How Long Will Food Last in a Mylar Bag?

If you’re serious about food storage, you’ve probably asked yourself: How long will food last in a Mylar bag? Whether you’re prepping for emergencies, bulk buying, or just want to reduce food waste, understanding the shelf life of various foods stored in Mylar bags is crucial. Mylar bags, combined with the right techniques, can preserve food for decades — but factors like oxygen presence and food type make a big difference. In this article, we’ll dive deep into the science behind Mylar bag storage, the role of oxygen absorbers, and exactly how long you can expect your food to last.

Do You Need Oxygen Absorbers in Mylar Bags?

One of the most important questions when using Mylar bags is whether to include oxygen absorbers. The answer is a resounding yes if you want to maximize shelf life.

Why Use Oxygen Absorbers?

Oxygen absorbers remove oxygen (O₂) from the sealed environment inside the Mylar bag. This is critical because oxygen promotes:

• Oxidation of food, which leads to rancidity and nutrient loss
• Growth of mold and bacteria
• Infestation by pests and insects

Without oxygen absorbers, oxygen levels inside a sealed Mylar bag can remain around 2% even after 48 hours, allowing spoilage to continue.

Shelf-Life Difference: With vs Without Oxygen Absorbers

Using oxygen absorbers drastically extends the shelf life of your stored food by creating an oxygen-free environment, preventing spoilage and pest damage. For long-term storage, they are essential.

Mylar Bag Food Storage Shelf Life Chart

Here’s a quick overview of estimated shelf life when foods are stored in Mylar bags with oxygen absorbers:

How Long Will Food Last in Mylar Bags?

Rice

• White rice: Can last up to 30 years when sealed with oxygen absorbers and stored in a cool, dry place.

• Brown rice: Has a shorter shelf life of about 5–7 years due to its natural oils, which can go rancid faster.
  Pro tip: Pre-freezing rice before sealing can kill any bugs or larvae, further protecting your stock.

Beans

Beans can last up to 30 years in sealed Mylar bags with oxygen absorbers, maintaining their nutritional value and taste over time.

Flour

• White flour: Can last 10–15 years when stored properly.
• Whole wheat flour: Lasts about 5 years max because of its higher oil content, which can spoil faster.
  Recommendation: Freeze flour before sealing to kill pests and extend shelf life.

Oats, Pasta, Sugar, Salt…

• Oats and pasta: Last 20–30 years in Mylar bags with absorbers.
• Sugar, salt, baking soda: These can last indefinitely and do not require oxygen absorbers.

Choosing and Using Oxygen Absorbers

To get the best results, it’s important to use the right size and amount of oxygen absorbers:

• Rule of thumb: Use about 300 cc of oxygen absorber per 1 gallon of rice.
• Oxygen absorbers come in sizes like 200cc, 300cc, and 1000cc. Choose based on bag size and food density.

Properly pairing your Mylar bags with the correct oxygen absorbers ensures your food stays fresh and safe for decades.

How to Seal Mylar Bags Correctly

Sealing Mylar bags properly is essential to ensure your food stays fresh and protected for the long term. Here’s a simple step-by-step guide:

1. Fill the Bag: Place your dry food into the Mylar bag, leaving enough space at the top for sealing.
2. Add Oxygen Absorbers: Insert the correct size oxygen absorber based on the volume of food and bag size. This removes oxygen and prevents spoilage.
3. “Burp” the Air: Gently press the bag to expel excess air before sealing. This reduces oxygen inside and helps create a tight seal.
4. Seal with Heat: Use a heat sealer or an iron (set to medium heat) to seal the top of the Mylar bag completely. Make sure the seal is continuous and airtight.

Tip: Use 5 mil thick Mylar bags for the best combination of durability and ease of sealing. Thinner bags are more prone to punctures and leaks.

Optimal Storage Temperature and Environment

To maximize the shelf life of food stored in Mylar bags, store them under ideal environmental conditions:

• Temperature: Keep storage below 75°F (24°C), with cooler temperatures preferred. Cooler environments slow down chemical reactions and prevent spoilage.
• Light: Store Mylar bags in a dark place or inside opaque containers to protect food from light, which can degrade quality.
• Moisture and Humidity: Avoid areas with high humidity or moisture, as this can cause mold growth and spoilage even in sealed bags.

How to Tell if Food in a Mylar Bag Has Gone Bad

Even with proper storage, it’s important to regularly check your food stock for signs of spoilage:

• Bloated Bag: Swelling indicates gas buildup from microbial activity or spoilage.
• Off Smell: Any sour, rancid, or unusual odors are a red flag.
• Color Changes: Discoloration or dark spots can signal mold or oxidation.
• Visible Mold: Any mold growth inside the bag means the food is unsafe to eat.

Common Causes: Spoilage often results from a failed seal, oxygen leaks, or moisture contamination during storage.

Common Mylar Bag Storage Mistakes

Avoid these pitfalls to ensure your food lasts as long as possible:

• Using Thin Bags (<5 mil): Thin bags are prone to punctures, tears, and leaks, compromising your food’s protection.
• Inadequate Oxygen Absorbers: Using too few absorbers or exposing them to air before sealing reduces their effectiveness.
• Storing in Warm/Humid Environments: Heat and moisture accelerate spoilage and degrade food quality.
• Not Rotating Stock (FIFO): Failing to use the “First In, First Out” method can lead to older food expiring unnoticed.

Pro Tips vs Best Practices

• Oversize Your Oxygen Absorbers: It’s better to use slightly larger or more absorbers than needed to ensure complete oxygen removal.
• Use Secondary Containers: Store sealed Mylar bags inside plastic buckets or steel drums for extra protection against rodents and physical damage.
• Label Everything: Clearly mark each bag with the date of packaging and contents to track shelf life and rotate stock efficiently.
• Reusing Mylar Bags: Yes, you can reuse Mylar bags if they are clean, dry, and have resealable tops.

Conclusion

When you combine high-quality Mylar bags with the right oxygen absorbers and store them properly, you can expect shelf lives ranging from 5 to over 30 years depending on the food type.

Key takeaways:

• Store food in a cool, dry, dark place below 75°F (24°C).
• Use the correct size and amount of oxygen absorbers to remove all oxygen.
• Seal bags properly with heat using 5 mil thick Mylar bags for durability.
• Protect your storage with secondary containers and label everything clearly.

Ready to start your long-term food storage journey? Shop premium Mylar bags and oxygen absorbers at kimecopak.ca trusted by preppers, bulk buyers, and small food businesses across Canada for reliable, high-quality packaging solutions.