One final plea

This is one last humble request on a topic I know I’ve ranted on about before.

It would be really good, when talking about how we are brewing espresso amongst professionals, to start by talking about the weight of the espresso.  We need to stop using volume.  It is useless. Utterly useless.  Saying 1.5oz is like saying “about a basket full of coffee”.  It gets me in the vague ballpark, but it doesn’t really help if I am trying to dial a coffee in.

I’ve been really enjoying the reviews of various blends over on Home Barista, but I’d have really loved to know how much people’s great/amazings shots weighed (especially with Vivace’s Dolce where unusual crema volume is reported) – it would have made the reviews a lot more interesting and transparent.  I am sure it would also have been useful for people following along with those coffees and similar machines at home.

I know Andy Schecter posted about this on Portafilter less than two months ago – and now I just sound like a broken, whining, complaining record.  But weighing espresso is just so useful.

Alright.  That was it, no more posts about it.  This was the last (hopeful!) try.  We shall now return to normal service….

UPDATE: It was in error that I used the Home Barista thread as an example as some of the reviewers were indeed using both mass and brew ratios.  Apologies!

17 Comments

  1. I think it’s an overstatement to state, “We need to stop using volume. It is useless. Utterly useless.”

    It’s what we use. You’d have more luck advocating for all espresso machines to have flowmeters (installed in a practically-appropriate spot in the plumbing, obviously) to correlate water volume along with shot times.

    Mass is indeed a constant. Volume = mass / density, and therefore depends on the density.

    However, while mass is a constant on paper, it is NOT a practical constant in this context.

    Simply put, you and I pull the same coffee at the same mass on similar machines and other relevant criteria. I still have little assurance that you and I are encountering sufficiently similar results.

    How many days off roast? How was our coffee stored? What’s your water like vs. mine? What about the baskets? How old are your baskets compared to mine? What is the “quality” of the basket manufacturing? What about your dispersion screen? WHAT ABOUT YOUR DOSING/DISTRIBUTION? What of the guy who’s doing everything the same, but has severe channeling (and, for whatever reason, doesn’t realize it)?

    Volume isn’t perfect. It’s not as good as mass. However, there are so many variables that mass, while a scientific “constant” by definition, is also not a reliable metric. Perhaps better than volume, but not better-enough to justify the paradigm shift.

  2. @Cho Still… If something is to be measured as a means of documentation of yield by process, (be-it for repetition, training or consistency) grams mass is far superior to that of sighted volume.

  3. For the record:
    Coffee dose weight, espresso weight, espresso volume, brew ratio, shot timing, brew temperature, roast age, etc. are provided in my reviews. I thought about adding sunspot activity and planetary alignment, but didn’t want to appear too geeky.

  4. I understand what Nick is saying but surely if we try to make static as many variables as possible then this is a good thing? Of course we al have different machines, different screens and baskets, machines running at differing temperatures, differen quality qrinders with differing wear on blades….you could go on for ever. Still, giving a weight would at least get rod of a bloody big variable!

    Lee

  5. @malachi and @RapidCoffee – retraction shall be posted above – though it would have been interesting to see brew ratios for all the espressos tasted.

  6. I would agree with this if I hadn’t found mass to be so useful. Great for diagnosing problems people are having with a coffee you know over the ether. Great for really understanding your own consistency with an espresso machine. Great for understanding how a coffee changes with age.

    How many days off roast? How was our coffee stored? What’s your water like vs. mine? What about the baskets? How old are your baskets compared to mine? What is the “quality” of the basket manufacturing? What about your dispersion screen? WHAT ABOUT YOUR DOSING/DISTRIBUTION?

    All of these are very good questions. Questions with answers we don’t really know. But using volume as a tool in working out the answers to these questions and the nuances of the variables won’t help as much as using mass. I don’t think that is up for debate.

    Yeah, I did indeed overstate things, but I don’t think by much.

    Why bother using an ExtractMojo when tasting coffee works well? With a little investigation and use the ExtractMojo yields unexpected uses and rewards. Many were initially skeptical – but the number of people getting into it is constantly growing and nearly all are pretty rabid fans of it. (Yes, the posting of iPhone screenshots is now getting people a bit grumpy….)

