Who roasts like coffee? 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 the worse roasters? And when exactly does a roastery become large? We wanted to understand more about who roasts how and spoke with very small and very large roasteries. We summarize the results here in an overview. In short: many things are not what they seem.

In coffee roasting, raw coffee is heated to specific temperatures over a certain period of time. During this process, the coffee undergoes various physical and chemical processes. The previously green beans become brown beans, which are then ground and extracted.

As simplified as the roasting process described here may seem, it's straightforward. Green becomes brown. The processes that occur during coffee roasting are the same – whether 50g of coffee, 5kg, or 500kg are being roasted. However, they differ in their intensity, duration, and precision.

The "800° for two minutes" roast

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

For example, the "800° roast for two minutes." Also known as the high yield roasting of the very large roasteries. Yes, it was roasted that way, and we can still find this roasting style in some places today, but probably far less widespread than assumed. Not every supermarket offers the worst coffee, and not every small roastery offers 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 described how they roast, as did the nano-roasteries Birchbach Coffee and Röststube Lübeck. We also opened up our roasting notes and explained what we actually do, for example here.

Contrary to expectations, we encountered extremely open ears. Very few roasteries refused our request. It seems that especially the large roasteries felt the need to explain their own perspective. Many saw it as an opportunity to correct mere assumptions and even to push back sharply – which in some cases was later softened by marketing departments. Some large roasteries were ultimately much more cautious.

Prologue: Gentle drum roasting vs. industrial roasting

Far too often we hear and read the same imprecise statements about large roasteries. They roast at 500° to 800° in two minutes, the raw coffee breaks down no chlorogenic acid, and the raw coffee quality is poor. In contrast, the concept of small roasting machines is presented, which roast with smaller batches, much longer roasting times, and at lower temperatures. It's supposed to be "gentle" and therefore better.

As coffee makers, we greatly enjoy small projects that are driven with passion, handcrafted work, and genuine interest in getting to the bottom of things. However, we find little merit in the statements above. The information content is thin, and the disparagement of one roasting style serves to elevate another roasting approach. Moreover, discussions about industrial and small roasteries are often conducted very emotionally.

Often it seems as if on one side there are small roasteries, which mostly work with drum roasters, and then on the other side of the spectrum there are the so-called industrial roasteries, which roast something or other. As if the coffee world consisted only of small and large, black and white, good and evil, and milk or no sugar. But it's far more complex.

We often hear criticism of large roasteries – in terms of coffee quality – from smaller roasters. Yet many roasters wouldn't need to speak disparagingly about other roasting approaches at all.

Mirjam Baumgartner installs the very large roasting machines for Bühler, one of the leading manufacturers of industrial roasting equipment. Baumgartner doesn't hold back with her assessment:

The quality of coffee doesn't depend on the size of the roastery but on the quality of the raw material and on 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 more or less know what's meant, but it's simply not clearly defined. Such statements are an attempt to distance oneself from big industry.

Mirjam Baumgartner

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

This article attempts to draw a differentiated 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 to be confident about it, rather than to profile themselves through disparaging differentiation.

A new categorization of the roastery landscape

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

"Industrial roasting" refers to roasters with a roasting drum capacity of 60 kilograms or more, which corresponds to the standard weight of a bag of raw coffee"

Probat, 2007

Coffee Circle in Berlin roasts on a 60kg Probat roaster, which would make it an "industrial roaster" according to Probat's definition, which only considers quantity here. Does that get us anywhere? Not really. Because Coffee Circle defines itself quite differently and wouldn't see itself as an "industrial roaster." Moreover, the term has become heavily loaded in recent years, especially with negative connotations.

A division into small and large roasteries, or into so-called artisanal and industrial operations, remains superficial. Here we attempt to reclassify roasteries according to precise criteria and rename them. We compare 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 by a conscious decision to set a maximum production quantity. Depending on size, roasteries encounter similar processes and challenges. This makes a division into size groups worthwhile. A division into five groups facilitates communication about roasteries and makes sense in terms of content due to similar processes and challenges.

This allows us to better differentiate between smaller roasteries and the middle field, and moves us 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 equipment that is only used a few days a week.

