Ewan Reid our dashing Technical & Quality Director, can often be found squeezing and sniffing in our roasting plant. Squeezing and sniffing coffee bags, that is. Why? It's all about valves.

Our coffee beans are packed in bags with clever one-way valves that work to keep the precious coffee fresh. Ewan gets technical again: "Each kilo of roasted coffee beans can produce up to 10 litres of gas. primarily CO2, depending on roast height and blend composition."

Ewan continues "Packaging coffee beans is like bottling champagne, except in reverse." How so? "With champagne, you need to keep the fizz in - with coffee, you have to let the gas out. But you mustn't let any other gas in." So, the valves in coffee packaging need to allow a one-way action. If the gas didn't escape, the bags would burst.

As for the bags themselves, Ewan goes all impressive again. "A good triple laminate foil package allows a slow outward migration of CO2 whilst limiting the loss of volatile aromatics, which are important to the development of real coffee aroma." In other words, our bags don't leak. Except when we want them to!

This article originally appeared in Fresh 5