Sterilising and correctly sealing your jars are key to ensuring your passata keeps for as long as possible.

Always sterilise your jars before use, and don’t forget to do the lid too. One method is to wash the jars with hot soapy water, then sterilise them in boiling water, and dry with a clean tea towel.
Once filled (fill just to the start of the neck, and not all the way to the top of the jar or bottle), simply screw the lid on until hand-tight, place the jars into a deep saucepan of cold water (always cold jars into cold water!), place an old tea towel in between the jars, bring the water to a rolling boil and simmer for 20 minutes.
Turn the heat off and allow to cool before removing the jars, which will now be hermetically sealed, from the water. Store in the larder or a cool dark airy place like under the stairs or in the loft.
If you like, you can flavour your passata with a slosh of olive oil and a pinch of salt (both are also preservatives), or add an extra ingredient such as basil, chilli, thyme or caramelised red onion. Just remember to label your jars!
There is never enough freezer space, so when it comes to passata versus freezer, for me, passata wins hands down. But if you have room, why not do a bit of both !