Author: Site Editor Publish Time: 30-10-2025 Origin: Site
Mylar bags are highly regarded for long-term food storage due to their ability to preserve food. They protect food from moisture, light, and oxygen. However, not all foods should be stored in Mylar bags.
In this article, we’ll identify which foods shouldn’t be stored in Mylar bags and why. You’ll learn about the risks and best practices for safe, effective food storage.
Mylar bags are made from a strong plastic film called BoPET (Biaxially-oriented polyethylene terephthalate), which is highly resistant to oxygen, moisture, and light. This material is used to make Mylar bags, which are known for their shiny, foil-like appearance. The bags are constructed by layering polyester with a thin aluminum coating, creating a barrier that helps preserve the food inside by preventing contaminants from getting in.
In food storage, Mylar bags are used with oxygen absorbers to create an airtight seal. The oxygen absorbers remove oxygen from the bag, which slows down oxidation, mold growth, and bacterial contamination, ensuring the food stays fresh for an extended period.
1. Oxygen Barrier: Mylar bags prevent oxygen from entering, reducing the chances of food spoilage caused by oxidation and bacteria.
2. Moisture and Light Protection: The aluminum coating reflects light and blocks moisture, keeping food dry and preventing nutrient loss.
3. Sealing: The airtight seal of Mylar bags keeps out pests and contaminants, preserving food in a safe environment.
Mylar bags are most effective for storing dry foods such as grains, legumes, and dehydrated foods. The bags help extend the shelf life of these foods by preventing moisture from causing mold and bacteria growth, while also protecting them from light and air. They are an essential tool for preppers, survivalists, and anyone looking to store food for long periods.
Fresh fruits and vegetables are high in water content, ranging from 70% to 95%. When stored in Mylar bags, the moisture inside these foods cannot escape. This trapped moisture creates an environment conducive to mold growth, bacterial contamination, and rapid spoilage. The result is that fresh produce can quickly rot inside an airtight container like a Mylar bag.
Why Moisture Matters: The lack of airflow inside a sealed Mylar bag prevents moisture from evaporating, leading to microbial growth that accelerates food spoilage. Fresh produce requires proper refrigeration or freezing to stay fresh.
Alternative Storage: Store fresh fruits and vegetables in the refrigerator or freezer, where they can be kept at appropriate temperatures to maintain freshness.
Dairy products, particularly soft cheeses, contain high moisture levels, which can lead to bacterial growth when sealed in Mylar bags. Milk-based products like butter and cheese can spoil quickly in low-oxygen environments, even with oxygen absorbers present. The lack of airflow also increases the risk of fermentation, mold, and unpleasant odors.
Why They Shouldn’t Be Stored in Mylar Bags: Dairy products are perishable and require a constant temperature and controlled humidity to avoid spoilage. Sealing them in Mylar bags traps moisture, creating an ideal environment for bacterial growth.
Alternative Storage: Keep dairy products refrigerated or consider freeze-dried versions for long-term storage.
While dry pasta and rice are great candidates for Mylar storage, their cooked counterparts are not. Cooked pasta and rice retain a significant amount of moisture, making them prone to mold, bacteria, and spoilage when stored in airtight containers. The moisture inside these cooked foods cannot evaporate, leading to rapid deterioration.
Why Cooked Foods Are Risky: When sealed in Mylar bags, the moisture in cooked pasta and rice remains trapped, promoting mold and bacterial growth. These foods need to be dehydrated to below 10% moisture content before being stored.
Alternative Storage: Dehydrate cooked pasta and rice before storage, or store cooked foods in the freezer, where the low temperatures prevent spoilage.
Nuts and seeds are high in oil, which can lead to rancidity when stored in Mylar bags. Even though Mylar bags create an oxygen-free environment, oils break down over time due to natural chemical reactions, causing unpleasant odors, flavors, and nutrient loss. This process is called oxidative rancidification.
Why Oils Go Bad: While oxygen is removed from the bag, the oils inside nuts and seeds are still exposed to slight temperature fluctuations and residual moisture, which can accelerate the rancidity process.
Alternative Storage: To extend the shelf life of nuts and seeds, store them in vacuum-sealed bags or in the freezer, where the low temperatures slow down the oxidation process.
Whole wheat flour contains natural oils in its bran and germ. When stored in Mylar bags, these oils break down over time, causing the flour to turn rancid. In contrast, refined white flour has a longer shelf life because it lacks these oils.
Why Whole Wheat Flour Rancidifies: The oils in whole wheat flour can oxidize even in an airtight environment, leading to the development of off-flavors and a loss of nutritional value.
Alternative Storage: Store whole wheat flour in vacuum-sealed bags or refrigerate it to prolong its freshness. Alternatively, use white flour for longer shelf life.
