Sweetness Indicator

originally posted by Warren Edwardes:
Great thanks.

So what changes in RS and TA produce no change in "Sweetness" in your opinion at , say, RS of 10 grams / litre and TA of 5 g/l Tartaric?

What would the TA have to be if the RS was 12 to result in the same "sweetness" as above (by your guess)?
Click to expand...
No clue at all, sorry.
 
originally posted by Warren Edwardes:
Great thanks.

So what changes in RS and TA produce no change in "Sweetness" in your opinion at , say, RS of 10 grams / litre and TA of 5 g/l Tartaric?

What would the TA have to be if the RS was 12 to result in the same "sweetness" as above (by your guess)?
Click to expand...
With minor chemistry equipment, or the collaboration of a local lab, you can prepare samples and do the experiment yourself. Add a little acid (of various sorts), titrate to the pH, do the blind triangle taste....
 
originally posted by SFJoe:
originally posted by Warren Edwardes:
Great thanks.

So what changes in RS and TA produce no change in "Sweetness" in your opinion at , say, RS of 10 grams / litre and TA of 5 g/l Tartaric?

What would the TA have to be if the RS was 12 to result in the same "sweetness" as above (by your guess)?
Click to expand...
With minor chemistry equipment, or the collaboration of a local lab, you can prepare samples and do the experiment yourself. Add a little acid (of various sorts), titrate to the pH, do the blind triangle taste....
Click to expand...

Will do. A project for a local university. Sounds really good fun - once I work out what "titrate to the pH, do the blind triangle taste" means.

On the same lines, I also wonder how much 6 bar of CO2 in wine changes perceived RS?
 
originally posted by Warren Edwardes:

On the same lines, I also wonder how much 6 bar of CO2 in wine changes perceived RS?
Click to expand...

Since dissolved CO2 forms carbonic acid, you're basically back to the TA vs. RS relationship.

Mark Lipton
 
originally posted by MLipton:
originally posted by Warren Edwardes:

On the same lines, I also wonder how much 6 bar of CO2 in wine changes perceived RS?
Click to expand...

Since dissolved CO2 forms carbonic acid, you're basically back to the TA vs. RS relationship.

Mark Lipton
Click to expand...

Quite.

How much TA comes from 6 bar of CO2?

Really interesting tasting and serving Cava and with the CO2 removed with a milk frother.
 
originally posted by Warren Edwardes:
originally posted by MLipton:
originally posted by Warren Edwardes:

On the same lines, I also wonder how much 6 bar of CO2 in wine changes perceived RS?
Click to expand...

Since dissolved CO2 forms carbonic acid, you're basically back to the TA vs. RS relationship.

Mark Lipton
Click to expand...

Quite.

How much TA comes from 6 bar of CO2?

Really interesting tasting and serving Cava and with the CO2 removed with a milk frother.
Click to expand...

Warren,
That is one of those seemingly simple questions that is actually a mess to solve for. To answer that question, we'd have to know the temperature of the wine and the pH. The solution lies in application of Henry's Law combined with the complex equilibrium of the acid dissociation of carbonic acid. Atmospheric scientists obviously have a vested interest in that same question as applied to seawater as atmospheric CO2 levels (expressible as a partial pressure) rise. To see one group's analysis, see this PDF file.

Mark Lipton
 
originally posted by MLipton:
originally posted by Warren Edwardes:
originally posted by MLipton:
originally posted by Warren Edwardes:

On the same lines, I also wonder how much 6 bar of CO2 in wine changes perceived RS?
Click to expand...

Since dissolved CO2 forms carbonic acid, you're basically back to the TA vs. RS relationship.

Mark Lipton
Click to expand...

Quite.

How much TA comes from 6 bar of CO2?

Really interesting tasting and serving Cava and with the CO2 removed with a milk frother.
Click to expand...

... we'd have to know the temperature of the wine and the pH. ..
Click to expand...

Beyond my pay grade this is.

Any idea with temperature at 20 degrees C at sea level and pH of 3.2?

Looks like Not Too Dry is defined as 25 grams/litre in California.
 
originally posted by Warren Edwardes:

Beyond my pay grade this is.
Click to expand...

