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The science behind fresh coffee

Picture this: you tear open the seal along your bag of Alfie & Co Coffee Roasters coffee. Maybe it’s the smooth London 1965. Perhaps you’ve picked the full bodied Barista Dark & Intense. As you take that first sip of your brew, a wave of flavour engulfs your senses, leaving you in a state of pure bliss. What's the secret behind this sensory delight? It's the magic of not just freshly roasted coffee, but matured coffee.

We’re all about transparency here at Alfie & Co Coffee Roasters, so when we say our beans are freshly roasted, they are, but that means they were roasted five to six days prior to being put into our bags. Why? Well, read on.

Freshly roasted coffee beans are akin to a fine wine—they need time to mature and develop their full flavour potential. Contrary to popular belief, coffee beans don't reach their peak flavour immediately after roasting. Instead, they undergo a process known as degassing. In short, it’s not actually a good idea to grind and brew beans that have just been roasted that day, or even for a few days after.

During roasting, coffee beans experience significant chemical changes. The intense heat of the roaster triggers a series of complex reactions, including the Maillard reaction and caramelisation, which give coffee its characteristic colour, aroma and flavour. Fresh roasted beans are also acidic, but along with all the other science taking place, the acidity slowly breaks down during the maturation, and the bean's oils and flavanoids continue to change and develop, which all adds to the final flavour profile.

However, and this is an important point, roasting also produces carbon dioxide (CO2) as a by-product, which becomes trapped within the bean's cellular structure.

In the days following roasting, coffee beans release this trapped CO2 through a process called off-gassing. This release of gas is crucial for achieving optimal flavour in your cup of coffee. Once the beans have been roasted and you grind it immediately or within the first few days, you’ll hear a noticeable hiss. This signals that the beans still undergoing this degassing process and are not perhaps quite matured.

But why does freshness matter, and how long does it take for coffee beans to reach their flavour peak? According to experts, freshly roasted coffee beans require approximately five to six days to degas fully and develop their full flavour profile. During this time, the volatile compounds responsible for aroma and flavour continue to evolve, resulting in a richer and more complex taste. This is where the art in artisan comes in to play, and an experienced roaster knows exactly how to guide the beans through this process to achieve the flavour profile they want.

Numerous scientific studies support the notion that coffee flavour evolves over time. Research published in the Journal of Agricultural and Food Chemistry found that certain flavour compounds in coffee, such as furans and pyrazines, increase in concentration during the first few days post-roasting, contributing to the coffee's overall flavour profile.

Furthermore, a study conducted by scientists at the University of Bath revealed that the aroma of coffee continues to evolve even after the degassing process is complete. They discovered that coffee aroma compounds undergo significant changes during storage, leading to subtle shifts in flavour perception over time.

To ensure that this degassing process occurs smoothly and efficiently, the choice of packaging is paramount. A freshness valve, incorporated into high-quality coffee bags, allows the built-up gases to escape while preventing outside air from entering. A bloated bag that you can squeeze and push the air around in suggests there's a build-up of gas inside, and cheaper bags can even rupture under the pressure of the de-gassing.

This is why, at Alfie & Co Coffee Roasters, we spare no expense in sourcing the best possible bags to support the maturing process of our coffee beans. We’ve tested dozens upon dozens of bags (and we’ve seen the cheapest bags rupture at the seams!) and we can confidently say that our chosen bags are some of the best on the market.

So the journey from bean to cup is a fascinating one, filled with chemical reactions and sensory delights. Freshly roasted coffee beans are a testament to the artistry of coffee roasting, and their flavour evolution over time is a testament to the science of coffee. For time though, our roasts will be generally in line with the accepted five to six days before we bag them up. Just because we talk about the maturing process for coffee, itdoesn’t give anyone an excuse to serve up beans that were roasted months or even years ago!

So, the next time you reach for your morning brew of our signature roast, you know that we’ve given you not just the freshest roast, but the freshest roast that’s ready for you.