Introduction: Why Barrier Performance Matters in Product Success
Packaging your product today is about protection, more specifically, protection from oxygen, moisture, and the elements. If your package can’t control the transmission of these outside elements into the package environment, your product is likely to fail before it ever reaches the end user.
Oxidation and moisture are enemies to any product. You see this phenomenon happening across all industries: food, pharmaceuticals, personal care, nutritionals, and even electronics. When exposed to as little as oxygen or water vapor, these products can begin to degrade. High barrier packaging solutions can slow down this transmission, allowing for longer shelf lives, less waste and efficient distribution channels around the world. It even helps to prevent product loss during long shipping distances.
The key performance indicators that drive packaging performance are Oxygen Transmission Rate (OTR) and Water Vapor Transmission Rate (WVTR). Before we dig into OTR and WVTR, it’s important to understand how each of these factors impacts your products and how to use them to your advantage when selecting materials and packaging structures.
What is Oxygen Transmission Rate (OTR)?
OTR refers to the amount of oxygen that can pass through a specific area of material in a defined period of time at set conditions. It’s quite possibly one of the simplest tests there is, but also one of the most important when determining your package’s performance.
Oxygen is considered the number one catalyst for speeding up product degradation. Once oxygen makes its way into your package, it will begin to oxidize the contents of your package. It results in changes in color, loss of flavor and even nutritional degradation. Oxygen can also accelerate spoilage by promoting the growth of aerobic microbes in your package. Food products are especially susceptible to this, such as sauces, dairy, and even processed foods.
The smaller the OTR value, the better the material can resist the transmission of oxygen. OTR, like many things, is not a constant value and will fluctuate based on surrounding conditions. As the temperature increases, so does the movement of molecules within your packaging material. It means that more oxygen can permeate through the material as temperatures rise. Similarly, as humidity increases, some packaging materials will begin to break down, losing their effectiveness as an oxygen barrier.
It is why when we look at OTR data from material suppliers, we need to look for packaging materials that will not only perform well in the laboratory but will also perform well during distribution, storage, and in varying climates.
What is Water Vapor Transmission Rate (WVTR)?
WVTR, also known as water transmission rate, is the amount of moisture that can pass through a material over a period of time. If oxygen breaks down the integrity of your product, moisture will change the physical appearance of your product.
Changes in moisture can cause your products to lose crispness, form clumps, or even grow molds. Unlike oxidation, these changes can be seen immediately by the consumer, making moisture control one of, if not the most important, factors for consumer acceptance.
Managing WVTR can be even trickier than OTR. It is because water vapor is extremely sensitive to fluctuations in temperature and humidity. As the surrounding environment becomes more humid, the transmission of moisture can increase exponentially.
When shipping products to other regions of the world that are exposed to tropical weather or environments with high humidity, it’s critical to select a material that has proven performance when it comes to WVTR. Otherwise, your package may perform well in the laboratory but fail under real-world conditions.
OTR vs WVTR: What’s the Difference?
OTR (oxygen transmission rate) and WVTR (water vapor transmission rate) certainly test barrier properties, but they are trying to stop completely different things. OTR is interested in oxygen ingress and keeping materials chemically stable. WVTR deals with the absorption of moisture and maintaining physical quality attributes.
OTR and WVTR matter because packaging needs to do both. Packaging cannot simply be rated as “low OTR” and have that mean success. Processed meats, for example, have incredibly low OTR needs but very little need for low WVTR. Stale crumbs can ruin snack foods, so they require low WVTR but don’t have to worry as much about oxygen ingress.
Designing packaging with proper barrier properties means balancing O₂ and moisture control. Ultimately, the goal is to engineer the lowest OTR and WVTR possible given the constraints of the application.
How Do OTR and WVTR Impact Shelf Life?
Packaging limits exposure to oxygen and moisture, which increases shelf life. The less time products spend exposed to oxygen and moisture, the longer they’ll stay fresh. It keeps food tasting good, colors bright, and nutritional value high. Increasing shelf life allows products to travel farther without damage. If you need your products to sit on shelves for months without going bad, you need high barrier packaging.
Moisture control limits oxidation and microbial growth. When both of these are reduced, the shelf life of products can increase. Fewer rotten or stale products mean less waste.
Strong barriers allow for cleaner labels. If your products are well protected from oxygen and moisture, you don’t need preservatives. It is because good packaging can extend shelf life without the use of chemical additives.
Materials and Their OTR/WVTR Properties
There is no perfect material that acts as a barrier to both oxygen and moisture. Every material sacrifices something, which is why most packaging uses multiple material layers.
Polyolefins such as PP (polypropylene) or PE (polyethylene) have fantastic moisture barrier properties. They are water-resistant and incredibly durable. Polyolefins are terrible at preventing oxygen ingress.
EVOH boasts some of the lowest oxygen transmission rates of any material. It means it is extremely effective at keeping oxygen out and your products fresh. EVOH’s weakness is high humidity. If EVOH gets wet, it loses its excellent barrier properties, which is why it is never used alone.
Metal based materials block 100% of oxygen and moisture. The downside to aluminum is that it isn’t see-through, it’s not flexible, and it can have defects. While it has amazing properties, it cannot always be used due to these limitations.
OTR vs WVTR—Which Barrier Matters More?
In order to achieve the performance unattainable by a single material layer, high barrier packaging structures are created by combining multiple materials in a unique system. One of the most popular high barrier packaging structures is the 5-layer co-extruded structure: PP / Tie / EVOH / Tie / PP.
The outer layer and inner layer of polypropylene provide structure, mechanical strength, and a moisture barrier. The middle layer of EVOH acts as an oxygen barrier to greatly reduce oxygen transmission. Each plastic layer’s tie layers are specifically designed to stick firmly to the other layers.
