Subjective Roast Levels

#1: Post by **Jimjam168** » March 4th, 2021, 7:42 pm

Hi folks- I think I've seen anecdotes that Starbucks Veranda is a solid barometer for what most coffee enthusiasts would deem medium. This is sort of useful since Veranda is available everywhere and is well known. However I brew a lot of George Howell as a hometown bias, so that is a much better barometer for my personal purposes.

So my question- What's the best way to verbally communicate roast level? To me, GH Alchemy or Single Origin Medium Roasts are on the medium to light end of the spectrum. Is that accurate?

Reason I ask is mainly for brewing advice and diagnostics as well as buying advice- Flow profiling/no profiling, etc.

#2: Post by **daustin777** » March 4th, 2021, 7:54 pm

There is the Agtron Gourmet Scale. You can use a device to read the beans or use color swatches to match the color of the coffee to the appropriate number on the Agtron scale. In addition to Agtron, there are similar scales, such as Roastrite that sells a swatch card for about 20 USD.

March 4th, 2021, 9:46 pm

Thank you David- Taking a look now and this is exactly what I'm looking for.

#4: Post by **KCcoffeegeek** » March 5th, 2021, 9:19 am

If you want to get a little fancier, you can also get an affordable instrument called the Roast Vision from Espressovision. They run $200-$300, I believe, which is a lot of money, but a lot cheaper than anything like it on the market, for sure. It reads its own scale from 0-35 but there is a conversion from Roast Vision to Agtron for standardization. Works really well, I've been using one for several months and it has a normal standard deviation of +- 1. Keep in mind, this is ONLY a "visual" analysis of the coffee and more goes into evaluation a roast than this. For example, I ran it on some beans a few months ago of an Oddly Correct coffee from here in Kansas City and it was reading in the "medium light" range, but the roaster told me this was, by far, the lightest coffee roast he has done based on the actual temperature specs for this bean. In other words, the coffee took on more color and looked darker than it tasted or was roasted to compared to other beans for whatever reason. Still, a useful device to have and I like having it for home roasting as well as evaluating coffees that I review.

March 6th, 2021, 9:33 am

I use a Tonino roast colour meter to measure coffee grinds. When dealing in, I can compare (through my Atago refractometer) the TDS (total dissolved solids in the cup) and EY (extraction yield of the beans) to my personal preferences, until I find the grind and machine profile I like best. This process yields a more or less different target for each coffee, which I can then use to measure changes over time of a coffee and compensate (by grinding and preinfusion) to keep the flavours and intensity as I like them. This process is made quicker and easier by having a starting point established by the degree of roast colour and prior experience with beans of that colour reading.

#6: Post by **jpender** » March 6th, 2021, 1:26 pm

mathof wrote:I use a Tonino roast colour meter to measure coffee grinds. When dealing in, I can compare (through my Atago refractometer) the TDS (total dissolved solids in the cup) and EY (extraction yield of the beans) to my personal preferences, until I find the grind and machine profile I like best. This process yields a more or less different target for each coffee, which I can then use to measure changes over time of a coffee and compensate (by grinding and preinfusion) to keep the flavours and intensity as I like them. This process is made quicker and easier by having a starting point established by the degree of roast colour and prior experience with beans of that colour reading.

Are you saying that you have been able to formulate a reliable correlation between roast colour and optimal extraction yield?

#7: Post by **mathof** » March 6th, 2021, 4:42 pm

jpender wrote: Are you saying that you have been able to formulate a reliable correlation between roast colour and optimal extraction yield?

No. Optimal -- to my taste -- extraction yield might be, say, 19% for one coffee and 21% for another coffee of the same roast colour. But both will probably be in the same ballpark for grind settings and preinfusion time/lever technique, et al. Think of the well-established differences between extracting dark and light roasts; it's the same thing, but with more refinement. If I know the roast colour of a bean, I know where to start dealing in (grind setting, brew water temperature, preinfusion parameters, &c). That's all.