The roastery project is conducted alongside a main job or grows into an existing business (café, roastery, shop). Most processes such as packaging are done manually. The raw coffee selection is relatively small, since the market typically offers 60 or 69kg bags, which must first be roasted in many small batches.

From practice

When we started our coffee maker roastery, we could roast seven tons of coffee in the first year. The designation "nano-roastery" fit well then. We're now in our 4th year and approaching 30 tons per year. The designation "nano" hasn't fit for some time, as we know dozens of roasteries that are smaller and just getting started. Flavio Lissandrello from Birchbach Coffee calls his project a "nano roastery" because he doesn't want to grow much larger either. Flavio roasts on a Bullet, a 1kg roaster

Examples: Birchbach Coffee, Röststube Lübeck

Micro (6t – 50t)

Work processes become professionalized over the years and the product range becomes established. The raw coffee purchasing strategy becomes 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 speak of a micro-roastery. Many roasteries consider at this threshold how much longer they want to continue roasting with their first machine, and when to upgrade to a larger roaster. A stable customer portfolio helps with this decision, and roasteries often upgrade right away. From 5kg to a 15kg, from a 12kg to a 35kg roaster, or from 15kg to a 45kg roaster.

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

In micro-roasteries, almost everything is packaged manually.

Meso (51-200t)

Anyone roasting that much coffee has already created 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 increasingly less packaged manually. Conveyor systems, volumetric-electronic pre-portioning, and software interfaces between orders and production planning help optimize workflow and increasingly shift focus to post-roasting. Roasting itself often runs automatically – a program created by the roasters is now often run by a computer. This allows more freedom and even more control. The focus at meso-roasteries increasingly turns to packaging and shipping. Logistics becomes more important and must be coordinated ever more precisely.

Macro (201-2000t)

A macro-roastery often roasts in multiple shifts and gets about 1500 tons per year out of a 250kg roaster. Such roasteries typically have additional smaller roasters (25-100kg) with which they can also respond to private label offerings. The roasting machine itself takes up less space in a macro-roastery. The surrounding periphery – mixing silos, loading the roaster, destoning, transport tubes, grinding equipment, and packaging equipment – resembles a well-thought-out work process. Utilization becomes a magic word here – such large equipment can rarely stand idle – especially roasteries of this size often offer private label services where coffee is roasted for others.

Example: Hochstrasser Kaffeerösterei

Mega (2000t – 100,000t+)

The difference compared to the very largest roasteries is mainly that more and more processes become mechanized. In a roastery roasting 20,000t annually, there are just six production employees per shift – in micro-roasteries, which are approximately 1000x smaller, there are similarly three to four people per shift when everything is manually packaged and shipped quickly. In mega-roasteries, coffee is hardly visible – after roasting it travels through various channels, possibly mills, until it's finally packaged by packaging machines.

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

Comparison 2: Roasting machines

It stands to reason that larger roasteries can only roast so much with larger machines. In contrast, small roasteries often roast on small machines for several years. Purchasing a roasting machine is not an easy undertaking for any roastery. Even a 1kg roaster means an investment of up to 10,000 CHF. A 400kg roaster along with necessary periphery and installation represents a million-franc investment.

Within the size ranges of roasting machines, there are of course technical and qualitative differences. Ultimately, however, a roasting machine is like a car. Every car gets you from A to B, you just need to know how. So with a focus on potential roasting quality, there's no such thing as a better or worse roasting machine. The demands placed on the machine, the roasting style, the reliability and convenience factors make the biggest differences.

Roasting machines at nano-roasteries

In recent years, more and more small-scale roasting machines have come to market, and so we see increasingly more nano-roasteries that can offer such small quantities to their clientele. These small machines roast beans mostly with hot air, lots of movement, and over a shorter roasting time. It simply doesn't make sense to heat a lot of material for small quantities and roast the beans via contact heat. Instead, convection receives much attention here. This roasting approach with a focus on heat transfer through lots of hot air goes back to Michael Sivetz's fluid-bed technology from 1975. Small quantities can be roasted precisely and replicated.