By combining multiple materials, packaging engineers can maximize both oxygen and moisture barrier properties within the same package. Through layer upon layer of specialized materials, high-barrier structures can achieve far better performance than their single layer counterparts.
Why Multi-Layer (5-Layer) Structures Are Used
The environment can have a large impact on barrier properties. Increases or decreases in temperature and humidity can make materials more or less resistant to oxygen and moisture transmission.
Higher temperatures increase the kinetic energy of the molecules within a polymer, allowing more opportunities for oxygen and moisture to permeate through the material. As temperatures rise, not only is the barrier weakened, but the products within the package are likely to have decreased shelf lives. Humidity can also affect barrier properties like oxygen resistance.
EVOH is known for its low oxygen transmission rate, but when exposed to increased levels of humidity, the polar ends of the molecules change configuration to accommodate the water molecules. This leaves more free space for oxygen molecules to pass through.
OTR & WVTR vary depending on the surrounding environment. As products are shipped all over the world, they often experience changes in climate. From hot, humid to cold, dry environments, it is important that your package performs well in a variety of conditions.
Where Are OTR and WVTR Used in Different Industries?
Pharmaceutical companies need very low OTR and WVTR to ensure the freshness and longevity of their products. Think of oxygen and moisture sensitivity in food products and how package performance is matched to different food products. Some foods are more oxygen-sensitive than others. The same theory applies to moisture sensitivity.
Think about some of the electronic components you own that require some sort of protective packaging. High barrier performance is critical for packaging that protects against oxygen & moisture in the long term. OTR and WVTR requirements vary from industry to industry and even within each industry. You cannot assume that just because one package has a low oxygen transmission rate, it will work for your application.
How to Determine the Right Barrier Performance You Need
Selecting the proper barrier performance for your package is more than just finding the lowest OTR or WVTR value. Knowing your products sensitivity to oxygen and moisture is critical.
If your product is not that sensitive to oxygen or moisture, you likely do not need a high barrier package. Also, consider where your product will be stored during transportation. Will it be shipped to or stored in a hot and humid environment? All these factors play a role in what barrier performance you should choose.
Last but not least, you have to consider your desired shelf life. If your product is going to be consumed relatively quickly or shelf life is not a large concern, you likely do not need a high barrier package. However, if your package will be distributed worldwide and sit on shelves for longer periods of time, you will need higher barrier performance. Cost factor as well when choosing the right barrier performance.
Benefits of High Barrier Packaging for Your Business
Lengthening shelf life not only means that your product can sit on shelves longer without going bad, but it also reduces pressure on your supply chain.
Consumers prefer high quality products and will continue to purchase from brands that they know and trust. If your product consistently tastes, looks, and performs as intended when opened, you will retain your customers, and they will buy from you again.
Let’s say you want to eliminate preservatives from your food product. If you’re able to limit the amount of oxygen and moisture that come into contact with your food, you can extend shelf life without using preservatives.
How Srlon Group Achieves High Barrier Properties
At Srlon Group, we create high barrier packaging by combining multiple materials into a single structure. We take EVOH, which has outstanding oxygen barrier properties, and place it in the middle of a 5-layer co-extruded structure (PP / Tie / EVOH / Tie / PP).
It provides our customers with a high barrier package that doesn’t sacrifice moisture barrier or package structure. Not only does Srlon produce high barrier packages, but we also make sure that the barrier performance is consistent. During manufacturing, we closely monitor and control layer distribution to ensure the highest level of package reliability.
Conclusion: Why are OTR and WVTR Important?
OTR and WVTR are ratings that determine the performance of high barrier packaging. As the world continues to seek packaging that offers longer shelf life, higher-quality products, and sustainable options, understanding these terms will become increasingly crucial.
High barrier packaging is about more than just using high performing materials. It’s about creating a better package that protects your products, reduces waste, and provides your customers with a quality product.
FAQs
1. What is a beneficial OTR value for packaging?
It depends greatly on the application. Oxygen-sensitive products like meat, dairy, and sauces will require extremely low OTR numbers to keep products from oxidizing and going bad. Other products aren’t as sensitive to oxygen and can have a higher OTR number. Generally, a lower OTR provides better protection against oxygen and extends the product’s shelf life.
2. What exactly is the difference between OTR and WVTR?
OTR is the rate at which oxygen passes through a material, and WVTR is the rate at which moisture passes through a material. Oxygen will cause your product to oxidize, while water vapor can cause mold, clumping, and loss of texture.
3. Why would I use EVOH in my packaging?
EVOH stands for Ethylene Vinyl Alcohol and is used to inhibit oxygen transmission into your packaging. It means that less oxygen will come in contact with your product, extending its shelf life. EVOH can be used on its own, but because it is moisture sensitive, it is normally used within a multi-layer structure to protect it.
4. How does a 5-layer structure improve barrier performance?
PP / Tie / EVOH / Tie / PP improves overall performance by allowing the combined benefits of each layer to be evenly distributed. Most single layers are good at one thing but poor at another. By combining multiple layers, you are able to create a product with strength, moisture protection, and oxygen barrier properties.
5. Can high-barrier packages replace preservatives?
Yes, in most applications. Exposure to oxygen and moisture are the two main factors that cause your product to go bad. By using a high barrier package you can keep oxygen and moisture away from your product longer, extending its shelf life without the use of preservatives. It makes it ideal for clean-label products.
6. Why do temperature and humidity impact package performance?
Heat causes everything on a molecular level to move faster, which means more moisture and gas will pass through your package at a higher rate. Humidity can also alter the physical structure of some materials (oxygen barriers are especially susceptible), thereby reducing their performance. That’s why packages are normally tested under conditions that mimic actual storage and distribution, not just in room-temperature labs.
