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Jul 15th, '11, 21:31
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TDS and Tea

by TomVerlain » Jul 15th, '11, 21:31

After reading in the Tetsubin Really thread about TDS (Total Dissovled Solids) in water, I was poking around the internet and found a chart for coffee showing the ideal relationship between amount of coffee, water and TDS, as extraction.

I was wondering if there is similar published data for tea ?

Also, as a session progresses, what the TDS values are. I assume the longer you go, the weaker the tea, and the less dissovled solids.

I just got a TDS meter and will probably play around this weekend to see what the numbers are like.

The coffee chart is called the SCAA chart.
http://dailycaffeine.posterous.com/meas ... caa-coffee

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Jul 16th, '11, 00:32
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Re: TDS and Tea

by Tead Off » Jul 16th, '11, 00:32

This is one area I am not venturing into. :D
The simple enjoyment of drinking tea or coffee can become an intellectual obsession. I guess it can be a nice science project. Have fun.

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Jul 16th, '11, 01:28
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Re: TDS and Tea

by Bob_McBob » Jul 16th, '11, 01:28

Commercial refractometer products with specific calibrated scales for measuring tea already exist, and I am sure they are in use at the many tea research institutes that exist all over Asia. However, I am pretty certain there will be basically zero interest in discussing this stuff here. The high-end coffee world is slowly coming around to the idea that scales and other measuring tools greatly improve quality and consistency, but most tea people scoff at the idea of weighing tea and timing infusions.

I am not sure how well you will get on with your TDS meter. They are not spectacularly useful for measuring strength (and calculating extraction) with coffee, just the same as cheap brix refractometers don't have anywhere close the required accuracy and precision. I also don't know how well the idea will translate to tea. Coffee is a one shot brewing process. There is a certain amount of water-soluble material that can be extracted from the roasted beans (about 30%), and there is a fairly narrow range of optimum extraction (about 17-21%). Strength is more a matter of personal preference, and recommendations vary by specialty coffee association.

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Jul 16th, '11, 06:30
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Re: TDS and Tea

by brandon » Jul 16th, '11, 06:30

Bob_McBob wrote:The high-end coffee world is slowly coming around to the idea that scales and other measuring tools greatly improve quality and consistency, but most tea people scoff at the idea of weighing tea and timing infusions.
I'll admit to scoffing at the idea of timing my seconds-long infusions, and rarely weigh tea when just looking at it will do. But I am very interested in being able to more scientifically describe the properties of water best suited to a certain tea. Not being a coffee guy, I am a bit out on a limb in my assumption that tea has a much wider range than coffee does. There is no kind of water that is ideal for all tea - sometimes I fake it by shooting down the middle. There is some accounting for taste, but hard water is just going to kill the aroma of light tea - it doesn't blend. Too soft water is going to make a bitter mess of your 2011 Dayi Sheng, but somebody out there is bound to love it.
Bob_McBob wrote:I am not sure how well you will get on with your TDS meter. They are not spectacularly useful for measuring strength (and calculating extraction) with coffee, just the same as cheap brix refractometers don't have anywhere close the required accuracy and precision. I also don't know how well the idea will translate to tea. Coffee is a one shot brewing process. There is a certain amount of water-soluble material that can be extracted from the roasted beans (about 30%), and there is a fairly narrow range of optimum extraction (about 17-21%). Strength is more a matter of personal preference, and recommendations vary by specialty coffee association.
I am not suggesting or using TDS meters to test extraction of tea - just the water before brewing, and also using it to test the relative efficacy of various water-treatment methods (tetsubin, silver, etc).

http://mattchasblog.blogspot.com/2011/0 ... water.html

If you are somebody who normally skips comments, that is where most of the meat is this time around.

Next, I imagine you will rightfully point out that two base waters with a TDS of 100 will taste very different. Mineralwaters.org is a good resource for the main components of big brand bottled waters world-wide, but it certainly doesn't have everything, esp the contents of what came out of your tap and went through Brand Y filter.

I'm using a ZeroWater brand filter for the base of some of these experiments, because I have a pretty good idea what minerals are left over - 0-1 PPM.

If you work at it, tasting the water will tell you a little more than the TDS tester, and of course, experimenting with your teas.

Hope to hear more.

