Timing the Drying phase

 Drying time in coffee roasting—the phase from charge to the yellowing/browning point (typically 100–160°C / 212–320°F)—is determined by the need to evaporate 10–12% moisture from the green beans. This stage usually lasts 4–7 minutes. 

Key factors influencing this duration include:

1. Bean Physical Properties

Density: Denser beans (e.g., high-altitude, strictly hard bean) are harder for heat to penetrate and require more energy and longer drying times.

Moisture Content: Higher moisture content requires a longer drying phase to evaporate water without creating uneven moisture pockets, which can lead to burnt exteriors and raw interiors.

Processing Method: Natural process beans often have higher sugar content and can dry faster, sometimes needing lower initial heat to avoid scorching compared to washed beans. 

2. Roaster Technology and Control

Roaster Type: Fluid-bed (air) roasters often dry faster than drum roasters due to more efficient convective heat transfer.

Batch Size: Larger batches hold more total moisture and have higher thermal mass, requiring more energy and longer time to heat evenly.

Charge Temperature: The initial temperature of the roaster affects how fast the beans turn color. A higher charge temperature generally results in a shorter drying phase, while a lower charge temp extends it.

Airflow Settings: Higher airflow increases the rate of evaporation, speeding up the drying phase. 

3. Environmental and External Factors

Ambient Temperature: A colder roasting environment will increase heat loss from the machine, requiring more time to reach the yellowing point.

Humidity: Higher humidity in the air can slow down the roasting process by making it harder for the beans' moisture to escape. 

Optimal Drying Strategy

Avoid Rushing: Rushing the drying phase can lead to uneven, underdeveloped, or "baked" coffee.

The "Yellowing" Target: A common goal is to reach the yellow/tan color shift around the 5-minute mark.

Aroma Cues: The stage ends when the aroma changes from a grassy/hay-like smell to a sweeter, bread-like aroma.

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Typically I like to see a ROR of about 18-25

It will be higher at the beginning as you are introducing more heat very quickly

Typically the time from "charge" to "dry end" = 50% of the total roast time

Browning = 30%

Development = 20%

These ratios though not exact give you a good idea if your roast is progressing in a timely manner

Behmor Roaster - general temps etc

Important nuance to note with your Behmor

The Behmor doesn’t directly display true bean temperature—it shows a chamber/wall temp. 

The actual bean temp isn't the sensor reading & the Behmor temps are nothing like what you'd expect from a standard drum roaster.

The Behmor uses an infrared quartz heating element that heats differently to a gas flame, hot plate, electric coil or air-convection. Quartz light provides near instant heat but unlike most heating elements it heats objects not the surrounding air. The infrared rays (similar to the sun) pass through the air and are absorbed by solid objects.

The Behmor roaster safety button requires users to press the START button  (or C button) within a 30-second window when the timer hits 75% completion (e.g., 2:30 remaining on a 10-minute roast), indicated by a flashing display. Failure to do so results in Error 7 (Err7) and an automatic, forced cooling cycle to prevent fire hazards.

🔥 Use Temp B (chamber) as your main reference

Why Temp B is better

+ It measures the air temperature in the roasting chamber

+ That’s closer to what the beans are actually experiencing

+ It responds more smoothly and predictably during the roast.

+ The B probe is attached below the drum chamber.

+ Most Behmor roasting guides and profiles are based on Temp B

🧱 Temp A is focused on measuring the exhaust temperature .

Exhaust temps are generally useful for measuring the momentum and total energy in a roaster, however Temp A doesn't seem to measure anything until latter in the roast cycle..

+ It is useful as a secondary safety indicator (e.g. overheating), but not for tracking roast stages.

+ The “A” temperature reading only becomes active midway through the roast when the fan kicks on. 

🎯 Practical takeaway

Track your roast stages (dry end, browning, first crack) using:

Temp B + time + sensory cues (smell, sound, colour)

Glance at Temp A only to make sure things aren’t running away too hot

🧠 Simple rule of thumb

Temp B = “what’s happening to the beans”

Temp A = “what the machine walls are doing”

🎯 Charging/Preheating

Charge temp

On a Behmor 1600 Plus Coffee Roaster, “charge temp” isn’t as tightly controlled as on a commercial drum roaster—but you can still think in terms of a preheat target (Temp B) before you drop the beans.

🔥 Good starting charge (preheat) temps:

The manual recommends:

 Press any weigh and then Start. Allow the system to run for up to 1:30 minutes. Press OFF,

insert roasting drum, tray and start your roast.

Use Temp B (chamber temp):

I pre heat to 104C-120C (220-250F).

+ Preheat with the chaff collector in (and if possible, the drum too).

+ Load beans quickly

+ Start on P1 or P2 (full or near-full power) in auto mode

    or P5 in manual mode.

