Acidity?

[Handy Andy]

In what ways and at what stages can PH levels be adjusted in grape wines?

 

[Scooter68]

The normal process is to 'set' the acidity before starting the fermentation. There is no accurate way to test or adjust the acidity when fermentation is ongoing.
During and immediately after fermentation the acidity typically will be very high (Significantly Lower pH numbers than at the start)
Once fermentation is over AND the wine has been degassed naturally or mechanically, then you can adjust the pH.

As far as what to add - To increase acidity Normally you add either an acid blend or the type of acid that is normally dominant in the grapes/Fruit. There are exceptions. (hopefully someone with a greater depth of knowledge of the pros and cons of each acid will chip in here.)
To decrease acidity you normally use calcium carbonate.

Key point - Increasing acidity is pretty quick and easy on the other hand reducing acidity is a bit tricky. For reducing the acidity you can calculate the amount of Calcium Carbonate needed then add no more than 1/3 of the calculated amount. Wait at least a full day, then recheck the pH. Go slow.

(I have played that game poorly once and it's no fun bouncing the pH lower then higher and back again. )

 

[montanarick]

Ok - I agree pretty much with Scooter68 that it's probably best to make pH adjustments before fermentation if possible but they can be made right up to bottling time. You're not indicating whether you need to raise or lower pH - the latter being a lot easier. If you need to lower I would use potassium carbonate as opposed to calcium carbonate and only attempt to drop acidity by no more than 1-2%. Malolactic fermentation followed by cold stabilization can yield as much as a fifty percent reduction in acidity. You can always back-sweeten to taste to counter any remaining unwanted tartness. Good luck

 

[Handy Andy]

I also make fruit wine some from oranges, and note orange wine does not oxidize as grape wine does. The only reason I have for this is Vitamin C ascorbic acid content. When adding acid, to reduce the Ph in a grape wine, would ascorbic acid have any anti oxidant advantages ???

I intend to have a play with Malolactic fermentation this year. I am still learning.

 

[Scooter68]

It's important to be very Clear when talking about Acidity. Handy Andy may not be a total beginner but some who read these threads might be very confused if we don't use the terms correctly.

To be correct with the terminology here:

Raise pH = Higher pH Number = Less Acid
Lower pH = Lower pH Number = More Acid

Adding Potassium Carbonate or Calcium Carbonate will Raise the pH and Lower Acidity.

 

[Handy Andy]

It's important to be very Clear when talking about Acidity. Handy Andy may not be a total beginner but some who read these threads might be very confused if we don't use the terms correctly.

To be correct with the terminology here:

Raise pH = Higher pH Number = Less Acid
Lower pH = Lower pH Number = More Acid

Adding Potassium Carbonate or Calcium Carbonate will Raise the pH and Lower Acidity.

Perhaps not a total beginner this year, last year I definitely was

I was busy spraying my vines for downy mildew this morning and my mind came back to this thread.

Reducing acidity by adding Potassium Carbonate or Calcium Carbonate, is a way of reducing acidity.

Would another viable way be to add water to dilute the acidity then sweeten with sugar to get the brix level to what is desired before fermentation??

I have done this with my orange wine and get a Ph of with 3.5 with 50,50 oranges and water + sugar and yeast.

Would adding ascorbic acid, if i can get it, reduce the wines ability to oxidise??

 

[Scooter68]

Handy Andy, posted "...Would another viable way be to add water to dilute the acidity then sweeten with sugar to get the brix level to what is desired before fermentation??

It would but at the cost of decreasing the flavor of the wine. Given a juice with a high acid content, diluting it will lower the acidity (assuming a lower acid level liquid is used) but that also pushes your flavor down as well. I don't like using "chemicals" any more than I have to but this is one of those situations that unless you have an over abundance of flavor, dilution is not a preferred option.

 

[Dmaley]

Ok - I agree pretty much with Scooter68 that it's probably best to make pH adjustments before fermentation if possible but they can be made right up to bottling time. You're not indicating whether you need to raise or lower pH - the latter being a lot easier. If you need to lower I would use potassium carbonate as opposed to calcium carbonate and only attempt to drop acidity by no more than 1-2%. Malolactic fermentation followed by cold stabilization can yield as much as a fifty percent reduction in acidity. You can always back-sweeten to taste to counter any remaining unwanted tartness. Good luck

Handy Andy, posted "...Would another viable way be to add water to dilute the acidity then sweeten with sugar to get the brix level to what is desired before fermentation??

It would but at the cost of decreasing the flavor of the wine. Given a juice with a high acid content, diluting it will lower the acidity (assuming a lower acid level liquid is used) but that also pushes your flavor down as well. I don't like using "chemicals" any more than I have to but this is one of those situations that unless you have an over abundance of flavor, dilution is not a preferred option.

