19/9/14 Nota Bene. This post was relevant to particular style of coffee (light to medium), roasted on a drum roaster (Diedrich IR5). Our current roaster (Loring Merlin) roasting a similar style of coffee leads some coffees – especially natural-processed coffees – to swell the bags up and occasionally burst. We currently cut open and vacpack these coffee bags again a couple of days after roasting. This is only the case for 1kg bags. 250g bags are not affected. We shall be ordering 1kg bags with valves in the future.
Yesterday I decided to do away with one-way valves on our roasted coffee bags when packing with a vacuum. It’s been something that I’ve been testing for many years now and time again I’ve come to the conclusion that they really don’t make that much difference to the coffee. Indeed, too often they provide an access point for oxygen to enter the bag and degrade the coffee.
One-way valves are supposed to let CO2 gas out of the bag while preventing O2 getting into the bag. Oxygen is the main culprit behind the staling of coffee and packaging is an attempt to extend the vitality of the beans. Continue reading