What is an infused coffee?

Is this coffee infused?


At Zest, we embrace the wide variety of flavours coffee can offer where each new brew can be an exciting discovery. The rise of infused coffees over the last few years has completely changed the landscape of coffee processing and fermentation and brought new horizons to be discovered.

Little did we know that these infused and flavoured coffees might open a Pandora’s box of hostilities towards producers, roasters and consumers embracing them.

The main accusations against infused coffees are based on the alleged lack of transparency from some producers but also the idea that adding “non-natural” coffee flavours to coffee takes away the variety and terroir characteristics of the coffee, with fear that some producers might compromise on good farming practices and leverage infusion techniques to make up for the loss in quality.

Specialty Coffee is built on transparency, in opposition to commercial coffee where coffee is used as a commodity and is, therefore, substitutable. Specialty coffee is centred around transparency from farm to cup and the consumer agrees to pay a premium price for that transparency and a higher cup quality.

Our team has travelled extensively to producing countries to work with farmers on some of those new infusion techniques and we quickly realised that making as coffee taste like pineapple wasn’t as simple as throwing pineapple into the fermentation tank and waiting for a couple of days.

This topic is complex, and we believe that there’s a lot of misinformation and misunderstanding out there. We spent several months, working with producers and experts worldwide to better understand the subject and bring an objective and unbiased set of eyes onto this topic – by trying to understand the point of view of various stakeholders in the value chain.


But first, what is an infused coffee?


Infusing is the act of steeping or soaking a substance in water or another liquid to extract the beneficial properties or flavours of that substance. An obvious example is infusing coffee into water. Adding ground coffee into water to extract the flavours of coffee and making flavoured water. This notion of transfer and extraction of flavours from substance A to substance B is key to understanding the general concept of infused/flavoured coffees.

Another term that is commonly used in the context of flavour extraction is maceration. Maceration is the process of softening and breaking down food by soaking it into a liquid, generally to extract flavours. In the context of coffee, maceration and infusion have the same general meaning. They both refer to this transfer of flavour from one substance to another. You can argue that infusions are generally implied to be relatively swift processes, occurring in a hotter environment to foster the chemical reaction and that macerations generally happen in a cold environment, over an extended period. But in the context of coffee fermentation and coffee processing, both terms literally mean the same thing.

You might also come across the term “adulterated” when referring to infused coffees. “Adulterated” means that something was made impure or contaminated by adding inferior substances, generally rending it poorer in quality. We do not support the use of this terminology in the context of infusion as it contains an element of subjectivity through the implications that the quality of coffee will necessarily decrease. In our experience, most successfully infused coffees will gain in quality (aroma, flavours but also acidity and body if the infusion also implied an enzymatic reaction), therefore, we decide not to judge and use subjective terminology.


What can be classified as an infused coffee?


Although the definition of an infused coffee is quite clear, what qualifies as an infused coffee is a grey area and is open to interpretation. Coffee processing and fermentations aren’t binary. There are a lot of nuances that go into them, and we are far from the days where coffee was either just Washed, Natural or Honey processed (see Christopher Ferran’s Glossary on coffee processing).

We, at Zest, consider a coffee to be infused if there is a trace in flavours of the substance that was added to coffee. For instance, if you add cinnamon to the fermentation tank and the final cup of coffee tastes like cinnamon, it is an infusion as flavours transferred from substance A (cinnamon) to coffee (substance B).

Now what if we add salt to the tank to perform a lactic fermentation? Or carbon dioxide to do a Carbonic Maceration? In these two instances, the addition of a new substance to coffee results in the final cup to taste different. However, it is highly unlikely that the coffee will taste salty or have a Co2 flavour into it.

Salt and Co2 therefore act to select and control the bacteria that will participate in the fermentation. They are not used to add their own flavour to the coffee. Therefore, we do not consider these to be an infusion.

The addition of fruits into the fermentation tank has become a more common practice worldwide, from Colombia to India through Burundi. However, adding fruits in contact with coffee does not always mean that the coffee will absorb those fruits’ flavours and that there is a situation of infusion.

Two main things can happen when fruits are added to coffee during the fermentation:

  1. Fruits serve to add flavours to the coffee and there is a transfer happening between the 2 substances – this is an infusion.
  2. Fruits act as a reactant in the enzymatic reaction with coffee. They become a source of sugar and natural yeasts which will foster the fermentation process and there is no direct trace of that fruit’s flavours è this is not an infusion.


In the case of the now infamous cinnamon infusion, there doesn’t appear to be any microbial reaction and the cinnamon is simply used as an additive, not a reactant in the fermentation process.

The addition of commercial or cultured yeasts is another way to create and develop flavours in coffee that overwise wouldn’t be available without fermentation such as 2 Phenyl Ethyl Alcohol chemical compound for rose, Saccharomyces Cerevisiae, Lactobacillus Plantarum, Candida producing high alcohols which then contribute to rose, jasmine, balsamic, butterscotch amongst others.

