Vacuum packaging is a process of packaging that removes air from a bag or container. The air removal modifies the atmosphere within the bag. The removal or reduction of oxygen increases shelf life several times longer than items not vacuum sealed. Vacuum sealing is an excellent, chemical-free way to preserve food.
The question is, can you vacuum seal any bag? If you are removing oxygen from a bag, won’t any bag work? The easy answer is no. Not any bag will work, most bags will not work. Read below to discuss a few options that will suffice and keep an eye out for when purchasing bags for vacuum sealing.
Before pointing out bags that will work, let’s explain why not every bag will work. Technically it has to do with the oxygen transmission rate of the bag. Not so technically speaking, it is how much air seeps out of the bag after being sealed.
Bags with a high oxygen transmittal rate are porous and allow air to escape after the bag is sealed. Clear polyethylene and polypropylene bags have high oxygen transmittal rates. After the air is removed from the bag, the vacuum is lost within seconds of being closed.
When looking for a bag to vacuum seal, the bag needs to specify being a barrier bag. The use of a barrier bag utilizes an oxygen barrier built into the bag. The material a barrier bag is made from will determine the amount of oxygen transmittal rate.
Most barrier bags start with an Oxygen transmission rate of less than 10 cc/100 in2/24 hr. The unit of measurement tracks the cubic centimeters of air loss in 24 hours.
In comparison, a standard low-density polyethylene bag has an oxygen transmission rate of over 450 cc/100 in2/24 hr. That is a significant difference, and barrier bags can achieve a much lower OTR than 10 cc. Below are three options to consider when looking for a bag to vacuum seal.
Coextruded Poly/Nylon Woven Bags
They are used for consumable and non-consumable products around the world. Most poly woven bags are clear and can be seen packaging meats, cheeses, and more. The most common thickness is a 3 mil thickness. Most 3 mil coextruded bags have an OTR of 5 or less.
They are perfect for freezer storage and packaging items for months of storage. We have had dried fruit last over one year in 3 mil coextruded vacuum bags with in-house testing. The vacuum held, and the trail mix was stored at room temperature. Upon opening, the taste and texture were fresh and undisturbed.
Any customers concerned with too high oxygen transmission rates can opt for thicker bags. Increasing the thickness of the bag will lower the amount of oxygen permeation.
Coextruded Poly/Nylon w/EVOH Bags
The EVOH additive is Ethylene Vinyl Alcohol. It is mixed with the resin for additional barrier protection. The EVOH additive does appear slightly more grainy than standard Coextruded bags without the additive.
The advantage is the lowered oxygen transmission rate. A 3 mil coextruded vacuum bag with an EVOH additive can lower transmission rates as low as .02 cc. This increased protection is excellent for any product that may be compromised with too high oxygen transmission. Some specialty products will not spoil with slightly higher oxygen transmission rates, though flavors and smells can be altered. This small change in the product can often have companies finding a better solution to preserve products after being packaged fully.
Foil provides a lower oxygen transmission rate than any plastic bag. Many foil barrier bags have a .0006 cc transmission rate or lower. In addition to the lowered transmission rate, foil bags block out light. Reducing light exposure can be very important for many dairy products, meats, and other edible items.
The PET in the foil bag allows the bag to hold seals. Many foil bags are 4 to 5 mils thick and maintain a phenomenal seal when properly applied. They are a favorite in the coffee industry for preserving the freshness of the coffee beans. Foil vacuum bags are used for many other applications, often with the use of gas flush. Gas flush a package help to further remove oxygen by replacing with a gas of choice. One of the most common gases used is nitrogen. The nitrogen flushes into the bag and replaces the oxygen.
Not any bag will work for vacuum sealing. Regular bags leak oxygen and will not hold a vacuum. When looking for a vacuum bag, be sure the bag specifies being a barrier bag. The amount of barrier will depend on the thickness of the materials and what the bag is made from.