Examples: Roest, Ikawa, Neotec, Aillio Bullet

Roasting machines at micro-roasteries

Micro-roasteries try to stand for the "real" and the artisanal with 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 match their vision of the craft they want to represent. At the same time, a roasting machine, in this case a drum roaster, simply makes a great impression on many people. A steel colossus of at least 500kg, which still has a shine to it, usually stands well-positioned in a roastery or café to show: roasting is still done here by hand.

Drum roasters are the first choice for many here. An outer housing is heated by direct or indirect heat and keeps the system hot. Inside, a drum rotates, depending on the manufacturer clockwise or counterclockwise, in which the raw coffee is moved by precisely shaped fins and paddles. Heat transfer in these roasting machines is a mix of air flowing through the roaster, heat transfer through the hot material, and bean-to-bean heat transfer.

Drum roasters sound like history, and for many represent the true way of roasting. But for the coffee to always taste the same, it requires precise understanding of how to operate the roaster, its peculiarities and behaviors.

Roasting machines at meso-roasteries

These roasteries have already purchased a second or even a third roasting machine. As a rule, it makes sense to upgrade from a 15kg machine to at least a 3x larger machine, as it can often be quickly put to full use.

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

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

Larger roasting machines also require larger conveyor systems, more efficient air filters, cyclones, and possibly an afterburner or other air filter. We're then no longer talking about just a roasting machine, but about a whole roasting system, where the roasting machine itself only takes up a third of the space.

"Classic" roaster brands like Probat, Joper, or Giesen have settled into these roastery sizes and offer complete systems there. Diedrich has an intermediate solution with a 25kg roaster in their lineup to cover this size transition.

Roasting machines at macro-roasteries

Macro-roasteries function technically similarly to meso-roasteries, just everything is a bit larger. A larger drum roaster, a more efficient conveyor system, a larger raw coffee lift, a larger packaging system – the Goliath of still artisanal-looking roasteries.

Drum roasters from 140 to nearly 300 kg per batch function on the same principle as their smaller versions, but they need significantly more energy. Anyone wanting to roast 300 kg of raw coffee in 15 minutes in a drum roaster needs a lot of gas and corresponding supply lines or tanks.

Roasting machines at mega-roasteries

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

Batch sizes reach 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 larger distances. A hot air stream surrounds the bean and can heat it quickly. These tangential or shell roasters take up a lot of space and require a lot of energy. However, they recycle some of the hot exhaust air back into the system, so the system retains heat.

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

Air temperatures always depend on the air-to-bean ratio. What's important, however, is the heat transferred to the beans and the temperature development of the bean itself. The flavor-forming chemical reactions occur in the bean, not in the surrounding air. Accordingly, you can roast at 450°C in 3 minutes if you want and have enough air available. Some of the world's commercially most successful coffee products use short-time roasting. Roasting air temperatures range between 450°C and 280°C.

Mirjam Baumgartner

The most extreme form of fast and efficient roasting is so-called continuous roasting. Unlike 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:

"Continuous roasters enable rather short roasting times with low waste due to the high convection component. (…)

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

Since the drum in this system is not perforated, raw coffees with a high broken bean content can also be processed without any problems."

P. 37, Industrial Coffee Refinement, 2007)

Broken bean content, quick roasting, grinding – this is primarily about the most efficient processing, more or less consistent taste, and no longer about quality.

Roasted coffee quality. Who roasts how, and most importantly, who roasts better? And why?

For me, good and less good roasteries differ mainly in whether they work consistently. Whether all batches taste as desired, or whether unexpected mishaps occur. Again: understanding your own machine is key here.

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

Large roasteries have a clear advantage here when it comes to differences between individual roasts. Large systems are more sluggish because they move more mass – but those who can use this to their advantage roast incredibly consistently.

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

If we only look at consistency, I've consistently seen much more consistent roasts from meso-, macro-, and mega-roasteries. The most inconsistent roasts I've seen have always come from nano- and micro-roasteries.

So what exactly is "industrially roasted coffee"?

It's obviously insufficient to divide the roastery world into micro and industrial. There are different sizes in between, and in their function some are far more industrial (more efficient, larger, more technical, more automated), even though they still look like artisanal roasteries.

Automation

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

With more automation, some of the romance that inspired so many roasteries to roast in the first place is lost. The manual, the artisanal, the risk, the possibility that something might go wrong because we as humans reacted incorrectly – the guarantee that things never work exactly as planned, has become for many the embodiment of true craftsmanship.

