Growing up in western Massachusetts, as soon as the snow started to melt each winter, my family would make our annual trek to a maple sugar house. I remember the silence as we stepped out of the car, save for a collective inhale of the early spring air, cool and thick with clouds of sweet, toasty sugar. Inside the shack, there was maple candy to nibble as we admired the setup for boiling and filtering the sap.
My mom, admirably frugal, would insist on lugging home a bargain-size container of the rich, amber liquid. But even though we ate mountains of French toast and pancakes, by the time summer rolled around she would invariably discover mold floating at the top of the two-gallon tin when she pulled it from the pantry.
“Not to worry,” she’d declare as she skimmed off the offending fuzz, boiled the syrup, and carried on with breakfast preparations.
Was her approach acceptable?
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Does Maple Syrup Go Bad?
To find out, I phoned Mark Isselhardt, maple specialist and maple program leader at the University of Vermont Extension. He reminded me that syrup “is a single-ingredient food—the sap from sugar maple trees—that’s prepared without preservatives.” That means it can spoil.
Until the early 2000s, the prevailing wisdom was to remove visible mold from maple syrup, boil it for a few minutes to kill any harmful microorganisms, and decant it into a clean container. In fact, those instructions are sometimes printed on syrup labels.
But those recommendations have changed. Allison Hope, executive director of the Vermont Maple Sugar Makers’ Association, pointed to a 2014 study published by maple educator Kathy Hopkins and others at the University of Maine. It showed that some molds in syrup produce mycotoxins that are harmful to consume, and they can't by killed by boiling.
What Should I Do If My Maple Syrup Has Mold?
If you see mold on maple syrup, you should throw the entire container away. (A less common occurrence would be to notice sour, fruity, or floral odor. This is a sign that the syrup has fermented and it’s also recommended that you discard it.)
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The Best Way to Store Maple Syrup
The experts recommend storing unopened containers of maple syrup in a cool, dark place, where they will have a long shelf life, though the syrup may darken over time since most materials—even plastic—aren't perfectly impervious to oxygen.
Once you open the container, transfer the syrup to the refrigerator where, per the USDA, it should last for about a year, or repack it in smaller glass vessels such as Mason jars to store in the freezer, where the rich color and robust maple flavor will be preserved.