Knowledgebase
Opened jar of jam crystallizing in fridge #877603
Asked July 17, 2024, 11:37 AM EDT
Clark County Ohio
Expert Response
Generally, commercially processed jam should not crystalize, but that could be mold growing within it and the recommendation would be to discard it. It's hard to discern your description of crystals? Here's the guidance from Penn State University for home processed Jam/jellies:
Formation of crystals
When the boiled mixture is cooled down, dissolved sugar molecules can become supersaturated and start to crystallize. Crystallization is most often a concern in clear jellies where they detract from the visual quality of the product. Adding too much sugar or concentrating the mixture well above the target 65% soluble solids limit can lead to crystallization problems. Even a few crystals remaining on the sides of the boiling kettle can provide a starting point for further crystallization. Agitating the sealed jars while they are cooling and fluctuating storage temperatures are also thought to accelerate crystal formation. Crystals in grape jellies can be caused by the precipitation of naturally occurring tartaric acid once the product is cooled.
Possible remedies:
- Train operators to accurately weigh out ingredients according to the written recipe.
- Cook the mixture at a rapid boil to thoroughly dissolve the sugar.
- Consider replacing some of the sucrose with corn syrups which can disrupt the crystallization process.
- Make sure the pH is at the optimal value for both pectin activity and inversion of some of the sucrose into glucose and fructose molecules.
- Rinse down the sides of the kettle and wipe with a clean cloth before filling to eliminate any residual sugar crystals.
- Skim off any surface foam before filling jars.
- Prevent tartrate crystallization in grape jellies by refrigerating the extracted juice overnight to allow tartrate crystals to settle out and then strain them out before making jelly.
If you have further questions please reach out to me at<personal data hidden> on Monday, thanks Melinda