May 25, 2022

What’s the difference between plastic and metal coffee pods?


Around the world, coffee pod consumption continues to grow at pace. By 2025, the global market is expected to be worth over US $29 billion. The factors driving this growth are convenience, cost, and the rising quality of coffee used in pods. 

The increasing popularity of coffee capsules has led many specialty coffee roasters and other coffee brands to start producing their own in recent years, aiming to improve the quality of coffee offered to consumers.

However, while it’s important to use high-quality coffee in pods, it’s also equally essential to use high-barrier materials for the packaging. With such a fine grind size, protecting the grounds correctly helps to improve freshness and quality, therefore improving the overall consumer experience.

Plastic and metal (mostly aluminium) are the two main materials used to manufacture pods. But which helps retain coffee freshness better? Which is stronger? And which is more sustainable? 

To find out, I spoke with the CEO of Novocapsule, Yuval Weinshtock. Read on to find out what he said.

You may also like our article on how roasters can diversify into the capsule market.

coffee brewed from a pod

Comparing plastic and aluminium capsules

With the skyrocketing popularity of coffee capsules and other single-serve coffee options, there are more materials available on the market than ever before. For pods, there are two main categories: plastic and aluminium.

But how exactly are plastic and aluminium capsules different? And what should consumers and roasters consider when buying them?

Recyclability & sustainability

Aluminium has been used in coffee capsule manufacture for decades, since Nespresso first began producing its pods. 

Plastic waste is understandably a major concern for many consumers. And while the production of “virgin” aluminium is energy-intensive, it is infinitely recyclable. Around 75% of the global aluminium ever produced is still in use today. 

A 2019 report from The Aluminium Association found that consumer recycling rates for aluminium cans in the US was almost 50%, while the industry recycling rate was over 63%. Figures from the European Aluminium Association estimate that in 2015, the aluminium can recycling rate for Europe was over 76%.

These high recycling rates also carry over to coffee capsules. Although aluminium-based pods can also include other materials (such as plastic linings), these can be separated so that the aluminium can be recycled.

As such, a number of coffee pod recycling schemes have emerged in recent years. However, uptake rates do vary. Consumer uptake of Nespresso’s global recycling programme, for instance, is estimated to be around 30%.

Other initiatives, such as Podback in the UK, support the curbside collection of coffee capsules, as well as launching drop-off points for consumers.

“Global warming is a crucial factor which is pushing retailers towards aluminium capsules,” Yuval explains. “However, for pod manufacturers, the price difference between aluminium and plastic is a real barrier.

“However, the price of aluminium could well fall in the future, and a smaller difference will make it a more competitive option,” he adds.

Furthermore, it is much easier to recycle capsules made from aluminium than plastic. Historically, one of the biggest criticisms of plastic use in the coffee pod segment has been concerning the use of No. 7 plastics. These contain a type of plastics known as polycarbonates, which are largely non-recyclable.

While this might seem to be conclusive evidence, Yuval does acknowledge that the market share of recycled aluminium coffee capsules is still relatively small.

“Only a fraction of the private label capsules [currently] on the market are made using recycled aluminium,” he tells me. “Most of the recycled aluminium is channelled to aluminium cans and automotive components, driving up the price of recycled aluminium for other applications.

“That said, plastic coffee pods are still in decline and retailers at all levels are switching to aluminium capsules,” he adds.

Maximising freshness

There are also understandable concerns about coffee freshness where capsules are concerned.

Freshness is a growing priority for today’s coffee consumers, and if the wrong materials are used or capsules are not properly sealed, it can cause coffee to become stale and lose its vibrant flavour notes more quickly.

Once ground, coffee’s surface area increases exponentially, which means that it becomes much more prone to oxidation and losing its complex and subtle flavours. The finer the coffee is ground, the more pronounced this issue becomes.

When preparing roasted coffee to be used in capsules, it must be ground finer than for espresso. This is one of the reasons that hermetic sealing is so important.

If capsules are not hermetically packaged and sealed, the coffee inside will quickly become stale.

“With aluminium capsules, performance and sealability is better than it is for plastic capsules,” Yuval explains.

He adds that the way this is measured in the coffee capsule segment is through something known as the oxygen transmission rate (OTR).

“At Novocapsule, our solution has a very low OTR,” he notes. “This is because our capsules have a polymer seal ring, as well as being manufactured from aluminium, which is a high-barrier material by definition. They are also PVC-free.”