Freshness

When it comes to freshness, small roasteries that sell directly or through their own shops score significantly better. Very large roasteries sell their coffee in retailers, which in turn have their own intermediate warehouses. From the time the coffee leaves the roastery, goes through the intermediate warehouse, and finally sits on the shelf, several weeks pass.

Raw coffee bags at nano- to macro-roasteries. In mega-roasteries, big bags of 1000kg per bag dominate.

There are differences between small and large. And whoever roasts more supplies more people with coffee, makes more friends, but also has more critics. More quantity smells like more consistency, and that smells like more uniformity. Uniformity in process and often uniformity to the point of 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 small quantities, so-called nano-lots. These are sometimes highly experimental raw coffees made for a boutique market.

These small quantities are extremely limited and therefore valuable – perfect for a 1 to 15kg roasting machine. But small batch size doesn't necessarily guarantee perfect roasting on the first try. Two to three batches are typically used to develop a roasting profile, sometimes more.

Limitation of creativity by one's own size

Meso and macro roasters cannot roast such small quantities because their roasting systems are calibrated for larger capacity. Large roasting systems must be loaded with at least 70% of their possible maximum load. Larger roasteries can't afford to create a few roasting profiles for top coffees or try something they've never done before. The material costs prohibit it – or who really wants to experiment with 140 kg of raw coffee?

Large roasteries therefore focus, because of their size, on raw coffees that are cheaper and sensorially less characteristic. They need coffees that have stable profiles 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 to being able to roast sensorially complex coffees, to experiment, and to take big leaps. However, many small roasteries also limit themselves by roasting the craft of roastery while then roasting the same raw coffees as the big players.

Flavio from Birchbach Coffee (Credit: Flavio Lissandrello)

That small roasteries do everything better is not how Flavio Lissandrello from Birchbach Coffee sees it at all.

"In my opinion, the opposite is often true. Small roasteries often do many things worse due to lack of experience, lack of funds, and lack of technology. Yes, in my opinion there are also good large ones."

Flavio Lissandrello

Mirjam Baumgartner from Bühler also often sees large roasteries being more professionally equipped.

The disadvantage of large roasteries is often that the raw materials 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 because they don't have the ability to use other technologies. Large roasteries can use more advanced technologies in many ways (e.g., variety of roasting profiles, self-correcting profile roasting systems, green coffee pre-heating, etc.). But of course there are always exceptions.

Mirjam Baumgartner

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

Knud's informative Instagram account

He also sees the fallibility of roasting as an advantage for himself:

"Since I only roast for myself, I don't depend on reproducibility. I don't have a customer base that relies on always the same coffee taste. So I keep the freedom to always experiment. Essentially, no roast is like the other. Even if I practice replicating particularly successful roasts."

Knud Buck

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

Really terrible coffee at the very large roasteries

When you're large, you can produce cheaply and target deep-discount markets – and these markets are huge. But the size of a roastery itself doesn't determine whether it buys defective coffee or not. It has to do with the approach and quality understanding.

Nespresso, which roasts probably well over 100,000t per year, doesn't buy defective coffee – it contradicts their quality promise and brand message. Others, meanwhile, who roast far less but want to target deep-discount markets, do resort to sensorially inferior coffee.

For those who need "just a coffee" or even better "a caffeine boost," quality doesn't matter. And the coffee quality reflects that exactly; you get what you pay for.

Cheap raw coffee is often poorly sorted, with lots of broken beans, etc., while better raw coffee also becomes more expensive. This equation is simple. So whoever really wants to pay little for coffee gets the scraps. And yes, you can sometimes find qualities in there that even laypeople would visually identify as bad coffee. But this coffee doesn't come in bean form; it comes ground, as instant coffee, or in pre-portioned units.

I've never heard of a small roastery successfully selling terrible coffee. Such a roastery would probably disappear quickly anyway. The really terrible tastes can be found at the very large roasters targeting deep-discount markets – but honestly: who would seriously expect the best quality at the cheapest prices?

One size fits all – roasting profiles

So if we assume that very large roasteries roast cheap raw coffee and do so as efficiently as possible, meaning lots of coffee in little time, then the optimal, finely-tuned profile isn't used.

