Posted Wed May 7, 2008, 7:31am Subject: How Does Ambient Air Temp Affect Roasting Profiles?
Now that it's considerably warmer, my programs are going to espresso when I run a full city + program.
If I punch cool cycle earlier based on color, I get a bean that is too light and less roasted inside.
Should the adjustment be for higher temps early on but shorter times, or a longer phase of low temps to high? Current setting is 3 min @ 375, 8 min at 450. This burns to fast.
In short, what is a good program for full city and full city + ?
Starchief Senior Member Joined: 7 May 2008 Posts: 16 Location: Rocky Mount, NC Expertise: Just starting
Grinder: manual Roaster: hot air
Posted Wed May 7, 2008, 8:11pm Subject: Re: Ambient Air Temp and Roasting Profiles
I don't have a programmable unit...only a modified hot air popper...and I simply use my eyes, nose, and ears. Due to the chaff, especially from Ethiopian Misty Valley, I roast outside, and have noticed a difference in profiles during hot weather and cold. The heat on my roaster is controlled by a variac, the fan is variable by rheostat, and I've mounted a thermocouple inside to monitor the temp. Using these and watching, smelling, and listening closely, I've gotten pretty consistent results. Not sure what I would do if it was an automated/programmable machine...sorry.
jcardina Senior Member Joined: 10 May 2007 Posts: 14 Location: Canada Expertise: I love coffee
Espresso: Silvia Grinder: Rocky Roaster: IRoast2
Posted Sat May 10, 2008, 3:20pm Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
mrhagerty Said:
Now that it's considerably warmer, my programs are going to espresso when I run a full city + program.
If I punch cool cycle earlier based on color, I get a bean that is too light and less roasted inside.
Should the adjustment be for higher temps early on but shorter times, or a longer phase of low temps to high? Current setting is 3 min @ 375, 8 min at 450. This burns to fast.
In short, what is a good program for full city and full city + ?
In my experience ambient temperate of even a slight difference can make a huge difference in the roast level. I'm not sure why to be honest. I would expect it if I went from indoors to outdoors where there is a huge temp. difference but it seems even a slight one indoors can make a huge difference. I program three different profiles from light to dark and do the first one at medium then pick the second one depending on the results.
RayT Senior Member Joined: 11 May 2008 Posts: 8 Location: Glendale, AZ Expertise: I live coffee
Posted Sun May 11, 2008, 9:22pm Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
Completely affects the roast.
Unless a person is roasting in a controlled environment i.e. inside with a thermostat controlling the temp, I would think that any roasting has to be done with no to little automation.
Posted Sun May 11, 2008, 9:52pm Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
Like Bruce, I run a poppery using Variac and Thermometer to guide the roast by time and temperature. It is entirely 'manual' but does not require constant adjustment of the variac to keep on track. I have been able to keep a consistent profile (batch to batch) in ambient temps from around 50-75F, simply by adjusting the Variac. I did observe a difference in roast results when temps were around 40F. I was able to achieve the same temperatures in the roaster by cranking up the voltage, but the beans appeared to be a darker roast than the temps would otherwise indicate. (some oil spots too, where I usually have a dry surface at Full City) My theory on this is that the 'maximum environmental temps' in the popper were significantly higher to make up for the heat losses due to the lower ambient temps. After a couple batches came out like this, I moved my winter roasting to the garage and set my lower limit to 50F for roasting. While it is possible to roast at lower temps, I don't get the same repeatable results. So I don't go there.
Posted Mon May 12, 2008, 7:33am Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
Now consider what's going to happen when temps outside hover at 102 everyday and at night cool to maybe 90.
Guess I'm wondering HOW to adjust. Is it better under those conditons to have a longer period at lower temps so that that bean gets completely roasted rather than burned quickly on the surface but barely roasted inside?
RayT Senior Member Joined: 11 May 2008 Posts: 8 Location: Glendale, AZ Expertise: I live coffee
Posted Mon May 12, 2008, 9:01pm Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
Yes, I'm in Phoenix and with an air-roaster and very little ability to adjust anything, I wind up with "summer" roasts.
moving up to a bigger and better roaster here pretty soon so I'll have a chance to figure this question out, but from what little I do know in manipulating the roast, I would think bringing it in slowly and then a quicker run up in temp at the end.
I might be wrong, but that's why I go to places like this.
Posted Tue May 13, 2008, 8:44am Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
Ideally you want to have the same roast profile regardless of ambient temps. Anything less is a compromise. The closest way to do this would be to control the 'bean mass' temp and adjust the heaters lower as ambient temps rise. There is no reason you can't roast with ambient temps of 90-100F. (I haven't had a reason to try it ...yet. ) I have no experience with your roaster though an analog knob on the heater output would seem to be a good approach.
CoffeeRoastersClub Senior Member Joined: 6 Jul 2005 Posts: 2,057 Location: Vernon Expertise: Professional
Espresso: Vintage La Pavoni Lever... Grinder: KitchenAid Pro Line Burr... Vac Pot: Vintage Silex Drip: Aeropress, French Press Roaster: "EL SUPREMO" w/QuikSPIN-CRC...
Posted Tue May 13, 2008, 11:21am Subject: Re: How Does Ambient Air Temp Affect Roasting Profiles?
mrhagerty Said:
Now that it's considerably warmer, my programs are going to espresso when I run a full city + program.
If I punch cool cycle earlier based on color, I get a bean that is too light and less roasted inside.
Should the adjustment be for higher temps early on but shorter times, or a longer phase of low temps to high? Current setting is 3 min @ 375, 8 min at 450. This burns to fast.
In short, what is a good program for full city and full city + ?
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