Everything You Didn't Know About Nitro-Flushing

The ‘Holy Grail’ of coffee production and packaging is ‘coffee freshness’. Coffee freshness is inherently linked to the presence of its “solubles” – various chemical compounds, oils and acids that give a coffee its flavour. The biggest culprit for loss of freshness is our good friend oxygen, which reacts with coffee’s solubles over time, causing a loss of flavour, becoming stale - not ideal! To reduce this, our production methods limit the presence of oxygen and the oxidisation of the beans.

Whole Bean Coffee Bags

One of the main reasons that we prefer to package our coffee as whole beans, instead of ground coffee, is to reduce the loss of coffee solubles. So if you’re an Aeropress or Kalita lover like we are, we definitely recommend investing in a grinder, buying whole beans from us, and grinding at the point of brewing! Ground coffee has a larger surface area than whole beans exposing more of the coffee material to oxygen, causing the coffee to turn stale faster. The taste difference is notable minutes after grinding, which is another reason that our baristas grind-to-order, rather than pre-grinding or pre-making shots.

What is Nitrogen Flushing Anyway?

Nitrogen is an inert (unreactive) gas that is both odourless and importantly, food-safe! This means that it won’t alter the flavours in the beans, so that you get the exact taste that our roaster intended. This also allows us to keep consistent coffees in rotation, producing the same flavours every time. Nitrogen is also heavier than oxygen making it the perfect gas to displace any pesky oxygen molecules that are trying to spoil your coffee!

Ever wondered what the little plastic valve that sits on the inside wall of our coffee bags is for? Well, you might remember from our Coffee Processes Blog that coffee beans are often in a constant state of fermentation – which is actively changing and developing flavours in the bean. This fermentation constantly releases large amounts of carbon dioxide from the beans. Although the presence of carbon dioxide doesn’t affect the coffee either, it needs a way to escape from the bag or the pressure could cause it to explode! This one-way valve is used to allow carbon dioxide to escape the bag, without letting the oxygen back in – keeping your coffee fresh for longer, and limiting those unwanted explosions!

Our Machinery

To fill our bags we use the Phil 2500 by Scayl - yes, seriously, our filler is called Phil. Phil is actually a pretty clever piece of tech! Using an intelligent microcomputer, we can simply programme the exact weight of the coffee that we would like to dispense (1kg, 250g, or 90g for our cute miniature Battle of the Christmas Roasts bundle!) After our bags are filled it’s on to nitro-flushing and sealing, which surprisingly all happens at once.

We use the Vacuum Power Sealer 720 by Audion, connected to our air compressor, which sucks, pumps and seals! We start by removing as much oxygen from the bags that we can using the air compressor, followed by the nitrogen flush which displaces any remaining oxygen. Finally, we heat-seal the bags to retain those great coffee flavours and aromas, ready to ship to you or the Café!

Now you know! When you grab a bag of Cartwheel coffee, you can rest assured that it will taste as fresh as the day it was roasted - just as our roaster intended. If you want to keep your coffee tasting fresh (for up to a month after opening), we recommend keeping your beans in an air-tight container to keep them fresh! And if you find that you’ve got a Cartwheel favourite, it will taste just as great every time; all thanks to our robots Phil and the nitro-flushing team.