Adjust based on goals:

+ Want more acidity / shorter roast → charge closer to 120C

+ Want more control / smoother profile → stay around 100°C

☕ What actually happens on Behmor

When you add beans, temp will drop hard (20–40°C)

Then it climbs back up as the roast progresses

So your “charge temp” is really about:

+ how much momentum you start with

+ how quickly you get through drying

⚠️ Behmor-specific quirks

Preheating too high (>150°C) can:

+ Trigger safety shutdown

+ Increase risk of scorching

As there is no direct bean temp probe → rely on:

+ time to dry end (~4–6 min)

+ time to first crack (~9–12 min)

🧠 Simple rule of thumb

Start around ~120°C Temp B, then adjust based on:

+ How fast you hit dry end

+ How soon first crack arrives

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🌡️ Dry End Temperature Range

~140°C to 160°C (302°F to 320°F bean temp equivalent)

Many Behmor users track dry end by time + visual cues:

Usually around 4–6 minutes into the roast (depending on batch size and profile)

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☕ Browning Phase (Maillard Reaction)

🌡️  temp (approx.).. B button

~140-150°C 

👀 What to look for

Beans shift yellow → light brown → cinnamon

Smell turns from hay → bread/toast → caramel

Surface becomes more matte and textured

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🔊 First Crack

🌡️  temp (approx.)

~141°C on the B probe.

👂 What to listen for

Distinct popping/cracking sounds (like popcorn, but sharper)

Beans visibly expand and shed chaff

Aroma becomes sweet, nutty, more “coffee-like”

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Afterburners.

Mid way through the roast there will be a temporary drop in the B temperature.

This is normal. The program is designed to have a fan come on to pull air/ smoke through the afterburners to burn off smoke and other impurities. 

When the afterburners come on, heat will be drawn over the beans and away from the sensor thus the reading on b drops.

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Below are 2 examples of standard medium roast profiles.

They are useful guides as to what sort of temperatures the Behmor will read during a standard roast.

The first is a 200g roast. @ 200g setting.

I press the200g button, then P1 button + "start".

Then press P5  (to enter manual mode)

Note that in manual mode, P5 = 100% power.

(Temp: just using the B button - for chamber temp only)

Note that my max temp for this roast is 160C (The Behmor automatically shuts down at 170C)

so one of my goals is to keep the B temperature below this value.

Charge temp: 120C

Time    Temp B

00.00 : 120C (charge)

00.30 : 120C (press P5)

01.00 : 126C

01.30 : 132C

02.00 : 138C

02.30 : 145C

03.00 : 151C

03.30 : 157C (press P4)

04.00 : 162C (press P3)... I dropped temp to P3 to avoid the shutdown feature

04.30 : 163C

05.00 : 160C (@ 5mins the fan will start & the heat will start to drop, so I'll need to increase the power)

05.30 : 146C (press P5)

06.00 : 142C

06.30 : 146C = Dry End

07.00 : 148C (press P4) ... I'm gradually reducing the temp...you can also open the door to cool the roast

                                           Also use fast drum (this mimics air flow in a drum roaster)

07.30 : 148C (press p3)... I'm stretching out the browning phase by making sure the 

                                          temperatures aren't constantly increasing.

08.00 : 147C

08.30 : 142C (press P4)... increase the temp a bit.. stabilise the temp .. avoid crashes or peaks

09.00 : 141C

09.30 : 141C

10.00 : 141C

10.30 : 141C --- First Crack  

11.00 : 142C (you could press P3 or P2 to lower the temp if desired).

11.30 : 138C 

12.00 : 140C... exothermic reaction !

12.30 : 142C

13.00 : drop

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This is an example of one of my standard medium roast profiles.

This is a 100g roast. @ 200g setting.

I press the 200g button, then P1 button + "start".

Then press P5  (to enter manual mode)

Note that in manual mode, P5 = 100% power.

(Temp: just using the B button - for chamber temp only)

Note that my max temp for this roast is 160C (The Behmor automatically shuts down at 170C)

so one of my goals is to keep the B temperature below this value.

Another goal is to aim for a 50% drying ratio, 30% browning, 20% develop.

So accurately marking Dry End, FC, etc is impt.

Actual Charge Temp : 92C (B setting)

I preheated the drum & machine to 110C but lost some heat when I opened the door & dropped

the beans into the drum.

Time    Temp B

00.00 : 92C (charge)

00.30 : 93C (press P5)

01.00 : 100C

01.30 : 101C

02.00 : 102C

02.30 : 120C

03.00 : 137C

03.30 : 143C 

04.00 : 150C 

04.30 : 155C

05.00 : 157C  - fan kicked on. The A temp is available now.

05.30 : 162C    I pressed P4 to lower temp. 

06.00 : 158C = Dry End @ 5.40

06.30 : 157C 

07.00 : 156C .. I'm gradually reducing the temp...you can also open the door to cool the roast

                                           Also use fast drum (this mimics air flow in a drum roaster)

07.30 : 155C (I could press p3 but the temp seems pretty stable for now)... 

