Roasting transforms the green beans into the aromatic brown beans we recognise. While this stage unlocks coffee’s power and flavour, it also leaves it vulnerable to its number one threat: oxygen. This happens due to a process known as degassing where the pressure resulting from the heat forces carbon dioxide to be released from within the coffee beans. Since this could cause packages to explode, many roasters allow the beans to rest in airtight silos for a while. Here the degassing process is sometimes assisted by nitrogen (added from the bottom of the storage tank to create a continuous blanket) which joins forces with CO2 to keep out the O2.
The next step in pursuit of the best cup of coffee is to put the roasted beans through the grinder. This is what determines the main categories of brew, with the coarse grind used for the French press and extra fine for the espresso machine. Grinding has the effect of releasing even more of the trapped CO2 and aromas, which is why it is usually brewed or packaged shortly thereafter. Whether it’s the roasted and rested coffee beans that are being packaged or the ground coffee, the packaging needs to deal with some gaseous realities namely: the coffee will continue to give out CO2 while sitting in the packaging. This means that there’s a good chance of the package exploding. If only there could be some way of letting out the CO2 without letting in the O2. This is where nitrogen and one-way valves pay a role.
Using MAP (Modified Atmosphere Packaging), the existing air is evacuated and replaced by food-grade nitrogen (a process known as nitrogen flushing) while the package is being filled with coffee, and before it is sealed. Nitrogen not only displaces any residual oxygen but being inert, keeps the coffee fresh, moreover the increased pressure in the package also has the effect of slowing down degassing. While some packaging might stop right there, speciality brands go further by placing a one-way valve in the packaging. This valve allows the CO2 to escape while keeping out the O2.
Of course, not all manufactures opt for nitrogen flushing with a one-way seal integrated into the packaging. Some packaging involves simple bagging the coffee without nitrogen flushing, especially when the contents are expected to be used within a week. Vacuum packaging which involves drawing out the air from the filled package before sealing, is another option as are metal and glass cans. Capsule packages are made for those who use coffee pod filling machines like the K-Cup. Nitrogen flushing is used in packaging such coffee pods as it serves to lower O2 levels and stretch its shelf life. Let’s not forget the increasingly popular nitro cold brew coffee that requires infusing nitrogen into coffee at high pressure to achieve a pleasant mouthfeel.
The advantages are clear:
Have you tried onsite nitrogen generation for your coffee business? Pneumatech makes it possible for you to produce all the nitrogen you need in-house with nitrogen generators that use Pressure Swing Adsorption (PSA) technology and membrane technology. Know more about how Pneumatech gas generators can work for your coffee business.
Many companies still purchase their nitrogen – even though generating oxygen on-site offers more advantages.