As most fresh produce naturally contains a population of bacteria, mould and yeast, it is important to preserve them accurately to destroy these contaminants and prevent growth during storage. That is, preserve them following the recommended method, processing temperature and processing time. By following these guidelines and storing your sealed jars of canned goods in a cool, dark and dry place, you can safely enjoy your preserved food all year long.
METHOD: Boiling Water Canner
This is the most common food preservation method, canning high acid (low pH) foods such as jam, jelly, marmalade, pickles, relish, chutney, fruit, fruit sauces, fruit pie fillings, mustards, etc. Most fruits have a natural high acidity (a pH below 4.6) and do not require additional acidic ingredients, the minority need a teaspoon to tablespoon of lemon juice, citric acid or vinegar added before canning (refer to recipes for specifications). Tomatoes are sometimes tricky - some varieties have a low pH, so lemon juice (or citric acid) must be added to all tomatoes if you wish to process them in a boiling water canner. Botulism will not occur in safely preserved high acid foods (the bacteria requires a low acid environment to multiply and produce the toxin) however mould and/or yeasts can occur if recipes are not followed closely and jars must be processed accordingly to heat contents before storage, creating a strong vacuum seal that keeps moisture in and contaminants out. As the boiling water will not exceed 100'C, it is important to use the pressure canning method for low acid food to kill the botulinum spores that can make you very sick. If you live at an altitude above 1000ft, water boils at a lower temperature, so follow the increased processing time as stated in the recipe for your altitude to ensure your jars are heated throughout during processing and kills any bacteria.
METHOD: Pressure Canner
This is the method to use to preserve low acid (high pH) foods such as poultry, red meat, fish, fresh vegetables, soup, stock, legumes, etc. Botulism (food poisoning) CAN occur in these low acid environments, so it is important to process jars according to the recipe, and re-heating jar contents when you open before serving. The high temperature achieved kills the botulinum spores (which make the toxin causing botulism), during the 20-100 minute processing (which varies, depending on the ingredients, refer to your recipe). If you live at an altitude above 1000ft, water boils at a lower temperature, so follow the increased processing time and/or increased pressure level as stated in the recipe for your altitude to ensure your jars are heated throughout during processing and kills any bacteria, especially the botulinum strain.
STORAGE
Store home canned foods in a single layer, on a shelf or in a box, in a cool dark and dry place for 12 months or more. Ensure they are labelled clearly and rotate jars, using the older of several batches first. Discard in the rubbish (do not compost) if spoilage is evident.
