loader image
January 30, 2017 /
VST:WTF Part 2

Now that I’ve covered what a refractometer is and how it works, it’s important to understand what it can and cannot do. There’s a lot of incorrect assumptions and opinions about these devices that I find myself constantly battling. Many baristas are understandably concerned about a device that might measure their effectiveness or replace their tastebuds. So this should set the record straight.

Here are some erroneous statements followed by my usual rebuttals.

“Extraction has nothing to do with the real taste of the coffee.”

Extraction is very very closely tied to the flavours experienced in a cup of coffee. There are many flavours in coffee that consistently occur alongside certain levels of extraction. You could call them extraction-specific or extraction-indicating flavours. When aiming to brew a coffee as well as possible, I’m trying to steer away from those flavours that indicate over or under-extraction. The result will be a well extracted coffee that’s true to the beans used.

When performing the same task with a refractometer, you can get to the same result faster, with more precision and accuracy (more on this later). In this case, the refractometer is helping you achieve taste-based goals; a long way short of “nothing”.

Measuring extraction does not tell you if a coffee tastes like citrus or milk chocolate. You might be able to get this kind of data from expensive gas chromatography, but I digress; “tasting” a coffee is not within the scope of a refractometer. That’s your job.

“I heard refractometers don’t measure anything meaningful. They’re just another toy.”

This couldn’t be further from the truth. As above, refractometers help you measure extraction, which is closely linked to flavour. There’s a couple of other insanely useful things that can also be garnered from this information:

Technique – if your grinds distrubution, pouring technique, tamping pressure or any other technique-related skills fall short, it can be detected by a refractometer. If you make two cups of coffee with identical recipes and equipment but differing techniques, the extraction will be higher when the technique is better, and lower when it is worse.

Roasting – More important and relevant than any color measuring device is the refractometer. It can tell you if a roast is under/overdeveloped, help you monitor consistency and aid the analysis of different roast profiles.

Equipment – Same experiment as above, put two products to the test by brewing identical recipes and seeing which gets the higher extraction. This works for baskets, tampers, grinders, burrs, showerscreens, pumps, espresso machines, pourover cones; anything that influences the way the coffee and water interact.

“We already make coffee well enough.”

No. You don’t.

“Taste buds are much better than a refractometer.”

Yes, they are. Taste buds are sensitive to an incredible array of flavours and are linked directly to your brain. They’re a marvel of biology, sensitive enough to detect a pinch of salt in a swimming pool. Hats off for taste buds.

The only problem with taste buds is that they’re attached to a human. An inconsistent, biased, emotional, volatile creature designed for anything but objective measurement of a liquid solution.

Refractometers are incredibly consistent, accurate, and precise. Three things we suck at. So why don’t we team up?

With a refractometer on your side, you become more consistent and accurate. Your off days can be detected, your preferences can be recorded and returned to, your prejudices can be exposed. Yes, your taste buds are better at tasting, but a refractometer is much better at not turning up to work hungover or with toothpaste in its mouth.

“I never agree with the results from refractometers.”

I doubt you could disagree with the refractometer. It doesn’t have an opinion. It’s much more likely that you disagree with the standards other people have applied to their coffees and shared with you. Perhaps you heard 18% extraction is the best, but you don’t like it when your coffee is extracted to 18%. Or maybe espresso above 8% doesn’t float your boat, but everyone else likes to drink it around 10%. That’s not you disagreeing with the refractometer, that’s you disagreeing with what others like.

Everyone should be using refractometers to measure the coffees they like to drink. Then, it becomes much easier to find that spot again. I like to think of it as a handrail. You can explore and move around the staircase, but if there’s a handrail you can always return to where you were.

You are absolutely entitled to your own opinion and preferences about coffee. What you taste is what you taste, no matter what anyone else says. The refractometer is a tool that can help you execute those personal preferences consistently; no one has to agree with them.

If you’re looking to get a refractometer, head to the US-based VST store or hunt down a local distributor from further down that page. I would recommend getting the refractometer, some spare syringes/filters and the iOS/Android app (which is now fully-featured with charts and recipe creation just like the desktop version). Start playing around, learning what you like and testing techniques or equipment. Your coffee will get better.

If you have found this useful and want to enjoy delicious coffee with the rest of the community – register for our monthly Superlatives coffee subscription. Or if you just want to keep up with every thing Barista Hustle – sign up to the Newsletter. 

Coaching Calendar

Find a course with a BH Certified Coach

January 2020

Mon Tue Wed Thu Fri Sat Sun
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
  • ITA: Barista One
17
18
  • UK: Barista One
19
20
21
22
23
24
25
  • UK: Barista One
26
27
  • FR: BARISTA ONE
28
  • FR: PERCOLATION
  • ITA: Barista One
29
30
31

News & Updates

Sign-up, Take part and keep in touch!

17
Leave a Reply

Please Login to comment
avatar
  Subscribe  
newest oldest most voted
Notify of
Erik G
Guest
Erik G

Another obvious question: is the VST really the only game in town for refractometers or can a hobbyist get by with cheaper models, like the Atago?

Pilgrim Coffee
Guest
Pilgrim Coffee

I’d love to borrow one every now and then if anyone has one in HK! Just to recalibrate every now and then…

Marshall Hance
Guest
Marshall Hance

Truth.