As a rule, these are one-size-fits-all profiles where the coffee is roasted over the same time but with more or less end temperature (= lighter or darker). The result is often that cheap coffee from large roasteries is roasted significantly darker. The strong roast can mask defects and level out differences.

But large roasteries of course also roast light coffees, which are often the "milds" and the "harmonics." The roasting depth, also called roasting degree, often marks the bigger difference in coffees from the very large roasteries than completely different blends. The same blends are often roasted lighter and darker to create a separate product.

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

And there large roasteries have the tricky task of tasting coffees precisely, blending them themselves or having them blended, so they always taste the same. This is sensorially monotonous, but not less demanding than tasting the most complex coffees.

Now let's talk frankly – who roasts how? Small and large in conversation

It's remarkable how many people talk about a "roasting secret" – the special way green beans are turned brown. I was also surprised that large roasters in particular spoke openly about how they roast coffee. Many probably saw it as an opportunity to finally dispel the rumors of "800° and two minutes." We asked around, at both ends of the spectrum.

Nano-roastery

How does Röststube Lübeck roast?

Knud Buck is probably as close as you get to a nano-roaster. Those who follow his Instagram channel see how meticulously Knud tries to perfect every parameter of roasting, but also preparation. A real laboratory. He roasts on a 1kg Giesen roaster, with batches around 750g.

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

Deliberately underfilling the roasting drum drastically shortens the roasting time. But the small roasting drum also has its weaknesses, according to Knud. "Larger roasting systems have, by design, a larger thermal mass, which, at least in theory, could provide more stability in the roasting process."

For him, roasting coffee is a hobby, but one he practices as precisely as few small roasteries do.

"I associate small roasters with craftsmanship, with more love, with more dedication, and thus ultimately with more quality in the cup. But that doesn't always have to be true!"

Knud Buck

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

Knud roasts, like many others I surveyed in a Facebook poll, based on first crack and development time.

"For most filter roasts I try to achieve the first crack (FC) after 9:00 minutes and from there I calculate a development time between 12 and 18%, depending on the coffee. Another reference point is the temperature development from FC to end temperature, here my range goes from +4°C for light filter roasts to +10°C for espressos. I don't roast darker than that."

The rate of rise (RoR) is also decisive for Knud: "Especially when discussing with other roasters and talking about roasting profiles, the RoR is much more informative than comparing absolute temperatures. For me, RoR is the decisive measure for assessing roasting profiles."

Micro-roastery

How do the coffee makers roast?

Our roasting philosophy is closely tied to the raw coffees we buy. We tend to use heavier coffees for espresso and floral and fruity coffees we roast more for filter coffee.

Yellow: Filter coffee, Red: Specialty espresso, Blue: APAS

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

We fill the 12 kg drum for filter with 4-5kg, for specialty espresso with 8-11kg, and for slightly more developed espressos with 12kg. Full drum capacity requires different gas consumption than a partially filled drum. We also thereby extend the roasting times.

We roast using Cropster roasting software and analyze live how we're roasting. We follow the roasting curves we've developed ourselves and can thus ensure that the roast – theoretically – tastes the same. In addition, we cup the batches and thus align the coffee sensorially with the roasting curve.

Over time, as a raw coffee sits in our warehouse, it's quite possible we'll adjust the roasting profile several times. If we receive a coffee in high summer and roast it by Christmas, we need to adjust the profile according to the outside temperature. That makes roasting coffee never boring.

Meso-roastery

How does Rast Kaffee roast?

Beatrice Rast from the Rast Coffee Roastery wrote me the following lines.

"I generally find it difficult to make value-based distinctions between large/small; we prefer to leave assessment (also regarding manufactory/industry) to the customer and focus on our work, meaning we prefer to focus on ourselves and are motivated to continuously develop and convince the customer of our work, our coffee, service and quality.

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

Our roasting times and temperatures vary depending on the machine, raw coffee, and roasting profile. Typically we roast around 15–20 minutes, and since we have everything in our range from light to medium to dark, the end temperatures are of course very different and vary accordingly.

Because of our tendency toward longer roasting times, a lot of chlorogenic acid can be broken down, making the coffee more easily digestible, but of course it's also more costly due to the high time investment.

