What's a light roast? - Page 11

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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Chert
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#101: Post by Chert »

I observe that the Quest and the Roest profiles shown on this thread have a TP at around 0:45 s. My Huky TP is invariably around 1:30. Almico's 5kg is a bit earlier like 1:17. I'm not sure if that is just hardware difference or speaks to faster roasting, earlier upfront heat.

I have been tasting the Ethiopia light roast from post #67 I have had muted citrus and slight underdevelopment shots compared to the earlier light roast with crash of the same bean. But more recent shots it is opening up some, until my noon shot today, which was a 10 second 3 bar preinfusion bloom, followed by declining 8 bar 40 sec normale extraction. Delicious and the overall taste impression was rootbeer. What the heck?!? I would not expect that from a light roast Ethiopian.
LMWDP #198

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Almico

#102: Post by Almico »

false1001 wrote:I recently got a Bullet (and will be forcing a reference to it in every subsequent post for the next month) and have been using some cast away beans from a local roaster's wholesale espresso blend (read: cheap and stale green) to season and learn how to control roasts. I have one bag that's ~8 months old and one that seems to be about a year old. It hit me about seven roasts in that you can tell a marked difference between the lots in FC... the year old ones have a soft and meandering FC, the 8 month old ones are a little louder and the cracks are closer together, and when roasting fresh SO's from sweet marias FC is loud and quick. I guess I only just noticed this is because the last time I roasted such low quality beans was years ago when I was just learning.

I think most of us roast at about the same high quality of green, but I think it's hard for the vast majority of home roasters to get truly super fresh green just due to middlemen and shipping time. Could a much larger part of the equation simply be that the top Nordic roasters have access to much fresher and higher quality materials, thus reducing FC time making it easy to roast hot and fast? There's bound to be more moisture creating far more pressure in the bean and a faster crack. I'd also bet moisture content distribution across individual beans is much tighter the fresher the beans as well.
Most coffee origins have a cycle. Ethiopia coffee, for example, is hitting warehouses this and next month. If you buy Ethiopian coffee in January, it is last year's crop. Some coffee holds their own for a year, others not nearly so long. I just tossed 40# of a very nice Guat that was just done. Unless I wanted to burn it, it tasted like cardboard and all that watermelon juiciness that was there just a few months before was gone.

One way to tell bean freshness is to throw a few green seeds on a wet paper towel for a few days. If it sprouts, it's very fresh.

Water activity, or the amount of moisture a bean will absorb and release post processing is a good indicator of how slow or fast a green will stale. Unfortunately, this is a fairly difficult thing to quantify and most green purveyors that I've come across do not know, or publish this information if they do. I think the coffee business is just too big and fast to bother micro-analyzing every nuance of a particular coffee. Hunt it, cup it, score it, buy it, sell it, next...If it sits around long enough to over analyze it, it's stale already or has at least morphed into something else. Better suppliers will recup their offerings mid season and rescore them to see how they are holding up. If the quality dips, they will adjust the price.

As a coffee hobbyist you can pick and choose the coffees you drink and only buy the freshest beans. As a roaster/retailer, it is trickier. I have customers that do not understand the seasonality of coffee and want what they want when they want it. I have to ensure I have those beans on hand all year at the expense of a little freshness. I keep my SO offerings much more seasonal, only buying a bag or two at a time and running out when it's gone and replacing it with something else.
Chert wrote:I observe that the Quest and the Roest profiles shown on this thread have a TP at around 0:45 s. My Huky TP is invariably around 1:30. Almico's 5kg is a bit earlier like 1:17. I'm not sure if that is just hardware difference or speaks to faster roasting, earlier upfront heat.

I have been tasting the Ethiopia light roast from post #67 I have had muted citrus and slight underdevelopment shots compared to the earlier light roast with crash of the same bean. But more recent shots it is opening up some, until my noon shot today, which was a 10 second 3 bar preinfusion bloom, followed by declining 8 bar 40 sec normale extraction. Delicious and the overall taste impression was rootbeer. What the heck?!? I would not expect that from a light roast Ethiopian.
My Cormorant is turning in under a minute with 100g charges. I can't seem to mitigate that, But I just had a cup of Rwanda roasted the other day that was spectacular, Huge Anise nose. I had customers stick their nose in the sample bag and everyone recognized it immediately. It smelled just like pink Good & Plentys. It even held up in the cup once the temp dropped a bit. How about that for a flavor note on a bag of coffee!!!

Image

EddyQ

#103: Post by EddyQ »

Chert wrote:I observe that the Quest and the Roest profiles shown on this thread have a TP at around 0:45 s. My Huky TP is invariably around 1:30. Almico's 5kg is a bit earlier like 1:17. I'm not sure if that is just hardware difference or speaks to faster roasting, earlier upfront heat.
TP is almost 100% due to probe response. The time may change a slight bit due to different amounts of heat happening at the time or with differences in beans. No matter what I do with air/heat with my Quest or North makes only +/-10second difference.

A more representative bean temp occurs 30-60s after TP and is a temperature/time worth noting. My TP are typically at 50sec. I like to compare the time when the BT crosses 200 or 250F, which is past TP. For a roast with slow start, it crosses 200F in 2 - 2.5 min. Fast is crossing 250F in less than 2min.

Interesting fact is the beans which rise from 70F(room temp) to 200F in 2min has a RoR average of 65deg/min and likely faster at charge. 250F in 2min is RoR of 90deg/min. So the high peak in our RoR curves is also a near meaningless point where probe catches up to true RoR.

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Almico

#104: Post by Almico » replying to EddyQ »

True dat. I'm using a 2mm probe in the Cormorant and a 3mm in the 5kg. The calibrating factor is when the coffee yellows.

Rush

#105: Post by Rush »

Drum thermodynamics factor into TP. Has anyone ramped up or down drum speed to see what happens to TP?

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Chert
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#106: Post by Chert » replying to Rush »

I can try that. I run mine at 54 and can ramp up to 72. But how much difference will affect a TP change? I'll check with next roast.
LMWDP #198

mathof

#107: Post by mathof »

Almico wrote: I have customers that do not understand the seasonality of coffee and want what they want when they want it. I have to ensure I have those beans on hand all year at the expense of a little freshness. I keep my SO offerings much more seasonal, only buying a bag or two at a time and running out when it's gone and replacing it with something else.
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Maybe it would be worthwhile to freeze your green beans, in the manner of George Howell.

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Almico

#108: Post by Almico » replying to mathof »

It might, but I don't have room for a freezer that size. I would need a walk-in freezer.

I just need to manage my coffee commitments better. But it's hard to resist buying a great coffee when it comes around. Before I know it I have more coffee than I can reasonably sell. I'm having that issue with this Rwanda right now. It smells like pink Good N' Plentys. Very sweet, very approachable acidity and very unusual. But I just have no room in the stable.

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Chert
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#109: Post by Chert »

Rush wrote:Drum thermodynamics factor into TP. Has anyone ramped up or down drum speed to see what happens to TP?
I went to 72 RPM. Louder sound of axel turning. My ET probe reading hugs a bit closer to BT. But TP has not noticeably changed. Still about 1:30.

[EDIT] to show graph with 72 RPM drum speed of tonight, background has my usual 54 RPM. Image
LMWDP #198

Rush

#110: Post by Rush »

Chert wrote:I went to 72 RPM. Louder sound of axel turning. My ET probe reading hugs a bit closer to BT. But TP has not noticeably changed. Still about 1:30.
Thank you for reporting back! I'll see if I can share similar data.