Who roasts coffee like this? An overview of roasteries from small to large.

Does coffee from small roasteries taste better than coffee from large ones? And are "industrial roasters" actually inferior roasters? And at what point does a roastery even become "large"? We wanted to understand more about who roasts what and how, so we spoke with both micro- and large-scale roasteries. We summarize the results here in an overview. In short: much is not as it seems.

When roasting coffee, green coffee is heated at specific temperatures for a certain period. During this process, the coffee undergoes various physical and chemical changes. The formerly green beans turn brown, which are then ground and extracted.

As simply as the roasting process is described here, it appears straightforward. From green to brown. The processes that occur during coffee roasting are the same – whether 50g, 5kg, or 500kg of coffee are being roasted. However, they differ in their intensity, duration, and precision.

The "800° for two minutes" roast

Many of these statements sound like truths, precisely because they are repeated over and over again. And when we hear the same statements repeatedly, they feel like truth (known in psychology as the truth effect).

For example, the “800° roast for two minutes.” Also known as a high yield roast from the very large roasteries. Yes, it was roasted that way, and in some cases, we still find this roasting style today, but probably much less common than assumed. Not every supermarket offers the worst coffee, and not every small roastery offers the best of the best.

We wanted to know more and spoke with very small and very large roasteries. Aldi, Melitta, UCC Switzerland, and Delica explained their roasting philosophy to us. Hochstrasser and Rast Kaffee explained how they roast, as did the nano-roasteries Birchbach Coffee and Röststube Lübeck. We also open our roasting notes and explain what we actually do, for example here.

Unexpectedly, we were met with extremely open ears. Few roasteries did not address our request. It seems that there is a particular need among large roasteries to present their own perspective. Many probably also saw it as an opportunity to correct mere assumptions and even retort sharply – although some of this was subsequently toned down by the marketing departments. Some large roasteries were, in the end, significantly more cautious.

Prologue: Gentle drum roasting vs. industrial roasting

Far too often, we hear and read the same imprecise statements about large roasteries. It is said that they roast at 500° to 800° in two minutes, that the green coffee does not break down chlorogenic acid, and that the green coffee quality is poor. In contrast, the concept of small roasting machines is presented, which roast smaller batches, with significantly longer roasting times and lower temperatures. It is said to be "gentle" and therefore better.

As coffee makers, we take great pleasure in small projects that are driven with passion, in craftsmanship, and in a genuine interest in getting to the bottom of things. However, we can make little of the above statements. The information content is thin, and the disparagement of one roasting style serves to elevate another roasting approach. Furthermore, discussions about industrial and small roasteries are often very emotional.

Often it seems as if there are small roasteries on one side, mostly working with drum roasters, and then on the other side of the spectrum there are the so-called industrial roasteries, which would roast "something". As if the coffee world only consisted of small and large, of white and black, of good and evil, and of with milk or without sugar. But it is much more complex.

Criticism of large roasteries – in terms of coffee quality – we often hear and read from smaller roasters. Many roasters wouldn't even need to express themselves disparagingly about other roasting approaches.

Mirjam Baumgartner installs the very large roasting machines for Bühler, one of the leading manufacturers of industrial roasting plants. Baumgartner does not hold back with her assessment here:

The quality of the coffee does not depend on the size of the roastery but on the quality of the raw material and the understanding of the craft. And this is a question of the roastery's philosophy.

Mirjam Baumgartner

And she continues:

“Gentle long-term roasting”, “hand-roasted” or roasted according to “traditional drum roasting methods” are about as specific statements as calling someone a “hipster”. You know roughly what it means, but it’s simply not clearly defined. Such statements are an attempt to distance oneself from large industry.

Mirjam Baumgartner

And Baumgartner is right about that. Differentiation through denigration is easy, but it ignores the fact that different roasting approaches, coffee, and green coffee qualities enrich the market and are necessary.

This article attempts to paint a nuanced picture of roasteries of all kinds. At the same time, it is a plea and a request to roasteries to communicate their own strengths in their marketing and thus be confident, rather than to profile themselves through disparaging differentiation.

A new categorization of the roastery landscape

In 2007, Probat provided its own definition for industrial roasteries in the standard work "Industrial Coffee Processing":

“One speaks of 'industrial roasters' when the capacity of the roasting container is 60 kilograms or more, corresponding to the standard weight of a green coffee sack.”

Probat, 2007

Coffee Circle in Berlin roasts on a 60kg Probat roaster, which, according to Probat's definition (which only considers quantity), would make it an "industrial roaster". Does that help us? Not really. Because Coffee Circle defines itself very differently and would probably not see itself as an "industrial roaster". Moreover, the term has become heavily loaded in recent years, especially with derogatory connotations.

A division into small and large roasteries, or into so-called artisanal and industrial operations, remains superficial. Here, we attempt to reclassify roasteries based on precise criteria and rename them accordingly. We compare them by size and roasting machines.

Comparison 1: The Size of a Roastery – from Nano to Mega

Roasteries are limited in size by customer demand, the choice of roasting equipment, or a deliberate decision for a maximum production volume. Depending on their size, roasteries share similar processes and challenges. This makes a division into size groups useful. A division into five groups facilitates communication about roasteries and is also relevant in terms of content due to similar processes and challenges.