Roasting follows profiles we've developed, times, colors, end and development times. When purchasing raw coffee or materials, we strive for long-term partnerships and want to maintain close relationships with our partners."

Macro-roastery

How does Hochstrasser roast in Lucerne?

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

With four roasting systems (5kg, 60kg, 120kg, and 240kg), Hochstrasser can meet various needs. The company has long stopped roasting only for itself and fulfills various private label requests.

The larger the roasteries, the more important private labeling becomes – it helps the roastery efficiently use large capacity. For private label customers, it's attractive because coffee can be produced consistently and cheaply by others.

Kevin Heer says: "We roast exclusively with drum roasters from Probat, the industry leader. Furthermore, we are very capable and can execute large orders in high quality, and we're flexible enough to handle small orders too."

Probat's largest drum roaster is almost as big as a small truck. With the surrounding periphery – exhaust and intake pipes, lines for roasted coffee transport, and the afterburner – the system takes up the space of a small single-family home.

The drum roaster also extends roasting times. So Hochstrasser roasts between 13 and 17 minutes, which is time-wise very similar to how we coffee makers roast too. The roasting masters at Hochstrasser also monitor the roasting process on a monitor, though this stands by the roaster. Physical proximity to the roaster itself is present, especially when special orders need to be roasted to specific points like the 1st or 2nd crack. The roasters mark these manually.

The roasting temperatures (hot air flow temperature) are between 230 and 250 degrees. Large systems offer some advantages, according to Heer:

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

Regarding gentle long-term roasting, Heer emphasizes that above all the energy supplied to the beans is gentler when heated by lots of hot air rather than direct drum contact heat.

Large roasteries like Hochstrasser sometimes quench the coffee, "but only with enough water so the roasted coffee doesn't absorb water," says Heer.

"From our perspective, quality is defined by roasting time and the roasting curve through the roasting system. If all these factors are right, it's possible to achieve more consistency with a larger roasting system. Other important factors for us are raw coffee qualities, quality controls of raw and roasted coffee (via cuppings), and then optimal packaging to protect the roasted coffee."

Mega-roastery

How does Melitta roast?

I was also able to have an interesting conversation with Melitta's production management. They were very open with roasting information. Later, my text, which I wrote based on an interview, was revised and adjusted to company guidelines. So the result is now a text based on mine but then modified.

How does Delica coffee roastery roast?

At Delica too, they know the arguments and claims of other roasteries that large roasteries don't roast well. Nicole Gisi, project manager, former roasting master, and author of the book "Coffee. Passion-Science-Enjoyment", responds:

"We're above that, because we know the truth. In the end, everyone is convinced they're doing the right thing. We at Delica AG are proud that our roasting methods are equal to commercial roasters. It's not the size of the roastery, but the experience, the roasting method, and the quality of the raw coffee, as well as the grinding and extraction method that make good coffee."

Gisi continues that small and large are neither good nor bad: "In my view, there are neither advantages nor 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 annually they roast about 17,000 tons of coffee.

She rejects the 2-minute and 800° claims – "we roast for at least 7 minutes, with the longest roasting times at 20 minutes."

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

"Those are marketing statements with little to say about quality.

Nicole Gisi on gentle long-term roasting

Of course there are parameters regarding roasting duration that point to high-quality quality. For me, "hand-roasted" is not a quality marker. The roaster stands by the roaster and ends the roast manually – depending on the roaster's experience, lighting conditions, and mood, the roasts will taste and smell different because 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 error. 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 the consumer gets stable end products."

On the topic of chlorogenic acid, Gisi commented extensively.

"Chlorogenic acid is understood as a group of esters from hydroxycinnamic acid and quinic acid. Chlorogenic acid as well as its breakdown products contribute significantly to taste and aroma formation as well as color formation in coffee. Since chlorogenic acid is thermally unstable, it breaks down during the roasting process through hydrolysis into quinic acid and caffeic acid. With strong roasting, almost complete breakdown into various phenolic compounds can occur. Its breakdown products can be sour and astringent. With incomplete or very light roasting, larger amounts of chlorogenic acid remain in the bean. It can cause intolerance and stomach upset in sensitive people."

