daktarz Senior Member Joined: 3 Jan 2004 Posts: 298 Location: Bay Area, CA Expertise: I love coffee
Espresso: Isomac Rituale Grinder: Mazzer Mini Drip: umm French Press? Roaster: Does an outdoor smoker...
Posted Tue Jun 15, 2004, 9:38am Subject: Re: When does a shot go blond?
afx Said:
I am looking for blondness parameters (time, pressure, expansion room, basket, grind, roast, phase of the moon, whatever).....
What exactly makes a shot go blond? What determines the time after which it goes blond? Why does the blond phase come abruptly in some cases, and gradually in others? Is there a strict/constant relationship between bitterness and going blond?
(a) Water running through coffee grounds that have no/little soluble coffee left in them.
(b) How much coffee is in the puck, speed with which water is flowing through.
(c) If the puck isn't solid (i.e. a channel forms) then the water will zip through the channel rather than percolating through the entire puck. Result is an abrupt change to blond. If uniformly percolating through then transition is gradual as all soluble are leeched away.
(d) Don't know what you mean by "strict". If you wait long enough the blond will turn clear (i.e. NO coffee being extracted) and the water will not taste bitter, it'll taste like water. There's a gradual transition and that's what makes espresso-making an art.
Posted Tue Jun 15, 2004, 10:35am Subject: Re: When does a shot go blond?
Regarding c: channeling of course is an issue. But what I also found is that different baskets seem to have different blond switch times. The Cimbali and LM are more gradual then the Oscar basket. The Cimbali and LM baskets will have dark streaks in a lighter flow while gradually switching from more dark to more light. Is there an optimal percentage for cut off?
Does the age of the beans have an influence here?
Regarding d: what I was thinking about is the taste turns more bitter when the blond phase starts. Of course, on the long run there will be only water.
jim_schulman Senior Member Joined: 19 Dec 2001 Posts: 3,772 Location: Chicago Expertise: I live coffee
Posted Tue Jun 15, 2004, 1:40pm Subject: Re: When does a shot go blond?
Here's a chart of extraction colors on volume and time axes. Low flowing shots like ristrettos stay dark longer than fast flowing ones, and extraction times have to be adjusted accordingly.
Different baskets, even those that hold the same weight of coffee, seem to "prefer" different shot lengths -- the LM is good for 2 ounces (50mL), the Cimbali seems to like about 1.5 (40mL). The Faema seems to prefer 1 to 1.25 ounce ristretos (30mL). Never tried the NS or Rancilio, but these hold less coffee (14 grams, not 18 to 20), so shots should be shorter in any case.
Posted Tue Jun 15, 2004, 3:33pm Subject: Re: When does a shot go blond?
Thanks Jim, I still don't understand the underlying chemistry, but that slide puts some variables very nicely together, I guess I need to revisit your slide collection ;-) The amounts you quote for LM and Cimbali are all for double ristrettos, right? That seems to fit with what I see on my WMF with the new Cimbali baskets. I seem to get less volume than with the Oscar and LM baskets.
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