This allows us to differentiate smaller roasteries and the mid-range better, and to move away from the emotionally charged term "industrial roastery". We propose: Nano-, Micro-, Meso-, Macro-, and Mega-roasteries.

Our proposal for a new categorization of roastery sizes (2020).

Nano (1t-5t roasted coffee per year)

A nano-roastery roasts between one and five tons of coffee. The roasting infrastructure consists of a 500g – 2.5kg roaster or a larger roasting apparatus used only on a few days.

The roasting project is run alongside a main job or grows into an existing business (café, roastery, retail store). Most processes, such as packaging, are done manually. The green coffee assortment is rather small, as typically 60 or 69 kg sacks are available on the market and these must first be roasted in many small batches.

From experience

When we started our Kaffeemacher roastery, we were able to roast seven tons of coffee in the first year. The term "nano-roastery" fit well then. We are now in our 4th year of roasting and are approaching 30 tons per year. The term "nano" no longer fits here, as we know dozens of roasteries that are smaller and have just started. Flavio Lissandrello from Birchbach Coffee calls his project "Nano Roastery" precisely because he doesn't want to grow much larger. Flavio roasts on a Bullet, a 1kg roaster.

Examples: Birchbach Coffee, Röststube Lübeck

Micro (6t – 50t)

Work processes are professionalized over the years and the product range has become established. The green coffee purchasing strategy is refined, and more customers have differentiated needs. Depending on the production location and cost structure, a full-time position is created and financed for approximately every 15 tons. The roastery is no longer a side project but established – we are talking about a micro-roastery. Many roasteries at this threshold consider how long they want to continue roasting with their first machine and when an upgrade to a larger roaster is due. A stable customer portfolio helps with this decision, and often roasteries then upgrade significantly. From 5kg to a 15kg, from a 12kg to a 35kg roaster, or from 15kg to 45kg roasters.

Examples: Kaffeemacher, Adrianos, Miro, Vertical Coffee, Günter Coffee Roasters

In micro-roasteries, almost everything is packed manually.

Meso (51-200t)

Anyone roasting this much coffee has already been able to create several full-time positions. With a larger machine, more coffee is roasted in less time, and production costs begin to decrease. At this volume, coffee is less and less packaged manually. Conveyor systems, volumetric-electronic pre-portioners, and software interfaces between order and production planning help optimize the workflow and increasingly focus on post-roasting. Roasting itself is often automated – a program created by the roast masters is now often executed by the computer. This allows more freedom and even more control. The focus in meso-roasteries is increasingly on packaging and shipping. Logistics become more important and must be coordinated with increasing precision.

Macro (201-2000t)

A macro-roastery often roasts in multiple shifts, producing a good 1500 tons per year from a 250kg roaster. Such roasteries typically have additional, smaller roasters (25-100kg) with which they can also cater to private-label offers. The roasting machine itself occupies a smaller space in a macro-roastery. The surrounding peripherals, i.e., mixing silos, loading the roaster, destoning, transport pipes, grinding plants, and packaging plants, are now much more reminiscent of a well-thought-out work process. Utilization becomes the magic word here – such large plants are rarely allowed to stand still – precisely roasteries of this size often offer private label services, where coffee is roasted for others.

Example: Hochstrasser Kaffeerösterei

Mega (2000t – 100,000t+)

The main difference to very large roasteries is that more and more processes are mechanized. In a roastery that roasts 20,000 tons annually, only six production employees work per shift – in micro-roasteries, which are approximately 1000 times smaller, three to four people also work per shift if everything is to be manually packaged and delivered quickly. In mega-roasteries, coffee is hardly visible anymore – after roasting, it travels through various channels, possibly grinders, until it is packaged by packing machines.

Work hours are significantly reduced by efficient facilities as a roastery grows larger.

Comparison 2: Roasting Machines

It is obvious that larger roasteries can only roast so much with larger roasting machines. In contrast, small roasteries often roast for several years on small machines. The acquisition of a roasting machine is not a walk in the park for any roastery. Even a 1kg roaster represents an investment of up to 10,000 CHF. A 400kg roaster, along with the necessary peripherals and installation, means a multi-million dollar investment.

Within the size categories of roasting machines, there are of course technical and qualitative differences. At the end of the day, however, a roasting machine is like a car. Every car gets you from A to B, you just need to know exactly how. With a focus on potential roast quality, there is no such thing as a better or worse roasting machine. The demands on the machine, the roasting style, the reliability, and the comfort level make the biggest differences here.

Roasting machines in nano-roasteries

In recent years, more and more miniature roasting machines have come onto the market, and thus we are seeing an increasing number of nano-roasteries that can offer such small quantities to their clientele. These miniature machines usually roast the beans with hot air, a lot of movement, and over a shorter roasting time. It simply doesn't pay to heat up a lot of material for a small quantity and roast the beans via contact heat. Instead, convection receives a lot of attention here. This roasting approach, with a focus on heat transfer through plenty of hot air, goes back to Michael Sivetz's Fluid-Bed technology from 1975. Small quantities can be precisely roasted and replicated.

