When the goal is recyclability, the usual answer is to simplify. Fewer materials, fewer additives, fewer colorants. But food packaging is rarely that simple. Pull a layer out of a structure and you have to ask what happens to the product on the other side of it. The USDA estimates that 30 to 40% of the U.S. food supply gets wasted, so a package that fails to protect what’s inside it isn’t much of a sustainability win either.
You can watch the full episode above or listen on Spotify, Apple Podcasts, or on our website.
Here’s a look at a few of the biggest takeaways from the conversation.
We opened with a game. Natalie named a food product, Mike and Jonathan called out what that product needs from its package. The point was to show how much barrier requirements can vary across a spectrum of food products.
Take a look at the products we reviewed together. Did you know these foods needed this much protection?
Let’s get deeper into the topic itself: what does “barrier” actually mean? Well, the container itself is a barrier, if you want to be literal about it. But what the industry usually means by the word is permeation: oxygen and moisture moving through the plastic and reaching the product.
Mike gave us four versions of the job, and it held up for the rest of the conversation. “I think that analogy of ‘outside in and inside out’ is the most appropriate. Sometimes you’re protecting the product from outside elements. Sometimes you’re protecting the product from the natural transitions that go on inside the package. And then sometimes you’re protecting the package from the product, or you’re protecting the package from the outside elements. I think those four contingencies are what we mostly focus on.”
Forming matters here too. You start with flat sheet and thermoform it down, so the thinnest point in the finished container is also the thinnest point in your barrier. Maintaining the integrity of the EVOH layer throughout the draw is therefore a critical part of high barrier food packaging design.
In a perfect world, a customer arrives with an OTR and MVTR target already in hand. Often, however, the customer starts with a target shelf life, and the packaging structure has to be designed backward from that goal. There’s a lot of industry data to lean on. As Natalie said, these aren’t the first people to ever package applesauce.
Jonathan walked through the sequence. Start with an assumption about EVOH content for the container’s depth and draw ratio. Test the flat sheet. Run Mocon testing to get real transmission values. Then hand cups over for the customer’s own shelf life work, which on a long shelf life product means accelerated aging: adding heat in steps against a recognized industry standard instead of waiting a year in real time.
EVOH is one of the more expensive components in the structure, so how much you actually need is a real question, not a rounding error.
Four base polymers cover most rigid food packaging, and each one is good at something and short somewhere else.
“That’s the thing I love about polypropylene,” Jonathan explained. “It’s got such a wide performance range, whether you’re incorporating a barrier or not, and the end of life scenario is really positive with those various structures.”
Here’s a key point we want our listeners to take away: barrier doesn’t equal shelf life, but shelf life includes barrier.
Everything else in the system sits in that equation alongside it. A packaging engineer is solving for one product, one filling process, one container, one internal environment and one shelf life target, with recyclability on top of that and a price the business can live with. Hot fill and aseptic systems do real preservation work, which is its own episode. So does whatever gets sealed inside the container. Build a beautiful barrier package for guacamole, leave oxygen in the headspace and the avocado still browns. Nobody’s buying brown guacamole.
Natalie raised a great example: think of this system as a terrarium rather than a container. You’re building one environment for one product and then holding it there, and everything in the system has to cooperate, the food included.
All of which puts a lot of weight on the seal. Peel initiation, peel force, sealing through protein contamination. Compromise the seal and your high barrier food packaging structure effectively becomes an open container.
Recycling favors simplicity and mono-materials, and barrier adds materials. There’s no clean way around that.
Some of it has gotten easier, though. Materials have improved enough that today’s applesauce cup uses a fraction of the gauge and the EVOH it would have needed 20 years ago. Past that, the base polymer drives the outcome, and every structure still has to meet APR design for recyclability guidelines.
PET is fully recyclable as a simple mono-material. Add color to block UV and you have an issue. Add barrier and you have a bigger one. Polypropylene holds up better here: add color, EVOH content or a barrier laminate, and as long as the components are standard materials, it stays recyclable.
The obvious question is why one gets accepted and the other doesn’t, and the answer has more to do with markets than with chemistry. “I don’t think the answer is scientific as much as it is market based,” Mike said. “When they do recycle polypropylene with a certain amount of barrier or a certain amount of color, there are end use applications that would utilize the recycled material within a next product.” Recycled polypropylene carrying a little barrier still performs in those applications, and it doesn’t drag down the value of the stream. Technically recyclable and practically recyclable are two different claims.
We closed by digging up the wildest structures we’ve helped customers put together. For anyone who hasn’t run into the term, a “monstrous hybrid” is a material combination that can’t be separated at end of life, which means it can’t be recycled in any form. It becomes trash.
First up: a replacement for a PVDC coated HIPS array tray, the kind that holds the dipping sauces you get at a fast food counter. The original worked fine. It just used PVDC, which is considered not recyclable. The replacement started at nine layers, got simplified to five, and still ended up a monstrous hybrid with high density polyethylene, possibly some PETG, and whatever else was going in by that point. Mike’s summary of the project: “It was four years of my life.”
Then there was the hybrid aseptic system that unspooled and respooled a flexible film layer during packaging, all so the food contact surface stayed clean without fully sterilizing the material. Every step in that process existed to avoid a different one. Natalie’s reaction sums it up: do less.
Thanks for tuning in to the latest episode of Crazy About Packaging! Barrier gets talked about like a spec you can dial up or down, when it’s really a set of decisions about one product, one process and one shelf life target.
If you’re working on a barrier structure, trying to hit a shelf life number with fewer materials, or sorting out what recyclability actually means for your application, this one’s worth a listen. Catch the full conversation on Spotify, Apple Podcasts, or on our website.
We’re also hoping to do a part two with a packaging engineer, to get the view from the other side of the table. Keep an eye out for that one.
If you’re looking for more guidance on high barrier food packaging, contact our team to discuss your material options.