How does Aldi roast?

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

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

"I'm always happy when I discover special microlots at small specialty roasters. Small roasteries have possibilities that we as a large operation don't have. They can work out taste details and are certainly an enrichment to the coffee landscape."

Michael Körnig, NewCoffee GmbH

Körnig made clear, like few others, that there are mainly technical differences that allow certain things or not. He didn't try to argue this away but rather explored the possibilities.

"I see much good in small roasteries, but we large ones also have our advantages. However, we can't buy microlots because we can't process small quantities. We need coffee amounts sufficient to supply about 1,940 stores."

In stark contrast: as coffee makers, we just bought a nanolot of 70kg. We do about three sample roasts from it and then sell 55kg – it's worth it for us because we roast filter coffee in 5 kg batches. For any larger roasters, it quickly becomes complicated to impossible.

While it's difficult for NewCoffee to process small quantities, using different profiles is possible. "Our business model is just different." He sees the leverage for large roasters especially in the degree of automation in packaging: "Among other things, we can package at lower cost. This reduces labor costs and puts us in a position to offer high-quality coffees at affordable prices."

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

For roasting times, NewCoffee distinguishes between ground coffees and coffees for coffee pods, which range from 6-9 minutes, and bean coffees, which typically roast for 12 minutes and in rare cases also 15 minutes. For large roasteries, these are times that wouldn't have been expected.

Körnig on this: "One reason for longer roasting times, especially for ground coffees, was the acrylamide issue. 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 mentions, like Gisi on chlorogenic acid, specific facts on topics large roasteries are repeatedly asked about. Smaller and medium roasteries conduct tests and samples for acrylamide, furan, and OTA and residues in coffee far less or not at all – even though none of these four topics can be ruled out.

On the "high yield method," Körnig is also precise – "we've never done that." According to internet research, this method roasted coffee in 90 seconds. 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's something to the 90-second roasting – the question is, is it still done that way today? I'm convinced, but I haven't reached the roasteries yet.

Körnig sees "gentle long-term roasting" differentiated:

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

Michael Körnig

Körnig also comments on chlorogenic acid: "Chlorogenic acids are in coffee, but especially in very short roasts. Since we roast for at least six minutes, the problem barely occurs for us. But we roast 90 percent arabica and hardly any robusta – and since the proportion of chlorogenic acid in robusta is much higher than in arabica, it doesn't 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, including major Swiss retailers among their largest customers. Benjamin Schütz from UCC spoke with me about their roasting style.

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

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

Such large drum roasters function because hot exhaust air is partly recycled and fed back into the system. So this "new" air doesn't need to be heated anymore. If only fresh air were drawn in, fast roasting with such a machine wouldn't be possible.

Per hour, UCC roasts four to five batches, which amounts to about 7,000 tons of roasted coffee per year. Per shift, besides the roasting master, there are about four other people who take care of downstream processes like grinding and packaging.

The roasting cycle is very high, meaning the time between batches is very short. Only about 10 seconds passes before the roaster is empty and new raw coffee is filled.

UCC roasts to the desired color, which determines when the roast ends. Here too, 1st crack, development time, and rate of rise play no role. Very different from roasteries with smaller systems, where these reference points are used much more.

Schütz doesn't comment much diplomatically on gentle long-term roasting. "That's like slow-cooking. With meat it tastes good, though." He has to smile about the idea that coffee is "hand-roasted." "Yeah, roasting machines can be operated by hand. But that would be about it."

Like many larger roasteries, UCC also quenches, meaning immediately cooling the roasted coffee after it exits the roasting drum with water. 70 to 74 liters are used for a 500 kg batch of coffee, which then means about 3–3.5% residual moisture in the bean. Quenching happens still in the drum after the specified end temperature is reached.

Schütz, like Gisi, has a scientific background and readily takes up the chlorogenic acid discussion.

"The stomach must be able to take up acids; that's its function. When acid comes, it has to buffer it with bases. But if it's already over-acidified, for example through animal proteins, then the body has a much harder time processing acidic foods. This can lead to heartburn."

Benjamin Schütz, UCC Switzerland

For Schütz, it's clear that chlorogenic acids alone aren't harmful to the stomach, but rather overall diet determines the body's ability to process coffee. And, clearly, whether sugar is added to the coffee also has an effect. 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.

