It’s such a joy to can vegetables, knowing you did it and to know the rewards you’ll reap is delicious tastes from canned vegetables that are as fresh as if they came directly out of the garden. It’s important to know what canning means…it’s a means of preserving vegetables or fruits and sealing them in airtight cans or jars. When they are canned at home, the food is heated or processed according to the times listed in a canning recipe book. The jars or cans are closed and hermetically sealed with a lid and a cap. As the jars heat, it expels air and halts any decay. Sit the jars on a counter-top to cool, you’ll hear a sound of ping, pop as the lid seals onto the rim and it creates a solid vacuum. If a jar hasn’t seal, it will “not” have an indentation in the top of the lid.
When we can fresh vegetables, they contain enzymes and naturally occuring microorganisms, i.e., molds, yeasts and bacteria by canning the vegetables, it limits the growth of enzymes and microorganisms.
There are two categories for canning vegetables: high acid or low acid. 1) High-acid foods like tomatoes, we process them by using boiling-water canning at a temperature of 212 degrees (100 degrees C). When we can by this method, we pack the jars and place them in a rack, and then lower them into a pot of boiling water (boiling-water processing). This is the best method for a home canner to use.
2) Low-acid foods are preserved by a steam-pressure canner at a temperature of 240 degrees F (116 degrees C). These foods, i.e., green and lima beans, carrots, beetroot, sweetcorn, etc. These foods are also processed according to the time listed in a canning recipe book to ensure having a safe food.
Requirements for processing properly canned vegetables:
(1) Selection of jar sizes heated in water (180 degrees F or 83 degrees C).
(2) Lids, caps, dry bands heated same manner as above.
(3) Large canning pot (with lid) and with an elevated canning rack half-full of water, heat to simmering (180 degrees F or 83 degrees C).
(4) Wash your tomatoes, blanch for 30 to 60 seconds (until skins crack), remove and dip in cold water.
(5) Core tomatoes and remove skins also any green areas; boil tomatoes for 5 minutes.
(6) Lift jars out of pot by handles on canning rack.
(7) Add amount of lemon or citric acid to each jar as specified in canning recipe book.
(8) Pack tomatoes into jars, leave a 1/2 inch (12mm) of headspace, fill jar with cooking liquid, removing any air bubbles.