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Preserving 101: Sterilising Jars

Preserving 101: Sterilising Jars

I’m not sure there is any greater satisfaction, for a cook anyway, than a shelf full of sparkling jars of fresh preserves. Jams, jellies, chutneys, and pickles are simple to make and so delicious to eat especially in the depths of winter but the path to this pantry nirvana can appear fraught with complicated lore that is enough to put the uninitiated off.
Small batch preserving can be easily achieved in an afternoon and requires nothing more in the way of equipment than a good heavy-based preserving pan, some quality jars, a heavy long-handled spoon, and some heavy oven mitts to handle your hot jars.

Although it’s tempting to skip straight to the fill, we always recommend you take the time to sterilise your jars. This is for two reasons:
• Over time, and it can be quite a short period, any bacteria present in jars may multiply to very dangerous levels which may not be apparent to the eye or tastebuds. It would be hideous to give your preserves away as a gift and then poison someone!
• Clean jars will help your preserves last longer. Any traces of even harmless organisms like yeasts and bacteria can encourage your preserves to spoil and even though they may not be harmful, no one likes scraping a layer of mould off the top of your jam!
There are several ways we here at Milly’s sterilise our jars – and when we say jars, we mean lids too. Everything that touches your preserves must be clean.

Always check your jars for chips and damage, especially around the rim. Chipped jars are unlikely to seal which will, again, shorten the life of your preserves.
Oven Method:
1. Thoroughly wash jars and lids in hot soapy water. Ensure that all labels and glue are removed and then rinse the jars thoroughly in hot water. Do not dry them.
2. Place jars, upside down, on a clean roasting tray and then put into an oven preheated to 150C for 15 mins. Turn the oven off and leave the jars inside so that they are still hot for filling.

Boiling Method:
1. Thoroughly check and wash jars as above.
2. Put jars into a large stock pot or similar of boiling water, ensuring that there is enough water to cover the jars thoroughly and that there are no air pockets sitting in the jars. Boil for 10 mins then using clean tongs remove the jars to a tea towel lined tray (upside down) to dry.

Dishwasher Method:
1. Thoroughly check jars as above.
2. Put your jars through the hottest cycle your dishwasher has. Run through both wash and dry cycles and ensure jars are bone dry when you use them. We generally like to do the jars on their own (rather than with greasy roasting dishes etc) to ensure we’re not introducing random bacteria. Leave the jars in your hot dishwasher until you’re ready to fill.

What about the lids?
Wash thoroughly then boil your metal or plastic lined lids for 15 mins in a small pot of water on top of the stove. Leave them in the hot water, covered, until you’re ready to use them.



A couple of other points:
1. Cold jars can shatter if you fill them with boiling hot preserves so ensure that your jars and lids are hot and dry before you commence filling. This can sometimes require careful timing so plan ahead.
2. If you’re using rubber or silicone seals ie Fido jars, remove these from the jars before sterilising.
3. It’s ok to reuse lids but always check these carefully for signs of damage or rust and discard those which are not suitable.

The team here at Milly’s have been making preserves for years and, as always, they are at their happiest when talking food so don’t hesitate to come in to see us with all your preserving queries. There are no mistakes we haven’t made so please don’t be shy!

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