Industrial compostable bioplastic coffee capsule for Nespresso for mass production.
Since 2010 many manufacturers have tried to make a compostable Nespresso capsule. Unfortunately, no one has (yet) succeeded in achieving the quality level of Nespresso.
This is particularly complex for a number of reasons.
The pressure build-up of the Nespresso machines is very different, this has caused many disappointments among a lot developers.
There are also many different versions of Nespresso machines. Especially the motorized devices (without hand controlled pressure lever) suffer from a lot of leakage, and therefore poor pressure build-up, and capsule-trays overflowing with coffee grounds.
The incision blades of the Nespresso machines (which make 3 pinch holes) come in different thicknesses.
Another reason is because the Nespresso capsule has a silicone edge.
And the recent Nespresso machines have a tooth edge in the “capsule lock-up mechanism”. For that reason almost all copy-capsules are leaking water. Older Nespresso machines do not have these tooth edges.
The positioning/centering of the capsule in the machines is varied, which makes the sealing difficult, resulting in a lot of leakage. The last change was medio 2016.
The grinding of the coffee beans is a particularly important element, grinding must be done in a 3 stage roller grinder. The partical size must be within a narrow band width. In these depicted reports you will find our Nespresso grinding measurements.
Because aluminum provides the best oxygen/moisture barrier, the shelf life of aluminum coffee capsules is the best.
The aluminum lidded capsule is placed in the machine and the capsule is punctured in 3 places.
The hot water (90 degrees Celsius) is squeezed into the capsule, moisturizing the ground coffee and the pressure begins to build up visibly. Because the aluminum lidding breaks open evenly at a specific pressure on the specifically formed outflow plate (provided with a wafer structure with small through holes) of the machine, an opening in the aluminum is formed at each cam in the outflow plate.
Because the interaction of the machine and the aluminum lidding is "preprogrammed", all 25 small outflow openings in the wafer structure are actually closed with the outside of the torn aluminum lidding.
Because the extract can only emerge through the almost closed holes, very thin slits between the aluminum and the wafer structure originate, which ensures the crema-foam layer. On the photo you see a wafer structure with a cut off
If the coffee is too fine and has not been milled within a certain bandwidth, the pressure may rise too high due to too small particles near the outflow openings, this also causes the effect that the openings closed by the torn aluminum are pressed more tightly. Because the too small, stuck particles block the passage, the extraction and foaming and processing time are below par. Also the pressure will be too high, often resulting in a jam.
Because the ground coffee is completely moisturized during the break-up of the aluminum and the openings in the aluminum are formed at the same time, the coffee bed can form an evenly homogeneous form, and the chance of bypass is almost 0. A bypass = the generation of channels in your coffee bed, which in addition to an uncontrollable pressure maintenance naturally reduces the extraction considerably as well as reducing the foam formation.
The lidding is a very important issue for a compostable Nespresso capsule, a lot of people falsely think they can fix it by using thin bio-foil or paper.
Paper-lidding: In case of good luck, and if the grinding is okay, the paper will tear seemingly suitable at a few places (undefined tearing) but where the openings are coffee crumbs will come through in the coffee extract. In a lot of situations you will have a paper taste or fibers in your extract. Because oxygen is everywhere, the grinded coffee will become dry and the structure and aroma will evaporate. If the capsule stays longer in the machine after use, the paper will dry and the capsule gets stuck in the wafer. In most situations, using paper lidding is a complete disaster.
Bioplastic film as lidding: The pressure build-up will often rise too high before the lid breaks. When the pressure is released and extraction takes place, bypass channels will form in an improperly formed coffee bed. The flow usually seems good, but this is only possible because the water can flow through the formed bypass channels with a low TDS and less foaming result.
Because there are only a few, for example, long cracks in the foil, the coffee grounds come into the coffee extract or the holes in the wafer structure get clogged. Due to the large cracks and the sudden explosion of the lid material, a possible intermediate layer -filter layer is usually not resistant. Because the film only has a few cracks and the other holes are closed off by the film, a jam or the coffee only coming out in drops is often the result.
A combination of paper and bioplastic as a 2 layer solution is uses ad well. In the photo you can see the bypass creating tears.
A smooth extraction surface is therefore key.
Prebrew (coffee bed construction) is key.
Bio plastics have a moderate oxygen barrier, the structure is open because it is made of natural materials.
The Stascafe Bio-lidding replaces the aluminum lid. The lidding closes the capsule in airtight-watertight manner (just like a bicycle tire) to preserve the aroma of the coffee. The lidding is made up of 3 layers of PLA and is 100% biodegradable. It seals excellent and fast on a PLA capsule. The lidding does not contain adhesive or coating layers and is food safe. The foil contains a laser-inhibiting elastic layer that ensures that the foil does not get holes all the way through.
The elastic layer ensures an airtight seal which pushes through the formed hole during the pressure build-up. A lot of bubbles will arise that fizz and self-regulating form tornado spouts, providing the foam layer. After extraction, the spouts close and will leave no coffee residue. The lasered holes have a crater edge that ensures that the film does not tear. The film can also contain printing.
The lidding can be lasered on a roll for processing in a capsule filling machine and / or the lidding can be lasered after sealing the capsule in the machine.
A very positive property is that the capsules are water thight. They can lay in water for weeks or months, and the coffee is still dry (watertest)
A convex lidding is created if the coffee is degassed less and added during filling, because the residual oxygen must of course be as low as possible. The foil and capsules are manufactured according to the EN13432 - ASTM d6400 standards and can be thrown in the GFT/green waste or compost after use.
The Viquotte label or OK compost label are allowed to be used for the lidding and capsules, according to EU packaging directive (94/62 / EEC).
The capsules must be packaged in an oxygen and vapor tight bag. After opening, the capsules can be kept and will retain the coffee aroma for 8 weeks.
At Stascafe we produce our own compostable PLA capsule. This is the only capsule that will fit in all Nespresso machines without leaking.