Special Offers Email

Each month we'll send you an email packed with deals on your favorite beer and wine making supplies. Sign up today and save!

Beer Equipment Kits Beer Filters & Funnels Carboy Accessories Fermentation Vessels Kegging Equipment Mini Kegs Siphons & Tubing Small Misc. Equipment Cappers & Caps True Brew Beer Kits High Gravity / Specialty Recipes Recipe of the Month Kits Hop Flowers Hop Rootings Brewers Best Liquid Malt Extract View More

Wine Making Equipment Kits Cordial Brewing Kits Straining Bags Testing Equipment Presses Wine Ingredient Kits Barrels & Spigots Carboy Accessories Crushers & Destemmers Fermentation Locks Fermentation Vessels Additives Clearing Agents Fruit Purees Fruit/Grape Wine Base View More

Cheese Cultures & Supplies Cheese Making Equipment Cheese Making Kits Small Presses for Berries & Herbs Mushroom Growing Kit Olive Oil Tomato Machine Complete Soft Drink Kit Soft Drink Extracts Vinegar Crocks & Barrels Vinegar Cultures & Additives Vinegar Making Kits View More

Beer Making & Recipe Books Beer Making Magazines Mead & Cider Books Food Preparation Vinegar Making & Recipe Books Cordial Making Books Distilling Books Wine Making & Recipe Books Wine Making Magazines View More

Acid Testing

The concentration of acids must be balanced with the sweetness and astringency of wines. The balance is critical because acidity, sweetness, and astringency represent 3 of the 4 tastes areas on our tongues. Wines have many naturally occurring acids but there are three primary acids, tartaric, citric and malic acids. It is important to adjust the acid content of the must prior to fermentation to promote proper yeast fermentation and prevent off-flavor development.

Total acidity is measured by titrating the must (or wine) with a 0.1N sodium hydroxide solution. The total acidity is expressed at % Tartaric Acid in the following example.

Collect the must in a clean container and place 3 cc of must into three separate containers, beakers, flasks or test tubes (See Figure 1).

Figure 1 Beaker and three flasks with must.

Add 6 cc of water, preferably distilled, to each flask for dark wines to lighten the color. This is not necessary for white wines.

Add 3 or 4 drops of phenolphthalein to each flask and swirl to mix. Label the flasks-control, 1 and 2.

Fill burette (or syringe) with sodium hydroxide solution and begin to titrate flask 1 by adding solution drop wise with mixing (swirl flask) until a color develops throughout sample. This is the endpoint. It is difficult to detect the endpoint so it is important to have good lighting and compare the control flask to the sample flask often (See Figure 2)

Figure 2 Control flask is on the left and sample flask is on the right

Read the amount of sodium hydroxide added from the burette or syringe (See Figure 3).

Figure 3 Read the amount of sodium hydroxide added at bottom of liquid.

In Figure 3 the amount of sodium hydroxide added is 2.1 cc. Repeat the titration with sample 2 and take the average of both numbers.

Calculate the acid content expressed as % Tartaric Acid by multiplying the cc's added by 0.25, for example, 2.1 x 0.25 = 0.525 % Tartaric Acid.

Adjust the acid content according to the type of wine you are making.

To adjust the acidity of the must, use the following guidelines:

1 ounce of acid in 5 gallons of must (or wine) will raise the acidity by 0.17% (tartaric acid)

The formula to increase the acidity is:

(A-B)/0.17 X C/5 = Ounces of acid needed per 5 gallons

A=Target tartaric acid
B=Actual tartaric acid
C=Volume of expected wine in gallons

Dissolve the acid or acid blend in warm water (1-3 cups) depending upon the amount of acid needed. Make sure the acid or acid blend is dissolved before adding to the must. Add the acid solution in increments, thoroughly stir and check after each addition. Be careful not over-shoot your target acidity. It is better to be slightly below your target than to significantly overshoot target. Acidity can be adjusted before bottling if necessary.

The formula to decrease acidity is:

(A-B)(C)/A = gallons of water to add per 5 gallons

Add water to the must in increments and check after each addition. If you are adding large quantities of water, don't forget to check specific gravity.

Note: Acidity can also be adjusted before bottling by blending with other wines.