When making jams, preserves, chutneys, cordials, canned vegetables or pickles, the idea is to keep them airtight and ready to eat for long periods of time. To prevent the contents from spoiling or growing mould, your jars should be properly sterilised as part of the canning process. Keep in mind that you should never use any bottles with chips or nicks on the lip of the jar, or any cracks in the jar, as this can cause your preserves to go off or the jar itself to burst.
How To Sterilize Glass Jars
If you’re going to water bath your jars with their contents, then it’s not necessary to sterilize the jars separately. Remember that certain foods like pickled onions will lose their crispness in a water bath.
Start by washing your jars in warm soapy water and then following one of the methods below.
Pour boiling water into the jars and over the lids and leave to stand for 10 minutes. Add another minute for every 300m above sea level you are.
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Pour boiling water into the jars and lids and then dry the jars in an oven at 160-180 degrees Celsius for 15 minutes.
Put the jars and lids into your dishwasher at the highest setting or steam setting.
Place wet jars in the microwave on full power for 45 seconds or until bone dry, and fill while the jars are still hot.