another_jim wrote:This is less pro versus am issue, and more science versus commerce one. The refractometer is a very normal case of the strengths and weaknesses of commercial R&D. Andy did the basic research on using refractometers for coffee TDS about four to five years ago.
I appreciate that you're giving me props for experimenting with the refractometer back when you and I were working on our espresso extraction project. But I think it's a gross exaggeration (and profoundly unfair to Vince Fedele) when you say, "Andy did the basic research on using refractometers for coffee TDS."
Among many other things, Vince did the truly massive amount of testing to correlate refractive index and temperature to coffee strength....he correctly identified that total dissolved solids, not total brew solids, was the correct variable to focus on....he tediously negotiated with several manufacturers to develop instruments that offered a reasonable compromise between accuracy and cost...he developed the software that crunched numbers, displayed data in an easily-understood graphical format, and made it easy to share with others...he developed instruments and techniques to measure both brewed coffee and espresso...etc, etc. And this is not to mention the fact that Vince had already been working on refractometers for coffee TDS while you and I were thinking about espresso extraction.
If you want your coffee to be at the official "golden cup" standard or your own personal extraction standard, the refractometer will allow you to do it with consistency.another_jim wrote:If you want all your brewed coffee to be precisely at the golden cup standard, this refractometer will do the job much more easily than the previous methods.
I strongly disagree with your statement here because:another_jim wrote:But it fails in fully exploring or controlling the extraction space. It was impossible to predict or predetermine the TDS, total solids and extraction yield from a given grind setting, coffee/water ratio, brew temperature and steep time. The conversions required for such a determination were not stable enough to be useful. So the refractometer needs extra data tables to fulfill its promise as a complete extraction controller.
(1) IMO the refractometer is a great success in allowing one to "fully explore" the extraction space. Using it, a skilled barista (home or pro) can navigate the extraction space with unprecedented ease, and with confidence that s/he knows where s/he is after each measurement.
(2) Accurately predicting or predetermining the TDS and extraction yield WILL ALWAYS be near-impossible, no matter how sophisticated the system. There are too many uncontrolled variables above and beyond the ones you list: coffee type, coffee age, roast variation, burr condition, grinder temperature variation, brewing agitation, water quality, and many others. I am amazed that you would criticize the VST refractometer and software for not living up to a standard such as the one you propose here. As I said previously, IMO this isn't a fair standard, it's more along the lines of a fantasy.
[disclosure: I have done and continue to do beta testing of VST refractometer/software systems. I have received free instruments, software, and coffee in order to do this testing. I have no financial interest in the company or its products]
[additional disclosure: text edited 1x to remove a phrase which made me sound "ever more like a shill" according to a very prominent HB person. I didn't think I was a shill, but perhaps I'm not a very good judge of whether I am or not.]
[additional additional disclosure: text edited 1x more to remove gratuitous sarcasm]
...split from Is there a new disconnect between coffee hobbyists and professionals? by moderator at Andy's request...