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Jul 16th, '11, 09:27
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Re: TDS and Tea

by TomVerlain » Jul 16th, '11, 09:27

I am not looking to surgically brew tea, or come up with a magic number on a meter to define what "good" water is.

I was more interested in how tea is "extracted" over multiple infusions. I was planning on using distilled water to start with initial conditions of zero.

Not really sure what I will find, but thought it would be interesting to what kind of curve I get over time

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Jul 16th, '11, 13:10
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Re: TDS and Tea

by Bakkoi » Jul 16th, '11, 13:10

Well here's the problem. Even if you know the TDS, the actual combination of minerals will differ. TDS represents multiple different minerals, many or all of which can affect the way tea tastes. There is only so much it can tell you about whether the water is good or not.

The best way to evaluate water is to brew with it. I have recently used a glacial bottled water with a TDS of <10 ppm, and it was terrible for the Sae Midori I brewed it with. It was flat. Then I tried another brand of glacial water, one with <35 ppm, and it was bitter. Same tea, same pot, same brewing parameters.

What might be nice is a list of bottled waters that are good for brewing tea...

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Aug 27th, '11, 00:10
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Re: TDS and Tea

by BioHorn » Aug 27th, '11, 00:10

How are your TDS meter experiments coming along? What results have you had?

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Aug 27th, '11, 00:13
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Re: TDS and Tea

by TIM » Aug 27th, '11, 00:13

TomVerlain wrote:I am not looking to surgically brew tea, or come up with a magic number on a meter to define what "good" water is.

I was more interested in how tea is "extracted" over multiple infusions. I was planning on using distilled water to start with initial conditions of zero.

Not really sure what I will find, but thought it would be interesting to what kind of curve I get over time
Under 80 for water, me think.

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Aug 27th, '11, 01:14
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Re: TDS and Tea

by tingjunkie » Aug 27th, '11, 01:14

But then you need a meter to measure the effectiveness and flavor capacity of your taste buds, or else your mouth won't be properly calibrated.

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Aug 27th, '11, 20:46
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Re: TDS and Tea

by TomVerlain » Aug 27th, '11, 20:46

Image

Basically, this shows mineral water (220 TDS) versus distilled water (0 TDS). The curves are similar, but not identical. It appears distilled water allows more tea to be taken up earlier, leaving less tea to combine with water as solids later. I.E., the higher the mineral content, the longer you should be able to brew.

In terms of taste, distilled was "flat" - It might reveal more of the tea character, but I am guessing there.

Cup Distilled Mineral Water TDS Net Delta
1 171 421 220 201 30
2 351 497 220 277 -74
3 290 445 220 225 -65
4 282 431 220 211 -71
5 252 443 220 223 -29
6 195 390 220 170 -25
7 188 357 220 137 -51
8 182 331 220 111 -71
9 165 325 220 105 -60
10 133 304 220 84 -49
11 129 283 220 63 -66
12 114 297 220 77 -37


I wasgoing to do sheng as well as adding more minerals to the water, but haven't got around to it

btw 600 wide graphics are so web zero

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Aug 27th, '11, 20:52
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Re: TDS and Tea

by TIM » Aug 27th, '11, 20:52

What is the general temp. when you measure the liquid? These look really low... Usually is in the 800s and up.

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Re: TDS and Tea

by TomVerlain » Aug 27th, '11, 21:09

I let them sit till they were about 100 degrees F. My meter automatically adjusts for temp variations. The teas were all ruby or slightly darker. I used 7 grams of tea. I brewed them one right after the other, so they did not sit a bit, otherwise the wet tea would have been more unpredictable. I could have brewed more, but it looked like I had enough data to see a trend, and I had a gallon of each kind of water and did not want to run out before the second test.

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Aug 27th, '11, 21:18
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Re: TDS and Tea

by TIM » Aug 27th, '11, 21:18

TomVerlain wrote:I let them sit till they were about 100 degrees F. My meter automatically adjusts for temp variations. The teas were all ruby or slightly darker. I used 7 grams of tea. I brewed them one right after the other, so they did not sit a bit, otherwise the wet tea would have been more unpredictable. I could have brewed more, but it looked like I had enough data to see a trend, and I had a gallon of each kind of water and did not want to run out before the second test.
Try cooling them down. That's how the coffee experts do.

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