Yeasts are essential to the fermentation process as they break down the complex sugars and starches available in the coffee fruits to turn these into simple sugars, which in turn, can produce ethanol and Co2 new flavour compounds. According to the definition of infusion that we use, most coffees inoculated with yeasts would not fall under the infused category as it’s highly unlikely that the final cup has a yeasty flavour (unlike the addition of yeasts into bread). In this instance, yeasts generally act as catalysts to unlock flavours that would otherwise not be available in coffee.

More recently, producers have experienced with cultivating their own yeasts, feeding it with water and sugar as fuel, but also with fruits, herbs or spices for that yeast to absorb those aromatic compounds. Once the mother yeast has grown enough, it is introduced in contact with coffee in a fermentation tank (or grain pro bag). Yeasts seemingly enable a much more efficient transfer of flavours between fruits and the coffee, without the requirement of having fruits in contact with the coffee itself. Yeasts, in this instance, act as a medium to transfer flavours from the fruit to the coffee. One can argue that the final coffee won’t taste like yeasts, but if those yeasts tasted like strawberries because it was feeding on them, and the final coffee also tastes like strawberry – then, for us, it clearly falls under the infused category.

Other examples of infusion include fermenting or ageing coffee (often as green coffee) into rum, wine or whisky barrels – to absorb aromatics from the environment. Any technique aiming to add flavour to the green coffee directly, post-harvesting would be considered an infusion.

The topic of infusion can become a grey area when a coffee is soaked in its own mossto (coffee fermentation juice). Mossto is a liquid packed with flavours and it will interact in the fermentation process thanks to its high sugar and natural yeasts concentration. Pulped coffee sitting in mossto will likely absorb some of its intense flavours, making mossto both a catalyst for fermentation and a way to add flavours into coffee. We decided not to label coffees processed this way as infused, as this technique generally uses components of coffee exclusively (we’ll come back to this later).


Can we recognize those coffees blindly?

We recently hosted a series of workshops around Australia where the participants were invited to taste 10 coffees blindly to try and find which coffees were infused/fermented with fruits. Not a single person out of over 100 participants was able to correctly identify all the infused coffees on the table.

Some of these coffees were fermented with fruits and yeasts and displayed obvious and intense flavours of those specific fruits, which most people were able to identify correctly. However, interestingly, very few identified correctly the coffees that were fermented with fruits without the addition of yeasts. One of those coffees was our “failed” pineapple infusion where we aimed at transferring flavours of pineapple into the coffee, which didn’t happen (for reasons we will talk about later in the article).

Without the presence of sufficient yeasts, sugar available in those fruits cannot be transformed, and the aromatic compounds of those fruits can’t be broken down enough to be absorbed by the coffee beans.

Most people thought there were more infused coffees on the table than we put. I would generally put 5 infused coffees out of 10, and on average, people would think there were 7 or 8 infused coffees, often picking anaerobic naturals or mossto fermented coffees as infused with fruits.

The general assumption and feeling towards infused coffees are that they display intense, obvious flavours. While that’s generally true, it does not mean that all coffees displaying intense and distinct flavours are infused.


Why should we embrace infused coffee?


During our workshop in Melbourne, Mohan Balaraman from Riverdale Estate joined us in this conversation around infused coffees. Riverdale estate embraces fruit fermentation. For them, it is a way to create new profiles of coffees and thus, to diversify their portfolio and offering. “The growing conditions aren’t the same in the south of India as they are in Central/South America” says Mohan. “We cannot simply decide to start growing several new varieties to diversify our coffee offering. Fruit processing and fruit infusion has been a cost-efficient way for us to create new and exciting profiles to elevate the SL9 variety while utilising locally grown fruits such as papaya, pineapple or peach.”

From an end consumer point of view, infused coffees can be an exciting gateway to specialty coffee. I remember how difficult it was to connect to the flavours in coffee when I first started. Infused coffees have the benefit of displaying more obvious and intense specific flavours, meaning that there can be a better link and connection between what the barista describes and what the consumer experiences to enhance customer service (World Barista Champion 2022 Anthony Douglas talks about this customer relationshipalthough he did not use an infused coffee).

When you announce that the Passionfruit infused Castillo from Jardines Del Eden tastes like… passionfruit – most customers will find it and agree to it, and this will be an extremely satisfying moment for them. At that moment, that customer might realise that coffee isn’t just coffee, that it isn’t a substitutable commodity, that it can have nuances and character. That customer might decide to change their consumption habits and give up on their 7/11 or McDonald’s coffee to start drinking specialty grade coffee.

Our last release of Felipe Arcila’s infused coffees last year was incredibly popular and these coffees sold out swiftly. For some people, those coffees are a way to have access to incredible flavours without having to break the bank and pay hundreds of dollars for a kilo of coffee.


Why are some infusion techniques more efficient than others?

To enable a transfer of flavours, certain aromatic molecules need to be broken down through fermentation to successfully penetrate the small pores of the coffee seed. That enzymatic reaction is made possible by the work of microbes (yeasts and bacteria).

