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Sour Taste In Wine?


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#1 Thach

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Posted 10 November 2005 - 07:17 AM

I have study in wine making for a while, and it seem like many of the wine making have to adjust pH to 3.5 . Which I think this pH have responsibility to the sour taste in wine. If every or almost wine maker have to start with pH 3.5. How come commercial wines some have sour taste tongue.gif but some are not.
If we knew what is responsible for the sour taste in wine, Can we intend to make wine without the sour taste like some commercial wine?, because I don't like the sour taste.

#2 P Cuthbert

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Posted 10 November 2005 - 07:50 AM

Thach;

You describe an interesting aspect of wine.

The "sour" taste of red wines in particular are a definite deterent to beginning wine drinkers. Many try them and find them too bitter so they go on to the medium sweet white wines and sweet red wines. As they experience more wine styles, the taste can change so that they can enjoy the nuances of the dry reds.

What makes a wine "sour" is a combination of 3 things. Acid, residual sugar, and tannin.

Dry red wines will generally have significant acid, but less than white wines. Acid in wine will cause your mouth to water.

Dry red wines will have very little residual sugar. This can be adjusted in the glass by adding a teaspoon of table sugar, more or less to your taste. Give this a try.

Tannins are another component of red wine that can give the impression of "sour". Tannins change as time passes, and become less harsh. Tannins in wine can be detected by an initial drying of the mouth.

Sweetening wines can be done by the home winemaker with the addition of sugar syrop or wine conditioner. If you decide to go this way, you MUST use sorbate and sulphite to prevent refermentation.

Hope this helps;

Pat

#3 Jack Keller

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Posted 11 November 2005 - 08:59 AM

QUOTE
How come commercial wines some have sour taste  but some are not?
...Can we intend to make wine without the sour taste like some commercial wine?,


Thach, technically, sour is the taste of acid. Some say bitter, but it really is not. Tannins are astringent -- a tactile sensation most often incorrectly identified with bitterness. Bitterness in wines is really caused (mainly) by flavonoid phenols and possibly terpene glycocides. So, if you say a wine is "sour," I assume you are referring to acidity. Pat is right in saying that a deficit in sugar makes either of these tastes more pronounced. Conversely, adding sugar will mask either to some degree.

But you specifically mentioned the pH of wines. This is a chemistry term, meaning the p(otential of) H(ydrogen) -- the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter. On a scale of 0 to 14, 7 is neutral, above 7 is alkaline and below 7 is acidic. A simple (although not entirely accurate) way of thinking of it is that a wine with a pH of 3.5 is twice as acidic as a wine with a pH of 3.6. All things being equal, a wine with a pH of 3.5 will taste more sour than one with a pH of 3.6 (assuming the wine is bone dry).

A wine with a pH of 3.6 is dangerously close to being biologically unstable. A wine with a pH of 3.4 requires 40 ppm of SO2 to be aseptic to most spoilage organisms, while one with a 3.5 pH requires 50 ppm and a wine with 3.6 pH requires 60 ppm. Another way of looking at it is 5 gallons of 3.4 pH wine requires 1.333 grams of potassium metabisulfite, while one with a 3.6 pH requires 2.000 grams. Ergo, winemakers typically favor wines with a pH range of 3.2-3.4, although wider variences are acceptable as long as the pH is factored into the finished wine (sulfite adjustment is one consideration, but residual sugar is another).

To answer you questions directly, I would say the absence of residual sugar accounts for the sour taste you don't like, and yes, you can make wines that don't have this objectionable taste. You simply need to make sweeter wines, not necessarily less acidic ones.

#4 muscadine

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Posted 11 November 2005 - 05:58 PM

Jack, thanks for the lesson on PH vs acidity vs K meta. I had never seen it expressed in this manner.

Regardless of ones age there is always room for more learning. Kind of like Jello!!! biggrin.gif

#5 Sassy

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Posted 12 November 2005 - 06:37 AM

QUOTE (P Cuthbert @ Nov 10 2005, 09:22 AM)
Thach;

You describe an interesting aspect of wine.

The "sour" taste of red wines in particular are a definite deterent to beginning wine drinkers.  Many try them and find them too bitter so they go on to the medium sweet white wines and sweet red wines.  As they experience more wine styles, the taste can change so that they can enjoy the nuances of the dry reds.

What makes a wine "sour" is a combination of 3 things.  Acid, residual sugar, and tannin. 

Dry red wines will generally have significant acid, but less than white wines.  Acid in wine will cause your mouth to water.

