In Search of A Greener Coffee Capsule

Single-serve coffee brewing continuously grew among consumers because of its simple operation, high freshness, variety of flavor choices and professional standards. Market share has expanded rapidly. According to the National Coffee Association, 41 percent of coffee drinkers owned a single-cup coffee brewing machine in 2018.

Its production process is simply grinding roasted coffee beans into coffee powder and then sealed into capsules. When packed within high barrier materials, each cup retains the freshness of the coffee beans up to 4 hours after roasting. In this manner, the authentic fragrance is preserved, along with the rich cocoa oil and smooth consistency.

The need for using good barrier materials is to eliminate the acidity of ordinary coffee beans or coffee powder due to exposure to air that leads to oxidation and other issues. For example, most top coffee capsule suppliers manufacture mainly classical multi-layer polymer capsules but this can be a challenge for those looking to use new eco-friendly materials.

Most plastic capsules are not biodegradable. When they are dumped into landfills, without the hope of bio-degradable, it poses a big challenge to the ecosystem. Now, the search of greener (Bio-based and/or biodegradable) compostable capsules is a hot initiative around the world. So far there are about 5% of coffee capsules that are related to compostable and growing each year.

So these new materials are great for the environment, but will they perform the same as standard plastic barrier materials? These barriers must be evaluated for its barrier quality and package integrity to ensure they meet the strict requirements for your product.

Many of the bio-based compostable (or bio-degradable) capsules have the oxygen transmission rate (OTR) levels of about 6 x10^-3 cc/(package*day), versus classic plastic barrier capsules of about 1x10^-4 cc/(package*day).

Although more efforts are needed to get over the challenges of developing successful compostable coffee capsules, the greener capsule also has a great opportunity for growth.

Recently, a few coffee capsule OTR testing projects were carried out at the AMETEK MOCON Permeation Testing Laboratory to test the performance of some of these compostable materials.

The following are some examples:

Test conditions: 23C, 50%RH

Test gas: 21% O2

Instruments: MOCON OX-TRAN® 2/21 and OX-TRAN 2/22

Fig 1  Test results

The above testing results demonstrate the promising outlook for improving compostable coffee capsules. These materials are now in the same range of oxygen barrier levels as classic polymer capsules.

If you are in the business of the compostable coffee capsule development and want to know how to evaluate its barrier quality and package integrity, here are some takeaways:

  • Conduct initial OTR barrier testing for material selection

  • Discuss processing optimizations with your suppliers