johnnybgoodetonight Senior Member Joined: 2 Aug 2012 Posts: 4 Location: portland Expertise: Just starting
Posted Thu Aug 2, 2012, 8:44am Subject: Looking for coffee data
Hello.
I am new to coffee and this is my first post on coffee geek. I'm looking to understand all the variables and interactions in the system of brewing coffee.
I'm looking for quantified documented brews that would include things like, particle size vs. extraction, extraction and/or strength vs. time, anything vs. time really.. My goal is to acquire enough data to create somewhat of an accurate computer model for a coffee. I understand it will never be accurate and that coffee is variable.
NobbyR Senior Member Joined: 10 Jul 2011 Posts: 1,612 Location: Germany Expertise: I love coffee
Espresso: Poccino Opus One, Ariete Grinder: Eureka Mignon Istantaneo,... Vac Pot: N/A Drip: Melitta Linea Unica de Luxe Roaster: N/A
Posted Thu Aug 2, 2012, 9:05am Subject: Re: Looking for coffee data
Welcome to CoffeeGeek!
That's one heck of a challenge you've chosen! Just for espresso the factors that influence the brewing process are numerous and include age and degree of roasting of the coffee beans, type of beans, fineness of grounds, humidity, dose, distribution, tamping pressure, and brewing temperature to name but a few. And all of those parameters interact, of course. It'll be very hard to create a computer model of that. Good luck!
*** "This drink of the Satan is so delicious that it would be a shame to leave it to the infidels." (Pope Clement VIII on coffee)
johnnybgoodetonight Senior Member Joined: 2 Aug 2012 Posts: 4 Location: portland Expertise: Just starting
Posted Thu Aug 2, 2012, 6:41pm Subject: Re: Looking for coffee data
Thank you. My roommate lent me the same book. I'm looking for scientific type papers where "experiments" were done. Anyone know where I can find data like "particle size vs. extraction, extraction and/or strength vs. time, anything vs. time really.."?
Posted Fri Aug 3, 2012, 5:43am Subject: Re: Looking for coffee data
Rao's books are very good, but only an overview for what you are looking for. Illy's Espresso Coffee: Science of Quality has LOTS of references for digging deeper.
Unfortunately, much of the technical papers for food industry science is "owned" (for lack of a better word) by Wiley Online or affilliates with a similar business model.
Great paper on infusion kinetics. Unless you're at a university, access to just this paper for 24 hours is ~$40.
You can look at my past posts - lots of brew data there, more recently with strengths. I have a pretty good model for coffee, and it is very good for prediction of the amount of produced coffee.
You'll run into the definition of "extraction" which can never be directly measured - only mathematically inferred (back-calculated). I'd reccommend your models work on prediction of strength (assuming you have a refractometer).
The simplest model for coffee is prediction of amount of coffee produced - it's the basis for the brewing control chart.
C = mass of dry ground coffee, call it "brew coffee" W = mass of brew water, call it "brew water"
So, now your produced coffee is predictable, based on the brew method - which you may determine for the method, based on experimentation. To my knowledge, there isn't a single paper that looks at this concept except as it is buried in Lockhart et.al. research on coffee strength and extraction as it relates to consumer acceptability of coffee taste. You are welcome to join SCAA to gain access to these papers.
From there, define strength, and define brew ratio... predict and understand the wet spent grounds (G) and what it is comprised of (water, water as a solution with coffee solute, undissolved coffee), and go from there.
More suggestions: don't just believe what you are told. Much of coffee "science" is really tribal knowledge.
For instance, many assume that if you grind coffee, mix it with hot water, and let it steep for 1/2 hour - you will automatically end up with extremely overextracted coffee. Nothing is further from the truth. If this were the case, than the procedure of cupping wouldn't work, right?
Another example - the brewing control charts encompass strengths up to about 1.65%, and water brew ratio of 11g water : g of coffee. The brew ratio for a moka pot, or cold brewed coffee or even an AeroPress may be much higher than that. Strong underdeveloped coffee tastes fine to many people, but much of this thinking in this area of brew ratio and strength is applied outside of the intended range of relevancy.
Yet another example: based on taste, brewing with distilled water produces coffee that "tastes" a lot like overextracted coffee - harsh, almost metallic at times, overly bright, unbalanced. Everyone assumes that using distilled water "overextracts". For this to work, the strength for a given brew ratio must be higher. Much to my surprise, it appears nobody has actually done the simple experiment of varying the water hardness and brewing several cups of coffee.
The kool thing is that the amateur garage hacker scientists have two major tools now that weren't available, affordable, or accurate just 15 years ago:
-Low cost, good accuracy (precision and repeatability) electronic scales that have resolution of 0.1g or 0.01g, -Reasonable, affordable, quick, accurate, low-sample-size method to determine strength.
Just these two tools alone would have been amazing in the hands of a food scientist in 1949. :D
Good luck on your journey into the world of coffee science. I'm a few years along in my own such journey.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
jpender Senior Member Joined: 11 Jul 2011 Posts: 401 Location: California Expertise: I like coffee
Grinder: Kyocera CM-50 Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Fri Aug 3, 2012, 10:13am Subject: Re: Looking for coffee data
Netphilosopher Said:
Unfortunately, much of the technical papers for food industry science is "owned" (for lack of a better word) by Wiley Online or affilliates with a similar business model.
If you're in Portland, OR you might be able to access this journal through the Multnomah County Library. You can call (or do an online chat) and ask them directly.
Netphilosopher Said:
For instance, many assume that if you grind coffee, mix it with hot water, and let it steep for 1/2 hour - you will automatically end up with extremely overextracted coffee. Nothing is further from the truth. If this were the case, than the procedure of cupping wouldn't work, right?
Posted Fri Aug 3, 2012, 1:05pm Subject: Re: Looking for coffee data
JP - I hadn't read that yet, as I only check out j7's site about once every 8 weeks. Can't say I'm surprised.
Interesting - I wonder how they come up with "extraction" for cupping, since yield is undetermined. Did they just use brew ratio in the input for mojoextract?
What do they plug in for coffee water lost? (same thing as identifying a "yield", basically the same thing as the definition of absorption).
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
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