Examples: Roest, Ikawa, Neotec, Aillio Bullet

Roasting machines in micro-roasteries

Micro-roasteries strive to represent the "authentic" and artisanal through their craft. For many, this includes a powerful roasting machine where much is done by hand. Some roasteries deliberately forgo any degree of automation because it doesn't align with their vision of the craftsmanship they want to embody. At the same time, a roasting machine, in this case a drum roaster, simply makes a great impression on many people. A steel behemoth of at least 500kg, still gleaming, is usually well-positioned in a roastery or cafe to show: here, roasting is still done in-house.

Drum roasters are the first choice for many here. An outer housing is warmed by direct or indirect heat and keeps the system hot. Inside, a drum rotates, clockwise or counter-clockwise depending on the manufacturer, in which the green coffee is moved by precisely shaped fins and scoops. The heat transfer in these roasting machines is a mixture of the airflow passing through the roaster, the transfer through the hot material, and the transfer from bean to bean.

Drum roasters evoke history and, for many, represent the true art of roasting. But for the coffee to consistently taste the same, a precise understanding of how to operate the roaster, its peculiarities, and its behavior is essential.

Roasting machines in meso-roasteries

These roasteries have already purchased a second, or even a third, roasting machine. As a general rule, it makes sense to upgrade from a 15kg machine to a machine at least 3 times larger, as this can often be quickly utilized to full capacity again.

If we assume that a roastery roasts 3-4 batches per hour, for 6 hours a day, 5 days a week, at full capacity of a roaster (15kg roaster = 15kg green coffee), then it can roast about 60+ tons per year, but roasting happens every day, and the strain on the infrastructure and the team is high.

A 35kg roasting machine, for example, roasts 70 tons per year in half the time, making it significantly more efficient. Many roasteries upgrade to a significantly larger machine at this point at the latest.

However, larger roasting machines also require a larger conveyor system, more efficient air filters, cyclones, and possibly an afterburner or another air filter. Here, we are no longer talking only about a roasting machine, but about an entire roasting plant, in which the roasting machine itself makes up only one-third of the space.

The "classic" roaster brands such as Probat, Joper or Giesen have settled on these sizes of roasteries and offer complete systems there. Diedrich has an intermediate solution with a 25kg roaster in its range, which is intended to cover this size transition.

Roasting machines in macro-roasteries

Macro-roasteries function technically similarly to meso-roasteries, only everything is simply a bit larger. A larger drum roaster, a more efficient transport system, a larger green coffee elevator, a larger packaging system – the Goliath of still artisanal-looking roasteries.

Drum roasters from 140 to almost 300 kg per batch operate on the same principle as their smaller counterparts, but they require significantly more energy. Anyone who wants to roast 300 kg of green coffee in 15 minutes in a drum roaster needs a lot of gas and a corresponding supply line or tanks.

Roasting Machines at Mega-Roasteries

Theoretically, the drum roasting principle could be made even larger, but the system loses efficiency more and more. And large roasteries are trimmed for efficiency – so the drum roasting method is out of place.

Batch sizes range up to 500 kg or even more. And here, roasting with hot air is significantly more efficient. These roasting systems blow and push the coffee in ellipses over longer distances. A hot air stream surrounds the bean and can heat it up in a short time. These tangential or centrifugal roasters take up a lot of space and require a lot of energy. However, they partially recycle the hot exhaust air, so the system retains the heat.

The temperatures in these systems are also significantly higher than in a classic drum roaster. Mirjam Baumgartner from Bühler again on this:

The air temperatures always depend on the air-to-bean ratio. However, the important factors are the amount of heat transferred to the beans and the temperature development of the bean. The flavor-forming chemical reactions take place in the bean, not in the ambient air. Accordingly, you can roast at 450°C in 3 minutes if you wish and have enough air available. Some of the world's most commercially successful coffee products use short-time roasting. Roasting air temperatures range from 450°C to 280°C.

Mirjam Baumgartner

The most extreme form of fast and efficient roasting is so-called consecutive roasting. In contrast to batch roasting machines, where coffee is processed in fixed batches, in continuous roasting, coffee is constantly added on one side and roasted coffee is removed on the other side. Probat writes about this:

“Due to the high convection content, continuous roasters enable shorter roasting times with low weight loss. (…)

My attempts to contact the very large roasteries with continuous roasters have not yet been successful. In addition to the fast processing of large volumes, the continuous roaster has another advantage, as this quote from the Probat book also shows:

Since the drum in this system is not perforated, green coffees with a high percentage of broken beans can also be processed without problems.”

P. 37, Industrielle Kaffeeveredelung, 2007)

Broken beans, fast roasting, grinding – the primary concern here is the most efficient processing, more or less consistent taste, and no longer quality.

Roasted Coffee Quality. Who roasts how, and above all, who roasts better? And why?

For me, good and less good roasteries differ primarily in whether they work consistently. Whether all batches taste as desired, or whether unforeseen mishaps occur. Again: understanding one's own machine is the alpha and omega here.

The smaller the batch, the greater the potential for deviations, and vice versa.

Large roasteries are therefore clearly at an advantage when it comes to the differences between individual roasts. Large systems are more sluggish because they move more mass – but those who can take advantage of this roast incredibly consistently.