Likely beyond mine, as well.

Any idea with temperature at 20 degrees C at sea level and pH of 3.2?
Click to expand...

Elevation is unimportant since you've got a 6 atm pressure of CO2 in the bottle, no?

With temp and pH, we can solve analytically using the known ionization constants for carbonic acid and bicarbonate ion. Caveat: in this analysis, I'm treating your cava as soda water, which it most clearly isn't. How much the alcohol and other dissolved goodies might affect the equilibrium is what's beyond my pay grade. We also have to decide if we're reporting TA in sulfuric or tartaric equivalents.

Here we go:

[H2CO3] (from Henry's Law) = 0.23 M
[HCO3-] = 15.4 mM (from known pKa1 = 6.38)
[H+] = 0.63 mM (from pH value)

total TA in units of mol per litre: 0.24 M

= 17.6 g/L (tartaric equiv)

OR

= 11.5 g/L (sulfuric)

This is what you wanted, isn't it?

Mark Lipton
 
The above calc illustrates the issue with ta measurements--it counts weak acids like carbonic in the same units as strong acids like malic.
 
originally posted by SFJoe:
The above calc illustrates the issue with ta measurements--it counts weak acids like carbonic in the same units as strong acids like malic.
Click to expand...

But that's why we quote both TA and pH, the former giving you a sense of buffering capacity and the latter speaking to the strength of the acid.

Mark Lipton
 
originally posted by MLipton:
...

Elevation is unimportant since you've got a 6 atm pressure of CO2 in the bottle, no?

Mark Lipton
Click to expand...

champagneflight.4.jpg
Yes the head was amazingly large at the altitude / cabin pressure. And I found that the release of bubbles was quite rapid and the wine was soon almost flat.

I asked Lisa and Tracey to ask the Captain for the altitude and cabin pressure all in the interests of science.

Altitude: 7500 metres
Cabin Pressure: 8.50 psi (0.59 bar)

= 17.6 g/L (tartaric equiv)

OR

= 11.5 g/L (sulfuric)

This is what you wanted, isn't it?

Mark Lipton
Click to expand...

Great. Thanks. Interesting.

So if the "base" wine (i.e. degassed not pre-tirage) is 5.4 grams/litre Tartaric we have a TA of 23 grams / litre Tartaric.

23 g/l seems a lot.

How does the pH change with 6 bar CO2?

Differences between bottle second fermentation, 5000 litre Charmat Method and injected? Just different levels of solution of CO2?
 
originally posted by Warren Edwardes:

Yes the head was amazingly large at the altitude / cabin pressure. And I found that the release of bubbles was quite rapid and the wine was soon almost flat.

Loading…

winedisorder.com
I asked Lisa and Tracey to ask the Captain for the altitude and cabin pressure all in the interests of science.

Altitude: 7500 metres
Cabin Pressure: 8.50 psi (0.59 bar)
Click to expand...

That's again a consequence of Henry's Law, since the partial pressure of CO2 at that altitude is down around 0.23 mbar, that'll result in a 26,000-fold reduction in the dissolved carbonic acid in your fizz.

So if the "base" wine (i.e. degassed not pre-tirage) is 5.4 grams/litre Tartaric we have a TA of 23 grams / litre Tartaric.

23 g/l seems a lot.
Click to expand...

That assumes that the pre-existing acidity doesn't alter the solubility of CO2 in the wine, which is probably not too far off reality.

How does the pH change with 6 bar CO2?
Click to expand...

No set answer to that question. It goes back to that buffering capacity thing SFJoe and I've been nattering on about.

Differences between bottle second fermentation, 5000 litre Charmat Method and injected? Just different levels of solution of CO2?
Click to expand...

Nah, Charmat and injected make crap wine, too.

Mark Lipton
 
originally posted by SFJoe:
Altitude is irrelevant, cabin pressure is the key.
Click to expand...

How about in an unpressurised log cabin in Aspen Colorado?

Surely the atmospheric pressure of the Cava in bars will change between San Francisco (6 bars) and Aspen?
 
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