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 worse roasters? And when exactly is a roastery considered large? We wanted to understand more about who roasts how and spoke with very small and very large roasteries. We've summarized the results here in an overview. In short: much is not what it seems.

When roasting coffee, green beans are heated to specific temperatures for a specific amount 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 is described here, it appears simple. 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're 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 the high yield roasting method of the very largest roasteries. Yes, it was roasted this way, and we still find this roasting style in some places today, but likely much less widespread than assumed. Not every supermarket offers the worst coffee, and not every small roastery offers the best either.

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 Coffee explained how they roast, as did the nano-roasteries Birchbach Coffee and the Röststube Lübeck. We also opened our roasting notes and explained what we actually do, for example, href="https://www.youtube.com/watch?v=toJzDzFoAUc"herehref="https://www.youtube.com/watch?v=toJzDzFoAUc".

Against our expectations, we encountered extremely open ears. Very few roasteries dismissed our request. It seems that especially the large roasteries felt the need to present their own perspective. Many also saw it as an opportunity to correct mere assumptions and sometimes push back hard – though in some cases the marketing departments softened this somewhat afterward. 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 in smaller batches, with significantly longer roasting times, and at lower temperatures. It should be "gentle" and therefore better.

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

Often it seems as if there are small roasteries on one side, 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 and read 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.

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

The quality of coffee depends not 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 adds:

"Gentle long-time roasting," "hand roasted," or roasted according to "traditional drum roasting methods" are about as specific statements as when someone is called a "hipster." You roughly know what's meant, but it's just not clearly defined. Such statements are an attempt to distance oneself from big industry.

Mirjam Baumgartner

And Baumgartner is right about that. Differentiation through disparagement is simple, 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 request to roasteries to communicate their own strengths in their own marketing and to be confident about them, rather than profiling themselves through disparaging differentiation.

A new categorization of the roastery landscape

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

"'Industrial roasting' is spoken of from a roasting container capacity of 60 kilograms, the standard weight of a raw coffee sack"

Probat, 2007

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

A classification into small and large roasteries, or into so-called artisanal and industrial operations, remains superficial. We attempt here to reclassify roasteries based on precise criteria and to rename them accordingly. 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 for a maximum production quantity. Depending on size, roasteries combine similar processes and challenges. This makes a classification into size groups meaningful. A classification into five groups facilitates communication about roasteries and is also substantively justified by similar processes and challenges.

This allows us to better differentiate the smaller roasteries and the middle field, and to move away from the emotionally charged term of "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 used only on a few days.

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

From practice

When we started our Kaffeemacher 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" no longer fits for quite some time, as we know dozens of roasteries that are smaller and just starting out. 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 has stabilized. The raw coffee purchasing strategy is refined and more customers have differentiated needs. Depending on production location and cost structure, one full-time position is created and financed per approximately 15 tons. The roastery is no longer a side project but is established – we speak of a micro-roastery. Many roasteries consider at this threshold how much longer they want to roast with their first machine and when an upgrade to a larger roaster is needed. A stable customer portfolio helps with this decision, and often roasteries upgrade properly at that point. 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 this 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 manually packaged. Conveyor systems, volumetric-electronic pre-portioners, and software interfaces between ordering and production planning help optimize the workflow and shift focus increasingly to post-roasting. Roasting itself often runs automated – a program created by the roastmasters is now often executed by the computer. This allows for more freedom and even greater control. The focus in meso-roasteries increasingly shifts to 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 and gets about 1500 t per year out of a 250kg roaster. Such roasteries typically have additional, smaller roasters (25-100kg) with which they can also accommodate private label offerings. The roasting machine itself takes up less space in a macro-roastery. The periphery around it – mixing silos, loading the roaster, destoning, transport pipes, grinding systems, and packaging systems – now much more resemble a well-thought-out work process. Capacity utilization becomes the magic word here – such large systems rarely stand idle – especially roasteries of this size often offer private label services where coffee is roasted for others.

Example: Hochstrasser Coffee Roastery

Mega (2000t – 100'000t+)

The difference from the very largest roasteries is mainly that increasingly more processes become mechanized. In a roastery that roasts 20,000t annually, just six production employees work in one shift – in micro-roasteries, which are approximately 1000x 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 mills, until it is then packaged via packaging machines.

The working hours are significantly reduced by efficient systems as a roastery grows larger.

Comparison 2: Roasting machines

It's obvious that larger roasteries can only roast so much with larger roasting machines. In contrast, small roasteries often roast on small machines for several years. Purchasing a roasting machine is never a walk in the park for any roastery. Even a 1kg roaster means an investment of up to 10,000 CHF. A 400kg roaster together with the necessary periphery and installation means an investment of millions.

