The Winemaker’s Think Tank: Vol 23 – How do I test for Acid?

What’s the Winemaker’s Think Tank?

Every Thursday we will post about a few frequently asked questions that our winemaker has answered. If you have a winemaking question you would like to have answered, please email us at support@juicegrape.com and we will try to get into next week’s post. Cheers! 🙂

How do I test for Acid?

When testing for acidity in wine, you are looking for the Total Acidity value, or the amount of acids in grams per liter of wine. While this may sound complex, it will help you in achieving a proper balanced flavor in your end product. You will need a few basic lab supplies:  a test tube, a small 10ml graduated syringe, phenalthalein, sodium hydroxide. Draw a 15ml sample of the wine to be tested into the test tube. Add three drops of the phenalthalein. Swirl the drops around in the wine to mix it in thoroughly. (Note: When using sodium hydroxide, be very careful. It is a strong base that can cause burns. We suggest wearing eye and skin protection.) Using the 10 ml graduated syringe, slowly drop in the sodium hydroxide by .5ml at a time. Every drop, swirl the test tube contents to mix and observe any color reactions. Upon adding the drop, you will see an immediate color change, that will then dissipate. For white wines, you will observe a pink color and for red wines you will observe a grey color.  Keep repeating the process of adding a drop, swirling and observing until the color change is permanent. The amount of sodium hydroxide used, when the color change is permanent, will give you the Total Acidity. If 6ml of Sodium Hydroxide are used, then the wine contains .6% or 6g/L of TA.

We hope this information helps with your winemaking. If you have any follow up questions or winemaking questions in general, please email us at support@juicegrape.com.