A guide to sterilising glass jars ready for filing with freshly made jam, preserves or chutneys.

One thing we all love about making jams, preserves and chutneys is the thought of being able to squirrel them away ready for the autumn and winter months.
So we certainly don't want to find that rather than deliciously maturing, our lovingly preserved preserves have in fact been busy cultivating a bunch of breeding pesky bacteria for the last few months and are thus inedible.
To avoid such a catastrophe all we need to do is follow a very simple process regards sterilising glass jars prior to filling them with our goodies.
Honestly, sterilising jars is a very simple process, so don't be put off giving it a go.

A lovely jam to make and keep for the colder months is my
Rhubarb and Apple Jam
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Top Tips
Check for signs of defects or damage to the jar and discard if not perfect ✔️
Make sure the lids are not dented, damaged or rusted and will fit tightly ✔️
Check that the seals are not damaged, if so do not use ✔️
Sterilise more jars than you think you will need, so that you have plenty spare if required ✔️
Use a heat proof jug to fill your jars with your jam or preserve, to help prevent any spillages ✔️
Gently bang your filled on your work surface to disperse air bubbles before sealing ✔️
Leave the filling to settle for 10-15 minutes before sealing ✔️
Equipment
Kilner 0.5L jars or Jam Jars
Jam jar lids if your lids are damaged
or use wax seals and cellophane

Oven method of sterilising glass jars
This is my preferred method because it’s simple and reliable.
Before you start : bear in mind that the jars need 15 minutes in your oven, so remember to sterilise just before your filling is ready.
Glass Jars
- Heat your over to 180°C/160°C Fan/355°F/Gas mark 4.
- Set aside a large, clean roasting tray that will hold your jars comfortably without them touching each other.
- Wash your jars thoroughly in hot soapy water.
- Rinse with warm water but do not dry.
- Place the wet jars, open side up, into your roasting tray.
- Place into your oven for 10 minutes.
- Remove and add your hot filling whilst the jars are also hot, be careful not to touch the inside of the jars to ensure they remain sterile.
Lids and seals
- Place your lids and seals and the end of the tongues that you will use to remove the lids and seals with when sterilised, into a small saucepan of boiling water.
- Simmer for 4 minutes.
- Remove the seals and lids with your sterilised tongues and place on the jars when filled.
Microwave method of sterilising glass jars
Before you start : bear in mind this method should only be used for jars that do not have any metal attachments. Also, you will need to sterilise your lids and seals in boiling water as per the method above.
- Wash your jars thoroughly in hot soapy water.
- Rinse with warm water but do not dry.
- Leaving the jars wet, place into your microwave and blast on full power for 30 seconds (larger jars leave for up to 45 seconds).
- Add your hot filling whilst the jars are still hot.

Dishwasher method of sterilising glass jars
Before you start: bear in mind for this method you need to know the timing of your hot dishwasher cycle, so that the cycle finishes at the time they you need to fill your jars.
Very simple this one, just pop your jars, seals and lids in on a hot cycle and away you go!
As with the other methods, you need to ensure that your jars are still hot before you add your filling.
Water bath (boiling) method of sterilising glass jars
Bear in mind: you will need a pan that is large enough to take your jars and deep enough to ensure they are totally immersed. Kilner do their own: Kilner Preserving Pan
- Wash your jars thoroughly in hot soapy water.
- Rinse with warm water but do not dry.
- Place the jars in your pot and cover with warm water.
- Bring the water to the boil, cover and simmer for 15 minutes.
- Remove the jars from the water when you are ready to use them and place upside onto a clean tea towel to drain .
- Fill the jars with your hot filling whilst they are still hot.
FAQ
Do I need to sterilise new jars?
How long does food stay safe in a steralised jar?
How long do the jars stay sterile?
Video
This is a short video that demonstrates the process.
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