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2 bags of coffee

Coffee bean packaging – Science of proper coffee storage

Ever noticed that you can smell your coffee beans, long before you’ve opened the pack? The aromas seem to still find their way to your nose. A vacuum pack of ground coffee on the contrary doesn’t smell like coffee at all – unless you open it of course.

Why can you smell the coffee beans? And not the ground coffee? Shouldn’t they both be sealed hermetically to preserve the aromas? Turns out, no! That is, if you don’t want your bag of beans exploding!

So before we continue. Do you have a pack of coffee beans nearby? Grab it, and have a look.

Notice a slight round unevenness somewhere on the bag? It might be at the front, or the back.

That’s a valve and it’s there for a good reason. To prevent exploding bags. And, it allows you to smell your coffee. So, what’s going on here? Why would your bag of coffee even be tempted to explode?

coffee bag
See that circle in the white plastic within the green circle? That’s the valve we’re looking for.

Why package coffee beans?

Yes, manufacturers package coffee beans to make it easier to transport them. To ensure that your cart isn’t full of loose coffee beans, when going to the supermarket. And to ensure that they don’t pick up dust and dirt along the way. But transport is just one reason why manufacturers package coffee.

Packaging also serves to keep coffee beans, ground or whole, as fresh as possible.

non-decafeinted green coffee beans, not roasted
Unroasted coffee beans, notice the green colour

Don’t let the roast escape

You’re most likely buying coffee beans that have been roasted. Roasting coffee beans transform a green, quite bland coffee bean, into a brown bean full of flavor and aroma. During roasting a range of chemical reactions, including the Maillard reaction, are the cause of these transformations.

Some of these newly formed flavorful molecules aren’t that stable. They evaporate easily. It is what allows us to smell them. They leave the bean, and enter the air in our noses. If we’d leave roasted beans without any protection, they would quickly lose a lot of these aromas. That results in stale coffee.

Proper coffee packaging helps prevent those aromas from escaping from the coffee.

Use a good barrier

To ensure the aromas don’t leave the coffee, you will have to use a material that doesn’t let these molecules pass through.

Examples of suitable materials are metal cans, or laminated packaging materials. Laminated films are made up of several layers of material, often containing a thin metal layer. Every layer has its own role. Some provide strength to the pack, others, such as the metal layer, serve as a barrier for roast molecules.

These materials are great from a shelf life perspective. However, these do tend to be almost impossible to recycle. It is not possible to easily separate those layers again.

On the opposite end of the spectrum, you’ll find paper bags. These bags are not good at keeping flavors in. Instead, gas molecules can freely move in and out of a package. You can easily smell the coffee flavor through your paper bag.

Keep oxygen out

You shouldn’t just keep the flavors inside. You should also make sure that the flavors of a coffee bean aren’t affected by outside factors.

A common ‘enemy’ of fresh foods is oxygen. Oxygen can cause foods to oxidize. This can result in the formation of undesirable flavors, or a loss of flavor.

Especially vulnerable for oxidation are unsaturated fats. Coffee contains some fat, which as a result can turn rancid. By creating a pack in which oxygen cannot enter, the quality of the coffee beans will stay good for a longer period of time.

Good quality coffee beans, makes good quality coffee, that’s definitely true for cold brew coffee as well.

Wakuli coffee pack
See the holes?

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Don’t let the bag explode!

So an important role of packaging coffee is to ensure it remains fresh and full of flavor for a longer period of time.

But, there is another crucial factor that coffee bean packaging designers need to keep in mind. One that we’ve mentioned earlier: the bag shouldn’t explode!

Explode? But why would a bag even be able to explode? To explain, we need to have a closer look at coffee beans.

Coffee beans are porous

Remember that a coffee bean starts out on a plant. As such, it is made of sturdy plant cells that are made out of a strong outer cell wall. Within, they also contain a big bag of water, a vacuole.

During roasting, you’re not just developing flavor in a bean, you’re also drying the bean further. Coffee beans are strong, so they don’t collapse. But, all these individual pockets of water do dry out. As a result, a roasted coffee bean is quite porous. If you’d cut one open and look at it under a microscope you’d find a lot of small holes.

plant cell

Gases are trapped during roasting

During roasting a lot of chemical reactions take place. During these reactions, carbon dioxide (CO2) gas is formed. The release of these gases can even continue for quite some time after roasting.

However, these gases don’t all immediately leave the bean. Instead, they can be trapped within the porous structure of the bean and will need some time to leave the bean. Darker roasts and faster roasting processes generally result in more gas formation.

As a result, for quite some time after roasting, gases continue to leave from those beans. If you’d package the beans in an air-tight pack, all those gases would be trapped. The pack will puff up more and more, much like blowing up a balloon. At some point, the bag might even explode!

freshly roasted coffee beans
Freshly roasted coffee beans, notice how they’d dried out?

Let the gases escape

When packaging coffee beans it is thus very important to be aware of the release of all these gases. There are roughly three ways that manufacturers can cope with these escaping gases:

  1. Leave the beans to degas so the majority of those gases have left the coffee beans before they’re packed. This may take a few hours, up to a few days. The majority of gases will escape in the first few days, with quantities flattening out over time.
  2. Pack the beans in a pack that can resist some pressure. Some degassing is likely still necessary, but when using a pack that can withstand some pressure you need to degas for a shorter amount of time.
  3. Use a pack that lets the gas out easily. However, that generally also means that your flavour molecules will disappear easily. This is best for shorter shelf lifes.
  4. Use a pack that lets gases out, but doesn’t let anything else come in! This is where that little hole, or valve inside your coffee pack comes it. It’s a one-way ticket for carbon dioxide to escape!
  5. Grind the coffee. By grinding the coffee you’re breaking down the porous structure of the coffee beans. As a result, the excess gases can escape a lot more quickly.

