Recently, I have acquired both decent grinders in each class of conical burrs( Pharos) and flat burrs(Major), this made me wondering about the differences between these two burrs. They might not be a representative of each class but they sure are an intresting comparison.
Initially, I was under impression that conical burrs give a brighter profile , but it seems that probably this is not true throughout all the conical burrs. I posted a question on Home-Barista forum and it seems that only some people agree that a conical grinder gives brighter profile, and that some conicals are actually not as bright as flat ones. This really come as a surprise for me.
Quoted from the thread itself:
"No, I don't think it's "generally accepted." There is a conventional wisdom in the industry that big conicals run their throughput faster and so build up less heat in a retail environment. Some think they clump less......I think you are taking the personal experiences of a few posters on H-Band expanding it to a rule that bears further testing."
"The Kony was brighter than the Jolly for many of the TGP tasters; the other flats and conicals did not show this level of difference."
So, if you have both conical and flat burr grinders, you could procceed to do this as a contribution to the survey. First you have to try and make both pulling condition as close as possible. This includes: brew temperature, brew ratio(coffee ground weight/shot weight), pulling time, coffee, taste time/temp between two. It would be best if there's an extra person to help you, preventing bias even before the result.
Here's what I do
i) Dial in both grinders.
ii) Have two similar demitasses. Prewarm first cup(Cup 1). Let the other cup at room temp(Cup 2).
iii) Grind and proceed to pull the first shot. Pull it when the the temp strip shows 194F and pressurestat is at the bottom of its cycle(like temp surfing)
iv) Pull to a desired brew weight ratio. I chose 50% (14g coffee : 28g shot) because that's how I brew my normal shots.
v) Grind the second one and pull the shot. Remember to cool the grouphead to the same temperature and pull at bottom of pressurestat cycle.
vi) Sit down, relax, and start tasting. Close your eye and swap the cup around so you don't know which is which.
vii) Jot down your thoughts and compare both. Rinse mouth with water in between.
If you have time, definitely, try it and share your results. This procedure is specific to my machine and could be modified to it yours. Repeat as needed to make sure that there is a consistent difference between the two results. I only did twice and draw my conclusion. Maybe that's where I fail. Also, my Olympia Cremina is probably a good lever machine. But when it comes to side-by-side comparison, it isn't precise enough to eliminate difference between shots. It's probably not the best candidate to do this test. La Peppina or 2 group Lusso is best delegated to this comparison testings.
Here's an interesting response I got(from Jim), but has nothing to do with the conical vs flat. It's an explanation to "Why underextracted shots tasted more acidic than a properly extracted one?" Just thought it's really worth sharing.
"An underextracted coffee has the fast dissolving compounds that, if the coffee is good, you want. This includes all the fruit acids and the short chain sugars. It will also have the medium speed compounds (unless you really screwed up) like the toasty, rooty, herbal, and nutty flavors. The mark of underextraction is that you are missing the caramels, along with the cola and cocoa flavors, and the long chain compounds that give the sensation of body and that reduce astringency (i.e. take the edge off the taste).
A fully extracted coffee is just as acidic as an underextracted one, it just has the sweetness and body to balance the sour tastes. When the coffee is very ripe and has a lot of sugar, a relatively underextracted cup will have more clarity and still be sweet; but that is rare. Older coffee looses its less stable, short chain compounds more quickly than the long chain ones; so coffee should be extracted less as it ages."
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