Microbes require simple sugar and water to reproduce. During that process, the simple sugars they consume (coffee fruits) become longer, more complex chains of starches (containing more sugar molecules). In the context of coffee, these complex starches will taste more complex and will manifest under the form of new flavour compounds.

For a long time, most producers saw fermentation as a mechanical process rather than a metabolic one. They didn’t see the potential of breaking down mucilage/pectin and the role yeasts and bacteria have at imparting more complex aromatic compounds into the coffee seed.

Certain strains of yeasts and bacteria thrive in specific conditions: ranges of oxygen levels, temperature, humidity, pH.

Adding fruits directly into the fermentation tank does not always result in an efficient infusion. Our pineapple experiment that we did at Jack Murat in Mareeba, Queensland, did not have in any pineapple flavours.

This “inefficient infusion” is likely due to an inefficient fermentation of the pineapple, in turn due to a combination of:

  1. Lack of sugars available: the pineapple we used was under ripe and lacked sugars for yeasts to break down.
  2. Lack of microorganisms in the tank: we solely relied on the microbes naturally present on coffee and on the pineapple and did not add yeasts to the fermentation tank. We also removed the skin of the pineapple which is loaded with microbes, and which would have helped break down sugars.
  3. The pH of the pineapple was too low: when we tracked the overall pH in the tank, everything seemed fine, sitting at 5.5 at the start of the fermentation. However, the pineapple itself was probably closer to 3/3.5 which is likely too acidic for yeasts and bacteria to do their job.


Some innovative producers like Felipe Arcila started cultivating their yeasts separately with fruits. This allows to have the yeasts multiply and fully consume all the simple sugars available on the fruits. When doing it all at the same time with coffee, chances are that the coffee will reach its fermentation limit before the microbes have had time to break down all sugars in the fruits added. This type of separate fermentation mitigates this issue and utilizes yeasts to absorb flavours from the fruits and transfer it efficiently into coffee.

Is there really a problem with infused coffees?

Infused coffees open new horizons not just for flavours in coffee:

  • They create new market segments which will bring more people to drink specialty coffee. They are a great way to improve cup quality at a lower cost which enables the end consumer to access tasty flavourful coffees at a reasonable price. They allow producers to diversify their portfolio of coffees. When planting exotic varieties or investing into expensive fermentation equipment isn’t an option, they can use fruits available on the farm or in the region combined with inexpensive commercial yeasts.

Currently, the main concern in the industry, which we deem legitimate is the plausible lack of transparency. If a producer adds flavours of mango through the process of infusion and does not disclose it, that might be an issue for certain buyers and consumers. It is certainly an issue for us if that producer claims that the mango flavour comes from the terroir or a specific variety as this would be a breach of trust between the two parties.

There have also been rumours about people falling sick after consuming pineapple infused coffees because they were allergic to pineapple. While there is no evidence of such claims and it seems more like an urban legend, it is highly unlikely that Ana c 1 (Recombinant Pineapple protein) would survive the roasting and brewing process.

Is labelling truly necessary?

Coffee processing in 2023 isn’t as binary as it was 10 years ago. Coffees are no longer either Washed, Natural or Honey processed, there are so many subtleties and nuances within each of these processes. A washed processed coffee can be pulped and dried prior to being washed, or even shortly fermented in full cherries. The water can be inoculated with yeasts or even changed at some stage. Coffee can spend a short time or an extended time into that water. The mineral content of that said water can also be manipulated. The list of variables that go into each of these processes is long, and they will all impact the final cup, creating nuances. It is simplistic to look at these processes in a dichotomous way.

As mentioned at the start of this article, Specialty Coffee was built upon trust and transparency throughout the entire supply chain, but can all producers realistically capture all possible data from farming and processing? Is it realistic from buyers to expect a never-ending amount of information? Most roasters surely do not capture all traceable data and communicate it to their customers.

And where is the line between transparency and intellectual property? If a producer spends years and money into developing farming practices or improved processing, fermentation or infusion techniques, can’t they just decide not to share that information? Thousands of roasteries around the World do not share the exact percentages of components in their blends or even their roasting curve profiles. It is their right to keep it for themselves and we respect that, so why can’t we do it for producers? Why do we need to know the exact strain of yeasts they used or the temperature and oxygen level into the tank at the 34th hour of the fermentation? I certainly did not share any of my competition water recipes (until recently) as I spent hundreds of hours building them and it gives me a competitive advantage.

Chaptalization is a process used by winemakers to add sugars and acid to the wine to improve its flavours, enhance the fermentation and regulate the pH. Most bottles do not disclose this information and it is something done at the winemaker’s discretion, and nobody seems to have an issue with it.


We need to rethink our relationship with transparency, especially when it involves people who live in underprivileged conditions. We need to show kindness and empathy towards those who produce coffee, the true heroes of the value chain. The ones that make it possible for us to get out of bed in the morning, work long hours, and enjoy incredible flavours every single day.