Within the range of roasting machine sizes, there are certainly technical and qualitative differences. In the end, though, 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 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 levels make the biggest differences here.

Roasting machines in nano-roasteries

In recent years, increasingly more small roasting machines have come on the market, and so we also see more nano-roasteries able to offer smallest quantities to their clientele. These tiny machines usually roast beans 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 a small quantity 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 in micro-roasteries

Micro-roasteries try to stand for the "real thing" and the handcrafted with their work. 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 idea of the craftsmanship 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 some shine to it, usually looks great positioned in a roastery or café to show: here coffee is still roasted by hand.

The drum roasters are the first choice for many. An outer housing is warmed 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 mixture of the airflow passing through the roaster, the transfer through the hot material, and the transfer from bean to bean.

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

Roasting machines in meso-roasteries

These roasteries have already bought a second, or even a third roasting machine. Generally, it makes sense to upgrade from a 15kg machine to a machine at least 3x larger, as it can often be quickly utilized at full capacity.

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

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

Larger roasting machines, however, also require larger conveyor systems, more efficient air filters, cyclones, and possibly an afterburner or different air filter. At this point we're no longer talking about just a roastingmachine, but about an entire roastingsystem, where the roasting machine itself takes up only about a third of the space.

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

Roasting machines in macro-roasteries

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

Drum roasters of 140 to just under 300 kg per batch function according to the same principle as their smaller versions, but they require significantly more energy. Anyone who wants 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 in mega-roasteries

Theoretically, the drum roasting principle could be made even larger, but the system loses increasingly more efficiency. And large roasteries are designed 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 much more efficient. These roasting systems blow and push the coffee in ellipses over greater 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 partially recycle the hot exhaust air back into the system, so the system retains the heat.

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

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

Mirjam Baumgartner

The most extreme form of fast and efficient roasting is so-called continuous 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. Probat writes about this:

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

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

Since the drum is not perforated in this system, raw coffees with a high percentage of breakage can also be processed without problems."

p. 37, Industrial Coffee Processing, 2007)

Breakage percentage, quick roasting, grinding – that's primarily about the most efficient processing, more or less consistent taste, and not about quality.

Roasted coffee quality. Who roasts how, and most importantly, 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 your own machine is the A and O here.

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

Large roasteries have a clear advantage here when it comes to differences between individual roastings. Large systems are more sluggish because they move more mass – but whoever can use this to their advantage roasts 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 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 characteristics of the machines – and I see much potential here in the small roastery scene.

If we only look at consistency, I have so far seen significantly more consistent roastings from meso-, macro-, and mega-roasteries. The most inconsistent roastings I've had so far have always been 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 various sizes in between, and in their function they are sometimes significantly more industrial (more efficient, larger, more technical, more automated), even though they still appear to be handcrafted roasteries.

Automation

It seems that the high degree of automation in large roasteries is what brings the industrial comparison into play. The degree of automation that seemingly only asks the roastmasters to monitor roasting curves on a screen, but not to actively intervene.

With more automation comes the loss of some of the romance that brought so many roasteries to roast in the first place. The manual work, the craftsmanship, the risk, the chance that something goes wrong because we as humans reacted incorrectly – the guarantee that nothing ever works exactly as intended, has become for many the epitome of true craftsmanship.

Freshness

When it comes to freshness, small roasteries that sell directly or through their own shop score significantly better. The very large roasteries sell their coffee through retailers, who in turn have their own intermediate storage. By the time coffee gets from the roastery through the intermediate storage to the shelf, several weeks pass.

Raw 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 supplies more people with coffee, makes more friends but also has more critics. More quantity smells of more consistency, and that of more uniformity. Uniformity in process and often also uniformity to the point of blandness 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. The 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 raw coffees 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 doesn't necessarily guarantee the perfect roast on the first try. Two to three batches are typically used to develop a roasting profile, sometimes more.

Limiting creativity through one's own size

Meso and macro-roasters can't roast such small quantities because their roasting systems are designed for larger capacity. Large roasting systems must be loaded with at least 70% of their possible maximum capacity. The 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 would seriously like to experiment with 140 kg of raw coffee?

Large roasteries therefore base their selection on cheaper and sensorially often less characteristic raw coffees due to their size. 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 micro-lots, containers instead of jute sacks, stable profiles instead of surprises.

