How do degassing valves work?

Nuvin Sithanen
October 31, 2022
How does a degassing valve work?

The goal of every roaster is to have each customer enjoy their coffee at its best.

Roasters often invest significant time into sourcing high-quality green coffee and dialling in the perfect roast profile to unlock its inherent characteristics.

In spite of all this effort and strict quality control, a negative customer experience is highly likely if the coffee is packaged incorrectly. If roast coffee is not packaged to preserve its freshness and quality, it will degrade quickly.

As a result, the customer may miss the chance the experience the same flavours the roast did while cupping. 

One of the most effective ways roasters can prevent the degradation of roast coffee is to fit their coffee bags with degassing valves.

Degassing valves are one of the most effective and common ways to maintain the sensory properties and integrity of the coffee.

Read on to learn more about how degassing valves and whether they can be recycled alongside coffee bags.

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A close up image of a degassing valve in a multilayer LDPE coffee bag of specialty coffee in an article explaining how a degassing valve works

Why do roasters use degassing valves in coffee bags? 

When coffee is roasted, there is a significant build-up of carbon dioxide (CO2) within the bean. 

This reaction also has a significant visual impact, as the coffee bean increases by about 40% to 60% in size. 

The same CO2 that is built up during the roast is slowly released as the coffee ages. When roast coffee is insufficiently stored, the CO2 is replaced by oxygen, which results in a degradation of flavour. 

An interesting demonstration of the amount of gas trapped within coffee beans is the blooming process.

Blooming is the process of pouring water over ground coffee to trigger the release of CO2 to facilitate the extraction process.

When freshly roasted coffee is brewed, there should be a high amount of bubbles that appear. Older beans may produce significantly less “bloom”, as the CO2 has likely been replaced with oxygen.

Essentially the one-way degassing valve was patented in 1960 to combat this problem.

When fitted into coffee bags, degassing valves allow for the CO2 to leave the packaging without allowing oxygen to enter.

More so, in some cases, the coffee may degas too quickly, which may inflate the coffee bag. Degassing valves help prevent the bag from popping by providing an escape for the trapped gas.

Several factors must be considered when fitting degassing valves into coffee packaging.

For instance, roasters will have to factor in the roast level, as darker roasts tend to degas faster than light roasts.

A dark roast accelerates degassing because the bean has degraded more. The sugars have had more opportunity to be transformed, and there are more tiny cracks that allow the CO2 to be released.

With light roasts, more of the bean is intact, which means it may require more time to degas.

Another factor to consider is the quantity. If a roaster is packaging small quantities, such as samples for tasting, they will be less concerned about the coffee bag popping.

The amount of CO2 released is directly proportional to the volume of beans in the bag. If a roaster is packing bag greater than 1kg for shipping, it is recommended they consider how the effects of degassing will affect the coffee bags.

An image of a barista brewing coffee in a chemex, displaying the coffee bloom in an article explaining how a degassing valve works

How do degassing valves work?

Degassing valves were first developed in the 1960s by the Italian manufacturer Goglio.

They tackled a major problem many coffee businesses were facing when it came to degassing, oxidation, and preserving freshness.

Over time, the design of degassing valves has evolved as they have become more cost effective and sustainable.

The degassing valves use today not only fit seamlessly into coffee bags but also use 90% less plastic.  

In essence, a degassing valve is made of a cap, an elastic disc, a viscous layer, a polyethylene plate, and a paper filter.

A rubber diaphragm is enclosed in a valve and the interior, or coffee-facing part, has a viscous layer of sealant liquid that maintains surface tension against the valve.

Pressure builds up as CO2 is released from coffee. Once that pressure passes the surface tension, the fluid will displace the diaphragm, allowing the excess CO2 to escape.

Simply put, the valve only unlocks when the pressure inside the coffee bag is higher than the pressure outside.

An image of a multilayer white LDPE coffee bag with a degassing valve in an article explaining how a degassing valve works

How sustainable are degassing valves?

As degassing valves are often an addition to coffee bags, roasters should consider how they will be disposed of alongside used packaging.

Notably, bioplastics have become a popular alternative to petroleum-based plastics.

Bioplastics, which are made by fermenting carbohydrates from renewable sources such as maize, corn starch, and sugar cane, have the same properties as traditional plastics, but with a significantly reduced environmental impact.

As a result, degassing valves made from these sustainable materials have become more accessible and affordable.

Recyclable degassing valves can help conserve fossil fuels, reduce a roaster’s carbon footprint, and communicate their commitment to sustainability.

Furthermore, they allow customers to correctly dispose of coffee packaging with minimal confusion.

When added to recyclable or compostable packaging materials, such as kraft paper with a polylactic acid (PLA) laminate, sustainable degassing valves offer customers a fully sustainable coffee pouch.

As well as providing an attractive option for new customers, this can help boost brand loyalty among existing customers who might otherwise have switched their allegiance to more sustainable competitors.

An image of a coffee roaster packaging roast coffee in a white multilayer LDPE coffee bag fitted with a degassing valve in an article explaining how a degassing valve works

At MTPak Coffee, we offer roasters the option to fit their coffee bags with fully recyclable, BPA-free degassing valves.

In addition to being versatile, lightweight, and affordable, our valves can be fitted to our entire range of sustainable coffee packaging options.

Roasters can choose from renewable materials such as kraft paper, rice paper, or multilayer LDPE packaging with an environmentally friendly PLA lining, all of which minimise waste and contribute to a circular economy.

More so, we give our roasters complete control over the design process by allowing them to build their own coffee bags.

Our design team is available to help you create the ideal coffee packaging.

Plus, we are able to custom-print coffee bags using innovative digital printing technology, with a quick turnaround time of 40-hours and 24-hour shipping time.

MTPak Coffee also offers low minimum order quantities (MOQs) to micro-roasters who are looking to remain agile while showcasing brand identity and a commitment to the environment.

For more information on sustainable, custom-printed coffee packaging, contact our team.

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