MedicineLakex

Cookbooks.hu

The Coffee RoasTeR's
Table of Contents
Acknowledgments vii
Preface ix
Introduction xi
1 Why We Roast Coffee Beans 1
2 Green-Coffee Chemistry 2
Alkaloids: Caffeine and Trigonelline Moisture Content Gases and Aromatics 3 Green-Coffee Processing and Storage 4
Primary Processing Methods Wet/Washed Dry/Natural Green-Coffee Storage Water Activity and Moisture Content
4 Physical Changes During Roasting 9
Classic Definitions of Roast Degree Structural Changes Inner-Bean Development Bean Size, Density, and Weight Loss 5 Roasting Chemistry 15
Green-Coffee Storage and Consistency Changes in Chemical Composition Ambient Conditions Development of Acids During Roasting Chimney Cleaning Aroma Development Managing Different Batch Sizes Maillard Reactions and Caramelization 12 Measuring Results 53
Caffeine Content and Roasting All About Bean Probes 6 Heat Transfer in Coffee Roasting 19
Choosing a Probe Convection, Conduction, and Radiation Installing a Probe Heat Transfer and Temperature Gradient Heat and Mass Transfer Within Coffee Beans Measuring Roast Degree Heat Transfer and Moisture Verification of Development Using a Refractometer 7 Roasting Machine Designs 22
13 Sample Roasting 57
14 Cupping 59
Indirectly Heated Drum Cupping Recommendations The Phases of Cupping 8 Progression of a Roast 29
Dry Aroma, or Fragrance The Illusion of the S Curve The Myth of the Drying Phase Tasting the Coffee When It Is Hot The Middle (Nameless) Phase Tasting the Coffee When It Is Cool How to Interpret Cupping Results 15 Roasting, Brewing, and Extraction 66
Development Time Testing Roast Development 9 Planning a Roast Batch 34
Calibrating Extraction Roasting for Espresso Setting Airflow Adjusting the Air–Fuel Ratio 16 Storing Roasted Coffee 70
Charge Temperature Machine Design 17 Choosing Machinery 72
Batch Size Features to Consider when Selecting a Roaster Bean Density Bean Processing Method Intended Roast Time Determining Roast Time Gas Control Drum Speed Bean Moisture, Density, and Size Automated Profiling Software 10 The Three Commandments of Roasting 42
Pollution-Control Devices I. Thou Shalt Apply Adequate Energy at the Beginning of a Roast II. The Bean Temperature Progression Shalt Always Decelerate Parting Words 79 III. First Crack Shalt Begin at 75% to 80% of Total Roast Time Glossary 80 11 Mastering Consistency 49
References 84 How to Warm Up a Roaster Between-Batch Protocol Other Tips to Improve Batch-to-Batch Consistency About the Author 89

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electing a roasting machine is a long-term commitment, and I hope read- S ers do their homework before buying a machine. Most small roasters,
especially first-time buyers, don't have the experience to evaluate machines properly, so if that's you, I recommend seeking expert advice before making what is probably your company's largest investment. You must choose carefully because the majority of machines on the market today will limit your coffee's quality or consistency, though their sales representatives may neglect to tell Features to consider when selecting a roaster
Every roasting company has its unique list of needs and preferences when
choosing a roaster, such as aesthetics, machine footprint, cost, and so on. While I can't comment on those company-specific requirements, I offer the following technical recommendations to help you choose a roaster.
