The foam contains a lot of air, so essentially you're increasing the headspace in the preserve. Potentially you're reducing the shelf life of the jam.

Also, personally I don't care for the texture or flavor of the foam, though some don't mind it.

You can either prevent it by adding 1 tsp. of butter to a batch of jam (keeps foam down) or eliminate by skimming. Your call.

Carol

Agree with Carol. Excess headspace and the air in the foam is trapped in the jar. That increase the odds of mold development and shortens shelf life. It isn't a major chore to skim.

Dave

I find that if I let the jam sit for 5 minutes or so off the burner, then stir again, most of the foam dissolves. I skim the small amount that's left into a bowl. The jam is still plenty hot to put into jars, I lose less to foam, and I make toast while the jam is processing to use up the foam!

Works for me!
Deanna

The foam also looks bad. The butter tip has saved me over and over. Now I keep a stick of butter near when I jamming.

make toast while the jam is processing to use up the foam!

Good idea Deanna! Any chance to sample the fruits of our labors. :-)

Dave

This post was edited by digdirt on Wed, Jul 17, 13 at 20:26

Thanks for your replies. I was just curious about it.