for your canner
Raw Pack – For food that will loose shape when cooked. Food goes direct into jars and boiling hot liquid is added. Pack firmly but do not crush. Once debubbled and lids applied jars are placed int he canner.
Hot pack – foor is cooked before packing. There will be less flating food using this method. Foods will have a better colour and flavour. Fewer jars are needed
Equipment for canning:
THE canner itself – op shops, trademe, oz farmer
Jars – agee, ball, arthur holmes
Tools – wide mouth funnerl, jar lifter, debubbler,
Before you begin: assemble all your tools and lay out your workspace. Check your lids for inperfections and your jars for any chips around the rim or cracks int he body of the jar itself.
Head space
The general rule for head space (the amount of free space at the top of the jar is:
1/4″ (1/2 cm) Jellied fruit
1/2″ 1 cm fruits, tomatoes, pickles
1″ – 1-1/4″ 3cm low acid foods, meats etc.
Too little head space and the food will bubble out and may not seal
too much head space and the food may discolour, not enough air will be forced out during the canning process and the jars may not seal.
Lids for canning
Jar types
‘Quart’ jars are around abour 1 litre 1000 mls (946.35ml to be precise)
‘Pint’ jars are 473.17 ml.
SO In NZ we treat 500ml jars or below as pints, and between 500ml-1000ml jars as quarts.
The neat thing about pints is you can stack you canner with TWO layers with a seperator – you may have an extra rack that came with your canner – if not don’t dispear! Take a few excess jar rings and zip-tie or twist tie them together into a makeshift rack – and you are in business!
NEVER stack the jars directly on top of each other.
Altitude and why it is important
Up to 1000 feet abouve sea level 10 pounds
Over 1000 feet 15 pounds.
whatsmyelevation.com
PROCESS:
2-3″ water in canner – enough so it does not boil dry
Jars in lid on High heat
Once it starts venting set timer for 10 minutes and allow to vent for 10 minutes before putting your weight on. Once the correct PSI has been achieved lower temp to maintain that pressure . Set timer for required time.
After canning: WAIT for the pressure to come down to 0 PSI. WAIT a further 2 minutes before removing your ‘jiggler’ or weight. WAIT 10 minutes at least before opening your canner.
When removing jars – Use a jar tool, the jars will be HOT. Keep teh cans as level as possible – do not tip them
The contents of the jars WILL continue to boil for some time – that is a good sign. A good seal is eminent!
Place on a wooden chopping board and walk away. Resist all urges to tweak teh rings. As they cool and seal you should hear a POP. SOme lids have a ‘button’ – a raised area in the centre and that will now be inverted. There is a noticable differece in sound between a sealed jar and a non sealed jar.
Continue SITTING ON YOUR HANDS for 12-24 hours. THEN Remove rings, and check the seals. If a jar has not sealed pop in the refridgerator and eat straight away or freeze.
Check your canners instructions for the minimum nuber of jars for correct operation.
LABEL! LABEL! LABEL!!! Contents. Date (month and year).
Useful books
acid vs non acid.
Why Pressure Can?
Shelf stable food
Preserving your harvest
Storing your canned goods
Store in a cool dry dark place. Avoid temperature extremes. Use within 18 months (after that food may loose nutritional value, taste and or colour)