grapestompers - winemaking supplies and wine kits
Search Products
Shopping Truck
Home
Catalog
Winemaking Information
Specials
Customer's Corner
Contact Us
About Us
Policies
Location

How to Test for Acidity in Strawberry Wine

Acknowledgement | Photos | References

Acknowledgement
We would like to thank Brian Shuhart for providing all the photos and the basis of the text for this page. He noticed that no one offered actual images of the entire process of adding reagent and swirling, as well as photos of the endpoint. We could not have made this page without his help.

Here is the note Brian sent::
I have only been making wine for a little over 2 years and have been blindly following recipes to the letter. Doing so, I have been creating wines that, to me, have an acid bite flavor. So I have been searching the web for a walk through process on how to test the acidity of wine that contains pictures. During my search, I came across a few forums with people looking for the same info. Since I could not find one, I recently bought a test kit from a local wine supply store, began testing, and created the attached document to share. You have my permission to use as is, or modify the attached document for your web page.

Photos
Here is a series of photos taken during the acid testing process. For this demonstration, I am using the Wine Acid Test Kit made by Crosby and Baker (Item #2716 in our online catalog), which comes with 4 oz. standard sodium hydroxide solution (0.1 Normal), 0.5 oz. acid indicator solution (phenolphthalein), calibrated syringe, test tube, and complete instructions.

I started with a 3 ml. sample of strawberry wine that has no additives. This is a good example of testing for acid in a blush colored wine. If you'd rather see a white wine being tested, please see our peach wine example.

strawberry wine - no additives

Photo 1

Strawberry wine:  no additives

This is our starting point, a small 3 ml. sample of wine or must. Make special note of the beginning color.

strawberry wine - after 3 drops phenolphthalein

Photo 2

Strawberry wine: after adding 3 drops phenolphthalein and swirling a bit to mix

No real color change noted. The phenolphthalein serves as our color indicator.

strawberry wine - after 0.5 ml NaOH

Photo 3

After adding 0.5 cc sodium hydroxide

  • left photo shows initial pink color when NaOH first added
  • right photo shows a little pink color at top that goes away after swirling
strawberry wine - after 1.0 ml of NaOH

Photo 4

After adding 0.5 cc more sodium hydroxide (for a total of 1.0 cc to this point)

  • left photo shows initial pink color when NaOH first introduced
  • right photo shows return to normal color after swirling
strawberry wine - after 1.5 ml of sodium hydroxide

Photo 5

After adding 0.5 cc more sodium hydroxide (for a total of 1.5 cc to this point)

  • left photo shows initial pink color when NaOH first introduced. Notice the color impact is more pronounced.
  • right photo shows return to normal color after swirling
strawberry wine - after adding a total of 2.0 ml of sodium hydroxide

Photo 6

After adding 0.5 cc more sodium hydroxide (for a total of 2.0 cc to this point)

  • left photo shows a darker pink color when the NaOH is first introduced. We're getting close!
  • right photo shows return to normal color after a longer swirling time.
strawberry wine - endpoint is reached

Photo 7

After adding 0.5 cc more sodium hydroxide (for a total of 2.5 cc to this point)

  • The pink color change becomes final. Swirling no longer makes the color go away.
  • once the color change begins to remain longer during the swirling, you should reduce the amount of Sodium Hydroxide added at a time.

OK - now that we've successfully found the endpoint of our acid titration, it's time to do a little math to discover the acid level of our wine.

According to the directions that came with the acid test kit, we multiply the amount of sodium hydroxide used (in ml) by 0.25 to find out the percentage of acid or T.A.:

2.5 ml NaOH
X   0.25
0.625 %

WARNING: All acid test kits are NOT the same; please refer to the instructions that came with your kit to determine the correct mathematical formula to use to arrive at your calculated acid level.

OK, this is good! I like my sweet wines to have an acid level between .55% - .65%. Since the acid level of my strawberry wine falls in this zone, I am going to leave this wine alone.

If you do need to make an adjustment based on your test results, here's a page that explains how to raise and lower wine acid levels.

See our page that shows an acid test being done on a peach wine. This is a white wine, so the colors you will see on that page are bit different than the strawberry photos you just saw.

Further Reading on this topic
Clicking on any of the reference links below will open a new browser window: