The other day, when refilling a coffee machine with coffee beans, I had to open a new bag of coffee beans. Even before opening the bag (which was properly sealed) I could smell the flavour of coffee wafting towards me. It smelled great!
Since the bag was completely closed, I had a closer look. Somehow the smell was coming out of the bag. I noticed a little round seal in the package. That triggered a post, let’s write about the science of coffee bean packaging.
Coffee bean packaging
Roughly said there are tree types of coffee bean packaging:
- Vacuum packed or airtight packaging
- Packed in a paper bag (e.g. freshly scooped in the store)
- Packed in a airtight pack, but with a one-way valve.
Let’s quickly walk through each type before we zoom in on the reasons for choosing one or the other.
Using an airthight or vacuum pack the coffee is complete closed of the outer world. No gases can come in nor out. The same goes for moisture or micro organisms. Ground coffee can be found in such a pack commonly.
Second is a normal paper bag. In a paper bag gases can go in and out of the bag and the coffee beans. Often, moisture will have a chance to come in as well. Paper bags do generally provide protection from light.
The last version is similar to the first, it is protected from air and moisture, but it does have a connection with the outer world: a one-way valve. This valve serves to release gases from the pack to the outside world, but should prevent other gases from coming in.
Science of coffee bean packaging
These three different types of packaging have diverse reasons for application.
After coffee beans have been roasted, they will continue to release a lot of carbon dioxide (CO2). Unfortunately, I haven’t been able to find a proper explanation of this release, but I assume it’s formed during various chemical reactions and simply takes a while to leave the beans.
Carbon dioxide is a gas and this escaping gas will cause the overall volume of the beans in a pack to expand. If the beans are packed in an air tight or vacuum pack, the pack will blow up and might even burst. When a one-way valve is usedor when the beans are packed in a paper bag, the carbon dioxide gas can escape pretty easily. (Coffee troupe has done a great experiment with this!)
Freshly roasted coffee beans have a lot of aromas. These are volatile and when you leave coffee beans open on a kitchen table they will quickly lose most of them. This will make a more bland coffee. Using a one way valve in a pack can allow part of the aromas to escape from the coffee, the same goes up when using a paper bag. (Read an interesting experiment here where they found that letting the beans rest for a little while before sealing them gave a better tasting coffee.)
Oxygen is a common enemy for a lot of products, for example olive oil, and is so for coffee as well. A lot of aromas in coffee are susceptible to reacting with oxygen in a so-called oxidation reaction. This will deteriorate the quality of the coffee.
By creating a pack in which oxygen cannot enter, the shelf life and quality of the coffee beans will stay good longer.
Translation to the best suitable pack
So which pack is best? From what I’ve read and heard there is no one best method. It al depends on the production process used. Here are some possible scenarios.
- Coffee beans are roasted and have to be packed immediately for further transport –> Airtight pack with valve
- Coffee beans have just been roasted and are sold to a custoer within a few days. This customer will use the beans within a few days as well -> Paperpack will work just fine
- Coffee beans have been roasted and there is place and time for the coffee beans to rest for a while (allowing carbon dioxide to escape) -> Airtight or vacuum packaging should work well here
There are several more factors that influence coffee bean packaging. Moisture should be kept away from coffee as well and lower temperatures are better for preservation than higher) not going as low as a fridge or freezer though. The scaa wrote a good article on the topic with a lot of scientific references for those interested.
Storing your beans at home
Then comes the dilemma, you’ve bought your beans, opened the pack and probably won’t use all the beans at once, what to do?
It is just about always best to not buy too much coffee in one go, it is hard to keep the quality high. Generally speaking it is best to store the coffee in an airtight container to prevent oxygen from coming in, as well as moisture and light. There is one exception. If your coffee beans have been roasted recently, they might still release carbon dioxide gases. If so, do not fully close the packaging to allow air to escape, close after a couple of days.
Design of packaging
When it comes to packaging, the science is important, but it’s just as important that the packaging looks good. If it doesn’t look appealing, or doesn’t fit with the image of a brand nobody will buy it, no matter how good the product.
Since this is a science blog, and since I’m not a design expert, I’d better not write about the topic but let someone else do so. I’ve got some great links for you:
- Here‘s a nice overview of several hip coffee bag designs of the daily coffee news. I don’t think they’re very mainstream, but they look nice. You will also see different packaging materials coming in, paper, plastic, probably some aluminium in there as well.
- Of course, there’s more. Here‘s another link from graphic swing with a lot of visual examples, also showing different type of packaging materials.
- Last but not last another long list of ideas from InspirationFeed, also using different types of materials for packaging.