Generally speaking, in terms of barrier properties, research over the past few years has indicated that aluminium is better at creating an impermeable barrier to oxidation. 

Strength & resistance

After months of sourcing, cupping, and developing roast profiles, roasters understandably want to make sure they are protecting the delicate flavour and aroma compounds in their coffee.

Exposure to moisture, heat, and oxygen can quickly degrade the delicate aromas and flavours in coffee, so quality packaging is critical to prevent this degradation.

As well as this, however, Yuval notes that the other factor to consider is physical strength. Coffee capsules spend a lot of their time in transit, as well as being put under some degree of physical force when they are filled and sealed.

When it comes to strength, he does note that thickness is more important than material as a general point. However, capsule thickness is difficult to perfect, as you want a solution which will protect your coffee as it journeys to the customer, but also one that isn’t too heavy or unsuitable for common capsule machines.

“The thickness of most aluminium capsules ranges between 97 and 115 microns,” Yuval tells me. “Novocapsule capsules are around 150 to 170 microns.”

Even though aluminium might be more protective, Yuval notes that roasters must exercise caution when handling and filling the pods.

“Plastic can be more robust than aluminium at lower thickness ranges, so there is a certain best practice for handling aluminium capsules during the filling process,” he says.

aluminium coffee pods and nespresso machine

How much plastic is actually used in the coffee capsule segment?

Since coffee pods first appeared on the market in the late 1980s, many have historically contained some amount of plastic, even if they are principally manufactured from aluminium.

In recent years, concerns about plastic waste have understandably started to increase. UN estimates from 2020 suggest that some 400 million tonnes of single use plastic waste is generated every single year. In response, we’ve seen a rising number of initiatives to combat this – whether that’s compostable or biodegradable products, or increasing access to plastic recycling streams.

Furthermore, as well as containing polycarbonates, No. 7 plastics can also contain bisphenol A (BPA). Research has shown that BPA can leach into food and beverages, especially when the plastic packaging is exposed to heat, which can include coffee capsule extraction. 

As well as affecting coffee flavour, there is evidence to show that the consumption of BPA could interfere with hormone production – potentially having a serious impact on consumers’ health.

However, no matter which type of plastic is used, there are still sustainability issues.

Some plastics can take up to 500 years to completely break down, and in many cases do not degrade entirely. This means microplastics can end up in soil, beaches, waterways, food supplies, and even human bodies.

Yuval says: “When considering the impact of plastic on global warming, PVC is considered among the worst of the different plastic materials.”

Polyvinyl chloride (PVC) can be used in the lacquer coating inside aluminium coffee capsules, but is largely non-recyclable and can be toxic when broken down.

“Having a capsule that is PVC-free is an advantage,” Yuval adds. “Novocapsule is the one of the only suppliers which offers a PVC-free capsule option.”

Compostable and biodegradable pods

While aluminium is a frontrunner as far as sustainability is concerned, there are plastic capsules emerging on the market which are biodegradable and compostable.

However, these options are still niche, and disposal or reuse can often be more difficult than it may initially seem. In many cases, alternative plastic capsule options are more porous than aluminium. This means that they often have a lower barrier, making freshness more of a concern. They are also generally more costly.

The biggest barrier, however, is a lack of awareness about disposal. For instance, in many cases, compostable capsules are actually certified industrial compostable – which means they are compostable in a specific industrial environment where pressure and temperature are controlled. 

Home compostable capsules are a lot rarer, which actually means that if consumers add many “compostable” coffee pods to their home compost pile, it won’t actually work. 

nespresso coffee

It can be challenging for many coffee roasters to create capsules which are both sustainable and guarantee freshness. However, by selecting the best materials, they can be sure that their coffee stays fresh, as well as reducing capsule waste.

Overall, aluminium capsules are arguably the best option for roasters looking to preserve freshness and contribute to a circular economy; research suggests that they are the best high-barrier option and also much easier to recycle in the long term.

However, whether or not the coffee pod market will continue to develop along this trajectory in the future remains to be seen. At present, the market for compostable and biodegradable pods is growing – but aluminium pod recycling schemes are also becoming more and more accessible.

Enjoyed this? Then read our article on whether or not capsules can be sustainable.

Photo credits: Novocapsule

Perfect Daily Grind

Please note: Novocapsule is a sponsor of Perfect Daily Grind.

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