How To Understand ph, and Take A Reading
The ph of your must is one of the biggest factors that can affect the outcome of your wine. Ph affects the flavor, aroma, color, stability and being able to survive the test of time in a bottle to say the least.
Wine ph is a logarithmic scale used by chemists to describe the number of hydrogen ions present in a solution. The scale is an “upside down” scale meaning the lower the number, the more ions that are in your wine. A reading of “0” represents the most acidic while “14” being the most basic. A ph of “7” being neutral. We accept water as being neutral.
The scale is logarithmic meaning that a reading of 3.0 contains ten times more ions than 4.0 The most accurate way to get a ph reading is with a meter, however in a pinch, litmus strips can be used as a rough gauge by dipping one into your must for a brief second then removing to compare to a color chart. Recommended ph ranges for wines are 3.4 to 3.65 for reds and 3.1 to 3.45 for whites and 3.5 to 3.6 for fruits.
Your ph value represents acids present in the wine and their strength. Wine ph is dependent upon the total amount of acids present, a ratio of malic acid to tartaric acid, plus the total amount of potassium present. Wine acids produce hydrogen ions while the ph is a measure of the number of hydrogen ions present in the must/wine.
The ph will be lower when titratable acid is higher but high titratable acid does not always produce low ph values. Potassium present in a must or wine can alter a wines ph. Malic acid is weaker than tartaric acid which can result in a wine high in malic acid have both a high total acid (TA) and a high ph level. When the total acid content is fixed, ph depends upon the relative amount of tartaric and malic acids present. This is why 2 wines may have the same ph, yet have different acid percentages.
Advantages of a low ph in your wine.
In the range of 3 to 4 ph there is a very little influence in the taste of the wine from the ph value.
The chemical and stability of wine at this range is greatly improved.
Commercial yeasts and their fermentations are not affected by normal ranges of the ph. The intensity of the color of your wine is improved.
Fining ingredients work at their best in these ranges at clearing proteins and sediment from the wine.
Less Sulfur Dioxide is needed to protect the wine.
Bacterial growth is greatly hindered in wines at low ph values.
Many of the problems associated with wine making are a result at least in part due to a high ph. This is why it is important to know your wines ph.
There are many different types of instruments you may purchase to monitor your wines ph. The one shown below is from Hanna Instruments model # 98128. It is water proof, adjusts for temperature (either F or C), calibrates easily and retails for around $120.00 You will also need buffer solutions “4.01 and 7.01” with this unit. With basic care it will last a long time.
Calibration of the tool is recommended monthly or more if used often. To calibrate this model, turn on. Then depress the “on” button and hold until the letters “CAL’ appear. Release the button, then “7.01” will appear. Insert the two electrodes fully into buffer solution 7.01 and wait while the unit calibrates to a 7.01 value. Once accepted the “4.01” value will appear. Immediately insert the unit into the “4.01” buffer solution. (If not done within 12 seconds a “WRNG” message will appear. Once the “4.01” is calibrated “OK 2” will appear and you are finished calibrating the meter. The meter will move to a normal reading mode.
After calibrating the instrument rinse off the two electrodes (one for ph one for temperature) with water and insert the probes into a sample of your must/wine. The LED reading will change a few times then after a few seconds stop, giving you your ph reading adjusting for the current temperature. If your must/wine is in the recommended range you need do nothing at all. If your must/wine needs adjustment, make the appropriate changes and test again (see below).
When finished, rinse off the electrodes and replace the protective cap filled with 4.01 solution. Always keep the electrodes wet. Should they dry out refer to the directions on how to “revive” them. Never store in distilled or tap water.
To adjust a must ph can be done via a number of ways. The addition of 1 level teaspoon per gallon of tartaric acid for grapes or acid blend for fruits will raise the acid level by approx. .15% (note the .) It is best to make changes prior to the addition of yeast as to avoid shocking them. Adjustments can also be made post fermentation. Blending with a must/wine of higher ph is an alternative method but not always feasible.
To lower acid (raise ph) you can add water. This may or may not be desirable. Sometimes juices can be so concentrated that the addition of water will lower the acid along with the specific gravity.
The addition of Calcium Carbonate to your must (preferably not wine) of no more than 0.3 to 0.4% as your flavor of the final product will be affected. One teaspoon (3.4 grams) of Calcium Carbonate per gallon will reduce acidity by approximately 0.1%
Potassium Bicarbonate de-acidifies a wine by neutralizing acid. Do not try to lower the acid by more than 0.03% and don’t use this if your ph is above 3.5 By using 1 teaspoon (3.4 grams) per gallon will lower acidity (raise ph) by approximately 0.1% Use a large container as excessive amounts of foaming will occur.
Cold stabilization for at least 3 weeks will also help to drop out some acid in your wine. Add 2 to 5 grams of Potassium Bitartrate (cream of tartar) per gallon of wine and stir daily to redistribute the crystals to expedite the dropping out of tartaric acid crystals (white diamonds). Rack afterwards before wine warms up.
Generally if you purchase/get juice from a professional winery your juice will most likely (but not guaranteed) to be sulfited and ph balanced. The amount and types of acid it contains will depend upon the reigon grown, amount of sunlight, temperatures, rain, soil when picked and countless other things.
Getting fruit from other sources is where you need to pay closer attention to your fruits sugar, ph and acid levels. It is best to make your changes prior to fermentation as proper levels will assist the fermentation process. Finally adjust as per your taste. The ranges above are basic standards but this doesn’t mean you can’t slightly adjust them to your own personal liking.