Degassing valves: Must they be fitted at the top of coffee packaging?

Aidan Gant
January 9, 2023
An image of a multilayer LDPE coffee bag with a PLA lining and resealable zipper with a recyclable degassing valve in an article on whether degassing valves must go at the top of coffee packaging

During the 1960s, the introduction of the one-way gas exchange valve revolutionised coffee packaging. 

Prior to its development, it was nearly impossible to preserve coffee in air-tight, yet flexible packaging. As a result, degassing valves have become the unsung hero of the coffee packaging world.

Degassing valves have helped consumers keep their coffee fresh for longer and allowed roasters to ship their products further than before. 

Flexible coffee packaging with an integrated degassing valve has become the norm, with several specialty roasters merging coffee bag designs to include them. 

That said, do degassing valves need to be fitted to the top of coffee packaging to be effective?

Subscribe to our weekly newsletter

Sign up
An image of a black custom-print coffee bag, LDPE coffee bag with recyclable degassing valve in an article on whether degassing valves need to go at the top of coffee packaging to work

How do degassing valves in coffee bags work?

Essentially, degassing valves are a one-way mechanism that allows gases to escape their one-time homes.

In a sealed environment, gases released from a packaged product need a way of escaping without compromising the integrity of the bag. 

In the coffee industry, the terms “out-gassing” and “off-gassing” are often used interchangeably with the degassing phase.

Degassing refers to the process by which previously absorbed carbon dioxide leaves roasted coffee beans.

That said, in the working terminology of chemistry, and in particular of geochemistry, there is some difference between out-gassing and degassing.

Out-gassing typically refers to a spontaneous and natural release of gases at the point of state change as they escape from their former solid or liquid housings.

Degassing, on the other hand, would more normally be used to imply some human agency in the separation of released gases. 

Extending this terminological semantic difference to coffee packaging, out-gassing valves and degassing valves often feature the same design.  

This is because gas exchange occurs naturally with the ambient external environment, or when a coffee bag is squeezed to encourage gas exchange.

Typically, degassing valves comprise five pieces: 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 of the diaphragm has a viscous layer of sealant liquid. This is what helps maintain surface tension against the valve.

Pressure builds up as coffee degasses and releases CO2. Once the pressure inside the roasted coffee bag passes the surface tension, the fluid will displace the diaphragm, allowing the excess CO2 to escape.

An image of a customer smelling fresh roast coffee in a custom-print coffee bag in an article on whether degassing valves need to go at the top of coffee packaging to work

Are degassing valves essential in coffee packaging?

Degassing valves are an important part of well-designed coffee bags. 

If they are omitted from packaging intended for freshly roasted coffee, gases are likely to build up in the pressurised environment. 

More so, depending on the nature and properties of the materials, the packaging could rupture or otherwise compromise the integrity of the coffee bag.

When green coffee is roasted, complex carbohydrates break down into smaller, simpler molecules, while both water and carbon dioxide are produced.

The iconic “first crack” that many roasters use to govern and control their roast profiles is actually caused by the sudden release of some of these gases and moisture.

However, following the first crack, gases continue to develop and only settle a few days after roasting. As this gas continues to be released from roasted coffee beans, it needs somewhere to go. 

A sealed coffee bag without a valve for proper gas release would be unsuitable for freshly roasted coffee.

An image of coffee bloom as a result of freshly roast coffee in an article on whether degassing valves need to go at the top of coffee packaging to work

Some of the carbon dioxide produced during roasting will remain within the beans and is released upon grinding the coffee and applying the first dose of water when brewing.

This is the bloom in pour-over brews and can often be a good indicator of a coffee’s freshness.

Similarly, an amount of carbon dioxide within the headspace of coffee bags can help extend shelf life as it keeps damaging oxygen from the ambient environment. Too much gas build-up, however, may cause the packaging to rupture.

It is also important for roasters to consider the sustainability of the valves used in coffee packaging. Material differences can impact end-of-life disposal options once the consumer is done with the product. 

If a roaster’s coffee bags have been designed to be industrially compostable, for example, it would be appropriate for the valves to be the same.

Using a recyclable degassing valve would be another option. Important to note is this option would leave customers with the task of separating the valves from the packaging and then disposing of them separately. 

Packaging elements often have the best chance of cradle-to-grave sustainability if they can be disposed of with as little consumer effort as possible, and ideally, as a single unit.

There is a range of solutions available for sustainable degassing valves. Produced using injection-moulded bioplastics made from renewable resources, such as crops, recyclable degassing valves have the same properties as plastics without the environmental impact.

It is important for roasters to remember to inform customers of how to dispose of used coffee bags to ensure packaging reaches an appropriate facility.

An image of a multilayer coffee bag LDPE coffee bag with a recyclable degassing valve in an article on whether degassing valves need to go at the top of coffee packaging to work

Where is the best place for degassing valves in coffee packaging?

Flexible packaging has become the industry-leading solution for coffee packaging, be it stand-up pouches or side-gusseted bags.

It is clear degassing valves are vital to ensure the packaging integrity of fresh-roasted coffee beans as they continue to degas. 

However, the exact placement of the valves is something that bears consideration. 

From an aesthetic point of view, roasters may either want to fit valves somewhere unobtrusive or somewhere specific to the design of their branding. 

While customisable valve placement is possible, are all spots born equal?

For optimal functioning, it would make sense to include the degassing valve somewhere in the headspace of the bag, as this is where most of the released gases will congregate. 

Furthermore, it is necessary to consider the structural integrity of the coffee bags. Placing a valve too close to a seam would weaken the packaging, so a central location is best.

That said, there is some leeway as to where roasters would like to install a degassing valve, specifically along the centre line, towards the top of the packaging.

Modern, eco-conscious consumers understand functional elements of packaging are there for a specific purpose, but bag design remains an important factor in purchasing decisions.

Tastefully incorporating degassing valves into the artwork on coffee bags may be a challenge, but it should not be overlooked.

An image of a custom-print black coffee bag made from LDPE coffee bag with a recyclable degassing valve in an article on whether degassing valves need to go at the top of coffee packaging to work

At MTPak Coffee, we offer roasters the option to fit their coffee bags with fully recyclable, BPA-free degassing valves, as well as traditional one-way 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, our entire range of coffee packaging is 100% customisable as we use innovative digital printing technology, allowing us to help you with a quick turnaround time of 40-hours and 24-hour shipping time.

For more information on recyclable degassing valves for sustainable coffee packaging, contact our team.

Subscribe to our weekly newsletter

Sign up

MTPak recommends