  7. This may be slightly off topic, but the idea of a standard method for parameters when brewing espresso may be a useful tool for the coffee community… for example, we could talk about the DDTTV of an espresso blend

    D- Date roasted
    D-Dose grams
    T-Temprature
    T-Time of extraction
    V-Volume

    If something like this was adopted as a standard reporting method it could be a great thing?

  8. I wouldn’t say volume is a complete waste. Before hand it was not shot time, we need to talk about volume and now its not volume, talk about mass. All bear in mind that water is interesting when it comes to weight and volume, as long as you are using metric units, that is kilograms and Litres or probably grams and cm cubed. They are both the same, the constant density = mass / volume actually happens to be 1 that is if you have 1 litre of water you actually have 1kg. So say if someone had recorded a double shot volume of 47cm cubed +- 1cm cubed. Then you would know that was 47g +-1g. The only really point of using mass is that scale accuracy is usually better. Simply because to get good accuracy using volume you would need a measuring cylinder, or maybe a burette if you want to go crazy.

  9. All bear in mind that water is interesting when it comes to weight and volume, as long as you are using metric units, that is kilograms and Litres or probably grams and cm cubed. They are both the same, the constant density = mass / volume actually happens to be 1 that is if you have 1 litre of water you actually have 1kg.

    The density of water is not constant it’s a function of temperature and pressure. Your interesting point about water is by the (early) definition of the kilogram, an SI unit of mass. At 1 atmosphere of pressure (sea level air pressure) and a temperature of 3.984˚C pure water is at its maximum density, for this water – thanks to the early definition – 1 litre is 1 kg.
    As well as temperature and pressure effecting the density of water so does the ‘impurities’ or disolved coffee solids that make up a shot of espresso. Accurately determining the mass of an espresso shot from its volume requires also knowing its temperature, ambient pressure and specific gravity (relative density to the standard of water described above).

  10. Okay fair enough, I figured that, but didn’t think it was too big of a factor. I guess I haven’t uped my level of espresso to the point that I need shot mass accuracy to with in +-1 gram. Using data on wikipedia at 100C a shot volume of 50cm cubed would actually weigh 47.92 grams which is a % error of 4.16%, for me that would still be a good enough accuracy. Nevertheless measuring shots from a la pavoni euro(like I have) would just be pointless anyways, since its shots also depend on boiler fill level, boiler pressure, etc. The list goes on, I’ve given up on scientific analysis, I’ve gone for the wet cloth and 50-75% filled boiler approach. Works when your dealing with a la pavoni euro. If your trying to dial in a coffee, say the same one someone else has and your using their data, you’ve weighed the coffee mass, tamped the same pressure, set the same pump pressure, set the same temperature. I would assume that even if you are using volume if all those variables are correct then why would measuring it using volume be affected by the disolved coffee solids, because you should get exactly the same shot as they did at that volume. To what degree does the impurities in water change its density. I really love science I’m taking electronic engineering at uni, but I ask myself all the time, how far do we need to go on a regular day to day basis to get the perfect cup of coffee. I despise the unscientific approach of big giant cafe’s and love to hear that people take the same interest in coffee as I do, but then again I think we can get too into the sciencey part and lose sight of actually enjoying coffee if we are always looking for something better and better and better.

  11. To what degree does the impurities in water change its density.

    That would depend on the composition and quantity of impurities. When it comes to calculating (or verifying) % TDS (impurities) for example, you determine it from the shots relative density – whether by measuring its refractive index or specific gravity – and maybe correct for temperature and ambient pressure.

    but then again I think we can get too into the sciencey part and lose sight of actually enjoying coffee

    Enjoyment is key to experiencing anything I think, science included. My suggestion for investigating how much impurities can change waters density is to experience some layered shots at the uni bar ;-)

  12. I give up, you win. but what do you do, if you dont have all the equipment at hand? then what? I wasn’t excluding science, thats the part everyone does miss out with coffee and maybe cooking as well. I didn’t mean to exclude it I was merely just stating a point as too how far do we take science in coffee, its not like were experiment on something thats going to help the scientific community other then keeping them awake with a really good tasting drink!

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