capacity
First, decide how much roasting capacity you need. Second, use a manufactur-
er's stated capacity as a starting point and look up a machine's BTU rating to estimate what its realistic capacity might be. Finally, given that every machine will have different heat-transfer efficiency, I recommend that you contact a few users of a given machine to ask about their typical batch sizes and roast times. Single-walled steel drum Using those three pieces of information, you should have a good sense of the machine's realistic capacity. a cast-iron drum (a small, newer roaster manufactured in Taiwan) and one machine with a sheet-iron drum, but every other machine I've ever seen has had a steel drum. A roasting machine's configuration probably has the greatest effect on the qual- Most roasting drums are made of carbon steel, but some manufacturers ity of coffee that it can produce. As I'm sure you've gathered by now, I recom- have recently begun building machines with stainless-steel drums; this seems mend single-pass roasters over recirculation roasters, despite the latter's energy reasonable, but I don't have enough experience with them to have an opinion efficiency. I also recommend an indirectly heated drum, or a double drum, over about their performance. Stainless steel drums may develop hot spots more a standard flame-on-drum design. A single-pass roaster with a double drum or easily than mild carbon steel ones, but that's probably not a serious concern, indirectly heated drum will maximize your chances of producing great coffee given the drum's rotation and an adequate thickness.
and minimize potential flavor taints due to bean-surface burning or a smoky airflow
I've come across few roasters with inadequate airflow but several machines
with poor airflow adjustment mechanisms. Ideally, your exhaust fan's RPM If you buy a classic drum roaster with a flame-on-drum configuration, I rec- should be adjustable in minute, stepless increments. Subtler airflow adjust- ommend choosing a machine with a carbon-steel drum. Contrary to popular ments will produce smoother roast profiles. Machines with two or three discreet belief, most old, German "cast-iron roasters" have carbon-steel drums, not cast- airflow settings, usually controlled manually by a damper, are acceptable but iron drums. Those machines and many others often have cast-iron faceplates, limiting. Not only are the settings usually too far apart, forcing the machine drum spokes, and drum paddles, but steel drums. I have seen one machine with operator to compromise and choose a suboptimal setting, but the large shifts choosing machinery
III. First Crack Shalt Begin at 75% to 80% of Total Roast Time
Experience has taught me that the roast time from the onset of first crack* to
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the end of a roast should make up 20%–25% of total roast time. Put another way, first crack should begin at between 75%–80% of total roast time. I'm confi- Mastering
dent that the optimal ratio is actually in a much narrower range, and the ratio should vary slightly depending on roast degree desired, but I don't have enough data yet to back up those beliefs. If first crack begins at earlier than 75% of total roast time, the coffee will probably taste flat. If more than 80% of the total roast time elapses before first uch like the elusive "God shot" of espresso, most companies roast the occa- crack begins, development will likely be insufficient.
M sional great batch but can't seem to reproduce it consistently. Variations
Most roasters seem to adjust a roast's "development time" separately from in a roaster's thermal energy, green-coffee temperature and moisture, ambient the rest of the roast curve, but such an approach will often lead to baked flavors conditions, and chimney cleanliness all collude to make roasting inconsistent. or underdevelopment. Instead of focusing on development time, I recommend I've designed the tips in this chapter to help you control or lessen the impacts of that roasters adjust the last phase of a roast curve to ensure it is proportional these factors. Following these recommendations will help any roaster improve to the entire roast curve. I hope roasters will find this suggested ratio useful and that the conversation among roasters shifts from "development time" to "development time ratio" or a similar phrase.
Ideal First-Crack Time Range
How to Warm Up a Roaster
At a cupping of some lovely Cup of Excellence coffees a few years ago, I noticed
that one of the samples was very underdeveloped and another was slightly Ideal First-Crack Time Range
underdeveloped. The other cups had varying degrees of good development. It dawned on me that those two cups had been brewed from, respectively, the first and second batches roasted that day. I suggested to my cupping host the order in which he had roasted the samples that morning. I had guessed the order Every roaster I've ever asked has admitted to having difficulty with the qual- ity of the first few batches of a roasting session. The problem is usually caused by inadequate warming up of the roasting machine. Most machine operators warm up a roaster to the charge temperature and then idle the machine at or near that temperature for some amount of time, usually 15–30 minutes, before charging the first batch. This protocol guarantees that the first batch will roast sluggishly compared with successive batches. The problem is that temperature probes are poor indicators of a machine's Temperature (°F) thermal energy. (See "Charge Temperature" in Chapter 9.) As a cold roasting machine warms up, although the temperature probes quickly indicate that the air in the machine has reached roasting-level temperatures, the mass of the machine is still much cooler than the air in the drum. If one charges a batch at this point, the machine's mass will behave akin to a heat sink and absorb heat from the roasting process, decreasing the rate of heat transfer to the beans. After several roast batches, the machine's thermal energy will reach an equi- librium range within which it will fluctuate for the remainder of the roasting The trick to normalizing the results of the first few batches of a roasting session is to seemingly overheat the machine during the warm-up, before stabi- first crack should ideally begin in the shaded zone.
