Chang94598 Senior Member Joined: 24 Oct 2007 Posts: 205 Location: SF Bay Area
Posted Sat Feb 13, 2010, 9:28am Subject: Re: Fuji Royal 200g Roaster
Just a suggestion, based on roastings with the HotTop and Mini500.
The approximate time from start of first crack to ending the roast is generally about 3 minutes. For brew coffee and dry processed beans, it can be shorter, like about 2:30. For espresso, it can be a bit longer, like 3:30. Denser, washed beans, like Guatemala SHB or Kenya, can use longer drying time and longer first crack to end roast time.
The Kona is less dense so generally it does not need as long of drying time.
The beans will turn yellow to signal the end of drying period; the environmental temperature is typically at 150-160C. At this stage, extra-cellular water turns to vapor. It is described as "vapor front", moving from outside the bean inward. It is now time to crank up the heat to reach first crack to accelerate the Maillard reaction. Once first crack starts, open the damper to let go of the water vapor and attenuate the increase in ET, but never let it drop. A drop in temperature at this stage will bake instead of roast the beans, due to incomplete formation of various melanoidins and Strecker degradation products of various ketones and aldehydes. The water is liberated intra-cellularly and creating a second vapor front, moving outward. By lengthening the duration of first crack and end of roast, the various chlorogenic acids are converted/degraded to other shorter acids like malic or acetic acid, so the astringency decreases. However, it should not be too long, not significantly longer than 3 minutes, otherwise the fragile, tasty, thiol compounds start to degrade.
The bean mass temperature will be helpful, but not essential, as long as the ET probe and the apperance of various roasting stages can be correlated reliably. This is when the sight glass and trier become handy. For Mini500, most beans will finish the drying stage around 160C, and first crack occurs at 188-191C. It is also helpful to fully open the damper for 30-60 seconds at finishing of the drying stage at 160C, to blow out the chaff.
These are my limited experience for the past three months with a gas roaster, so please take it with a grain of salt.
Chang94598 Senior Member Joined: 24 Oct 2007 Posts: 205 Location: SF Bay Area
Posted Sat Feb 13, 2010, 2:48pm Subject: Re: Fuji Royal 200g Roaster
Simon, another suggestion:
Once the ET temperature is reached, in your case 160C, turn off the gas and load the beans. The ET will initially drop for about 1 to 130 minutes, until it increases again. Record this temperature and time; it is called "turning temperature" or "turning point". By turning off the gas, the cold beans will equilibrate with the drum, and when the gas is turned back on after turning point is reached, they absorb heat as a single unit.
If you don't mind, can you post some pictures of your previous roasts? I suspect some beans will show "tipping". The ends of a coffee bean have lower density and absorb heat faster. If not enough time is allowed for the heat to be transmitted to the coffee bean body, the ends will char, due to short drying time, and applying heat before turning point is reached.
It must be a really nice roaster for USD$4200! It appears to be a capable roaster with plenty of controls. :)
Posted Sun Feb 14, 2010, 2:52am Subject: Re: Fuji Royal 200g Roaster
germantownrob Said:
Edit: Looking at the temperatures more I am a little confused. Your first crack is happening at a low temperature, bean temperature at 1st crack is generally around 204c but you are reporting around 155c. Could you explains some of the details of the temperature measuring probe and it's location? I am wondering if you may be exhausting to much which is effecting the reading yet the heat is still there to progress to first, I am really just guessing though.
The probe is located at the upper part (above axial) of the drum which should measure the environmental (hot air within) temperature. I have checked with Fuji and they told me the readings are normal, as the difference between 1st and 2nd cracks is 20C, with their design. They told me when they roasted the day before, they found 163C(1st) and 185C(2nd).
I don't think I have exhausted too much, as this is a semi-hot air machine, part of the heat was transferred through conduction via the drum.
Chang94598 Senior Member Joined: 24 Oct 2007 Posts: 205 Location: SF Bay Area
Posted Sun Feb 14, 2010, 10:52am Subject: Re: Fuji Royal 200g Roaster
Dear Simon,
The roasted Kona looks beautiful. I was wrong in thinking there may be tipping.