Small roasting machines are more susceptible to fluctuations – the small amount of material stores less energy than larger systems. Temperature fluctuations in the roastery can affect small drums, as can slightly different air pressure. Of course, it is also possible to work precisely and consistently with small roasters, but it requires an intensive engagement with the technical peculiarities of the machines – and here I see a lot of potential in the small roaster scene.

If we only look at consistency, I have so far had significantly more consistent roasts from meso-, macro-, and mega-roasteries. The most inconsistent roasts I have always had from nano- and micro-roasteries.

So what exactly is "industrially roasted coffee"?

It is obviously insufficient to divide the roasting world into micro and industrial. There are various scales in between, and these are in some ways significantly more industrial in their function (more efficient, larger, more technical, more automated), even though they still have the appearance of an artisanal roastery.

Automation

It seems that the high degree of automation in large roasteries brings about the industrial comparison. The degree of automation that apparently only asks the roast masters to monitor roasting curves on a screen, but no longer actively intervene.

With more automation, some of the romance that first led so many roasteries to roast themselves is also lost. The manual, the artisanal, the risk that sometimes something can go wrong because we as humans reacted incorrectly – the guarantee that not everything will always work as desired has become for many the epitome of true craftsmanship.

Freshness

In terms of freshness, small roasteries that sell directly or through their own shop score significantly better. The very large roasteries sell their coffee to retailers, who in turn have their own intermediate storage. Several weeks pass until the coffee goes from the roastery to the intermediate storage and then to the shelf.

Green coffee sacks at nano to macro roasteries. In mega roasteries, big bags of 1000kg per sack dominate.

There are differences between small and large. And whoever roasts more, provides more people with coffee, makes more friends, but also has more critics. More quantity smells of more consistency and this of more uniformity. Uniformity in the process and often uniformity, even monotony, in taste.

Do coffees from small and large roasteries taste different?

Ideally, coffees from smaller and medium-sized roasteries taste more diverse than those from very large roasteries. Nano-, micro- and micro-roasteries with their smaller drum roasters can roast smaller batches. The smaller batch size invites roasting even tiny quantities, so-called nano-lots. These are sometimes highly experimental green coffees that have been made for a boutique market.

These small quantities are very limited and therefore valuable – made for a roasting machine of 1 to 15kg. But the small batch size does not necessarily guarantee the perfect roast right away. Two to three batches are usually used up for creating a roast profile, sometimes even more.

Limitation of creativity by one's own size

Meso- and macro-roasters cannot roast such small quantities at all, because their roasting plants are designed for a larger capacity. Large roasting plants must be loaded with at least 70% of their maximum possible load. Larger roasteries cannot afford to create a few roast profiles for top coffees or to try something they have never done before. The cost of goods prohibits it – or who likes to experiment with 140 kg of green coffee?

Large roasteries therefore, due to their size, rely on green coffees that are cheaper and often less sensorially characteristic. They need coffees that have a stable profile and are available in large quantities. This approach defines the entire supply chain differently than a small roastery would: mega instead of microlots, containers instead of jute sacks, stable profiles instead of surprises.

Practically speaking, large roasteries limit themselves by their size in terms of being able to roast sensorially complex coffees, to experiment, and to make big leaps. However, many small roasteries also limit themselves by communicating artisanal roasting but then roasting the same green coffees as the very large ones.

Flavio from Birchbach Coffee (Credit: Flavio Lissandrello)

However, Flavio Lissandrello of Birchbach Coffee does not believe that small roasteries do everything better.

“In my opinion, it's often the opposite. Small roasteries, unfortunately, often do many things worse than the big ones, due to inexperience, lack of funds, and technology. Yes, in my opinion, there are also good big ones.”

Flavio Lissandrello

Mirjam Baumgartner from Bühler also often observes that large roasteries are often more professionally equipped.

The disadvantage of large roasteries is often that the raw material for popular products must also be available in large quantities. On the other hand, large roasteries are often more professional in terms of coffee knowledge and understanding and can afford better equipment. For example, small roasteries are usually limited to drum roasting technology, as they do not have the opportunity to use other technologies. Large roasteries can use more highly developed technologies in many respects (e.g., variety of roasting profiles, auto-corrective profile roasting systems, green coffee preheating, etc.). But of course, as always, there are exceptions.

Mirjam Baumgartner

Knud Buck from Röststube Lübeck confirms this. "Sometimes there is more human error than I'd like." Knud mainly roasts for himself on a 1kg Giesen roaster.

Knud's informative Instagram Account

However, he also sees the fallibility of roasting as an advantage for himself:

“Since I only roast for myself, I am not dependent on reproducibility. I don't have a customer base that relies on the same coffee taste every time. This gives me the freedom to keep experimenting. In principle, no roast is like the other. Even if I practice re-roasting particularly successful roasts.”

Knud Buck

Experimenting on a very small scale is possible, but again, with a batch size of 150 kg and more, the reason for an experiment must be really good.

Really Nasty Coffee from the Big Players

Those who are big can produce cheaply and target low-price markets – and these markets are huge. But the size of a roastery itself is not decisive as to whether it buys clean (defect-free) coffee or not. It has to do with the approach and the understanding of quality.

