Saturday, May 21, 2011

How to sterilize glass jars

Sterilizing glass jars is extremely important if you want to preserve jams, marmalades, jellies or chutneys. It is unhealthy and risky for you to do otherwise.

Preheat your oven to 100 degrees Celsius.
Wash the glass jars and their lids with soap in hot water. Place them, while still damp and without touching the inside of the jars and lids, on a baking tray lined with a clean tea towel. Make sure you place them open sides up. Put the tray in the oven for 35 minutes.

Take tray out of the oven and carefully pour your hot jam, jelly, marmalade or chutney inside the hot jar. Be careful not to touch the inside of the jar. Close the lids tightly (not too tightly).

At this point, you can turn the jars upside-down and leave them to cool completely. You can keep them in the refrigerator for up to 3 months.

If you want to preserve the jam/chutney/marmalade for longer outside the fridge, then fill a large, heavy-bottomed pan with water and once it comes to the boil, fully submerge the glass jars in it, placing them in the pan upright, with the lid side up. Leave them in the boiling water for 10 minutes and then, using tongs, carefully remove them from the pan. Allow the glass jars to cool completely. Check to see if the lids have sealed. If a lid of a jar hasn't sealed properly, put the jar in the refrigerator and use it first.

Store the filled jars in a cool, dark and dry place. Once you open them, place them in the refrigerator.

After this process the jam/chutney/marmalade/jelly can be kept for up to a year unopened.

Important: Don't recycle mayonnaise, jam, mustard or any other jars for your canned goods. Buy new canning jars and once you have used the lids once, buy new lids. Never use the same lids twice.
It is also important to inspect the glass jars for scratches, chips or cracks. They must be in pristine condition.

You will find this helpful in the following recipes:

Cherry Tomato Jam

Cranberry Chutney

Homemade Fig Jam

Nectarine Jam

Pomegranate Molasses


  1. Hi, thanks for this article however buying new jars every single time you want to make jam/chutney etc isn't very financial feasible for some let alone quite wasteful throwing jars out! I've reused jam jars many times for homemade jams and chutneys and they're completely fine. Just wanted to add that in case someone reads this whom can't afford to buy jars every time that its entirely safe to reuse! Thanks.

    1. Hi Anthony. Nowhere have I written that someone needs to buy a new jar every time they make jam. What I do mention is to buy new lids for the jars each time they use them. When it comes to mustard and mayonnaise jars that you buy from stores, it is impossible, at least here in the Netherlands to find new lids to fit these types of jars, that's why I suggest you don't use them.
      Thanks and have a Happy 2015.