Dry red wines will have very little residual sugar.  This can be adjusted in the glass by adding a teaspoon of table sugar, more or less to your taste.  Give this a try.

Tannins are another component of red wine that can give the impression of "sour".  Tannins change as time passes, and become less harsh.  Tannins in wine can be detected by an initial drying of the mouth.

Sweetening wines can be done by the home winemaker with the addition of sugar syrop or wine conditioner.  If you decide to go this way, you MUST use sorbate and sulphite to prevent refermentation.

Hope this helps;

Pat



Hi Pat, I was reading your post, quite informative. My question is this, I want to sweeten a wine that is bulk aging, I am not going to do it for another month or so. I plan to use wine conditioner, this is my first time doing this. What is the smallest amount of sulfite I can use and what is sorbate? I had posted a similar question a while back and had some great answers but am still a little unsure. Thanks, Sassy

#6 Thach

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Posted 12 November 2005 - 09:47 AM

Thank you for all the answers

Can we make dry wine without the sour taste (unsweet wine)? or we have to add small amount of sweetener anyway?

#7 muscadine

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Posted 12 November 2005 - 06:37 PM

Jack, you have provoked my thought process.

I only check the PH of the must...it's a one time thing for me. But from your explanation of PH and the addition of K-meta maybe I should be checking the PH at every racking. Does the PH change as the fermentation process goes on and if so, can a PH meter then take the place of an SO2 test? In all fairness I should tell you that I don't have either an acid tester or an SO2 tester. If I can get by with just a PH meter that would suit me just fine.

Regards, David

#8 Jack Keller

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Posted 13 November 2005 - 09:37 AM

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I only check the PH of the must...it's a one time thing for me.  But from your explanation of PH and the addition of K-meta maybe I should be checking the PH at every racking.  Does the PH change as the fermentation process goes on and if so, can a PH meter then take the place of an SO2 test?

David, both TA and pH (by the way, it's a small "p") change constantly during fermentation, so measuring either after pitching the yeast and before the finished wine is degassed is a waste of time and resources. Measure them initially, before pitching the yeast, and before bottling but after the wine is degassed.

Why do they change? Well, to simplify the discussion let's limit it to grape wine, as more information is available on it than on then hundreds of non-grape wines. Grapes, as we all know, naturally possess mostly tartaric acid, but also a good deal of malic acid as well as a little citric acid. During fermentation, carbonic, succinic and lactic acids are produced in trace amounts, with carbonic being the greater. Both sulfurous and sulfuric acids result from elemental and compound sulfurs in or on the grapes and from sulfite additions. Hydrochloric and orthophosphoric acids can derive from aseptics added to the must. Dioxymalic and dioxytartaric acids form from the oxidation of natural acids in the grapes, and some acetic acid is always produced by fermentation alone, although formic acid can also appear. Under certain conditions, seven other acids can form (gluconic, glycuronic, glycolic, glyoxylic, glyceric, saccharic, and high fatty acid). There are others that have been detected in trace amounts, but they are considered rare. The point, however, should be obvious -- acidity increases (and then fluctuates) during fermentation.

When fermentation slows to an immeasurable crawl (there is positive pressure inside the secondary but no bubbles escape the airlock), carbon dioxide is being absorbed into the wine and some of it is being changed into carbonic acid. Degassing the wine will drive out the carbon dioxide, but as the carbonic acid then breaks down more CO2 will be released. This is why degassing should bridge a 3-day period.

Checking the pH will never tell you how much SO2 is in the must or wine -- only how much bisulfite or metabisulfite addition is required to reach aseptic levels. An SO2 test kit will cost between $10-$14 US and is good for 10 testings. I buy them 3-5 kits at a time to get a break on the price. You can save money buying them from Canadian suppliers, but if you have any problems (lost shipment, broken ampules) you could find it difficult to get satisfaction unless you have the delivery insured (which just about eats up the savings).

The key, however, is knowing the pH and (to a lesser degree) TA. Once you know the pH, you then calculate how much metabisulfite to add and trust the calculation to deliver it. After that, it is wise to test SO2 again after, say, 30-45 days. This will give you an indication of how rapidly the SO2 dissipates. After the wine is still, I might test SO2 again in 2 months, but rarely ever again after that. Such testing is usually not necessary for better quality kit wines, as these are well balanced and the instructions have worked out when to add what in premeasured amounts.