Nespresso, who probably roast well over 100,000 tons per year, do not buy defective coffee – it contradicts their quality promise and brand message. Others, however, who roast far less but aim for low-price markets, do resort to sensorially inferior coffee.

For those who "just need a coffee" or, even better, "a caffeine boost," quality plays no decisive role. And coffee quality reflects this exactly; you get what you pay for.

Cheaper green coffee is often poorly sorted, with many broken beans, etc., while better green coffee also becomes more expensive. This equation is simple. So, if you absolutely want to pay little for coffee, you get the rejects. And yes, sometimes you find qualities in there that even laypeople would optically qualify as bad coffee. However, this coffee does not come in bean form, but ground, as instant coffee, or in pre-portioned units.

I have never heard of a small roastery successfully selling nasty coffee. Such a roastery would probably quickly disappear from the scene. The really nasty tastes can be found at the very large roasters who target the low-price markets – but honestly: who would seriously expect the best quality at the lowest prices?

One Size Fits All – Roasting Profiles

If we assume that the very large roasteries roast inexpensive green coffee, and do so as efficiently as possible, meaning a lot of coffee in a short time, then the optimal, finely elaborated profile is not used.

Generally, these are one-size-fits-all profiles, where the coffee is roasted for the same amount of time, but with more or less final temperature ( = lighter or darker). As a result, inexpensive coffee from large roasteries is often roasted significantly darker. The strong roast can mask defects and smooth out differences.

But large roasteries also roast light coffees, which are often the "mild" and "harmonious" ones. The roast depth, also known as the degree of roast, often marks a greater difference in the coffees of the very large roasteries than completely different blends. Often the same blends are roasted sometimes lighter, sometimes darker, to create a unique product.

The roasted products of the very large roasteries are more standardized, sensorially undemanding, but extremely consistent coffees that serve their purpose for the vast majority.

And here, large roasteries have the tricky task of precisely tasting coffees, blending them themselves or having them blended, so that they always taste the same. This is sensorially monotonous, but no less demanding than tasting the most complex coffees of all.

Let's get down to business – who roasts how? Small and large in conversation

It's amazing how many people talk about a "roasting secret" – about the special way green beans are turned brown. I was equally surprised that it was precisely the large roasters who openly talked about their way of roasting coffee. Many probably also saw it as an opportunity to clear up the rumors of "800° and two minutes". We asked both the very small and the very large.

Nano-Roastery

How does Röststube Lübeck roast?

Knud Buck is probably the closest thing to a nano-roaster. Anyone who follows his Instagram channel can see how meticulously Knud tries to perfect every parameter of roasting, as well as preparation. A real laboratory. He roasts on a 1kg Giesen roaster, with batches of 750g.

"This amount can be excellently controlled and I can do twice as many roasts, thus gaining twice as much experience than if I always chose the maximum batch," says Knud.

Intentionally underfilling the roasting drum drastically shortens the roasting time. However, the small roasting drum also has its weaknesses, according to Knud. "Larger roasting plants have a larger thermal mass due to their design, which, at least theoretically, could ensure more stability in the roasting process."

For him, roasting coffee is a hobby, but one he pursues with a precision few small roasteries achieve.

“I associate small roasters with craftsmanship, with more love, with more dedication and thus, ultimately, with more quality in the cup. But that's not always true!”

Knud Buck

Knud's roasting times range from 7 to 15 minutes with maximum bean temperatures of 205°C. These temperature specifications must always be treated with caution, as they cannot be compared.

Knud, like many other roasters I surveyed in a Facebook poll, roasts according to the 1st crack and development time.

“For most filter roasts, I try to reach the First Crack (FC) after 9:00 minutes and calculate a development time between 12 and 18% from then on, depending on the coffee. Another indicator is the temperature development from FC to final temperature; here my range goes from +4°C for light filter roasts to +10°C for espressos. I don't roast any darker.”

The Rate of Rise is also crucial for Knud: "Especially when exchanging with other roasters and talking about roasting profiles, the RoR is much more meaningful than comparing absolute temperatures. For me, the RoR is the decisive variable for evaluating roasting profiles."

Micro-Roastery

How do the Kaffeemacher roast?

Our roasting philosophy is strongly linked to the green coffees we purchase. We tend to use heavier coffees for espresso and roast floral and fruity coffees more for filter coffees.

Yellow: Filter Coffee, Red: Specialty Espresso, Blue: APAS

We treat each coffee a little differently. Not because we simply want to, but because the coffee demands it. A coffee from Brazil from the APAS cooperative, for example, behaves differently in the roasting drum than a coffee from our Finca Santa Rita in Nicaragua.

We fill the 12 kg drum with 4-5 kg for filter, 8-11 kg for specialty espresso, and 12 kg for more developed espressos. The full utilization of the drum requires a different gas input than a less full drum. We also extend the roasting times with this.

We roast with Cropster's roasting software and analyze live how we roast. We follow the roasting curves we have developed ourselves, ensuring that the roast will – theoretically – taste the same. In addition, we cup the batches and can thus sensorially compare the coffee with the roasting curve.

Over the time that green coffee is in our warehouse, it is quite possible that we will adjust the roasting profile several times. If we receive a coffee in midsummer and roast it until Christmas, we have to adjust the profile according to the outside temperature. This makes roasting coffee never boring.

