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Everything You Ever Wanted to Know About Oxygen Absorbers (But Were Afraid to Ask)
Posted by Ola Griffin on Oct 27th 2025
Everything You Ever Wanted to Know About Oxygen Absorbers (But Were Afraid to Ask)
By Ola Griffin – PackFreshUSA
I get lots of calls and messages asking how to use oxygen absorbers — and honestly, I love those questions! Oxygen absorbers are one of the most powerful tools in food preservation, but they can seem a little mysterious if you’re new to them. I’ve heard everything from “Why is there moisture in my pack?” to “Can I use these in sugar or salt?”
So today, I want to share some of my favorite tips and best practices for using oxygen absorbers the right way — plus a few important notes on when not to use them. Once you understand how they work, you’ll see just how simple (and essential!) they are for long-term food storage.
Think of this as your friendly guide from someone who’s sealed more Mylar bags than she can count — helping you get the longest shelf life, best freshness, and safest results from your food storage efforts.
Condensation
Condensation in oxygen absorber packs is something many people notice and worry about—but it’s completely normal! Think of it like being in a crowded room. When lots of people are together, it gets warmer. When fewer people are in the room, it stays cooler. Oxygen absorbers work the same way: the more absorbers reacting in a confined space, the more heat they’ll produce.
When you open a large pack of oxygen absorbers, every absorber immediately begins to react with the oxygen in the air. That reaction generates a little heat and sometimes visible moisture—similar to steam. It’s simply the iron powder inside activating, and it means they’re doing their job!
How to Use Oxygen Absorbers Correctly
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Only take out what you’ll use within 20 minutes of opening a new pack.
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Reseal unused absorbers immediately in a vacuum-sealed or airtight container.
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Store remaining absorbers with as little air exposure as possible (in a small jar, Mylar bag, or vacuum sealer bag).
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Choose the correct size absorber for your container—using extra won’t extend freshness and can actually create more heat and moisture.
When used properly, oxygen absorbers are one of the most effective tools for extending shelf life. They remove oxygen, which prevents oxidation, rancidity, and spoilage—keeping your food fresh for years or even decades.
When Not to Use Oxygen Absorbers
Not every food benefits from an oxygen-free environment. Some items are either too dry or too moist, and adding oxygen absorbers can cause unwanted results.
❌ Do NOT use oxygen absorbers with:
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Sugar – It will turn hard as a rock because it naturally needs a little moisture to stay granulated. (will make it clumpy)
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Salt – It’s a mineral, not an organic food product, so it doesn’t spoil and doesn’t need oxygen removal. (will make it clumpy)
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Baking Soda or Baking Powder (or products they may be in like pancake mix) – These are leavening agents; removing oxygen can change their chemistry and make them lose effectiveness. (can cause the bag to expand because of off-gassing)
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Dehydrated Fruits (that are still sticky) – Foods like raisins, apricots, cranberries, or dates contain too much natural moisture. Removing oxygen can create a low-oxygen, high-moisture environment that could promote botulism.
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Brown Sugar or Molasses-Based Foods – They contain natural moisture that reacts poorly with oxygen absorbers and causes clumping.
When to Use Oxygen Absorbers
Use oxygen absorbers for dry, low-moisture foods (below 10% moisture). These are ideal candidates for long-term food storage:
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Rice, beans, lentils
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Whole grains and flour
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Pasta
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Freeze-dried fruits and vegetables
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Powdered milk
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Dry herbs and spices
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Dehydrated (brittle-dry) produce
For these foods, oxygen absorbers help create a truly oxygen-free environment, extending shelf life and preventing bugs, oxidation, and nutrient loss.
PackFreshUSA Pro Tip
DEHYDRATED FOODS: When in doubt—do a quick “snap test.”
If your dehydrated food snaps or crumbles easily, it’s dry enough for oxygen absorbers.
If it’s bendy or sticky, it still has moisture and should be stored in an airtight bag without an absorber (or kept refrigerated).
FREEZE-DRIED FOODS: If you are vacuum sealing jars or bags, lower the level of oxygen absorber by 1/4 to 1/3 of what originally was recommended. (see chart)
The Science Behind the Magic
Oxygen absorbers use a simple, safe chemical reaction—iron powder reacting with oxygen—to create an environment that’s 0% oxygen. This prevents oxidation and the growth of aerobic bacteria, molds, and insects. It’s the same method used by professional freeze-dried food manufacturers to safely preserve food for up to 25 years.
So the next time you see a little condensation or warmth after opening a fresh pack of absorbers, don’t worry—that’s just science in action!
Check out this other blog on oxygen absorbers -
Final Thought
Oxygen absorbers are small but mighty. When used correctly (and in the right foods), they’re your best friend in long-term food preservation. But remember: not everything needs an absorber. The key is understanding the balance between moisture, oxygen, and storage time.
Store smart, seal tight, and let PackFreshUSA help keep your food fresh for decades—not days.
Here is a few tips that I give to customers as they call our customer service telephone number when it comes to oxygen absorbers.
Happy Prepping!
Ola D Griffin
Long-term Food Storage Expert
Customer Service, Safeguard Brands, Inc. dba PackFreshUSA
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