Understanding barrier performance in sustainable coffee bags

Paul Clearfire
November 16, 2023
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Sustainable coffee bags have several boxes to tick. While their main purpose is to keep roasted coffee in one place, it also serves several other functions. Every detail of manufacture, from the colour palette to the materials used, conveys a message to the consumer. 

Therefore, the bag’s shape must be self-supporting and elegant to display its story for all to see. Additionally, the materials must be strong enough to maintain this shape while preserving the integrity of the coffee through multiple forms of transport. 

Ideally, the packaging materials will also be recyclable, home or industrially compostable, or biodegradable. Beyond this, they must be made in such a way as to minimise negative environmental impact. 

That said, the materials used in coffee bags must not degrade before they’ve completed their job of preserving the coffee’s flavour and freshness. To ensure customers get fresh coffee with every purchase, specialty coffee roasters must understand the barrier properties of the packaging materials they choose. 

I delved into the barrier performance of sustainable coffee bags and spoke to players in the specialty coffee sector about it. 

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Exploring multilayered coffee packaging

To preserve the unique attributes of roasted coffee, the bag must seal and protect the beans against destructive elements such as oxygen, moisture, and light. In addition, it must allow roasting byproducts such as carbon dioxide (CO2) to escape the bag without allowing oxygen to enter. 

Furthermore, once consumers open the coffee bag, they must be able to reseal it on demand to preserve freshness as long as possible. That’s a lot to ask of any packaging material. Notably, modern materials science has yet to devise a single material that adequately meets these design criteria for all types of perishable and non-perishable goods.

As the name suggests, multilayered packaging employs multiple or composite layers of different materials. These materials can be various plastics, paper, or films. Packaging designers choose the materials of each layer to fulfil a specific function or set of functions. 

Packaging manufacturers then employ techniques such as co-extrusion, lamination, or various coating technologies to form each layer. These are then bonded together into an amalgamated and homogenous whole. Given this use of disparate materials, each with specific disposal requirements, most traditional multilayered packaging is neither recyclable, compostable, nor biodegradable. 

When disposing of traditional multilayered packaging, consumers have to find a recycler capable of separating the various layers for appropriate processing. However, these are uncommon. 

Specialty coffee roasters committed to providing sustainable coffee bags face significant design challenges. One aspect of multi-layer packaging that presents especially difficult challenges is the barrier layer. 

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Why is barrier performance important in sustainable coffee bags?

In food packaging, barrier layers preserve desirable flavours and aromas, prevent undesirable oxygen and moisture from getting in, and extend shelf life. 

Common traditional barrier layers are ethylene vinyl alcohol (EVOH), metallised films, and aluminium foil. EVOH is commonly layered with polyethylene (PE) and polypropylene. However, these materials present environmental challenges that can make them unsuitable for use in sustainable coffee packaging.

To create sustainable coffee bags that are either fully compostable, biodegradable or recyclable, designers need to find eco-friendly alternatives to these materials. That said, a recent article states that “despite numerous academic research efforts to promote the application of biodegradable polymers in packaging, there are few bio-based/biodegradable polymers in the market that can meet the high demand for food packaging within modern society.”

“This results from challenges in obtaining oxygen/water vapour barrier performance at comparable levels to traditional petroleum-based plastics or their combinations,” the article continues. 

There is good news for specialty coffee roasters. However, to understand the options available, they need to understand how barrier performance is rated.

Manufacturers tend to rate the performance of barriers on a scale from ‘very high’ to ‘high’, ‘medium’, and ‘low’. Some applications require a rating for blocking light transmission or for resistance to certain solvents or other chemicals. 

For coffee packaging, ratings for blocking the transmission of oxygen and moisture are typically sufficient. Notably, barriers often have different rating levels for each function. A barrier material may have a high rating for oxygen, but a low rating for water vapour. This, again, is where designers will leverage multiple layers to take advantage of their different barrier properties. 

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How to ensure barrier protection in sustainable coffee bags

The good news for specialty coffee roasters is that their product is shelf-stable and has lower barrier requirements than those for many other perishable foods. That said, exposure to oxygen and moisture will quickly degrade the flavour and aroma of roasted coffee. More so, the flavour profile of ground coffee will degrade even faster. 

Those wanting to retain a high degree of coffee flavour and aroma for several months or more will need a barrier with a high-performance rating for both oxygen and water vapour. In such cases, multilayer coffee bags may be the best solution. 

If possible, coffee roasters should try to select packaging with layers that can be disposed of in the same waste stream. For instance, sustainable coffee bags made from materials that are all home-compostable or all recyclable from the same curbside bin. 

Additionally, they should check with local waste management companies to find out what services are offered and what materials are accepted. If the materials chosen cannot be co-processed locally, coffee roasters should print disposal instructions on the bag. 

Another option is to offer customers a coffee bag return and collection programme. For example, Vienna Coffee in Marysville, Tennessee, was unable to find a local recycling programme for its foil bags. The brand’s solution was to partner with Honolulu-based processor Savor Brands. Savor provides a shippable collection box for Vienna’s coffee bags, which are then transformed into building materials.

Coffee roasters can also reduce their barrier needs via their distribution model. For instance, Andy Newbom of Torque Coffees takes a holistic approach to packaging. 

He designs every aspect of his business model to work in concert to optimise environmental impacts, a philosophy he calls “Destroy Less”. 

“We’re not concerned much with barrier,” says Andy. “We sell direct to the consumer, roasted to order. So the oldest the customer might have is a bag sitting at their house that they forgot to open for 14 days. We ship the same day it’s roasted and always will. So, barrier performance is immaterial, within reason.” 

Andy’s distribution model allows him to use sustainable coffee bags that are entirely plant-based and plastic-free. More so, they are compostable, along with the resealable zippers and degassing valves. 

At MTPak Coffee, we understand the importance of providing consumers with coffee packaging that can be disposed of easily. We offer 100% recyclable LDPE packaging that uses just two layers, compared to the three or four in many coffee bags around the world. 

Furthermore, we are able to fully customise the size, shape, look, and feel of your coffee bags for your specific business needs. Plus, we are able to custom-print coffee packaging using innovative digital printing technology, with a quick turnaround time and shipping time. 

For more information on sustainable multilayer coffee bags, contact our team

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