Meso Roastery

How does Rast Kaffee roast?

Beatrice Rast from Rast coffee roastery wrote me the following lines.

"I generally find it difficult to make judgmental distinctions between large/small; we prefer to leave an assessment (also regarding craft / industrial) to the customer and focus on our work, i.e., we prefer to focus on ourselves and are driven to constantly develop further and convince customers of our work, our coffee, service, and quality.

We roast in Ebikon on Probat drum roasters, in various sizes (5, 12, 45 & 90kg). This makes us very flexible and allows us to better cater to our customers to guarantee them our fresh roast. The roasted coffee is air-cooled on all machines.

Our roasting times and temperatures vary depending on the machine, green coffee, and roasting profile. We usually roast for about 15 – 20 minutes, as we offer everything from light to medium to dark, so the final temperatures are, of course, very different and vary accordingly.

Due to our generally long roasting time, a lot of chlorogenic acid can be broken down, which makes the coffee more digestible but is also more costly due to the high time expenditure.

Roasting is done according to our developed roasting profiles, times, colors, final and development times. When purchasing green coffee or materials, we strive for long-term partnerships and want to be in close relationships with our partners."

Macro Roastery

How does Hochstrasser roast in Lucerne?

At Hochstrasser AG coffee roastery in Lucerne, I spoke with production manager Kevin Heer and roast master Andy Strittmatter. Hochstrasser is one of the ten largest roasteries in Switzerland and roasts approximately 1500 tons of coffee annually.

With four roasting machines (5kg, 60kg, 120kg, and 240kg), Hochstrasser can meet a wide variety of demands. The company has long ceased roasting only for itself but fulfills a wide range of private label requests.

The larger the roasteries, the more important private labeling becomes – it helps the roastery to efficiently utilize its large capacities. For private label customers, it is attractive because coffee can be produced externally consistently and affordably.

Kevin Heer says: "We roast exclusively with drum roasters from industry leader Probat. Furthermore, we are very efficient and can handle large orders with high quality, and we are also flexible enough to handle small orders."

Probat's largest drum roaster is almost as big as a small truck. With the periphery around it, the exhaust and supply air ducts, the lines for roasted coffee transport, and the afterburner, the system takes up the space of a small single-family house.

With the drum roaster, roasting times also increase. Hochstrasser roasts between 13 and 17 minutes, which is very similar in terms of time to how we, the Kaffeemacher, roast. The roast masters at Hochstrasser also monitor the roasting process on a monitor, which is located next to the roaster. Physical proximity to the roaster itself is given, especially when special orders are to be roasted according to key points such as the 1st or 2nd crack. The roasters mark this manually.

The roasting temperatures (the hot air flow temperature) are between 230 and 250 degrees. The larger systems offer several advantages, as Heer states:

"With large roasting systems, you have much greater consistency, also due to the many setting options of the system."

Regarding gentle long-term roasting, Heer emphasizes that the energy supply to the beans is gentler when heated by a lot of hot air rather than directly by the contact heat of the drum.

Large roasteries like Hochstrasser sometimes quench the coffee, "but only with so much water that the roasted coffee does not absorb any water," says Heer.

"From our point of view, quality is defined by the roasting time, the roasting curve, and the roasting plant. If all these factors are correct, it is possible to achieve more consistency with a larger roasting plant. Other important factors for us are the green coffee qualities, the quality controls of green and roasted coffee (through cuppings), and subsequently optimal packaging to protect the roasted coffee."

Mega Roastery

How does Melitta roast?

I also had an interesting conversation with Melitta's production management. The handling of roasting information was very open. Later, my text, which I based on an interview, was modified again and adapted to the company's guidelines. The result is a text that is based on mine but has been modified.

How does Delica – Coffee Roastery roast?

At Delica, they are also aware of the arguments and claims of other roasteries that large ones don't roast well. Nicole Gisi, Project Manager, former Roast Master and author of the book "Kaffee. Genuss-Passion-Wissenschaft" (Coffee. Enjoyment-Passion-Science), comments:

"We are above that because we know the truth. Ultimately, everyone is convinced that they are doing the right thing. At Delica AG, we are proud that our roasting methods are on par with those of commercial roasters. It's not the size of the roastery, but the experience, the roasting method, and the quality of the green coffee, as well as the grinding and extraction method, that makes good coffee."

Gisi further explains that small and large are neither good nor bad: "In my eyes, there are no advantages or disadvantages, because you have to adapt to the situation and take appropriate precautions."

Gisi and her team roast on tangential and centrifugal roasters. Batch sizes range between 140 – 500 kg, and they roast about 17,000 tons of coffee annually.

She doesn't believe in the 2 minutes and 800° claims – "we roast for at least 7 minutes; the longest roasting times are 20 minutes."

Regarding gentle long-term roasting, Gisi makes it clear that this is not about quality, but only about marketing a roasting style:

"These are marketing statements, with little to say about quality.