lizing it at normal roasting temperatures. To my knowledge, there is no practi- cal, precise way to measure a roaster's thermal energy. However, the operator * I consider the beginning of first crack to be the moment the operator hears more than one can apply some informed experimentation to establish a protocol that brings a or two isolated pops.
the Coffee RoasteR's Companion Which Roast is More Developed?
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Which Roast Is More Developed?
The Three
of Roasting
lease don't take the word "commandment" too seriously. One may trans- P gress some of these rules harmlessly on occasion. As with a certain other
Temperature (°F) list of commandments, however, if you make a habit of ignoring the rules, you might end up in a bad place.
As a roaster and a consultant over the past nineteen years, I've had the opportunity to cup and view the roast data for each of more than 20,000 batches roasted on a variety of machines by various methods. About five years ago, I spent several days poring over reams of roast data in an attempt to find the common elements in the best batches I'd ever tasted.* To be clear, I'm not refer- ring to "really good" batches. I focused only on the data from batches so special Batch A and batch B had identical charge temperature, drop temperature, and roast time. Given that that I could "taste" them in my memory months or years after physically tasting batch A's bean temperature initially rose more quickly than batch B' Comparison of Temper
s, batch A is more developed.
them. That effort yielded what I think of as the "commandments of roasting." A method graduated to a commandment only if it seemed to apply to a great variety of coffees and roasting machines. I've been testing and refining the com- Comparison of Temperature Gradients
mandments for five years, and so far I've yet to find a situation in which coffee tastes better when a commandment is broken. I've also had opportunities to test the commandments in reverse; the times I've tasted stellar roasts from others and the roaster was kind enough to share the roast data with me, sure enough, the profiles conformed to the commandments. I can't fully explain why these methods work. But I'm confident that if you remain open-minded and apply these techniques carefully and completely, you will be impressed by how much better your roasts taste.
i. thou shalt apply adequate energy at the Beginning of a roast
Applying sufficient heat at the beginning of a roast is essential to achieving Temperature (°F) optimal flavor and proper bean development. While one may begin a roast with too little heat and still cook the bean centers adequately, the flavor of such cof- fee may suffer because the operator must lengthen the roast time excessively to compensate for the insufficient early heat transfer.
This graph illustrates the importance of establishing a large DT early in a roast. In batch A, the machine operator applied sufficient energy early in the roast, creating a large DT, which gave the inner bean the impetus to smoothly "catch up" to the outer bean by the end of the roast. Batch B began sluggishly, creating a smaller early DT. Relative to batch A, the operator applied more heat * I compiled and evaluated my roast data by using a pencil, calculator, and spreadsheet. mid-roast to adequately cook the outer bean in a similar total roast time. However, the extra energy These days one can analyze such data much more efficiently with the aid of computer was too little, too late for the inner bean's temperature to match that of the outer bean, and batch B software such as Cropster's "Roast Ranger" application.
was underdeveloped.
the three commandments of roasting
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Roasting
coffee-roasting machine is a specialized oven that transfers heat to coffee A beans in a stream of hot gas while continually mixing the beans to ensure
they roast evenly. Several types of roasters are in use today in the specialty coffee industry: classic drum roasters, indirectly heated drum roasters, fluid- bed roasters, recirculation roasters, and several others. Recirculation roasters return a portion of the exhaust air to the burner chamber to assist in heat gen- eration for roasting. I will use the term "single-pass" to refer to machines that do not recirculate exhaust air. Each roaster design has distinct advantages and disadvantages, though no new design has eclipsed the popularity of the classic drum roaster, the design of which has not changed much in the past century.