Granola and trail mix often contain a combination of nuts, seeds, and dried fruits, all of which have high-fat content. The oils in these foods can cause rancidity over time, particularly when stored in Mylar bags. The presence of sugars can further accelerate oxidation, leading to spoilage.
Why These Foods Spoil in Mylar: The fats in nuts and seeds, combined with the sugars in dried fruits, make these foods prone to oxidation. Mylar bags cannot prevent this natural chemical breakdown.
Alternative Storage: Store granola and trail mix in vacuum-sealed bags or refrigerate them to prevent oxidation and maintain freshness.
Brown sugar is hygroscopic, meaning it absorbs moisture from the air. When stored in Mylar bags, it loses its moisture balance, hardening into a solid block. Similarly, salt can clump when exposed to humidity, and while it doesn't spoil, it can be difficult to use if it becomes too hard.
Why They Shouldn’t Be Stored in Mylar Bags: The airtight nature of Mylar bags traps moisture, causing these products to clump or harden, which makes them difficult to use.
Alternative Storage: Store brown sugar in a moisture-controlled container or use a moisture absorber. Salt can be stored in a sealed container, away from excess humidity.
Certain foods, such as raw potatoes, garlic, and wet beans, can develop botulism spores when stored in a low-oxygen environment. Mylar bags, in combination with oxygen absorbers, create such an environment, which can lead to the growth of Clostridium botulinum, a bacteria that causes botulism.
Why Botulism Occurs: Mylar bags are excellent at removing oxygen, but some bacteria thrive in anaerobic (low-oxygen) conditions. Foods like garlic, raw potatoes, and homemade jerky are at higher risk for botulism in these sealed environments.
Alternative Storage: Use refrigeration or freezing for these high-risk foods, or store them in containers that allow some airflow to prevent botulism development.
While Mylar bags are effective for preserving many foods, they create an environment that is too conducive to the growth of harmful bacteria for some foods. The lack of oxygen can allow harmful microorganisms to thrive, leading to foodborne illnesses.
Proper Storage Conditions: Some foods, like raw potatoes and garlic, should be stored in a cool, dry place with proper airflow. For meats and other high-risk foods, refrigeration or vacuum-sealing may be a safer option.
Certain foods that are at risk for botulism should never be stored in Mylar bags. Instead, these foods should be stored in containers that allow airflow, like glass jars or vacuum-sealed bags, or refrigerated or frozen to maintain their safety.
Before storing food in Mylar bags, ensure it is thoroughly dehydrated. Foods with high moisture content can cause mold and spoilage if not properly dried. Dehydration removes moisture, making foods more stable and less prone to bacterial growth.
Best Practice: Use a food dehydrator or freeze-drying process to reduce moisture to below 10% before storing in Mylar bags.
Oxygen absorbers are a critical component of food storage in Mylar bags. They remove any residual oxygen, preventing oxidation and spoilage. Make sure to use the correct size for the Mylar bag and food type.
Best Practice: For a gallon-sized Mylar bag, use a 300-500cc oxygen absorber, and adjust based on the food volume.
To ensure the best preservation, seal Mylar bags carefully and store them in a cool, dry place, away from sunlight. Proper sealing prevents air and moisture from getting inside, keeping your food safe and fresh.
Best Practice: Use a heat sealer to ensure an airtight seal and store Mylar bags in a temperature-controlled environment to extend shelf life.
Not all foods are suitable for storage in Mylar bags. High-moisture foods, fatty items, and those that need airflow should be stored differently. Understanding what works with Mylar bags ensures food stays fresh and safe. Following best practices like dehydration and proper sealing can maximize the benefits. For effective food packaging, M-star Packaging provides high-quality Mylar bags, offering long-lasting solutions for safe and efficient food storage.
A: Foods with high moisture content, like fresh fruits, vegetables, dairy, and cooked pasta, should not be stored in Mylar bags. The lack of airflow and moisture control leads to mold and bacterial growth, causing spoilage.
A: Oily foods, such as nuts and seeds, can go rancid in Mylar bags due to the oils breaking down over time. Oxygen removal cannot stop this oxidation, making them unsuitable for long-term storage.
A: Yes, dry foods such as grains, beans, and dehydrated fruits are ideal for Mylar bags. They remain fresh and safe due to the airtight seal and moisture protection, especially when used with oxygen absorbers.
A: Mylar bags provide a strong barrier against moisture, light, and oxygen. These properties help extend the shelf life of dry foods, preventing spoilage and nutrient loss.
A: Yes, Mylar bags are perfect for long-term food packaging. They create an airtight environment, preserving food by blocking oxygen and moisture, ideal for items like rice, pasta, and dried legumes.
