Last week I made a batch of Guava Jam and even though I had boiled it for a long time it just didn’t get to that perfect setting point. I don’t use additional pectin, only natural pectin from added lemon zest and stone fruit pips that are then removed after the boil. But this time it just didn't work.

I had already jarred and cooked the jam and I wasn’t happy with it being runny. So this week I had a gap of time and decided to reboil the jam and hopefully get a better result.

How to reboil undercooked jam

First I empty the jam into my large pot.

Rinse and then wash all the jars and lids in soapy water.

Place the jars in a 100•C oven for 10 minutes to sterilise.

Dry the lids thoroughly.

I decided to add more lemon zest to increase the pectin levels and boiled on high heat for 5 minutes to release the pectin and then brought down to a lower heat for an additional 10 minutes. I didn’t want to burn the jam after going through this whole process.

Stir every few seconds to preventing burning on the bottom.

I tested the jam on a plate in the fridge and looked far better than the previous batch so I decided to go ahead and bottle the jam.

I use a cool silicone hand mitt because the jars are extremely hot when they come out of the oven.

Carefully ladle the jam into the sterile jars and place the lids on tightly while hot.

I managed to get 10 jars after the reboil where I had originally had 12 jars which mean that a lot of the water content from the fruit had boiled off and allowed for a thicker jam.

This reboiled batch of Guava Jam is far superior to the initial batch that was more like a runny paste than I thick and chunky jam.

Now it’s ready for market!

Have you ever had this problem?