I made a decent amount of apricot marmalade about a month or so ago and canned them in a clean and new containers and the lids appeared to be air-tight. A few days ago I opened one:
I did a Google search and decided to toss them away. How could I prevent it? I also read about it, some people suggested freezing that doesn't sound like the best solution to me. What's your suggestion?
Ratio of apricot to sugar was 2/1 and approximately half of the sugar I used was light brown sugar. I'm not entirely sure but it probably wasn't hot-packing.
Best Answer
There are two parts to the process of making jams, marmalades (and the like) shelf stable for extended periods:
The first part is the recipe - It must contain the correct combination of fruit, sugar, acid and pectin. (If the sugar ratio is not correct it may lead to mold or yeast growth.)
The second part is the canning - Using sanitized canning jars and lids, filling the jars to the recommended level (usually 1/4" from top) then processing in a boiling water canner for the recommended time for your altitude and checking the lids afterward to make sure they sealed properly.
In the case of your recipe, there was not enough sugar and no added acid. This probably would have kept for a while in the refrigerator, but not long term. Filling a jar and putting on an airtight lid does not make your jam shelf stable, there is still air in the jar along with microscopic microbes that can cause mold and illness. Proper canning will remove the air, creating a vacuum seal that can last for many years.
All that being said, I hope you are not discouraged by the above answer. Jam making and canning are not difficult, with a few proper tools and a good resource to learn the proper steps involved, you can be making all kinds of preserves that can last in your pantry for a year (or more).
To get started please check out this link National Center for Home Food Preservation - Apricot Jam. The website has tons of information on how to get started. Freshpreserving.com/canning-101 is also a good resource, but they do promote their own products.