When I test TA and pH (do this long enough and taste can tell you a lot), I test my musts initially and possibly again after making any adjustments to acidity at the end. I have never found it necessary to test after fermentation unless the wine simply tastes flat and lifeless (an indication of insufficient acid) or I am entering a wine in a competition that requires the TA, pH and SO2 levels (I hate competitions that require this, as such numbers cannot help but affect an objective judgment on the wine itself).

Anyway, I hope this helps.

#9 Purple Tooth

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Posted 13 November 2005 - 02:02 PM

QUOTE (Jack Keller @ Nov 13 2005, 08:09 AM)
David, both TA and pH (by the way, it's a small "p") change constantly during fermentation, so measuring either after pitching the yeast and before the finished wine is degassed is a waste of time and resources.  Measure them initially, before pitching the yeast, and before bottling but after the wine is degassed.

Why do they change?  Well, to simplify the discussion let's limit it to grape wine, as more information is available on it than on then hundreds of non-grape wines.  Grapes, as we all know, naturally possess mostly tartaric acid, but also a good deal of malic acid as well as a little citric acid.  During fermentation, carbonic, succinic and lactic acids are produced in trace amounts, with carbonic being the greater.  Both sulfurous and sulfuric acids  result from elemental and compound sulfurs in or on the grapes and from sulfite additions.  Hydrochloric and orthophosphoric acids can derive from aseptics added to the must.  Dioxymalic and dioxytartaric acids form from the oxidation of natural acids in the grapes, and some acetic acid is always produced by fermentation alone, although formic acid can also appear.  Under certain conditions, seven other acids can form (gluconic, glycuronic, glycolic, glyoxylic, glyceric, saccharic, and high fatty acid).  There are others that have been detected in trace amounts, but they are considered rare.  The point, however, should be obvious -- acidity increases (and then fluctuates) during fermentation.

When fermentation slows to an immeasurable crawl (there is positive pressure inside the secondary but no bubbles escape the airlock), carbon dioxide is being absorbed into the wine and some of it is being changed into carbonic acid.  Degassing the wine will drive out the carbon dioxide, but as the carbonic acid then breaks down more CO2 will be released.  This is why degassing should bridge a 3-day period.

Checking the pH will never tell you how much SO2 is in the must or wine -- only how much bisulfite or metabisulfite addition is required to reach aseptic levels.  An SO2 test kit will cost between $10-$14 US and is good for 10 testings.  I buy them 3-5 kits at a time to get a break on the price.  You can save money buying them from Canadian suppliers, but if you have any problems (lost shipment, broken ampules) you could find it difficult to get satisfaction unless you have the delivery insured (which just about eats up the savings). 

The key, however, is knowing the pH and (to a lesser degree) TA.  Once you know the pH, you then calculate how much metabisulfite to add and trust the calculation to deliver it.  After that, it is wise to test SO2 again after, say, 30-45 days.  This will give you an indication of how rapidly the SO2 dissipates.  After the wine is still, I might test SO2 again in 2 months, but rarely ever again after that.  Such testing is usually not necessary for better quality kit wines, as these are well balanced and the instructions have worked out when to add what in premeasured amounts.

When I test TA and pH (do this long enough and taste can tell you a lot), I test my musts initially and possibly again after making any adjustments to acidity at the end.  I have never found it necessary to test after fermentation unless the wine simply tastes flat and lifeless (an indication of insufficient acid) or I am entering a wine in a competition that requires the TA, pH and SO2 levels (I hate competitions that require this, as such numbers cannot help but affect an objective judgment on the wine itself).

Anyway, I hope this helps.


Jack if we could get new poster to read your post(s) you might cut WinePress membership questions by 90% and book sales by 75%. Of course maybe you're getting a kick-back from Jon Iverson, which might hurt and make it pretty boring here. btw short term I'm going with an in-line diaphragm pump, but still hope to order that carbouy lift. Probably another ss 28 gal tank 1st to avoid all the lifting and hospital visits. 2nd btw so if I drink this left over unfrozen concentrated alcohol wine instead of senting it to you will I die or my hair fall out? Do I report myself on my income tax form to the IRS?

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#10 Jack Keller

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Posted 13 November 2005 - 09:23 PM

QUOTE
Of course maybe you're getting a kick-back from Jon Iverson, which might hurt and make it pretty boring here. . . . so if I drink this left over unfrozen concentrated alcohol wine instead of senting it to you will I die or my hair fall out? 

Wish I did get something from Jon, but no such luck.

No harm will come to you if you were to make an unfrozen concentrated alcohol wine and drink it. Just don't drink and drive.




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