classic drum
A classic drum roaster consists of a solid, rotating, cylindrical steel or iron drum
laid horizontally on its axis, with an open flame below the drum. The flame Classic drum roaster. Beans (brown arrows) enter the roasting drum (1) through the loading funnel heats both the drum and the air to be drawn through the drum. A fan draws (2). After roasting, the beans cool in the cooling bin (3). Air (blue arrows) passes from the combus- tion chamber (4) through the roasting drum and exhausts through the chimney (5) by way of the hot gases from the burner chamber through the rotating beans and exhausts cyclone (6), which traps chaff.
the smoke, steam, and various by-products of roasting and combustion out of the building through a vertical pipe, or "stack." The drum's rotation mixes the beans while they absorb heat by conduction from direct contact with the hot drum and convection from the air flowing through the drum. At the completion of a roast, the machine operator opens the door to the drum, dumping the beans into the cooling bin, which stirs the beans while a powerful fan draws room-temperature air through the bean pile to cool it rapidly. The best classic drum roasters have a double drum of two concentric layers of metal separated by a gap several millimeters wide. In a double drum, direct contact with the flame heats the outer drum, while the inner drum remains cooler. A double drum decreases conductive heat transfer and limits the risk of tipping, scorching, and facing. (Henceforth, these three are referred to in this text as "bean-surface burning.") If you buy a classic drum roaster, I strongly suggest finding one that has a double drum. Advantages: The single pass of the roasting gas provides a clean roasting environment, and the drum serves as an effective heat-storage system, provid- ing conductive heat transfer, especially during the first few minutes of a batch.
Disadvantage: Overheating the drum metal can easily lead to bean-surface Single drum (left) and double drum (right) Outer Drum roasting machine designs

To understand the Maillard reactions' contribution to flavor, consider the different effects of roasting and boiling on the flavor of meat: Roasting imparts n  6  n
aromatics, complexity, and depth of flavor absent in boiled meats. Maillard reactions contribute similar roast-flavor traits and complexity to coffee beans. During roasting, once a bean's internal temperature is high enough to boil Heat Transfer
off most of its moisture, the temperature rises more rapidly, speeding Mail- in Coffee Roasting
lard reactions. This is one reason aroma development accelerates at mid-roast. Maillard reactions become self-sustaining at above 320°F (160°C). Unlike Maillard reactions, caramelization is a form of pyrolysis, or thermal decomposition. Caramelization begins at approximately 340°F (171°C),19 as the offee roasting machines transfer heat to beans by convection, conduction, heat of roasting breaks apart molecules of sugar and produces hundreds of new and radiation. Each roasting machine transfers heat by a different mix of compounds, including smaller, bitter, sour, and aromatic molecules and larger, these mechanisms. The following is an overview of how machine design affects brown, flavorless molecules.19 Although most people associate the word "cara- heat transfer. I discuss roasting machine designs extensively in Chapter 7.
mel" with a very sweet dessert food, caramelization, ironically, decreases the Convection, Conduction, and Radiation
sweetness and increases the bitterness of a food or beverage. Lighter roasts are sweeter, and darker roasts more bitter and caramelly, primarily because of "Classic" (my term) drum roasters, which apply heat directly to the drum, cook beans primarily by convection and secondarily by conduction. Radiant heating from hot roasting-machine surfaces and between neighboring beans makes a Caffeine Content and Roasting
small contribution to heat transfer as well. In a personal communication with me, Despite what almost everyone has heard, darker roasting does not decrease a representative of a well-known German manufacturer estimated heat transfer the caffeine content of coffee beans. Caffeine levels are virtually unchanged in his company's drum roasters to be 70% by convection and 30% by conduction.
by roasting,3 as caffeine is stable at typical roasting temperatures. Given that Indirectly heated drum roasters segregate the drum from the heat source to beans lose mass during roasting, their proportion of caffeine by weight increases maintain a cooler drum during roasting. Convection contributes a higher pro- during roasting. Therefore, assuming one brews coffee of all roast degrees with portion of the heat transfer in these machines.
