How to sterilise jars

How to prepare glass jars for filling with jam, chutney and relish by heating them in the oven so the contents don't spoil.

Points to remember

  • Wash your jars and the lids in hot soapy water, but do not dry them. Instead, leave them to stand upside down on a roasting tray while they’re still wet.
  • Pop the tray of clean, wet jars and lids in to a preheated oven at 160-180ºC for about 15 mins.
  • Ladle the hot preserve into a heatproof jug to make it easier to transfer the mixture into the hot jars. Be very careful not to touch or get any of the mixture onto the rim of the jars as this could introduce bacteria.
  • Ideally you want to fill the jars not quite to the top, leave about 1/4 inch (1/2 cm) gap at the top between the preserve and the lid.
  • While everything is still hot, cover the jars with their lids or top with wax paper and a piece of cellophane secured tightly with an elastic band.
  • Once in sterilised jars like this your preserves should keep for about 6 months in a cool, dark place, but do check the recipe you’re using for a more accurate shelf life as some preserves will last longer than others.
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TIPS
JAM AND CHUTNEY HEALTH & SAFETY

It’s very important to sterilise your jars properly so that you remove bacteria in the jars, which could cause your preserves to spoil. Timing is important because you should put your preserve into a hot jar whilst the preserve itself is still piping hot – it’s a good idea so start preparing your jars when your preserve is about 20 mins away from being ready.

HOW TO PREPARE JARS WITH A RUBBER RING SEAL

For jars with a rubber ring seal, remove the seal before washing the jars and place in a small saucepan. Cover with water and boil for 2-3 mins to sterilise. 

HOW MANY JARS TO STERILISE

It’s a good idea to sterilise one or two more jars than you think you’re going to need to make sure you have enough for all of the preserve mixture.

CHUNKY JAMS AND CHUTNEYS

For chunky chutneys or jams it’s a good idea to tap the jar gently on the work surface once filled, just to remove any air bubbles. 

EXTEND SHELF LIFE

Fill the jars with the preserve, screw on the lid then wrap each one up in newspaper. Pop the wrapped jars in a large saucepan, cover with water then bring to a simmer, then simmer for 20 mins. Turn the heat off then leave the jars to cool completely in the pan.