What to Consider When Selecting Barrier Materials for Food Products
In order to prevent food product from spoiling within the expected shelf life, proper barrier materials are required for different products.
There are many types of barrier materials available:
Gas Barrier
– Oxygen
– Carbon Dioxide
Light Barrier
– Visible
– Ultraviolet
Moisture Barrier
Aroma and Flavor Barrier (chemical barrier)
This article explains what you should consider when selecting the proper barrier material for food packaging.
"It is important to understand how your product could interact with various barrier materials."
Many years ago, I tested a flexible package for ready-to-eat ham. The ham looked very juicy with visible liquid around it, and it was packed in a clear film pouch. The product spoiled before its anticipated shelf life and the film had delaminated. The ham manufacturer complained that the vendor sent them defective film. They wanted the film tested to prepare for legal action.
The specified film was multilayered with nylon embedded in the structure. The tested OTR (oxygen transmission rate) of the package was 0.05 cc/(package*day) conducted at 4C, dry. They were asked to supply both new, empty packages and packages with spoiled product. I repeated the dry OTR test and got the same result.
Then I measured the interior relative humidity of the package containing the ham which was 75% RH. This lead me to retest OTR with 75% RH. The results with 75% RH were 0.4 cc/(package*day), eight times higher than the results tested at dry condition. This level exceeded the manufacturer’s specified OTR for the ham product, meaning too much oxygen was getting into the package.
No surprise the OTR went from 0.05 to 0.4 just by adding humidity because there was nylon integrated into the film structure. Nylon is a good oxygen barrier when it is dry. However, it is also a hydrophilic material. When a hydrophilic polymer is exposed to moisture, it absorbs moisture and swells which reduces its barrier properties significantly and causes delamination if it is in a multiple layer structure. Considering the juicy ham product had 75% RH, the manufacturer should have requested the OTR to be tested at 75% RH instead of dry condition.
I reported that the film from the vendor met its stated specification but was inadequate for the application. Product spoilage was due to lack of knowledge about how the barrier material properties can be influenced by the nature of the product. The ham manufacturer should have used film materials that are not moisture-sensitive. If nylon were still chosen, the lamination should have had a better moisture barrier to protect it.
No matter what food products you are packaging, when selecting barrier materials for food products, consider these 4 tips:
Wet or dry products require different barrier materials and test conditions.
Understand the properties of the packaging material you choose. Hydrophilic materials such as nylon are good oxygen barriers in dry environments but not where moisture exists.
Product/packaging material interaction should be assessed. If the protective layer of nylon is not thick enough, nylon will swell when in contact with high humidity and liquid, resulting in delamination.
When testing packaging materials, proper test conditions should be selected to best mimic realistic conditions. In this case, the OTR of film and the bag should have been tested with 75% RH instead of dry condition. Click here to learn more about instruments that can perform this type of OTR testing.
What is the cost of selecting the wrong barrier packaging material?
If the wrong barrier material is selected, the product will spoil, people might get sick, and product will get returned. Further consequences could include regulatory recall and lawsuits. This could cause financial loss and damage to your brand reputation.
To select the proper barrier material, pay attention to the nature of your product in relation to the properties of the barrier material.
Georgia Gu is Applications Specialist at AMETEK MOCON. You may contact her at georgia.gu@mocon.com or view her contributor page.
To learn more about shelf life testing or barrier testing and selection, visit www.mocon.com - www.dansensor.com or www.modifiedatmospherepackaging.com