Nicole Gisi on gentle long-term roasting

Of course, with regard to roasting duration, there are parameters that indicate high quality. "Hand-roasted" is not a quality feature for me. The roaster stands next to the roaster and manually finishes the roast – depending on the roaster's experience, lighting conditions, and daily form, the roasts will taste and smell differently, as the process is not standardized – this is also a philosophy, but if the customer always expects the same result, standardization of the process is necessary." (Craftsmanship involves people and thus increases the risk of errors. The higher the degree of automation, the fewer surprises – but also the less courage).

"We try to keep the error rate as low as possible at all stages, so that the consumer gets stable end products."

Gisi also spoke at length on the topic of chlorogenic acid.

"Chlorogenic acid refers to a group of esters of hydroxycinnamic acid and quinic acid. Chlorogenic acid and its degradation products contribute significantly to the formation of taste and aroma, as well as color in coffee. Since chlorogenic acid is thermally unstable, it is degraded during the roasting process by hydrolysis to quinic acid and caffeic acid. In strong roasts, almost complete degradation to various phenolic compounds can occur. Its degradation products can be acidic and astringent. In an incomplete, or very light roast, larger quantities of chlorogenic acid remain in the bean. It can lead to intolerance and stomach discomfort in sensitive people."

How does Aldi roast?

In a conversation with Michael Körnig from NewCoffee GmbH, Aldi's coffee roastery, I also learned a lot about the recent history of large-scale roasting.

But first, I wanted to know how he felt about smaller roasteries?

"I am always happy when I discover special microlots at small specialty roasters. Small roasteries have opportunities here that we, as a large company, do not. They can bring out nuanced flavors and are certainly an enrichment for the coffee landscape."

Michael Körnig, NewCoffee GmbH

Körnig made it clear, as few others did, that there are primarily technical differences that allow or prevent certain things. He did not attempt to dismiss this, but rather explored the possibilities.

"I see a lot of good in small roasteries, but we big ones also have our advantages. However, purchasing microlots is not possible for us, as we cannot process tiny quantities. We need coffee quantities sufficient to supply approximately 1940 branches."

In stark contrast: we, as Kaffeemacher, just bought a nanolot of 70kg. From this, we do about three test roasts and then sell another 55kg – for us, it's worth it because we roast filter coffee in 5 kg batches. For all slightly larger roasters, it quickly becomes complicated to impossible.

While it is difficult for NewCoffee to process tiny quantities, using different profiles is possible. "Our business model is simply different." He sees the leverage for large companies primarily in the degree of automation in packaging: "Among other things, we can package more cheaply. This reduces labor costs and enables us to offer high-quality coffees at favorable prices."

NewCoffee roasts for ALDI as well as other external clients at two locations – in Ketsch and Mülheim an der Ruhr.

Regarding roasting times, NewCoffee distinguishes between ground coffees and coffees for coffee pods, which range between 6-9 minutes, and whole bean coffees, which are usually roasted for 12 minutes and occasionally for 15 minutes. For large roasteries, these are times that one probably would not have imagined.

Körnig adds: "One reason for longer roasting times, especially for ground coffees, was the acrylamide problem. If it's too short, the acrylamide level would be too high. That's why none of our roasting times are under six minutes."

Körnig, like Gisi on chlorogenic acid, cites specific facts on issues that large roasteries are repeatedly questioned about. Smaller and medium-sized roasteries encounter studies and samples on acrylamide, furan, OTA, and residues in coffee significantly less frequently, if at all – although all four topics cannot be ruled out there.

Körnig also expresses himself precisely on the "High Yield Process" – "we never did that". According to internet research, coffee was roasted in 90 seconds using this method. The volume of the coffee increased much more than usual, the density was low, suddenly 400g of roasted coffee took up the space of 500g of roasted coffee. This can be read in a 1984 article from Der Spiegel.

So there is something to the 90-second roasts after all – but the question is, is that still the case today? I'm convinced, but I haven't gotten to the roasteries yet.

Körnig views "gentle long-term roasting" with a nuanced perspective:

"What is gentle? Long-term roasting brings a different flavor profile, but acids are also broken down. Unwanted and wanted ones. Coffee then often just tastes baked."

Michael Körnig

Körnig also comments on chlorogenic acid: "Chlorogenic acids are present in coffees, but especially in very short roasts. Since we roast for at least six minutes, the problem hardly arises for us. But we roast 90 percent Arabica and hardly any Robusta – and since the proportion of chlorogenic acid in Robusta is significantly higher than in Arabica, this does not affect us as much."

How does UCC Switzerland roast?

UCC, the Ueshima Coffee Company from Japan, roasts in Switzerland in Zollikofen near Bern. UCC roasts a lot of private label, and large Swiss retailers are among its biggest customers. Benjamin Schütz from UCC spoke with me about their roasting style.

Schütz sees the advantages of large roasting plants in consistency. "We define 12 to 13 key points in a profile and the roaster follows them, come what may." UCC roasts on two Lilla roasters from Brazil, each with a capacity of 500 kg.

Batch sizes range between 400 and 500 kg. The Lillas are drum roasters, so they are different systems from what we encountered at Aldi, Delica or Melitta. Drum roasters are less efficient than hot air systems, and so the roasting times are also significantly longer on average: a roast at UCC takes between 12 and 16 minutes.

