I love pickling and preserving fruit and vegetables, but I find I frequently have to rummage through old recipes to remind myself of how to sterilise jars correctly.  So partly to help myself, and partly to help any readers also a bit stumped by sterilisation, I’ve put together this quick and easy guide on exactly how to sterilise glass jars in the oven, microwave, dishwasher and aga to suit all preferences!

Sterilising jars is quite an important part in preserve making.  For a start there is a risk of botulism if you don’t sterilse your jars.  And secondly, your preserves will last longer – up to a year – as bacteria is less likely to grow and spoil your hard work, so don’t be tempted to skip the sterilisation stage!

how to sterilise jars

How to Sterilise Jars In Any Situation

How to Sterilise Glass Jars in the Oven

aka my favourite method

1.  Heat your oven to 140°C /  275°F / Gas Mark 1.

2,  Wash your jars and lids in warm soapy water, and rinse well to ensure no traces of soap.  Do not dry your jars.

3.   Place a piece of baking paper on a baking tray and place your wet jars on it.  Ensure the jars aren’t touching each other.

4.  Place in the oven and heat for twenty minutes.

5.  Whilst the jars are in the oven, place your wet lids in a saucepan of water, and boil for twenty minutes.

6.  That’s you done!  If your jam/pickle/preserve hasn’t finished cooking once the twenty minutes are up, keep your jars in the oven with the door closed and keep the lids in the saucepan of water.  Cold jars will crack or shatter if you put hot food/liquid in them so you want to keep them warm.

NB: to sterilise kilner jars with rubber seals it’s best to remove the rubber seal and boil that in water as rubber doesn’t tend to react well to being dried in hot air.  The jar (minus the rubber seal) can be placed in the oven no problem.

How to Sterilise Glass Jars in the Microwave

This method of sterilising jars in the microwave is a good quick trick to have up your sleeve.  Particularly if you find that you’ve used up all of your jars that you sterilised in the oven and still have jam/pickle/preserve waiting to be jarred!  Just don’t put metal lids or jars with metal clasps in your microwave – that would be very bad!

If you’re recycling old jars, make sure you’ve removed any label that might have had any kind of metallic paint/ink on it too.

Now that we’ve gotten the safety stuff out of the way, the quickest way to sterilise jars in the microwave is just to wash your jar in hot soapy water, and rinse as before.  Then place your wet jar in the microwave on full power for about 45 seconds (or until bone dry), and fill whilst the jar is still hot.

If you’re in a proverbial pickle and need to sterilise metal lids quickly, even just washing them in warm soapy water then placing in a bowl of boiling water while you microwave your jars quickly is probably sufficient.

How to Sterilise Glass Jars in the Dishwasher

To sterilise jars in your dishwasher just put your dishwasher on at it’s maximum temperature (my dishwasher has a top heat of 70°C) and allow it to run through a full wash and dry cycle, so that the jars and lids are bone dry and still hot when you take them out.

Sterilising jars in a dishwasher does take a bit of planning though, so be warned!  Bearing in mind the jars have to be warm and bone dry when you jar up your preserve, you have to know exactly how long it takes for your dishwasher to complete a whole wash and dry cycle.

How to Sterilise Glass Jars in an Aga

I don’t have an Aga, but I have it on good authority that to sterilise jars in an Aga simply wash your jars in the same manner as above.  Then place the jars in the simmering oven of your Aga for twenty minutes, again in the same manner as you would the oven.

Other Notes on Sterilising Jars

  • Check your jars for any cracks or nicks before you start.  If you find any put them in your glass recycling – the high temperatures involved in sterilisation could cause them to smash or shatter.
  • Sterilisation liquid or tabs are fine for sterilising jars intended for pickles or chutneys, or anything else strongly flavoured, but avoid if you’re making delicate flavoured jams.
  • Any lids that are a bit rusty looking should be put in your recycling.

I hope you’ve found this guide on how to sterilise jars useful!  If there are any hints or tips I’ve missed out on, or if you do things differently then do share in the comments below!

ps: here are some preserve recipes you might like: easy organic marmalade, blackberry and vanilla jam, and pickled cucumber with fennel flowers.  I’ve also pinned this delicious sounding recipe for plum season this year.

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