How does it taste? I noticed the duration of time from loading the beans to first crack, about 6 minutes, and then another 6 minutes followed the start of first crack. Typically, 1st crack lasts about 2 minutes, followed by 2 minutes of silence, then 2nd crack starts. I was a little worried that 2nd crack is not reached in 6 minutes, which could mean the beans were baked.
Short drying time can be obtained by smaller load and faster drum rotation. In this manner, the roast takes on properties of hot air roast, or a fluid bed like, flavor. The drying period is used to prepare beans for the chlorogenic acids to be converted to other shorter chain acids. If this process is not complete, more residual chlorogenic will be present at end of roast to attribute to astringency.
A longer post first crack time is described in Taguchi Mamoru's book, which you probably have a copy. It will expand the cellular structure more, so at retail, beans appear prettier. It also decreases the "rawness" at the center of the bean, so if the bean is cut for examination, the whole structure appears uniform. I used to think a completely uniform roast is a virtue, but now I am leaning toward having some uneveness for more complex flavor. By prolonging this time for much longer than 3 minutes, coffee can taste smooth, but possibly flat.
If you don't mind, please try the next roast by lower initial gas, and slightly higher gas after first crack. I noticed you started at 1.4 kPa then decreased it to 0.4 kPa, which is about one third of the starting heat. This decrease may slow down the Strecker reactions, as it needs heat to procceed. Hypothetically, it could start 1.2 kPa, then turn down to 0.8 kPa about 152C (2-3 degrees prior to expected 1st crack), since you know first crack is at 155.1, then finally turn off the gas about 30 sec before you drop the beans. This way, you can use the residual heat from the drum to coast to the end, without scorching.
I am always looking to read and learn more and was interested in the book you referenced. Is it available in English and if so, do you know where I can purchase a copy?
Chang94598 Senior Member Joined: 24 Oct 2007 Posts: 205 Location: SF Bay Area
Posted Sun Feb 14, 2010, 7:30pm Subject: Re: Fuji Royal 200g Roaster
Gary,
The book is available in Chinese and Japanese, unfortunately not in English.
It is a good read about roasting from a different perspective. For example, his typical profile is about 20+ minutes, which probably will not occur in the US. However, because many artisanal cafes in Asia use siphon and manual drip, not just espresso, and acidity is considered a taste defect, this style of roasting makes good sense.
Posted Mon Feb 15, 2010, 12:40am Subject: Re: Fuji Royal 200g Roaster
Chang94598 Said:
Dear Simon,
The roasted Kona looks beautiful. I was wrong in thinking there may be tipping.
How does it taste? I noticed the duration of time from loading the beans to first crack, about 6 minutes, and then another 6 minutes followed the start of first crack. Typically, 1st crack lasts about 2 minutes, followed by 2 minutes of silence, then 2nd crack starts. I was a little worried that 2nd crack is not reached in 6 minutes, which could mean the beans were baked.
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 1,621 Location: Philadelphia Expertise: I love coffee
Espresso: N.S. Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: pour over Roaster: Diedrich IR-1, HT B
Posted Mon Feb 15, 2010, 7:05pm Subject: Re: Fuji Royal 200g Roaster
SimonCHAN Said:
The probe is located at the upper part (above axial) of the drum which should measure the environmental (hot air within) temperature. I have checked with Fuji and they told me the readings are normal, as the difference between 1st and 2nd cracks is 20C, with their design. They told me when they roasted the day before, they found 163C(1st) and 185C(2nd).
I don't think I have exhausted too much, as this is a semi-hot air machine, part of the heat was transferred through conduction via the drum.
I was wondering wondering about the temperatures you have for 1st crack because the internal temp of a bean at 1st is around 180c and surface is around 205c so the 163c threw me for a loop. I was wondering if your exhaust settings where pulling cooler air in front of the temp sensor to create lower readings then the heat that was actually present in the chamber and bean.
The pics of the Hawaiian are great, the blue shading really helps to make the bean color stand out much better then white background photos I have seen.
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 1,621 Location: Philadelphia Expertise: I love coffee
Espresso: N.S. Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: pour over Roaster: Diedrich IR-1, HT B
Posted Tue Mar 9, 2010, 1:55pm Subject: Re: Fuji Royal 200g Roaster
SimonCHAN, if you would be so kind as to post more about your roasting. I still have a few more months before I will be upgrading to a gas roaster and it is inspiring to see what you and Henry are doing with each of your machines.
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