Sealing coffee bags effectively is one of the most important stages for coffee roasters.
As coffee degrades once the beans are roasted, the bags must be well sealed in order to preserve the coffee’s freshness and quality characteristics.
The National Coffee Association (NCA) recommends storing fresh roast coffee in airtight containers to help maximise and maintain the flavour and aromatic compounds of the product. This helps to limit the coffee’s exposure to air, light, heat, and moisture.
Essentially, coffee bags are sealed by fusing together two layers of packaging material by applying both heat and pressure.
That said, coffee roasters may use different types of coffee packaging structures in order to match brand design, product type, or market sizes. For example, some may use stand-up pouches, or quad-seal pouches – all of which require different sealing methods.
What to consider when choosing a coffee bag sealer
Roasters will have to consider several factors when choosing a coffee bag sealer.
For small or newly established coffee roasters, it may be possible to package and seal coffee by hand.
This option is more flexible than investing in an automatic sealer, as it allows roasters to package coffee according to demand.
On the other hand, large-scale roasters may find an automatic sealer more useful as they often have temperature control options, allowing roasters to seal different material bags.
Therefore, roasters will have to have a good understanding of their packaging materials.
For instance, the material type and thickness can help roasters determine whether they require constant heat or impulse heat.
Additionally, roasters will have to consider the width of the coffee bags. This will help determine the maximum sealing length required, and advise roasters on how wide the seal needs to be.
More so, roasters will need to consider the speed at which they need their coffee bags sealed. Determining how many bags must be sealed in a set period can help determine which is the most effective sealer model.
Coffee bag sealing processes commonly used in the industry
Coffee bags can be sealed using a number of different processes.
Some of the most common are impulse sealers, which only use power when the sealer’s jaw is lowered onto the packaging material. Impulse sealers are often considered more economical and environmentally friendly, as they use less electricity.
Impulse sealers send a short burst of electricity through a wire, turning electrical energy into heat energy. This heat then flows into the sealer’s jaws, which are pressed against the sides of the coffee bag to melt them together.
The process is followed by a cooling period, allowing the seal to set and provide consistent maximum seal properties. The coffee bag is then sealed permanently until it is broken open by the consumer.
Alternatively, direct sealers maintain constant heat, using electricity as long as the machine is operating. As a result, these sealers tend to possess better heat penetration to seal thicker packaging materials.
That said, when using a direct heat sealer, roasters will have to factor in a warm-up time into the production process, and be aware the machine will remain hot throughout use.
Another option for roasters is vacuum sealers, which remove the oxygen from the bags before they are sealed. Vacuum sealing can be highly effective at preventing oxidation, spoiling, and corrosion.
That said, it is a less common method with polypropylene (PP) or polyethylene (PE) coffee bags, as they are porous and less suited for long-term product storage.
Hand and foot sealers are also commonly used by roasters. Hand sealers use resistance wires or sealing bars at the point where the packaging must be fused together.
The device must be closed for several seconds, depending on the packaging material used.
Alternatively, foot sealers allow for high-volume heat sealing. Roasters can push down on the foot pedal to activate a single-side heating element. This creates the seal by heat-bonding one side of the coffee bag to the other.
A double-impulse foot sealer is highly effective for packaging materials that require higher temperatures. These machines are often used by roasters who have invested in heavy-duty packaging material that is between 10 and 20 millimetres (mm) thick.
Additionally, double-impulse sealers have the advantage of heating strips on both sides, providing a stronger bond.
Important to realise is the seams in packaging can often be a weak point, allowing oxygen and moisture to enter and effectively spoiling the beans. This means coffee must be sealed without creating pinholes, punctures, or wrinkles in the packaging.
Should roasters invest in hand & foot coffee bag sealers?
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 may cause them to lose 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.
Hand sealers are the ideal option for those looking for portable, heat-sealing technology that can be used for materials of different lengths.
Commonly, they are limited to a sealing thickness of up to 10mm and between 4 and 40 inches wide. More so, they may be able to seal between 6 and 20 packages per minute.
Foot sealers are ideal for continuous sealing where both hands are needed to position the coffee bags. They tend to be faster than hand sealers and can accommodate materials that are up to 15mm thick and between 12 and 35 inches wide.
On average, a foot sealer should be able to seal between 8 and 20 coffee bags per minute.
Regardless of the chosen sealing method, roasters should ensure the coffee bags themselves also offer high-barrier properties.
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.