AndyS
Guest
AndyS

I have never heard of a difference of 7 to 8% in extractable material from any two competently roasted, quality coffees. Illy’s book (“Espresso Coffee”) goes into detail about the constituents of arabica and robusta beans, and the book does not support your claim. Could you please cite a source?

Jeff Verellen
Guest
Jeff Verellen

Contents of green beans vary quite strongly.
Try to roast and extract a Brazil from 2-3 years old, then a sparklin fresh top
Kenya.

The bigger swings are 7 to 8 % difference between greens in total extractable material.

So if you are shooting for 20% ectraction of that past crop brazil, its going to taste overextracted.

If you are shooting for 20% of that sparkling fresh Kenya it might taste underextracted.

Doesn’t it put a big chunk of the theory to the test? Still measuring is correct and you can learn from that.

Barista William
Guest
Barista William

Hi Matt, thanks for sharing these useful info about VST refractometer for us. Actually, i am concern about how to corporate with refractometer in order to brew the best quality of coffee. In other words, what’s the best way to match TDS from refractometer to coffee recipe. For example, i brewed a espresso which TDS was 10% and customers like it. Thus i should keep this recipe for future use. Or say,this batch of coffee is suit for TDS 10%. However, roasting job is hard to make consistency and it might change from batch to batch. Therefore, i should measure… Read more »

A Szabo
Guest
A Szabo

Hey Matt,

First off thanks for your hard work, loving the hustles so far and great to see that you’re actively creating a community that’s about sharing information and helping each other out.

Just a quick question regarding the use of refractometers: you haven’t mentioned cleaning and calibration, and I’d be curious to hear your opinion on these. How often do you calibrate, what do you recommend cleaning the lens with etc.

Thanks and best wishes,

Akos

Federico Bolanos
Guest
Federico Bolanos

The VST refractometer is easily one of the most valuable brewing tools ever produced. When explaining the benefits of using it to baristas, I always tell them to try to think of the refractometer as a GPS. It tells you with pin-point accuracy where your brew stands. This is extremely useful because if you like the taste of your brew, you could use it to come back to that very same spot or to move to a different spot by. Without the refractometer, it would be like travelling without a roadmap… you can eventually get to where you want to… Read more »

Jeff Verellen
Guest
Jeff Verellen

One other important question: what coffee or blend is the Scaa brewing chart based on.
And how was it roasted? What were the properties of the green coffee that was used? This whole theory is hinged on that yet nobody questions this. Mind you this was 1950s USA.

Jeff Verellen
Guest
Jeff Verellen

Measuring tds is giving a lot of insight into coffee. No doubt. But this is one topic that is almost ignored. I roast about 40 differen coffees a year, we come into contact with almost everything on the planet. There is a lot of difference in greens that is ignored. You can eg. not just roast for an extraction % on cupping the coffee to choose your profile. It really doesn’t connect taste wise sometimes, I’m talking more about a fresh Costa rica honey vs an older washed sidamo grade – 2. In the paper there is a lot of… Read more »

AndyS
Guest
AndyS

I agree, what does “quality” mean? I don’t think Yemen coffees are the best ones to draw conclusions from, since they are extremely variable. I’ve had some so-called “specialty” Yemens that were delicious and some that were so defective they went straight to the compost. The study you cite showed huge variation in chemical content, but came nowhere near trying to quantify “total extractable material.” I can repeat what refractometer users have said dozens of times already: No one is saying there is a magic extraction percentage that makes the best tasting coffee. The best tasting extraction percentage depends on… Read more »

Jeff Verellen
Guest
Jeff Verellen

I don’t have the book handy but I had some pages marked in the llly book, but it deals mostly with arabica vs robusta, no?

Anyway a quick search gives: http://escijournals.net/JFCN/article/download/162/237

This is only between yemen(!!!) imagine if you compare with all origins, multiple years.

Granted 7-8 is rare, but is certainly possible.

AndyS
Guest
AndyS

Please re-read these two posts by Matt.

SCAA brew chart? I don’t think he mentioned that.
“Shooting for 20% extraction?” I don’t think he mentioned that.

Personally, I like my espresso made from single origin filter-oriented roasts ground on an EK at around 24% extraction yield. You probably have preferences different from mine. That’s OK with me.

Espresso was never ON the SCAA charts. I don’t care. If espresso had been on the SCAA charts, 24% might have been “off the charts.” I don’t care.

Please re-read these two posts by Matt.

Jeremy
Guest
Jeremy

this is a great post. excellent points!

writefish
Guest
writefish

The VST is reputed to be the best, most accurate device. That said, on a limited budget, I use a couple of opticals, which might rankle the pros, but better than nothing and they definitely help zero in on better extractions. 1-10 range for pourover, 1-30 range for espresso.

Full disclosure: Amateur enthusiast here– not a pro.

writefish
Guest
writefish

Typo: “distrubution” should be “distribution.” 😉

Jeff Verellen
Guest
Jeff Verellen

Another thought:
Unless you are extracting that coffee where the SCAA brewing chart is based on, extraction rates are ALWAYS false.

Copyright © 2019 Barista Hustle, All Rights Reserved!

You have Successfully Subscribed!

You have Successfully Subscribed!