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

Flavio from Birchbach Coffee (Photo: Flavio Lissandrello)

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

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

Flavio Lissandrello

Mirjam Baumgartner from Bühler also often sees that large roasteries are 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 because they don't have the possibility of using other technologies. Large roasteries can use more advanced technologies in many ways (e.g., variety of roasting profiles, auto-corrective profile roasting systems, green coffee pre-heating, etc.). But of course there are always exceptions.

Mirjam Baumgartner

Knud Buck from the 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

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

"Since I only roast for myself, I'm not dependent on reproducibility. I don't have a customer base that relies on always the same coffee taste. So I retain the freedom to always experiment again. In principle, no roast is like the other. Even though I practice roasting particularly successful roasts again."

Knud Buck

Experimenting on a very small scale works, but again, at a batch size of 150 kg and more, the reason for an experiment has to be really good.

Really nasty coffee at the very large roasteries

Whoever is large can produce cheaply and target budget price markets – and these markets are huge. But the size of a roastery itself doesn't determine whether they buy defective coffee or not. It has to do with the approach and quality understanding.

Nespresso, which likely roasts well over 100,000t per year, doesn't buy defective coffee – it contradicts their quality promise and brand message. Others, who roast much less but want to target budget price markets, do resort to sensorially inferior coffee.

For those who "just want coffee" or better yet "a caffeine boost," quality is not a deciding factor. And coffee quality reflects that exactly; you get what you pay for.

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

I myself have never heard of a small roastery that successfully sold bad coffee. That roastery would probably quickly disappear. The really bad tastes can be found at the very large roasters which target budget price 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 a lot of coffee in a short time, then the optimal, finely tuned profile doesn't apply.

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

But large roasteries certainly also roast light coffees, which are often the "mild" and "harmonious" ones. The roasting depth, or roasting degree as it's also called, often marks a bigger difference in coffees from the very large roasteries than completely different blends. Often the same blends are roasted lighter or darker to create their own 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 that's where large roasteries have the tricky task of tasting coffees precisely, blending them themselves or having them blended, so they always taste the same. That's sensorially monotonous, but no less demanding than tasting the most complex of all coffees.

Now let's be frank – who roasts how? Small and large in conversation

It's remarkable how many speak of a "roasting secret" – the special way to turn green beans brown. I was equally surprised that especially the large roasters spoke openly about their way of roasting coffee. Many likely also saw it as a window to finally clear up the rumors of "800° and two minutes." We asked, both at the very small and very large roasteries.

Nano-roastery

How does the Röststube Lübeck roast?

Knud Buck is probably what comes closest to a nano-roaster. Following his Instagram channel, you see how meticulously Knud tries to perfect every parameter of roasting, but also preparation. A true laboratory. He roasts on a 1kg Giesen roaster, with batches of 750g.

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

Intentionally 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, greater thermal mass, which could theoretically 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 are between 7 and 15 minutes with maximum bean temperatures of 205°. These temperature readings should always be taken with caution, as they can't be compared.

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

"For most filter roasts I try to achieve the first crack (FC) after 9:00 minutes and calculate from there with a development time between 12 and 18%, depending on the coffee. Another reference point 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 darker than that."

The rate of rise is also decisive for Knud: "Especially when you exchange ideas with other roasters and talk about roasting profiles, the RoR is much more meaningful than the comparison of absolute temperatures. For me, the RoR is the deciding factor for evaluating roasting profiles."

Micro-roastery

How do the Kaffeemacher roast?

Our roasting philosophy is strongly connected with 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 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 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 somewhat more developed espressos with 12kg. Full drum utilization demands different gas consumption than a less-filled drum. We also extend the roasting times this way.

We roast with roasting software from Cropster and analyze in real-time how we roast. We follow the roasting curves we've developed ourselves and can thus ensure that the roast – theoretically – tastes the same. Additionally, we taste the batches and can thus align the coffee sensorially with the roasting curve.

Over the time a raw coffee sits in our storage, it's quite possible we'll adjust the roasting profile multiple times. If we receive a coffee in the middle of summer and roast it until Christmas, we must adjust the profile according to the outside temperature. This keeps roasting coffee never boring.

Meso-roastery

How does Rast Coffee roast?

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

"I generally find it difficult to make evaluative distinctions between large/small; we prefer to leave an assessment (also regarding manufactory/industry) to the customer and concentrate on our work, meaning we prefer to focus on ourselves and have the drive to constantly develop further and convince the customer 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 we can better meet our customers' needs to guarantee them our roasting freshness. The roasted coffee is air-cooled on all machines.

