The length of time flour remains fresh for use when packed in Mylar bags, depends upon how the flour is stored and packaged. Mylar bags are designed to keep oxygen, moisture and light from entering the bags.

Under standard pantry conditions, in its original paper bag, white flour typically lasts 6 to 12 months before quality starts to decline. When sealed in Mylar bags, that timeline changes significantly.

The shelf-life of flour packaged in Mylar bags with oxygen absorbers stored in a cool, dry and dark place is, at most, 25 years. White flour has the longest life, while whole hheat flour has a shorter lifespan due to the natural oil content.

How Long Does Flour Last in Mylar Bags?

When combined with an oxygen absorber, flour stored in Mylar bags can last 5 to 25 years.

• White flour is approximately 10-15 years.
• Whole wheat flour is approximately 5-10 years due to the higher natural oils present.
• All-purpose flour is usually more than 10 years when stored in a cool, dark place.

Without oxygen absorbers, flour stored in Mylar bags has a shelf life that is greater than that of flour stored in a pantry; usually between 1-3 years. 

What is the Absolute Maximum?

These estimates are the highest possible longevity, provided that the storage conditions are the best for preserving flour. In other words, if you store flour using food grade Mylar bags, heat sealed correctly, with oxygen absorbers, under zero moisture conditions, and in a cool (under 65°F), dark, and stable environment, your flour could last for the following amounts of time:

White flour: 20-25 years

All-purpose flour: 15-20 years

Whole wheat flour: 10-15 years

Although the actual safe storage times for each type of flour would likely be lower in everyday situations, these times represent the highest numbers given optimal preservation conditions.

View mylar bags perfect for flour storage. 

Why Mylar Bags Will Extend the Life of Your Flour

The multiple layers of Mylar bag material are engineered to keep external contaminants out of the packaging system. The barrier properties of Mylar are much superior to those of Paper and thin plastic, allowing for a true barrier.

Mylar Bags provide the following benefits:

- When used correctly, they are airtight.
- Mylar bags prevent moisture from contaminating flour.
- The Mylar Bags block out light exposure that otherwise destroys nutrients.
- It also protects flour from insects and rodents.

When used together with oxygen absorbers, mylar bags will create an environment in which flour remains viable for years, as opposed to only months.

Brandmydispo manufactures mylar bags and customized Mylar bags for long-term food storage, bulk purchasing and business. Shop personalized mylar bags here. 

Do You Need Oxygen Absorbers?

Oxygen absorbers are essential for long-term food storage. If you plan to do long-term storage of food, you must use an oxygen absorber.

Without using oxygen absorbers:

• Your flour will only keep for 2 – 3 years at the very most.
• Your flour will still oxidize.
  

With the use of oxygen absorbers:

• The oxygen content is reduced to less than 0.1%
• Insects and larvae cannot thrive.
• The color, taste and baking qualities are maintained.

What Type of Oxygen Absorbers Should I use For Flour in Mylar Bags?

For flour storage the use of a 300cc to 500cc oxygen absorber for each gallon-sized Mylar bag is recommended.

The Best Storage Conditions for Flour in Mylar

Here are the ideal storage conditions for flour put into Mylar bags so that even perfectly sealed bags could be compromised if not stored correctly.

The ideal storage conditions are:

- At temperatures below 70 degrees Fahrenheit

- At low humidity levels

- Out of direct sunlight

- Inside bins or boxes for extra protection

- Not in garages, attics, or sheds where there is a lot of temperature variation. 

Temperature stability is more important than anything else in maintaining the integrity of the bag.

White Flour vs Whole Wheat Flour Shelf Life

Both white flour and whole wheat flour are affected by their grain components. However, this doesn't affect every person in the same way.

White flour has longer shelf life than whole wheat flour because it lacks bran and germ. Both bran and germ are high- in oil content, and their oil can turn rancid over time, thus diminishing the quality of the flour.

Whole wheat flour does not have the same amount of shelf life as white flour, there is still the possibility of extended shelf life if it is stored in Mylar bags. But even with Mylar packaging, whole wheat flour will have a longer shelf life than other methods of storing but not nearly as long as white flour.

If you want to achieve the utmost shelf life from your flour products, it is best to purchase white flour.

Signs Your Flour Has Gone Bad

Even flour that has been stored for an extended period of time should be evaluated prior to baking.

Flour spoilage indicators & Signs to look for include:

1. A sour or bitter odor.
2. Color fading or yellowing.
3. Lumps caused by moisture.
4. Unusual taste after baking.

Obtain your own conclusion when deciding whether or not to discard flour that has a foul odor. While mylar continues to slow spoilage, it's important to understand that it will never completely eliminate spoilage.

Are Mylar Bags For Storing Flour Safe?

Yes, provided they have been designated food safe and meet the necessary manufacturing criteria for food contact materials (i.e., the Mylar bag must be made of safe inner layers, have food safe inks used on the bag and have a proper seal).

However, not all Mylar bags currently available for purchase on the market have been produced under the same applicable standards. Many low-quality, poorly manufactured Mylar bags may present some risk when used for storing flour.

For additional information about food safety and Mylar bags, see our detailed article; Are Mylar Bags Safe for Food?

So, How Long Does Flour Last in Mylar Bags?

The shelf life of flour ranges from 5 to 20+ years if it is stored correctly in a Mylar bag under the correct conditions. The proper sealing and storage conditions for flour should include the use of Mylar bags and oxygen absorbers.