Explain the popularity of semi-auto espresso machines over volumetric to me?

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Tritone
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Joined: 8 years ago

#1: Post by Tritone »

Hi, everybody. By the way, this is my first post. Happy to be a part of this community.

So anyway, I was a "barista" at a Starbucks clone for a year during college. I don't remember the brand of our machine, but I pulled a few thousand shots on it. Back then, though, I didn't really know much about espresso. Recently I tried some "third wave" espresso at Paul Bassett's in Shinjuku and was completely blown away. I'm hooked. Now, I'm looking at getting a nice dual boiler machine when I move back to the states in a year or so. Doing research over the past couple of weeks, I was really surprised to find how many machines are for sale for over 2k USD that don't include a volumetric setting. This was honestly not something I would've expected to see, as it seems like such an important feature. I don't mean because of the convenience of being able to walk away from the machine, I mean because of the ability to pull a shot where as many variables stay as close to "ideal" as possible.

Maybe some people are visually checking to see when a shot "blonds", but is that reliable? These guys from G&B Coffee and La Marzocco seem to think not, saying, "there's also the idea that you can choose when to... stop an espresso shot based on crema... The idea is that once it starts to blond, that's when you need to stop it. But that is... somewhat insane... the crema of every coffee is going to be a little bit different. Instead by focusing on the recipe and the brew ratio, paying attention to your dose and paying attention to your yield and getting those things like exactly where you want 'em, that'll result in a much better espresso than just looking at the color of the crema." ( https://www.youtube.com/watch?v=HbPBOtp4th0 )

Furthermore there's this blog post ( http://www.lamarzoccousa.com/blog/ben-k ... lumetrics/ ) at La Marzocco showing that for consistency, auto-volumetric is far superior than judging by sight and time alone.

So what is it I'm missing about lever-controlled semi-automatic machines? Can you pull better shots with them, or is there some other advantage I'm missing? Or does everyone with a semi-auto machine put a digital scale under their demitasse cups?

cpreston
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#2: Post by cpreston »

You may get replies disputing the La Marzocco study with various explanations, but having brewed many espressos to target weight on a scale I agree with LM on the whole. I think flowmeter volume is a reasonable if imperfect proxy for weight from shot to shot for a given bean and target weight, after you have dialed in by taste/blonding etc.

I wonder if the problem is that there is no way to modify the volume setting. You have to anticipate that you will pull a definitive shot, hit the program button, then pull and hope it turns out exactly as planned in order to set a target volume. This is awkward but workable if you're consistent but then you will want to adjust the volume setting to try variations. You have no way to tweak it incrementally without recording a whole new shot and then you're stuck with the new one. And I'm not aware of a machine that simply lets you save the *last* manually timed shot as the setting if you happen to think it was just right. Instead you have to choose program mode before pulling the shot.

Not all volumetric flow meters are as repeatable as LMs. But I think the larger issue is the lack of adjustability. Given this limitation I too find volumetric buttons useless.

1yay1
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#3: Post by 1yay1 »

Is there any difference between volumetric and just weighing the shot while it pulls?

cpreston
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#4: Post by cpreston »

The weight is what you actually want. The flowmeter volume is not quite proportional because it doesn't include the extracted solids in the cup and does include the water left in the puck.

The solids should end up around 20% of the dose weight, e.g. 3g of a 15g dose might end up in the cup; I don't know about the water left in the puck. But for maintaining shot to shot consistency, not absolute values, a good (not all are) flowmeter's volume setting should be quite repeatable. But then you have to deal with the ridiculous way it is set it that I complained about earlier.

After initial dialing in I usually pull on a scale, as I find it easy to do and easier to read than a blonding point. But you do have to allow for the lag in the scale reading.

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RapidCoffee
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#5: Post by RapidCoffee »

Tritone wrote:Maybe some people are visually checking to see when a shot "blonds", but is that reliable? These guys from G&B Coffee and La Marzocco seem to think not, saying, "there's also the idea that you can choose when to... stop an espresso shot based on crema... The idea is that once it starts to blond, that's when you need to stop it. But that is... somewhat insane... the crema of every coffee is going to be a little bit different.
Not insane in the slightest. Visual feedback is the most straightforward way to monitor the extraction. When the pour blonds, you have extracted most of the flavor from the grinds. From that point on, further extraction serves primarily to dilute the shot.
Tritone wrote:Furthermore there's this blog post ( http://www.lamarzoccousa.com/blog/ben-k ... lumetrics/ ) at La Marzocco showing that for consistency, auto-volumetric is far superior than judging by sight and time alone.
One study under one set of conditions, resulting in a very small difference in standard deviation from the mean (extraction yield) - hardly "far superior". Note that the numbers don't quite add up (compare the min/max values to the range). Sorry, but if they can't do simple arithmetic, this leads me to question the validity of the study in general.
Tritone wrote:I was really surprised to find how many machines are for sale for over 2k USD that don't include a volumetric setting. This was honestly not something I would've expected to see, as it seems like such an important feature. I don't mean because of the convenience of being able to walk away from the machine, I mean because of the ability to pull a shot where as many variables stay as close to "ideal" as possible.
For whatever reason, you are assuming a generic extraction consistency. If every extraction was identical, volumetric dosing might be more consistent. But this is not the case. Different blends, roast level, bean age, and grind settings will all change the extraction. How can you best monitor the change? The answer is obvious: visual observation of the extraction, followed by tasting results in the cup.

There is nothing wrong with volumetric dosing, and it's particularly convenient when you are serving several espresso drinks. But improved extraction consistency? Probably not in the home setting. In addition, many home baristas enjoy the "mano" aspect and prefer semi-autos and levers. Hence the continued popularity of those machines.
John