Our roasting times and temperatures vary depending on the machine, raw coffee, roasting profile. Generally we roast for about 15 – 20 minutes, as we have everything from light through medium to dark in our assortment, the final temperatures are of course very different and vary accordingly.

Through our rather long roasting times, a lot of chlorogenic acid can be broken down, making the coffee more digestible, but of course due to the high time investment it's also more cost-intensive.

Roasting is done according to roasting profiles, times, colors, end and development times we've developed. In raw coffee purchasing or material purchasing we strive for long-term partnerships and want to be in close relationship 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 roastmaster 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 since not only roasted for itself, but fulfills various private label wishes.

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

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

The largest Probat drum roaster is almost as big as a small truck. With the periphery around it – the exhaust and intake pipes, the 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 Kaffeemacher roast as well. Roastmasters at Hochstrasser monitor the roasting process on a monitor, which is positioned at the roaster. The physical proximity to the roaster itself is there, especially when special orders are to be roasted according to parameters like the 1st or 2nd crack. The roasters mark these manually.

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

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

On gentle long-time roasting, Heer emphasizes that especially the energy input to the beans is gentler when they're heated via lots of hot air rather than directly through the drum's contact heat.

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

"From our perspective, quality is defined through the roasting time, the roasting curve through the roasting system. If all these factors are right, it's possible with a larger roasting system to achieve more consistency. Other important factors for us are the raw coffee qualities, the quality controls of raw and roasted coffee (through cuppings) and subsequently 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. The handling of roasting information was very open. Later, my text, which I had written based on an interview, was changed again and adapted to the company's guidelines. The resulting text is based on mine but was then modified.

How does Delica Roastery roast?

At Delica as well, they know the arguments and claims of other roasteries that the large ones don't roast well. Nicole Gisi, project manager, former roastmaster, and author of the book «Coffee. Enjoyment-Passion-Science» on this:

"We're above that, since we know the truth. Ultimately, everyone is convinced by themselves that they're doing the right thing. We at Delica AG are proud that with our roasting methods we stand on par with 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 makes good coffee."

Gisi goes on to explain that small and large is neither good nor bad: "In my eyes 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, annually they roast about 17,000 tons of coffee this way.

She dismisses the 2 minutes and 800° claims – "we roast at least 7 minutes, the longest roasting times are 20 minutes".

On gentle long-time roasting, Gisi makes clear that this isn't about quality, but only about marketing a roasting style:

"Those are marketing statements with little information about quality.

Nicole Gisi on gentle long-time roasting

Of course, there are parameters regarding roasting duration that point to high-quality results. For me, "hand roasted" is not a quality indicator. The roaster stands next to the roaster and ends the roasting manually – depending on experience, lighting conditions, and the roaster's mood that day, the roastings 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 errors. The higher the degree of automation, the fewer surprises – but also less courage).

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

On the topic of chlorogenic acid, Gisi expressed herself 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 is broken down during the roasting process by hydrolysis to quinic acid and caffeic acid. With strong roasting, a nearly complete breakdown to various phenolic compounds can occur. Its breakdown products can be acidic and astringent. With an incomplete, or very light roast, larger amounts of chlorogenic acid remain in the bean. It can lead to intolerance and stomach problems in sensitive people."

How does Aldi roast?

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

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

"I'm always pleased when I discover special micro-lots at small specialty roasters. Small roasteries have possibilities here that we as a large operation don't have. They can develop taste details and are certainly an enrichment for the coffee landscape."

Michael Körnig, NewCoffee GmbH

Körnig, like few others, made clear that there are mainly technical differences that allow for specialties or not. He didn't attempt to argue this away, but rather sensed out the possibilities.

"I see a lot of good in small roasteries, but we large ones also have our advantages. However, the handling of micro-lots is not possible for us, as we cannot process smallest quantities. We need coffee quantities sufficient to supply around 1,940 stores."

In stark contrast: as Kaffeemacher we just bought a nano-lot of 70kg. We make about three test roasts and then still sell 55kg – for us it's worth it because we roast filter coffee in 5 kg batches. For all somewhat 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 simply different." He sees the large roasteries' leverage primarily in the degree of automation in packaging: "We can, among other things, package more cheaply. That lowers labor costs and allows us to offer qualitatively high-quality coffees at reasonable prices."

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

Regarding roasting times, NewCoffee distinguishes between ground coffees and coffees for coffee pods, which are between 6-9 minutes, and bean coffees, which are usually roasted for 12 minutes and in exceptional cases up to 15 minutes. For large roasteries, those are times you probably wouldn't have imagined.