                      I'm stretching out the browning phase by making sure the temperatures aren't 

                      constantly increasing.

08.00 : 155C

08.30 : 142C (press P4)... increase the temp a bit.. stabilise the temp .. avoid crashes or peaks

09.00 : 144C

09.30 : 147C --- First Crack  ?

10.00 : 150C

10.30 : 152C Drop

If you intend to run the full cooling cycle  press "cool" on 1st crack since the roast will continue to develop while the hot chamber cools.

Behmor roaster P3 test - Vietnamese Robusta

 Trialing some Vietnamese Robusta on the P3 setting of a Behmore 2020 roaster.

Profile P3  auto mode – Soft Bean, Low Grown, Espresso Blend

 Brazilians, Africans, Southeast Asians, Malabar*, Jamaican Blue Mountain and Yauco Selecto

 (Puerto Rican)

 Press appropriate weight button (100, 200 or 400) then press P3 button, then press Start button .

I used 200g

I didn't preheat the roaster and just let it run the Auto P3 cycle including the full 12 min cooling cycle.

A = Exhaust temp

B = Side wall temp

Time       A          B

0            0        0 

0.30        20        26 

1.00        20        31

1.30        22        39

2.00        22        47

2.30        22        50

3           23        63 

3.30        23        72

4           25        78

4.30        27        86 - smell bake ... end of drying phase

5           27        91

5.30        88        97

6          110        100

6.30       129        103

7          143        106

7.30       154        109 -- yellow phase

8          163        112

8.30       167        111

9          179        123   

9.30       185        128

10         189        123  - browning

10.30      189        135

11         194        139

11.30      195        141 - 

12         205        132

cooling - 12 mins

200in, 179 g out

10% weight loss.

Thus light roast

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Behmor Coffee roaster Brazil

These are my readings using a Behmor roaster .

Auto mode P2 

Brazil - high altutude

 1200m 

Cerrado Arabica

 200g start

Cold start - no preheating

https://en.wikipedia.org/wiki/Cerrado

Brazil Cerrado coffee is a 100% Arabica bean known for its smooth, balanced profile with low acidity, a medium body, and a sweet finish often featuring notes of chocolate, caramel, and nuts. 

It is highly versatile and frequently used in espresso blends because of its soft, rounded cup and creamy texture. The region's sustainable farming practices also contribute to its quality and unique flavor. 

Flavor and characteristics

Tasting Notes: Chocolate, caramel, nuts, and sometimes hints of dried berries or citrus.

Body: Medium to full, with a smooth and creamy mouthfeel.

Acidity: Low, making it a mellow and balanced coffee.

Aftertaste: Clean and sweet, often with a caramel aftertaste.

Best for: Espresso blends and single-origin brewing, as it is very drinkable and well-suited for different preparations. 

Region: The Cerrado region in Brazil, a vast area known for its optimal growing conditions and fertile savannahs.

Grade: Considered a fine cupping Arabica and a high-grade Brazilian bean.

Farming Practices: Many farms employ sustainable methods such as shade-grown cultivation and water conservation techniques. 

Suitability

Espresso: Excellent for espresso blends due to its low acidity, smooth body, and ability to create a rich, rounded cup.

Versatility: Works well as a single-origin coffee for drip or pour-over methods as well.

Overall: A popular choice for those who prefer a mellow, well-balanced, and sweet coffee without high acidity

Start weight : 200g

End weight 170g

15% weight loss = dark end of medium roast.

Just before 2nd crack

A = Exhaust temp

B = Side wall temp

Time       A          B

0               0        0 

0.30        20        32  

1.00        20        42

1.30        18        58

2.00        18        69

2.30        20        78

3             20        89 

3.30        22         98

4             22        106

4.30        23        112 - smell bake ... end of drying phase

5             47        114

5.30        84         113

6            113         110

6.30        132        108

7            143        108

7.30        153        108 -- yellow phase

8            162        108

8.30       167        111

9            173        116   

9.30       180        119

10          184        123  - browning

10.30     188        127

11          190        129

11.30      188        127 - FCrack

12           198        135

12.30      198        137

13           203

Profile P1 (Default) - Hard Bean (Highest Heat Profile)

 All Centrals, Peruvian and Colombians

 Press appropriate weight button (100, 200 or 400), then press Start button

Note, Profile P2  is also for Hard Bean All Centrals, Peruvian and Colombians 

 P1 in Auto Mode raises the temperature as fast as possible without scorching (and doesn't cut the power). 

P2 in auto raises the temperature as fast as possible (like P1) and then it  drops in power to 70% at the 2/3 mark of the roast. It holds this power setting till 9/10 of the roast time where the power rapidly increases to 100%.

These temps are a indication of what to aim for in manual mode.

my graph

A = exhaust temp .... more useful than the side wall temp

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