HM jam going mouldy - what am I doing wrong?

CCP

A few weeks ago I made my second ever batch of home-made jam - a nectarine one - but, when I looked at the jars this morning, I can see that the tops are going mouldy already. The same thing happened with my first batch (plum and ginger, if that makes a difference) so I scraped off the mould and half an inch or so of jam underneath, reboiled and re-jarred it, and that seemed to solve the problem. With the nectarine jam, though, it is already so solidly-set (I rather over-did the pectin ) that I don't think this will be possible, so I've got a horrible feeling I'll have to throw it all away.

I followed all the tips I could find on making HM jam - the jars were well washed and sterilised in a warm oven before use, the jam was jarred while still hot, and each jar was sealed with purpose-made waxed discs and plastic covers - so why is it still going mouldy? I would really appreciate some help as I'd love to try again, but don't want to waste any more fruit until I know what I'm doing wrong!



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candlelight_2013

You might not have used enough sugar.

Candlelight

Mojisola

What proportion of sugar to fruit did you use?

As candlelights says - it's the sugar that preserves the fruit.

CCP

I used just under the same amount of sugar as fruit, which seems to be what most recipes recommend. Should I use more and, if so, how much more, do you think?

candlelight_2013

I usually use the same weight of sugar as of fruit, so it sounds as though you were almost there.

Hope that helps.

Candlelight

wondercollie

I freeze my jars until I need them. Once the jars are cooled to room temperature I pop them in the freezer and then use them one at a time.

Mojisola

CCP wrote: »

I followed all the tips I could find on making HM jam - the jars were well washed and sterilised in a warm oven before use, the jam was jarred while still hot, and each jar was sealed with purpose-made waxed discs and plastic covers - so why is it still going mouldy? I would really appreciate some help as I'd love to try again, but don't want to waste any more fruit until I know what I'm doing wrong!

CCP wrote: »

I used just under the same amount of sugar as fruit, which seems to be what most recipes recommend.

As you've done everything right, I'm out of ideas!

Katzen

Did you fill them right to the top to minimise air pockets? Did you sterilise the lids and seal whilst hot? If you've got enough sugar to make the environment difficult for mould then the contamination is the other likely cause.

CCP

Katzen wrote: »

Did you fill them right to the top to minimise air pockets? Did you sterilise the lids and seal whilst hot? If you've got enough sugar to make the environment difficult for mould then the contamination is the other likely cause.

That does sound like the most likely explanation - the waxed discs came from a packet so I assumed they were already sterile, but obviously not. What would be the best way to sterilise them, do you think?

JulieGeorgiana

After washing, I fill my jars with boiling water and turn over to clean the inside of the lids. Careful because it always leaks...

Then I drain and put the jars and lids in the oven to dry.

[Deleted User]

I never get mouldy jam and this is what I do:

wash jars and rinse, put upside down on a tray in a cold oven and heat to about 120 then switch off and leave. Just before jam is ready, put small amount of water to boil then put all lids in for a couple of minutes. Take out with tongs and lay on a clean tea towel.

Pour the jam into hot jars then add a tsp of alcohol such as whisky or vodka or gin. I never use wax discs

Screw lids on and tighten after a few minutes. Soon you will hear a pop as the lids get sucked down and you will have the vacuum needed. Store dark and cool.

I have jams and marmalades 3 years old and as good as new. Stored under the stairs on the north side of the house