Can hermetic coffee bags improve the sensory characteristics and shelf life of coffee?

Paul Clearfire
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May 20, 2024
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The sensory characteristics of coffee are essential metrics for establishing value throughout the supply chain. Workers across all stages pay careful attention to thousands of details to ensure that quality remains intact consistently throughout. Along the way, hermetic coffee bags play a critical role in preserving quality and ensuring value. 

Maintaining the quality of green coffee can be challenging in environments with high moisture, or when it is in storage for long periods. Such conditions can introduce off flavours that reduce cupping scores and negatively impact purchase prices. These factors can ruin farmers’ efforts to produce high-quality lots and reduce or even reverse profit margins. 

I spoke with Brandon Damitz, the owner and CEO of Big Island Coffee in Puna, Hawai’i, and  Adam Klein, the founder and CEO of Coffee Unified in San Francisco to discover the real-world impacts that hermetic green coffee bags have on the quality and price of green coffee.

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How hermetic coffee bags impact the sensory characteristics of green coffee

The term “hermetic” derives from the Greek god Hermes, who was the god of science and art, among other things. Ancient alchemists associated Hermes with “Hermes Trismegistos” (“thrice mighty Hermes”), whose legend says invented the airtight glass tubes using a secret seal. Hence, the word hermetic has come to mean “completely sealed”. 

Creating a complete seal is critical to hermetic packaging’s ability to preserve the sensory attributes of green coffee. Essentially, hermetic coffee bags achieve this seal in two ways:

  • First, they employ several bonded layers of high-barrier plastic. This provides excellent protection against oxygen and moisture.
  • Second, the top is resealable, typically through the use of a zip tie or a built-in zip-lock style plastic zipper. 

Additionally, some applications employ a vacuum and heat sealer to provide an extra degree of preservation. Some might also add a moisture-absorbing sachet, or desiccant, to further control moisture content. The majority of green coffee bags are coloured to help reduce the damage caused by ultraviolet (UV) light. Additionally, they’re thick enough to withstand the stresses of shipping and storage. Beyond this, producers and distributors will typically sleeve hermetic bags within a traditional jute sack for added protection.

In their 2018 paper, “Analysis of Green Coffee Quality Using Hermetic Bag Storage,” published in the Journal of Stored Products Research, authors Natalie K. Donovan et al. studied the efficacy of hermetic bags in preserving sensory characteristics. The study took place in the extremely humid environment of the central mountains of Columbia. Producers in this area face great challenges in controlling moisture levels in green coffee, particularly during storage. 

According to the authors, it is readily known in the Colombian coffee culture that high moisture content poses threats of mould, discolouring, and off flavours. The report states that this forces Colombian farmers to sell green coffee soon after harvest, immediately after the drying step. 

“However, cooperatives must collect a high volume of green coffee to qualify for export and therefore must store for up to 2 months. Due to these market and environmental constraints, the storage phase of the coffee supply chain is an ideal place for technological interventions to raise overall quality and price,” the report explains. 

The study revealed conclusively that the use of hermetic coffee bags preserved the quality of green coffee beans stored for up to 6 months. Additionally, researchers found that the bags inhibited moisture transfer between the environment and the green coffee beans. 

The lead author’s doctoral thesis combines the results of this study with a highly detailed analysis of sensory scores and pricing. The work demonstrates how the benefits gained from the use of hermetic bags during storage can lead to higher received prices and positive returns on investment for farmers, cooperatives, and distributors.

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How hermetic coffee bags make a critical difference for farmers

When Brandon of Big Island Coffee purchased a small coffee farm in Puna, Hawai’i in 2010, his dream was to revitalise the failing property and bring a little-known Hawaiian cultivar to market. 

“I’d prefer to be in the field 8 to 10 hours a day,” he says, “But I need a sense of greater purpose and meaning in my life. I could grow some really great coffee a few acres at a time, but what am I really doing? Not a whole lot from that angle, so it seemed like a selfish endeavour. 

As a farmer and processor, Brandon explains that he wants “to help people do what they love. It’s so economically challenging being in a place where real estate is so valuable. I soon found out I’m better at supporting farmers.” 

Now Brandon and his wife, along with 23 employees, support the work of farmers in Puna and nearby Ku’u as processors and distributors. 

When the brand first started offering services to the farmers in the community, not many were using hermetic coffee bags. However, as he began to educate others on the difference that they could make, farmers quickly began to adopt them. 

“They have a direct impact on what I can pay a farmer,” Brandon says. “I say to them: ‘If you use these bags to preserve the coffee, I can pay this price, but if you don’t, then I can pay this other price, which you’re probably not going to like very much’.”

Brandon adds that his pride lies in the ability to pay farmers their asking price–sometimes more. “It makes me feel amazing that we can put $1.8 million into the hands of farmers on the Big Island. That’s money that stays on the island and helps to create economic viability.”

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Hermetic coffee bags: Preserve value after import

On the import side of the supply chain, Adam Klien explains the benefits that hermetic bags bring to green coffee importers. 

“After a few decades of experience using hermetically sealed bags, it has become somewhat of an automatic to include them on our shipments from origin. The quality retention provided by liners is unquestionably worth the cost of the bags themselves.” 

That said, due to natural fluctuations in market demand, they can sometimes have green coffee sitting in their warehouse for months on end. “In these instances, I can’t imagine not using [hermetic] liners, as we still see a near intact level of quality compared to when the coffee first arrived,” Adam says. 

At MTPak Coffee, our hermetic green coffee bags offer specialised storage and packaging solutions that seal in freshness and maintain the sensory attributes of your product. Multiple layers of high-barrier packaging mean these airtight bags extend shelf life significantly, preserving natural oils and flavours for richer, nuanced profiles.

Our range of hermetic green coffee packaging is made using high-strength PE and boasts superior water and air properties. More so, they can keep your products fresh without the help of pesticides or insecticides, for over a year. Our range of green coffee packaging includes: 

  • Multilayer coffee sample bags
  • Multilayer coffee storage bags
  • Vacuum storage bags. 

Learn more about our green coffee packaging solutions

Article body image courtesy of Big Island Coffee 

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Paul Clearfire
Paul Clearfire

Paul Clearfire is a coffee historian and author living in Portland, OR, and has spent the past 20 years perfecting the art of manual espresso extraction. He's been writing for Perfect Daily Grind Media since 2023.

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