a particular ratio of water to ground-coffee mass, rather than volume, darker Fluid-bed roasters have no drum, and they roast by keeping the beans aloft roasts will yield brewed coffee with higher caffeine content.
in a high-velocity stream of hot gases. Recirculation roasters, such as the Lor- ing Smart RoasterTM, capture and reuse a proportion of the exhaust air from the roasting process. Both of these roasting machine designs transfer heat almost exclusively by convection. At the beginning of a roast batch, charging the beans introduces a large volume of room-temperature beans and air into the hot roaster, sending the environmental temperature in the roaster plummeting. During the first few minutes of a batch in a classic drum roaster, conduction from the hot drum plays a significant role in transferring heat to the beans. As the air temperature in the roaster rebounds after its initial plunge, convection comes to dominate heat transfer. In such a machine the drum acts as a "heat-storage" device that jump-starts development early in a batch. Convection-oriented machines call for the use of hotter charge temperatures to provide adequate heat transfer early in a roast and compensate for lack of a heat-storing drum.
Establishing a high DT Heat Transfer and Temperature Gradient
early in a roast and The first two-thirds or so of roasting is an endo- minimizing it by the end thermic process, meaning the beans absorb of a roast is essential energy, and heat is conducted from the outer to creating good inner- bean to the inner bean. The temperature gra- bean development dient, or "DT," within the beans largely deter- and a uniform roast. mines the rate of heat transfer. Simply put, a the Coffee RoasteR's Companion n  1  n
acids, 2–3, 15–16, 31, 64, endothermic flash, 32 afterburner, 77–78airflow, 35–36, 73–74 air–fuel ratio, 36–37 freezing of coffee beans alkaloids, 2–3 aroma development, 17 automated profiling software, 76–77 baked flavors, 33 green coffee, 1–8, 15–17, 39, 41, 51 batch planning, 34–41 size, 34–35, 52 between-batch protocol, 50 heat transfer, 17–21 blending, 68–69 heat-sink effect, 49 machinery. See: roasting caramelization, 2, 17–18, 31 Maillard reactions, 9, 17–18, 31 charge temperature, 4, 37–39 chemistry of roasting, 1–2, 15–21 moisture content, 7, 21 chlorogenic acid, 16cleaning your roasting machine, 49, 51–52 color changes of beans during roasting, 3, 9–12, 17–18, 31, 55, 57–58 commandments of roasting, 33, 42–48 planning a roasting session. See: batch, consistency between batches, 41–55 pollution control, 77–78 probe, bean, 29–30, 32, 35, 37, 49–50, 52– first, 9–10, 12, 14, 16, 21, 30, 32, 45–48, processing methods, 4 second, 11–14, 33, 45 dry, (natural) 4 Cropster, 44–45, 75 pulped natural, 4 wet, 4purchasing a roasting machine, 72–78 Ddevelopment time, 29, 33, 48 rate of rise (ROR), 32, 42–47, 65 types, 19, 22–26, 37–40, 72–73 refractometer, 55–56, 66–67 drying phase, 9, 29–31 seasonality, of green coffees, 8 consistency, 49–52 software, roasting, 28, 42, 75–77 ambient conditions, 51 chimney cleaning, 51 of green coffee, 5–7 green storage, 51 of roasted coffee, 70–71 degree cinnamon roast, 10 French roast, 12 effect on bean storage, 5–7 full city roast, 11 gradient, 19–20, 43 Italian roast, 12 probes, 49, 53–54 Viennese roast, 11 of bean development, 13, 53–55, 65–68 development, 13, 31, 33, 39–40, 42–48, tools, 55, 66–68 thermometric lag, 30 third-wave coffee, 10 classic drum, 22–26 double-drum, 22–23       fluid-bed, 26 indirectly heated, 24–26 warming up a roaster, 49 recirculation, 27–28 water activity, 7 weight loss of beans during roasting, 13–14, maintenance, 51–52 selection, 72–76 time, 39–40 the Coffee RoasteR's Companion

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