	Nano	Nano	Micro	Meso	Macro	Mega	Mega	Mega	Mega
	Röststube Lübeck	Birchbach Coffee	Kaffeemacher	Rast	Hochstrasser	UCC Switzerland	Delica AG	Aldi / NewCoffee GmbH	Melitta
roasted quantity per year in tons	<1	3	26	n.a.	1500	7000	17000	n.a.	n.a.
Number of roasting machines	1	1	1	4	4	2	3	n.a.	n.a.
Minimum batch size	0.7	1	4	5	230	420	140	n.a.	n.a.
Maximum batch size	0.7	1	12	90	280	500	500	n.a.	650
Minimum roasting time	7:00	8:30	9:00	15	13	10:30	07:00	06:00	07:00
Maximum roasting time	15:00	10:00	16:30	20	17	15:00	20:00	15:00	20:00
Definition of roasting end
Time	x	x	x	x	x		x
End temperature		x	x	x	x	x	x	x	x
Color				x	x	x	x	x	x
Priority in roasting philosophy
1st crack	1	3	1		1
2nd crack		3
RoR (rate of rise)		1	1		1
End temperature	1				1	1	1	1	1
Development time	1	2	1		1
Roasting color		4	2		1	1	1	1	1

Who roasts according to 1st crack, rate of rise, development time, end temperature…

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

The "total roasting time" got not a single vote in the roaster forum, end temperature only three.

Mirjam Baumgartner from Bühler confirms these findings:

In my experience, only small, manual operations orient themselves to 1st and 2nd crack in daily production. These operations roast with much expertise and roasting master attention.

At a large roastery, of course 1st and 2nd crack are discussed when developing new roasts, but it's unthinkable that a roasting master observes these parameters 1:1 with every roast. In this case, one relies on the roaster's reproducibility and breaks, in most cases, at temperature. This can also be the case at small roasteries.

In other words: if the roasting machine has temperature management under control, then 1st crack and 2nd crack always occur at exactly the same time. The roasting master of a large system doesn't need to pay attention to cracking anymore.

So now what? Where's the journey headed?

Large roasteries are getting larger

It shows every few weeks: large roasteries are getting even larger, and roasting machine manufacturers feel it. Again, Baumgartner on this:

Bühler's core competency as a machine-building company is system building, 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 system in the US with two Infinity Roasts produces about 6 t/h in continuous operation, but we have large roasteries as customers worldwide.

Our proposed five-category division – nano, micro, meso, macro, mega – will likely soon be supplemented with "giga," and this already applies to certain roasteries today.

There are more and more small roasteries

At the same time, there's a counter-trend: that of nano and micro roasteries. It will be exciting to watch whether nano roasteries grow large, whether micro roasteries limit their growth, become meso roasteries, or even merge with another micro roastery. We maintain a current collection of coffee roasteries in Switzerland, Quijote Coffee maintains a collection of roasteries in Germany.

Coffee quality is improving

It's increasingly enjoyable to drink coffee out. Generally, the coffee offering is becoming more colorful – and here we're not talking about drink categories but flavor profiles that consumers can get today.

More and more nano and micro roasteries focus exclusively on specialty coffee. For the reasons extensively discussed, these smaller roasteries can take a different approach than large ones.

The big players are playing small

Jacobs and Dallmayr have led the way, others will follow. Large roasteries increasingly rely on smaller projects, smaller roasteries that should open up this segment for them, which they otherwise can't address. The large players have understood that the artisan idea isn't purely marketing but really a message that makes many consumers feel like they're holding something genuine in their hands. No beautiful brochures and campaigns get around that – for many, the small is simply the more authentic.

The question remains how credible the small projects of large roasteries will be. There won't be a lack of know-how, access to raw coffee, or roasting understanding – but I see consumer acceptance in a specialty coffee-oriented audience as limited. The large name would likely still stand above what's offered for many. I'm curious to see who will separate the product from the name.

We're all learning together – together

This article on roasting will continue to be supplemented by me. More manufacturers and roasteries should be added. Maybe there's a roastery or two willing to contribute roasting profiles.