If I may ask, why is Potassium carbonate better than Calcium Carbonate? I don't have a clue so that's why I'm asking. I am working on a stubborn Cranberry wine (5 gallon) made from 100% juice with a OG of 1.118 (white granulated sugar added). After the slow-ish fermentation stopped at about 1.060 after 10 days of fermentation, I adjusted the PH up from 2.4 to 3.7 with Calcium Carbonate. Took about 1.5 tsp/gallon. Fermentation did not restart after a few days so, then I made an apple juice starter (about 1 gallon), got it going well for a few days and combined into the cranberry. It's going decently now, but I'm not confident about how it will turn out since i had to add what I have read is the max dose of calcium carbonate. Using EC-1118, BTW.

 

[sour_grapes]

If I may ask, why is Potassium carbonate better than Calcium Carbonate? I don't have a clue so that's why I'm asking. I am working on a stubborn Cranberry wine (5 gallon) made from 100% juice with a OG of 1.118 (white granulated sugar added). After the slow-ish fermentation stopped at about 1.060 after 10 days of fermentation, I adjusted the PH up from 2.4 to 3.7 with Calcium Carbonate. Took about 1.5 tsp/gallon. Fermentation did not restart after a few days so, then I made an apple juice starter (about 1 gallon), got it going well for a few days and combined into the cranberry. It's going decently now, but I'm not confident about how it will turn out since i had to add what I have read is the max dose of calcium carbonate. Using EC-1118, BTW.

@Dmaley , may I ask how you are measuring your SG? Hydrometer or refractometer?

 

[Raptor99]

This discussion spurred further research. According to this article potassium bi/carbonate is better than calcium carbonate: Deacidification - The Australian Wine Research Institute They recommend potassium bicarbonate as the best way to reduce acidity.

 

[Raptor99]

Here's another very helpful article sponsored by Scott Laboratories: Potassium Bicarbonate and Cold Hardy Hybrids – Midwest Wine Press

 

[Dmaley]

@Dmaley , may I ask how you are measuring your SG? Hydrometer or refractometer?

Hydrometer. I have a refractometer but other than measuring the SG of water I don't know how to use it. I tried to use it to measure the OG of this cranberry must but it showed no blue line anywhere on the meter. . I figure I'm doing somthing wrong.

 

[sour_grapes]

Hydrometer. I have a refractometer but other than measuring the SG of water I don't know how to use it. I tried to use it to measure the OG of this cranberry must but it showed no blue line anywhere on the meter. . I figure I'm doing somthing wrong.

Great. The reason I asked was that we often see people thinking that there fermentation has stalled, because they are measuring with a refractometer. (These cannot easily be used during fermentation, as the alcohol skews the reading.)

So, sadly, it seems that your sluggish fermentation is, indeed, sluggish! I would have advised you to do exactly what you did, viz., make a healthy starter, so perhaps you should just maintain your patience for now.

 

[Dmaley]

Great. The reason I asked was that we often see people thinking that there fermentation has stalled, because they are measuring with a refractometer. (These cannot easily be used during fermentation, as the alcohol skews the reading.)

So, sadly, it seems that your sluggish fermentation is, indeed, sluggish! I would have advised you to do exactly what you did, viz., make a healthy starter, so perhaps you should just maintain your patience for now.

Thanks for the info! I did not know that about refractometers. I got the Refractometer for Christmas from someone equally as clueless as I (in wine making) and I have no idea how to use it. I read the directions and tested with distilled water and I see the blue/white transition at 0. However, when I tried it with my cranberry must (at 1.118) there was no blue/white demarcation... Just a white scale. I figure I dont know what im doing. Sounds like it's best to just stick with the hydrometer anyway. On the sluggish fermentation... Do you think its the low PH? My first batch I did was a 5 gal apple mead with about 12-14 lbs of honey in it. I think my OG was about 1.110 and it fermented very vigorously in about 7-8 days down to about 1.0. But I have no idea what the PH on it may have been becasue I didnt know to be concerned about it, at that time.

 

[Raptor99]

I takes a little practice getting used to the refractometer. I place several drops of must on the prism surface, and make sure that the entire surface is covered one I lower the plastic cover. I have also found that if the must is very cloudy it is difficult to read. I have gotten around that by running a small sample through a paper coffee filter before I take my measurement.

After some practice, I found that my Brix/SG readings with the refractometer were very close to the ones I took with my hydrometer. While you are learning, it is good to measure it both ways. Once fermentation has started, you can easily find the current SG by entering the original and current Brix into this calculator: Homebrew Refractometer Calculator

 

[Dmaley]

I takes a little practice getting used to the refractometer. I place several drops of must on the prism surface, and make sure that the entire surface is covered one I lower the plastic cover. I have also found that if the must is very cloudy it is difficult to read. I have gotten around that by running a small sample through a paper coffee filter before I take my measurement.

After some practice, I found that my Brix/SG readings with the refractometer were very close to the ones I took with my hydrometer. While you are learning, it is good to measure it both ways. Once fermentation has started, you can easily find the current SG by entering the original and current Brix into this calculator: Homebrew Refractometer Calculator

Thanks for the tip Raptor. I'll keep trying on the refractometer. Interseting articles. Seems that I may have salt crystals precipitating out for some time.