I have had two problems recently in the strawberry jams I make:
Recently, I have noticed an issue in the two flavors of strawberry jam I make. After around a month, the top of the jar oxidizes and turns a slight brown hue. Since the seal is still intact, it is obviously not a safety issue, but it provides a large cosmetic problem.
I have also found that while water bath canning, small, foamy air bubbles accumulate towards the top of the jar. Sometimes, there is a layer of foam at the top.This happens often, no matter how much of the foam I skim from the tops of the jars before processing. The bubbles don't exist before processing, only afterwards.
How do I prevent these issues? Could the air bubbles in the jam contribute to the oxidation?
Thank you,
Eli