How low can TDS of water be to extract properly?

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
mitch236
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#1: Post by mitch236 »

I admit to not knowing much about water but I've been trying to determine the cause of my chronic underextraction problem and all I can come up with is my water is too soft. My preliminary measurement puts me at 50 ppm. I've read that 150 ppm is ideal. How much does mineral content affect extraction?

I would consider technique issues but my extraction yields are so consistent (Measured with a refractometer). My equipment is good. I've tried many different coffees at different times during their resting period. Has anyone done any experimentation with varying the mineral content of water and measuring extraction yields?

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Marshall
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#2: Post by Marshall »

mitch236 wrote:Has anyone done any experimentation with varying the mineral content of water and measuring extraction yields?
Yes. Lots of it. But you have to pay to read it. You could start here: http://onlinelibrary.wiley.com/doi/10.1 ... x/abstract.

Also: the SCAA Water Quality Handbook, p. 31 (which reports the results of different mineral contents as cupping results, rather than specific yields).
Marshall
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mitch236 (original poster)
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#3: Post by mitch236 (original poster) »

Thanks Marshall. You are always a great resource. I don't think I want to sift through all the data though. Has anyone had a similar situation to mine (surely someone has soft water)?

As an aside, are there any other options for increasing my water's TDS other than the Cirqua system?

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another_jim
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#4: Post by another_jim »

The study Marshall references was performed by Cirqua, and may overstate the degradation in coffee quality as TDS declines. It certainly contradicts the overwhelming experience of many in the PNW or NYC who use the low mineral, 50ppm non-scaling water with good results.

When I did the water faq, I made shots with distilled water, 50 ppm, and 120 ppm natyral and softened water. There was not much to chose from between the unsoftened and softened high mineral water. The distilled water did not produce recognizable espresso. The 50ppm shot was slightly sharp, presumably through underextraction, but not badly so. Subsequent triangle cupping tests with brewed coffee confirmed these results

In those days I didn't know about manipulating grind and dose, so I do not know if the taste deficit is easily correctable. However, since I've had good espresso in the PNW and NYC, I always assumed it was. In particular, our own Abe Carmeli uses RO plus calcite cartridge water that clocks in at around 35ppm, and I've had excellent shots at his place.

My assumption is that you are running into the Linea's crazy high water debit, and may be able to correct the problem with a smaller group jet or an adjustable needle valve, along with a longer interval on your preinfusion timer -- just a guess
Jim Schulman

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Marshall
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#5: Post by Marshall »

another_jim wrote:The study Marshall references was performed by Cirqua, and may overstate the degradation in coffee quality as TDS declines. It certainly contradicts the overwhelming experience of many in the PNW or NYC who use the low mineral, 50ppm non-scaling water with good results.
This sounds like Ken Fox's old conspiracy theories. It would be helpful if people who describe the Water Quality Handbook would buy a copy. It is only $25. The TDS-specific taste tests were performed blind by six members of the SCAA Technical Standards Committee at the SCAA Labs in Long Beach, CA. in 2010.

The overall water quality standards were initially developed in New York after extensive consumer tests by the former Coffee Brewing Center in 1967 and later adopted by SCAA.

They are, however, aimed primarily at brewed coffee, where one does not have to deal with water held at steaming temperatures (which precipitates scale more quickly). Owners of espresso machines might sacrifice a bit of minerals to help preserve their equipment.
Marshall
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#6: Post by mitch236 (original poster) »

Jim, I hope you're right about the Linea. The Strada is due here the end of the month. I hope I'm happier!!

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another_jim
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#7: Post by another_jim »

Marshall wrote:This sounds like Ken Fox's old conspiracy theories.
Let me be clear: I use Chicago's 150 ppm water for my coffee and espresso without softening because it does taste better. However; I also think it is not so much better that people using softer water are somehow missing out on high quality coffee. In particular, it is possible to make good brewed coffee and espresso with 50 ppm water by appropriately using finer grinds, extending extraction times, and/or raising extraction temperatures; that is by appropriately changing the brew recipes -- something I believe the report does not address.

The study's conclusions would have been strengthened if it had used a two stage design. In the first stage, blind testing should have been used to to establish the best tasting brew recipe at each level of water TDS. Then the best recipe for each TDS level should have been compared in the second stage blind tasting to determine how much better the best possible brew at the best possible TDS level is compared to all the demonstrably best alternatives at other TDS levels. Not to have done this misses out on the undoubted fact that cafes using softer or harder water can and usually will do the best possible job they can given that water.

[OT: When a company conducts a study that confirms its own commercial interests; subjecting that study to added scrutiny is not paranoia. That it seems to be in poor taste might say more about the current state of the SCAA's taste than about my current state of mind]
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Marshall
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#8: Post by Marshall »

another_jim wrote:Let me be clear: I use Chicago's 150 ppm water for my coffee and espresso without softening because it does taste better. However; I also think it is not so much better that people using softer water are somehow missing out on high quality coffee. In particular, it is possible to make good brewed coffee and espresso with 50 ppm water by appropriately using finer grinds, extending extraction times, and/or raising extraction temperatures; that is by appropriately changing the brew recipes -- something I believe the report does not address.

The study's conclusions would have been strengthened if it had used a two stage design. In the first stage, blind testing should have been used to to establish the best tasting brew recipe at each level of water TDS. Then the best recipe for each TDS level should have been compared in the second stage blind tasting to determine how much better the best possible brew at the best possible TDS level is compared to all the demonstrably best alternatives at other TDS levels. Not to have done this misses out on the undoubted fact that cafes using softer or harder water can and usually will do the best possible job they can given that water.
And they could have repeated all of those tests for 20 different coffees brewed 4 different ways. But, this is, as the title says, simply a "handbook," and it is designed for shop owners, whom, if they are lucky, can treat their water to a single standard for all their drinks (brewed coffee, espresso and tea), and if they have the resources, to three different standards.
another_jim wrote:[OT: When a company conducts a study that confirms its own commercial interests; subjecting that study to added scrutiny is not paranoia. That it seems to be in poor taste might say more about the current state of the SCAA's taste than about my current state of mind]
I don't know how many ways I can say this but, Cirqua did not conduct these studies, the prinicipal one of which predates Cirqua's founding.
Marshall
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#9: Post by another_jim »

This is turning into a rehash. The original thread makes good reading for those who might be interested.
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Peppersass
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#10: Post by Peppersass »

Some additional points not covered in the original posts on this subject:

The Illy book, "Espresso Coffee, The Science of Quality", makes essentially the same point Jim made here: you can compensate for low or high extraction due to water mineral content by changing grind, extraction time, temperature, etc.

IMHO, the first consideration about water has to be its effect on the machine. Excessive hardness or excessive acidity can and will destroy one's equipment investment if not addressed. In particular, I think the coffee community is just beginning to realize that certain treatment systems may produce water that's great for flavor but maybe not so good for the machine (ask Synesso about how their warranty is affected by use of certain water treatment systems.)

Once the range of acceptable treatment options is known, the shop owner or home barista can focus on how the water affects extraction. That could influence choice of a treatment system and/or brew recipes to compensate for the mineral content.

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