Some types of coffee are always made with ground coffee, Turkish coffee is just one of many examples.

Here’s what happens if the valve isn’t working well. The bag on the right side was completely closed, causing it to blow up by excess gas within. The bag on the left had a functioning air valve through which the gases could flow to the outside.

Types of coffee bean packaging

Knowing this you can now start looking for suitable packaging. You have several options:

  1. Paper bag
  2. Airtight packaging (e.g. a plastic bag)
  3. Airtight packaging with a one-way valve (allowing gases to escape)
  4. Vacuum packaging
  5. Metal cans

So which pack is best? There is no one best method, but there are best methods for several most common use cases!

Choosing packaging for any product can be one of the more challenging aspects of scaling up production. Your paper bag might no longer suffice and you need something else. We’ve written a pacakging guide to help you along the process.

Paper – Buy it and use it

If you buy or make coffee that will be used within as little as a few days, there is no need to use special packaging to prolong shelf life. A paper bag will serve you just fine. The beans can degas without any issues and not enough time passes for the flavors to get lost or the oxygen to do its work in oxidation. Paper is also cheap and easy to recycle.

Airtight + one-way valve – Optimal freshness

If you need to store your coffee beans for a longer period of time, a pack with a one-way valve is the way to go. This pack allows you to pack the beans quite quickly after you’ve roasted them. That way, you’re able to keep a lot of that flavor within and protect them from oxygen.

A major disadvantage is the recyclability of these packages, which is noticeably worse than that of a paper bag.

Airtight + time – A compromise

If you don’t want to or can’t use the one-way valve but want a longer shelf life than the paper bag, a ‘regular’ closed bag is fine. However, you have to wait longer to pack these beans. You have to make sure that all that carbon dioxide has had a chance to escape.

Vacuum packs

In vacuum packs, the air has been pulled out of the pack. This slows down flavor losses – there’s no oxygen to oxidize the coffee. But, it is not a good measure against exploding packs. Gases in beans can still be released, causing the pack to puff up.

It’s why vacuum packs are mostly used for ground coffee. Since ground coffee is also more prone to losing its flavor over time, the extra vacuum protection helps it stay fresh longer.

Metal cans

Another common option (depending on where you live) is to find ground coffee stored in metal cans. These provide some sturdiness and again aren’t very well penetrable for any gases.

What to do once the pack is open?

No matter how advanced the pack, at some point, you have to open it up and start using those beans. But, you probably won’t use them all at the same time though. What to do?

First of all, don’t buy too much at once. If it takes you 6 months to finish a bag, that’s a waste of coffee. Better buy smaller portions more frequently.

That said, once you’ve opened the bag of coffee, it’s generally best to store it in an airtight container. 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.

And, of course, enjoy your coffee!

coffee bean packages glass jar and plastic bag
Once a coffee bean pack has been opened it is best to store them airtight, for example in a glass jar.

References

Inspirationfeed, 30 Stimulating & Creative Coffee Packaging Designs, July-12, 2019, link ; for design inspiration!

Ohl, Danielle, Are One-Way Valves Right for Your Coffee Packaging Process?, Viking Masek, April-15, 2018, link

Roasting House, What kind of packaging is best for freshly roasted coffee?, 2015, link ; a nice experiment between packaging types, but they only tested a shelf life of 7 days

Sage, Emma, What is the Shelf Life of Roasted Coffee? A Literature Review on Coffee Staling, SCA (Specialty coffee assocation), Feb-15, 2012, link

Samo Smrke, Marco Wellinger, Tomonori Suzuki, Franz Balsiger, Sebastian E. W. Opitz, and Chahan Yeretzian, Time-Resolved Gravimetric Method To Assess Degassing of Roasted Coffee, J. Agric. Food Chem.2018, 66, 5293−5300, link

Niya Wang, Physicochemical Changes of Coffee Beans During Roasting, Guelph University Thesis, link

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7 Comments

  1. Nice.
    What I would like to know is how many days does it take after roasting of beans to safely pack them in vacuum pack

    • Hi Amar,

      Great question! I must admit that I’m not a coffee roaster myself and there is very little published on this.
      That said, you can vacuum pack ground beans immediately after grinding (in fact, that’s what you should do, as soon as the coffee has been ground into powder it will start losing flavour).
      You should only grind the beans once they’re cooled down completely. Grinding warm beans will give issues with both grinding as well as packaging afterwards. As far as I know, there is no specific wait to hold on to before grinding apart from the initial cooling.

  2. Thanks. Although I have some experience in cofee roasting, grinding etc., Still I need more information on packaging which can keep coffee aroma intact and also has better shelf-life.

    • That is a great question Anthony and whereas I’m sure it will make a difference it will depend also on the market you’re in, the message you want to send to your customers (e.g. premium vs low cost). An ‘ideal’ color will probably be different for every brand, might be worthwhile to do a (digital) test with this!

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