Coffee Processing: What Is Carbonic Maceration?

Matteo Pavoni
March 31, 2021
carbonic maceration

Black honey, malic fermentation, frozen natural – there are a number of experimental processing techniques in coffee, each one able to influence the distinct characteristics of coffee.

However, one of the most exciting to emerge in recent years is a technique known as carbonic maceration. Introduced by champion barista Saša Šestić in 2015, it’s a method of fermentation that involves placing whole cherries in a stainless steel barrel and allowing them to sit in a carbon dioxide-rich environment.

Carbonic maceration is inspired by winemaking, which uses the process to develop grapes before crushing. Similar to wine, the extent to which carbonic maceration affects the flavours of a coffee is often determined by other factors, such as terroir. Yet for roasters, it is often an effective way of promoting their brand and setting themselves apart from competitors.

Read on to find out more about carbonic maceration and how specialty roasters can use it to stand out among other coffee brands.

See also: Why Should Specialty Roasters Offer Honey Processed Coffee?

An image of ripe red coffee cherries in an article about coffee processing and Carbonic Maceration

The Role Of Fermentation In Coffee Processing

Before coffee is ready to be roasted, it must undergo a period of fermentation as part of its processing. Fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms. While it has existed since the Neolithic age, its intentional use in coffee is relatively new.

Fermentation begins naturally when microbes, which exist on virtually every surface, find an entry point into the fruit. This could occur when the cherries are picked or when there is damage to the skin while still on the tree.

The aim of intentional coffee fermentation is to remove the fruit mucilage from the seed. Typically used in washed processing, it involves leaving pulped coffee in a tank to ferment until the mucilage surrounding the bean is loose enough to remove. It also occurs in natural processing when the mucilage dries around the seeds. 

According to Maxwell Colonna-Dashwood, author of The Coffee Dictionary, fermentation can have a dramatic impact on the characteristics of a coffee. Changes in temperature, time, sugar, and bacteria can all produce vastly different results. Therefore, it’s important that farmers understand how each factor can manipulate flavour so they can ferment their coffee accordingly.

For example, when coffee is fermented for the right length of time, it can refine qualities such as acidity, body, and sugars. But if fermentation goes on too long, it often produces a vinegary taste that detracts from its characteristics.

“Fermentation creates chemical compounds with sensory characteristics,” says fermentation expert Lucia Solis in an interview on Scott Rao’s blog. “Most of the differences between coffees are usually attributed to cultivars, climate, and growing conditions, but the contribution by microbes is frequently overlooked. The tiny microbes (yeast and bacteria) that transform the cherry fruit into parchment have the potential to impact flavour in a big way.”

An image of coffee cherries being processed in an article about coffee processing and Carbonic Maceration

What Is Carbonic Maceration?

As more is discovered about the role of fermentation in coffee, it has opened the door to a broad field of experimentation. Among the most popular discoveries is a process known as carbonic maceration.

Borrowed from the production of wine, carbonic maceration is a fermentation technique that first came to prominence in the coffee industry in 2015. Looking to create a coffee with more aromatic complexity and a low concentration of acetic acid, barista champion Saša Šestić introduced carbonic maceration when he used it for a Barista Championship-winning coffee.

Alongside his collaborator, Colombian farmer Camilo Merizalde, Šestić developed the technique after learning about its use in wine. In wine, carbonic maceration uses the injection of carbon dioxide (CO2) to ferment the grapes without breaking the skins, so that the process happens inside each grape individually. The initial fermentation is not caused by yeast, but instead occurs intracellularly, or from the inside out.

In coffee, it involves placing harvested coffee cherries in airtight barrels before pumping in CO2 to create a CO2-rich environment. The CO2 allows the cherries to break down different levels of pectins, often producing bright and winey coffees with strong notes of red fruits.

According to Šestić, all the flavours and aromatics produced by carbonic maceration have no way to escape. Instead, they’re absorbed by the coffee parchment, contributing to a stoned fruit quality in the cup. During the process, they use low temperatures to avoid alcohol build-up.

Once the coffee has reached its desired level of fermentation, the cherries can be processed by either washing or drying. (Both processing methods are suitable for carbonic macerated coffee.)

Unlike anaerobic fermentation, carbon maceration can take months to produce the right flavour coffee. This because the cherries are left whole when they are placed in the barrels, rather than being pulped.

An image of custom-printed coffee packaging in an article about coffee processing and Carbonic Maceration

Designing Packaging For Carbonic Macerated Coffee

In the coffee industry, experimental processing methods have grown in popularity in recent years. According to Colonna-Dashwood, exploration of coffee processing has never been more extensive and detailed. As a result, more and more consumers are taking an interest in coffees produced using different processing methods.

Carbonic maceration is one of the top trends in the coffee industry at the moment. When it was introduced by Šestić in 2015, it became an overnight sensation. And while its impact on the characteristics of coffee are subjective, coffee businesses can set themselves apart by adding it to their line of offerings.

For specialty roasters, it’s important to make processing information as clear and intelligible as possible on their packaging. Carbonic maceration is a unique selling point and it should be made obvious for time-pressed consumers.

When browsing products on a shelf, it takes only a few seconds for consumers to make a purchasing decision. Therefore, the processing method should be put front and centre to help the coffee stand out from the competition.

For those looking for a more minimalist design, QR codes can be added to packaging to reduce the amount of text. QR codes are scannable barcodes that direct consumers to websites, apps, and social media pages where they can find out more information about the product.

The Cerrado Coffee Growers Federation is one organisation that have done precisely this. Green coffee from Cerrado Mineiro in Brazil is provided with QR codes that, when scanned, provides information about the farm and the farmer’s story, the coffee variety, processing method, and lot size. It also includes information for roasters, such as the suggested roast profile.

The QR code is attached to the bags of green coffee, however it can also be added to bags of roasted coffee, where it is more commonly found. This means detailed information is available at every stage of the supply chain. This is a useful tool for specialty coffee roasters, who may otherwise struggle to include all this information on their packaging without overwhelming consumers. 

An image of sustainable coffee packaging made from rice paper in an article about coffee processing and Carbonic Maceration

Despite being a relatively new concept in coffee, carbonic maceration has become a popular selling point for specialty roasters. Intrigued by the perceived flavours that it can impart on coffee beans, consumers are taking a greater interest in experimental processing, with carbonic maceration already a firm favourite for some.

At MTPak Coffee, we can help you promote the distinct processing methods of your coffee with our high-quality packaging and creative design services. You can choose from a range of materials, components, and bag structures to ensure your coffee arrives at the consumer in the best condition possible, as well as attracting attention on the shelf.

For more information on our compostable takeaway coffee cups, contact our team here.

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