Does Compostable Coffee Packaging Prevent Exposure To Light?

Matteo Pavoni
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March 9, 2021
translucent coffee packaging

Once coffee has been roasted, the battle to preserve its freshness and prevent it from losing those all-important characteristics begins. If specialty roasters want to ensure their coffee arrives at the consumer at its peak, they must take certain measures to limit its exposure to external factors, such as oxygen and moisture.

However, of all the factors responsible for the degradation of roasted coffee, one of the most immediately detrimental is light. When roasted coffee is exposed to light over a significant period of time, it causes the breakdown of chemical compounds in the beans. Known as “photodegradation”, it can lead to the loss of aroma and flavour, resulting in stale, often rancid, coffee. 

There are a number of measures specialty roasters can take to prevent their coffee from being exposed to light, even once it’s been packaged and distributed to consumers. To find out more, I spoke with marketing executive at Voyager Coffee, Tobias Taylor.    

See also: A Guide To Preserving The Freshness Of Roasted Coffee

roasted coffee exposed to light

Why Does Light Cause Roasted Coffee To Become Stale?

Together with oxygen, heat, and moisture, light causes irreversible changes to the distinct characteristics of roasted coffee. While the UV rays from the sun have the most significant impact, the light from electric lamps can also have an adverse effect.

Over time, exposure to light will result in the loss of a coffee’s flavours and aromas. It will accelerate the staling process and produce a bland taste in the cup. For specialty coffee roasters, this could lead to a drop in return customers, who will inevitably be disappointed with the quality of the coffee.

The reason light affects roasted coffee is due to a process known as photodegradation. Photodegradation refers to the breakdown of chemical compounds in objects and substances due to an overexposure to light. Affecting everything from wine to oil paintings, the speed of photodegradation depends on various factors, such as the wavelength of the light.

According to three-time national barista champion Ishan Natalie, the reason light affects roasted coffee is predominantly due to the loss of natural oils (or lipids) present in the beans.

“Light speeds up the rate at which natural oils in coffee are brought to the surface,” he says. “The beans will start to dry up, causing the flavour and aroma to go flat. It can also produce rancid, bitter notes in the cup.”

Dark roasts, with their weaker and more porous cellulose structure, naturally lose these oils much quicker than light to medium roasts. Therefore, when dark roasted beans are exposed to light, they will become stale more rapidly.

Lipids are closely linked to the quality of coffee. In a study of Central American coffees, a panel of cupping experts found a direct correlation between lipid content and beverage quality. The coffees with a higher percentage of lipids were considered higher quality due to an improved retention of aroma.

coffee packaging

How To Protect Roasted Coffee From Exposure To Light

Naturally, the aim of any roaster is to ensure their coffee is at its peak when it arrives at the consumer. No matter how high quality the beans, stale or rancid coffee will immediately put people off buying from that roastery again.

However, from the moment coffee is roasted, the steady decline of freshness begins. Around 40% of the carbon dioxide (CO2) stored in the beans is released within the first 24 hours and natural oils immediately start to rise to the surface. 

As a result, aroma and flavour begin to degrade. If the roasted beans are exposed to light of any form, this process will only accelerate, ultimately leaving customers with a disappointing bag of coffee.

Therefore it’s paramount for specialty roasters to take measures to protect their coffee from exposure to light, both in storage and transportation.

Tobias Taylor is marketing executive at Voyager Coffee, a multi-award-winning roastery based in Devonshire, UK. He explains that because not all coffees lose their freshness at the same time, they should be treated on a case-by-case basis.

“For most of our coffees, which we sell in compostable pouches, we’re happy if they’ve been consumed within two months,” he says. “We’ve found that natural coffees are actually a lot better after a longer post-roast resting period of around ten days. This is in comparison to washed coffees, which can start to taste a little flat after just six weeks.”

Nevertheless, to extend the shelf life of any roasted coffee, whether washed or natural, it should be stored in a dark, airtight container before being distributed to cafés and customers. Degassing valves can be fitted to the packaging to allow each coffee to “rest” for as long as it needs, so that it’s at its best when consumed. These can be attached to any type of pouch, from kraft paper to polylactic acid (PLA).

However, one of the problems faced by specialty roasters who use sustainable coffee packaging is how to keep out light when their coffee is on the shelf. Environmentally coffee packaging, such as compostable pouches, is often thinner and more translucent than plastic or foil-lined packaging. This is so that the materials effectively break down when placed in a composting environment. As a result, they don’t always offer the best protection against light.

Tobias tells me that their solution is to keep the compostable bags destined for the shelf in cardboard boxes for as long as possible. “Generally, compostable packaging has a lower resistance to light, especially if you’re talking about sunlight,” he explains. “But does it need to have a huge barrier to direct sunlight? We don’t think so.

“We made a decision to combat this for the only type of our coffee that could end up on a retail shelf exposed to light. The majority of our retail coffees are a compostable bag made from 100% plant starches but sat inside a mostly recycled small card box. This helps in two ways: it gives the bag more durability in transit and it also removes all its exposure to direct light.”

An alternative is to use multilayer packaging using coextrusion or lamination. Multilayer packaging helps to extend the shelf life of coffee by providing added protection against externalities. Although plastic laminates and foil-lined pouches are not sustainable, at MTPak Coffee we use PLA to laminate our coffee packaging. This bioplastic is fully compostable in commercial facilities and can be added to any compostable or recyclable material.

sustainable coffee bags

Light – alongside oxygen, moisture, and heat – is one of the four enemies of roasted coffee. It can speed up the process of staling, leading to rancid-tasting coffee. 

To preserve the quality of roasted coffee, choosing the right packaging is vital. Not only does it need to be airtight, it must also protect against exposure to light, which will help extend the shelf life of the coffee inside.

At MTPak Coffee, we offer a range of environmentally friendly packaging that will both protect your coffee from light exposure and showcase your commitment to sustainability. Our multilayer pouches use PLA laminates to maintain the recyclable and compostable properties of the packaging, while providing additional barriers to oxygen, light, heat, and moisture.

For more information on our sustainable coffee packaging, contact our team here.

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Does Compostable Coffee Packaging Prevent Exposure To Light?
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