Körnig on this: "One reason for longer roasting times, especially with 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. "

Like Gisi regarding chlorogenic acid, Körnig cites concrete facts on topics that large roasteries are repeatedly asked about. Smaller and medium roasteries conduct tests and samples on acrylamide, furan, OTA, and residues in coffee much less or not at all – even though all four topics can't be ruled out.

On the "high yield method," Körnig also expresses himself precisely – "we never did 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 roasted coffee. You can read more about this in a 1984 Spiegel article.

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

Körnig sees "gentle long-time roasting" with nuance:

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

Michael Körnig

Körnig also expresses himself on chlorogenic acid: "Chlorogenic acids are present in coffees, but mainly with very short roasts. Since we roast for at least six minutes, the problem hardly occurs with us. But we roast 90 percent Arabica and hardly any Robusta – and since the percentage of chlorogenic acid in Robusta is significantly 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 large Swiss retailers among their biggest 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 reference points in a profile and the roaster follows them, come what may." UCC roasts on two roasters from the company Lilla from Brazil, each with 500 kg capacity.

Batch sizes range between 400 and 500 kg. The Lillas are drum roasters, so different systems than we encountered with 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 for a roast at UCC.

Such large drum roasters work because the hot exhaust air is partially 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 per year of roasted coffee. In one shift, in addition to the roastmaster, about four other people work who take care of downstream processes like grinding and packaging.

The cycle rate of the roastings is very high, meaning the time between batches is very short. Only about 10 seconds is the roaster empty before new raw coffee is added.

UCC 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. Very different from roasteries with smaller systems, where these orientation aids are used much more.

On gentle long-time roasting, Schütz expresses himself less diplomatically. "That's like slow cooking. But with meat it tastes good." When asked what he thinks about the claim that coffee is "hand roasted," he has to smile. "Yes, roasting machines can be operated by hand. But that's about it."

Like many larger roasteries, UCC also quenches, i.e., immediately cools the roasted coffee after it exits the roasting drum with water. 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 occurs in the drum after the specified final temperature is reached.

Schütz, like Gisi, has a scientific background and welcomes the chlorogenic acid discussion.

"The stomach needs to be able to absorb acids, that's its function. When acid comes, it must catch it with bases. But if it's already oversaturated, for example from animal proteins, then the body has much more difficulty processing acidic foods. Heartburn can result."

Benjamin Schütz, UCC Switzerland

For Schütz, it's clear that chlorogenic acids alone are not stomach-damaging, but rather diet in general determines the capacity of the stomach to handle coffee. And, clearly, whether or not 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 organized them 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 end of roast
Time	x	x	x	x	x		x
Final 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
Final 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, final temperature...

The roasting stages are measured differently by roasteries. In a Facebook survey, almost all specialty and small roasters I asked mentioned the following order:

The "total roasting time" received not a single vote among the roasters in the forum, final temperature received 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 roastmaster.

At a large roastery, of course, the 1st and 2nd crack are discussed when developing a new roast, but it's unimaginable that a roastmaster observes these parameters with every roast 1:1. In this case, you rely on the roaster's reproducibility and in most cases end roasting based on temperature. But this can also be the case at small roasteries.

In other words: if the roasting machine has the temperature control under control, then the 1st crack and 2nd crack always occur at exactly the same moment. The roastmaster of a large system doesn't need to pay attention to cracking at all in that case.

And now? Where does the journey go?

Large roasteries are becoming larger

It shows every few weeks: large roasteries are becoming even larger, and roasting machine manufacturers notice this too. Once again, Baumgartner on this:

Bühler's core competency as a machine-building company is system construction, 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 through auto-corrective profile roasting. Our largest system produces around 6 t/h in continuous operation in the USA, but we have large roasteries worldwide as customers.

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

There are increasingly more small roasteries

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

Coffee quality is improving

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

More and more nano and micro-roasteries are focusing entirely on specialty coffee. For reasons discussed extensively, these smaller roasteries can set their focus differently than large ones.

The large ones do small

Jacobs and Dallmayr have shown the way, others will follow. Large roasteries increasingly focus on smaller projects, on smaller roasteries that should open up this segment for them, which they couldn't otherwise approach. The large ones have understood that the manufactory idea is not just marketing but really a message that for many consumers creates the feeling of holding something genuine. No fancy brochures and campaigns can 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. It won't fail due to know-how, access to raw coffee, and roasting understanding – but I see limited acceptance from an audience oriented toward specialty coffee. The large name will likely still overshadow what's offered for many. I'm curious to see who manages to separate the product from the name.

We all learn together

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