What Causes Maple Syrup Mold? And How to Remove It Safely

Pulling a jar of homemade maple syrup from the pantry is a proud moment—until you notice an unsightly film floating on top. That fuzzy, grayish-white scum? It’s mold. And yes, it can even grow on nature’s sweetest preservative.

Hi there, I’m Claire Holloway—forestry science graduate, family sugarmaker, and storyteller behind Dragonfly Sugarworks. If you’ve spotted mold in your syrup stash, don’t worry: you’re not alone. Today, we’re diving into the sticky science of what causes mold in maple syrup, how to remove it safely, and how to prevent it from coming back.

Let’s get into it—neighbor to neighbor.

Why Does Mold Grow on Maple Syrup?

At first glance, it seems unlikely. Maple syrup is mostly sugar, right? And sugar is known to be shelf-stable. But here’s the truth: mold can grow on improperly stored syrup, especially if it’s not sealed or refrigerated.

Here are the most common causes:

1. Too Much Air in the Container

Air is mold’s playground. Once oxygen enters a jar—especially one that’s been opened and not refrigerated—it creates the perfect environment for mold spores to thrive on the surface.

2. Storage at Room Temperature

Many folks keep their syrup in the pantry. But unless it’s factory-sealed and unopened, syrup should be refrigerated. Mold loves warmth and moisture, and even a cool pantry can invite trouble over time.

3. Unsterilized or Reused Jars

Old jam jars or reused plastic bottles may carry invisible mold spores. This is why we always recommend storing your syrup in Ball wide-mouth jars. These jars can be boiled, sterilized, and sealed for safe, long-term storage—plus, that wide opening makes pouring (and cleaning!) easier.

4. Low Brix (Sugar Content)

The industry standard for maple syrup is 66° Brix, which refers to the sugar concentration. Anything lower than that can make your syrup susceptible to fermentation and mold. If you’re sugaring at home, be sure to check with a hydrometer or refractometer.

5. Improper Sealing

After bottling, your syrup should be hot-packed at 180°F or higher and poured into sterilized jars. If the seal isn’t tight, oxygen slips in, and mold follows.

Is Moldy Maple Syrup Safe to Eat?

Good question. The short answer: yes—if the mold is removed properly.

Unlike some foods where mold signals a definite “toss-it” moment (we’re looking at you, soft cheese and leftovers), maple syrup is dense and sugary enough that surface mold doesn’t always mean spoilage. Most mold doesn’t penetrate the syrup’s body; it simply grows where air meets sugar: the surface.

But here’s the catch: You can’t just scoop it out and call it a day. Proper sanitization is key. Let’s walk through that next.

How to Safely Remove Mold from Maple Syrup

If you’ve discovered mold in your syrup, here’s what to do:

Step-by-Step Removal

Remove the Mold
Carefully skim off the mold from the top using a clean spoon. Discard the mold in a sealed compost bin or trash bag.
Reheat the Syrup
Pour the syrup into a clean pot. Bring it to a low boil (about 190°F–200°F), stirring gently. This kills off lingering spores.
Sterilize Your Jars
Boil your Ball wide-mouth jars and lids in water for 10 minutes. These jars are perfect because they’re heat-safe and seal tightly.
Repackage the Syrup
Pour the hot syrup into the sterilized jars, leaving about ¼-inch headspace. Wipe the rims clean, then secure the lids tightly.
Refrigerate
Once the jars cool, move them into the fridge. Maple syrup should be refrigerated after opening or after the seal is broken—even if it’s homemade.

🧊 Pro Tip: If you prefer storing your syrup at room temperature, consider canning it properly with heat processing for a vacuum seal. This works especially well with Ball jars.

How to Prevent Maple Syrup Mold in the First Place

Like many things in the sugarmaking world, prevention is easier than correction. Follow these tips for mold-free syrup year-round:

✅ Use sterilized containers like Ball wide-mouth jars
✅ Store syrup in the fridge once opened
✅ Always hot-pack your syrup when bottling (180°F+)
✅ Maintain proper sugar content (66° Brix)
✅ Seal jars tightly and wipe rims clean
✅ Label jars with bottling dates and storage instructions

Product Spotlight: Ball Wide-Mouth Jars

Let’s talk jars. In our own sugarhouse, Ball wide-mouth jars are our go-to for safe, efficient syrup storage. Why?

Easy to Sterilize: Glass holds up to boiling water.
Perfect Seal: Lids screw on tight, minimizing oxygen exposure.
Roomy Mouth: No sticky mess while pouring or ladling.
Airtight & Reusable: Ideal for gifting and long-term use.

You can grab a 12-pack and never worry about running out during sugaring season. Pair them with your homegrown syrup and you’ve got the ultimate homemade pantry win.

FAQs About Maple Syrup Mold

Can you still eat maple syrup with mold?
Yes, most surface mold on maple syrup can be removed safely by reheating and repackaging the syrup in sterilized jars. Just be sure to refrigerate it afterward.

What causes mold to grow in maple syrup?
Mold grows when syrup is exposed to oxygen, stored at room temperature, packed in unsterilized containers, or when the sugar content is too low.

How do I prevent mold in maple syrup?
Always store syrup in sterilized, airtight jars like Ball wide-mouth jars, refrigerate after opening, and ensure the syrup is hot-packed and properly sealed.

Do I need to refrigerate unopened maple syrup?
Unopened factory-sealed syrup can be stored at room temperature. However, once opened—or if it’s homemade—it should be refrigerated to prevent mold.

What does mold in maple syrup look like?
It usually appears as a whitish-gray film or scum on the surface of the syrup. It may look fuzzy or clumpy, floating at the top of the jar.

The Sweet Takeaway

Maple syrup is a treasure—one that deserves proper care. While mold can be alarming, it doesn’t mean your syrup is ruined. With the right knowledge and tools, like Ball wide-mouth jars, you can prevent and remove mold safely, ensuring every spoonful stays pure and delicious.

So the next time you bottle a batch or crack open a homemade jar, do it with confidence. And if your pantry isn’t stocked with the right jars just yet, we highly recommend investing in Ball’s tried-and-true lineup.

👉 Ready to make mold a thing of the past? Pick up a set of Ball wide-mouth jars here and give your maple syrup the clean, cozy home it deserves.

From our sugarbush to your table,
Claire Holloway
Dragonfly Sugarworks

What Causes Maple Syrup Mold? And How to Remove It Safely