What to look for when choosing a coffee bag sealer

Jane Merchant
December 30, 2021
recyclable coffee bag being sealed

For coffee roasters, it’s important to spend time, money, and effort finding the perfect coffee packaging. This is to ensure it not only protects the coffee between roastery and consumer, but also preserves its freshness.

However, if the packaging is not sealed correctly, its barrier properties will quickly become negligible.

Even if it appears airtight, poorly sealed bags can let in pathogens and oxygen, leading to stale or rancid-tasting coffee. This can damage your reputation as a roaster and may reduce your opportunities for repeat purchases.

Investing in the right sealing equipment will ensure your coffee arrives at its destination with its quality intact. But what are the best bag sealers? And how can you be sure your coffee bags aren’t letting in any externalities?

To find out more about what to look for when choosing a coffee bag sealer, I spoke with 2021 German Brewers Cup champion, Nicole Battefeld-Montgomery.

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recyclable kraft paper coffee bag

The importance of well-sealed coffee bags

Well-sealed, airtight coffee bags are crucial to preserving the freshness of roasted coffee. This is because of two simultaneous reactions: oxidation and the degassing of carbon dioxide (CO2).

Oxidation occurs as a result of the degassing process, in which oxygen replaces the CO2 that has escaped and causes the compounds in the coffee to change. Research suggests that for every 1% increase in the oxygen levels in coffee, there is a 10% increase in the rate of degradation.

Nicole says that a well-sealed bag preserves the CO2’s “protective cloud” around the coffee, while preventing oxidation from occurring.

“Degassing is at its most intense during the first 72 hours after roasting,” she explains. “But if you pack and seal the coffee straight away in a bag without a degassing valve, it could explode due to the buildup of pressure.

“Whereas if you wait 24 hours before packing the coffee, the CO2 creates a secure atmosphere in the bag and keeps the coffee fresher for longer.

“Once exposed to oxygen, coffee oxidises rapidly, resulting in the loss of flavour and aroma. A properly sealed bag can prevent that from happening by minimising the oxygen entering the bag.”

sealing recyclable coffee packaging

How are coffee bags sealed?

Sealing coffee bags is a time-consuming, yet essential part of being a roaster.

While there are a number of different approaches, the most common is a method known as “heat sealing”.

Heat sealing is the process of sealing a bag by fusing together the opening using high temperatures. It is performed by a direct contact method typically involving the use of a heated die or a sealing bar, which applies heat and welds the opening together.

Nicole tells me that, in her experience, a heat sealed bag can prolong a coffee’s lifespan dramatically compared to those which are clipped together. Her preferred method is using a “hot wire” thanks to its practicality and ease of use.

“You have a hot wire contact that heats up once you press a lever down,” she says. “It then applies heat to the bag so it melts a little – just enough to seal it. You don’t need any glue or chemicals that might affect the coffee’s taste.”

A common type of wire sealer is a wire impulse sealer. These create thinner seal seams, can work with materials under 2 mm in thickness, and can remove excess film after sealing. They’re also a popular option for multilayered packaging. 

As well as being relatively safe to use, wire impulse sealers apply heat in bursts so the wire never remains hot for very long.

It also offers complete control over the seal wire’s temperature, the pressure being applied, and the machine’s cooling cycle. This reduces power consumption and operational costs.

coffee bag sealer

What to consider when sealing your coffee bags

A common dilemma for small or newly established coffee roasters is when they should invest in a sealing machine.

For those who sell only a small number of bags per month, it is possible to package and seal the coffee by hand, rather than automating the process.

Nicole explains that this option is more flexible as it allows them to package their coffee according to demand.

“If you’re a bigger roastery, on the other hand, it is worth opting for an automatic sealing machine that can seal different sizes and has a temperature control so you can seal different material bags,” she says.

She also advises against purchasing a machine on price alone, particularly as low-cost machines don’t tend to offer any maintenance support. This means that if your sealer breaks down, it could end up costing a lot to repair or replace it.

Automatic machines are a good choice if your business wants to move into full production. Most come with automatic sealing cycle times to help you create production goals and predict your outcomes.

When it comes to finding a place for your sealing machine, Nicole says to keep it away from the roaster. This is because the dust and chaff from the roaster can affect the effectiveness of the sealing machine.

Instead, she recommends keeping it in a spacious area near your storage shelves. By dedicating a shelf to the coffee you can implement a “first-in-first-out” rule, which ensures you sell your oldest coffee first.

When packaging and sealing your coffee, Nicole recommends using bags that come with a zip lock so that customers can reseal them at home after opening.

She also recommends considering recyclable or biodegradable bags as they are better for the environment and have excellent flavour and aroma protection. 

coffee bag heat sealer

For specialty coffee roasters, it’s essential to ensure their coffee arrives at the consumer with all its original qualities intact.

The loss of aroma or development of unpleasant, rancid flavours can damage their reputation and lose them repeat customers.

By investing in an effective bag sealer, roasters can limit the risk of oxidation and preserve the protective blanket of CO2 within the bag. However, it’s also important to ensure the bags themselves also offer high-barrier properties.

At MTPak Coffee, we have a range of sustainable packaging options that will not only protect your coffee, but also showcase your commitment to the environment.

Each one can be customised according to your preferences, including recyclable degassing valves and resealable zippers.

For information on our resealable coffee bags, contact our team.

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