Such large drum roasters work because the hot exhaust air is partly recycled and returned to the system. This means that this "new" air no longer needs to be heated. If only fresh air were drawn in, fast roasting with such a machine would not be possible.

UCC roasts four to five batches per hour, which amounts to a good 7,000 tons of roasted coffee per year. In one shift, in addition to the roast master, about four other people work, who take care of the downstream processes such as grinding and packaging.

The timing of the roasts is very high, meaning the time between batches is very short. The roaster is only empty for about 10 seconds before new green coffee is added.

UCC then roasts until the desired color is reached, by which they determine the end of the roast. Here, too, the 1st crack, development time, and rate of rise play no role. This is quite different from roasteries with smaller systems, where these guidelines are used much more.

Schütz is not very diplomatic about gentle long-term roasting. "It's like slow cooking. But with meat, it tastes good." When asked what he thinks about the statement that coffee is "hand-roasted," he smiles. "Yes, roasting machines can be operated by hand. But that's all it would be."

As with many larger roasteries, UCC also quenches the coffee, i.e., cools the roasted coffee with water immediately after it exits the roasting drum. 70 to 74 liters are needed for a 500 kg batch of coffee, which then means about 3-3.5% residual moisture in the bean. Quenching takes place in the drum after the specified final temperature has been reached.

Like Gisi, Schütz has a scientific background and gladly embraces the chlorogenic acid discussion.

"The stomach must be able to absorb acids, that is its function. When acid comes, it must neutralize it with bases. But if it is already over-acidified, e.g., by animal proteins, then the body has much more difficulty processing acidic foods. This can lead to heartburn."

Benjamin Schütz, UCC Switzerland

For Schütz, it is clear that chlorogenic acids alone are not harmful to the stomach, but that diet in general dictates the coffee's absorption capacity. And, of course, whether sugar is added to the coffee also has an influence. More sugar means more acid in the stomach.

Comparison Table. Who roasts coffee how?

We extracted the information from the conversations and arranged it in a table for comparison.

Who roasts according to the 1st crack, rate of rise, development time, final temperature…?

The roasting stages are measured differently by roasteries. In a survey on Facebook, most specialty and small-batch roasters gave me the following order of priority:

The "total roasting time" received not a single vote from the voices in the roaster forum, and the final temperature only three.

Mirjam Baumgartner from Bühler confirms these findings:

In my experience, only small, manual operations orient themselves to the 1st and 2nd crack in daily production. These operations roast with a lot of expertise and attention from the roast master.

In a large roastery, the 1st and 2nd crack are certainly discussed when developing a new roast, but it is inconceivable that a roast master would observe these parameters 1:1 for every roast. In this case, one relies on the reproducibility of the roaster and, in most cases, stops the roast based on temperature. This can also be the case in small roasteries.

In other words: If the roasting machine has temperature control under control, then the 1st crack and 2nd crack always occur at exactly the same time. The roast master of a large facility no longer needs to pay attention to the cracking in this case.

So now what? Where is the journey heading?

Large roasteries are getting larger

It's clear every few weeks: large roasteries are getting even larger, and roaster manufacturers are feeling it too. Baumgartner on this again:

Bühler's core competence as a machine building company is plant engineering, which is why the Infinity Roast is our flagship roaster. It comes in 180 kg, 360 kg, or 540 kg batch sizes, offers full flexibility and reproducibility through variable air-to-bean ratio and auto-corrective profile roasting. Our largest plant in the USA produces around 6 t/h in continuous operation with two Infinity Roasts, but we have large roasteries as customers worldwide.

Our proposed classification into five categories: Nano, Micro, Meso, Macro, Mega, may soon be supplemented by "giga" – and this already applies to certain roasteries today.

There are more and more small roasteries

At the same time, there is a counter-trend of nano- and micro-roasteries. It will be interesting to observe how large nano-roasteries become, whether micro-roasteries limit their growth or become a meso-roastery, or even merge with another micro-roastery. We maintain an up-to-date collection of coffee roasteries in Switzerland, Quijote Kaffee maintains a collection of roasteries in Germany.

Coffee quality is improving

It's becoming increasingly enjoyable to drink coffee out. In general, the coffee offerings are becoming more diverse – and here we're not talking about beverage categories, but about the flavor profiles that consumers can experience today.

More and more nano- and micro-roasteries are fully committing to specialty coffee. For extensively discussed reasons, these smaller roasteries can place their focus differently than larger ones.

The big ones pretend to be small

Jacobs and Dallmayr have shown the way, and others will follow. Large roasteries are increasingly focusing on smaller projects, on smaller roasteries, to open up this segment that they otherwise cannot access. The big players have understood that the artisanal concept is not pure marketing, but truly a message that gives many consumers the feeling of holding something authentic. Beautiful brochures and campaigns won't hide this – for many, the small is simply more genuine.

The question remains how credible the small-scale projects of large roasteries will be. It will not fail due to know-how, access to green coffee, or roasting expertise – however, I see limited acceptance among an audience geared towards specialty coffee. For many, the big name will still overshadow what is offered. I am curious to see who will separate the product from the name.

We all learn together

This article about roasting will be further supplemented by me. More manufacturers and roasteries are to be added. Perhaps one or the other roastery will also be willing to contribute roasting profiles.