The variation in specific gravity due to the range of coffee temperatures is a lot more than the variation in specific gravity due to typical coffee concentrations. That means you will have to very carefully calibrate for temperature to get meaningful results.
So using the hydrometer for measuring coffee is probably a massive PITA. But hey, after a couple homebrew beers, maybe it'll be a lot of fun! ;-)
The variation in specific gravity due to the range of coffee temperatures is a lot more than the variation in specific gravity due to typical coffee concentrations. That means you will have to very carefully calibrate for temperature to get meaningful results.
So using the hydrometer for measuring coffee is probably a massive PITA. But hey, after a couple homebrew beers, maybe it'll be a lot of fun! ;-)
Ah, I wish I still had some homebrew... I make do with Sierra Nevada nowadays.
I realize that this probably will be an exercise in futility in some respects... but just going through and doing the math and making the measurements will help me understand the fundamentals much better.
I was looking at the SCAA coffee control chart on the Bunn site today and did the math (minus any TDS or extraction % measurements) on our office coffee and realized that I had to draw new lines on the chart to plot where the coffee here is. 2.5 oz Starbucks pre-ground packages brewed into 2.2 l airpots to an estimated volume of 1.95 liters. That's about 2.4 oz / half-gallon or 68 g / 1.9 l. So I corrected the dosing by making a pot with an extra half bag and now it tastes like coffee with some body instead of bitter hot water. It also explains the difference in effect between drinking one cup of coffee at home and braving multiple cups at work.
I did pick up a hydrometer at a beer and wine making store the other day and figure it'll take a 250 ml (8.5 oz) sample to float it in my graduated cylinder... that's a lot of coffee to cool down to room temp and measure, but I'll probably do this with my Vac Pot brews, my Clever Coffee Dripper, and the Americanos I make with the Aeropress and see what's going on. I'll probably also save the grounds and try dehydrating them in the microwave or toaster oven and do some before and after weight measurements.
This isn't something I'd do all the time, but I'd like to see what I can measure about my different coffee prep techniques.
Enkerli Senior Member Joined: 1 Aug 2004 Posts: 711 Location: Montreal, Qc Expertise: I love coffee
Espresso: (At cafés, not at home) Grinder: Hario hand grinders Vac Pot: (Moka Pot) Bialetti Brikka Drip: Steep and release pour-over Roaster: iRoast-2
Posted Sun Oct 25, 2009, 7:37am Subject: Re: Measurements (Brix, Mass, Temperature...)
Chris, I like your attitude. You sound like a true geek! Making measurements did teach me a lot. Not really in terms of the data points themselves. I don't necessarily trust these data points, though I did notice patterns. But I learnt a fair deal about my process as well as about the range of tastes I could get. It was all about experimentation and experience. Compared to homebrewing, it's much easier and way quicker to experiment with coffee. By comparison, you get nearly-instantaneous results. And if you try a variety of (coffee) brewing methods with the same beans, you can easily notice the differences made by the process.
Basically, it's more about paying attention to coffee in a different way. It's a bit like the Hawthorne effect. Your coffee improves because you're more careful with it, a bit like workers will be more efficient as they're experimentally measured. In this case, the "investigator" is the one changing her/his perception and process. But the "magic" is similar: you don't even have to consciously tweak any parameter to make a noticeable difference in terms of coffee enjoyment. It just happens.
I did pick up a hydrometer at a beer and wine making store the other day and figure it'll take a 250 ml (8.5 oz) sample to float it in my graduated cylinder... that's a lot of coffee to cool down to room temp and measure, but I'll probably do this with my Vac Pot brews, my Clever Coffee Dripper, and the Americanos I make with the Aeropress and see what's going on. I'll probably also save the grounds and try dehydrating them in the microwave or toaster oven and do some before and after weight measurements. -Chris
After a long hiatus, I've been thinking about this again. I started taking Brix measurements with a borrowed FG-111 optical refractometer. I kept putting this off and making it into a project and I kept seeing the borrowed refractometer sitting on the shelf, so I decided to just start measuring and not worry about making it a big, huge, afternoon project (that I'll have time for sometime in 2011).
This morning, I measured my Clever Coffee Dripper brew of a Brazil Vargem Grande I roasted up to City + last night, and then later I made some measurements on the airpot at work.
For the CCD, I used 452 ml of hot water (30 seconds off the boil) added to 28 g (two level AeroPress scoops) of ground coffee. First I added about 100 ml of water and allowed the coffee to bloom for 30 seconds before adding the balance of the water and steeping for an additional 3 minutes of contact time before starting to drain the dripper. The dripper yielded 389 ml coffee and I got a brix of 1.5 % for a TDS (Total Dissolved Solids) estimated at 1.5 x 0.85 = 1.28 %. I calculated the % Extraction at TDS * Yield / ground coffee = 1.3 % * 389 / 28 = 17.7 %, a little low from the coffee control charts, but it tastes good.
Looking at the coffee control chart, it looks like my next step should be lowering the coffee from about 70 g / liter down to 60 - 65 g / liter and lengthening the contact time to increase the extraction. I think I'll go back to 30 sec + 4 minutes that I was using before I fined up the grind on Sunday and then maybe start playing with James Hoffmann's Grind Size Experiment, which I heard about after I started fining up the grind.
My first measurement at work was on an pre-existing pot that was thin and weak. It measured 0.95 % Brix or about 0.81 TDS. We make coffee in airpots at work with 70 g Starbucks pre-ground packets, but to get the right balance, you really need to use about 1-1/2 packets of coffee... this pot was clearly made with only one packet. I guess the Brix meter could be a good judge of the coffee at work to determine if it was made right.
Next I made a pot myself, measuring 106 g of coffee (about 1-1/2 packs) and taring the airpot so I could measure the yield, 1.47 liters of coffee. The Brix on this one was very close to what I got at home, 1.49 % for a TDS of 17.59. The coffee now, besides tasting over-roasted due to the fact they came from Starbucks, tastes better with a good strength and a more balanced taste.
I wish I had brought in some of my fresh roasted coffee, I could've extended this to a test of the AeroPress here at work.
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.
= No New Posts since last visit 