How Much Alcohol Is In Wine
If you’ve decided to make your own wine at home, probably one of the most frequent questions you ask is how much alcohol is in wine.
Ethyl alcohol represents between 9 and 16% of the volume of the wine, as alcoholic fermentation is inhibited at higher concentrations. But if you want to brag about your wine, then you might want to determine the real alcohol concentration of your beverage.
The Role Of Alcohol In Wine
Alcohol plays different actions in wine.
- The first and most important is the antiseptic action against the yeast, whose sensitivity to alcohol varies according to the species. This explains why the alcohol concentration varies in the different types of wine.
- Secondly, the alcohol also has a stabilizing action, decreasing the solubility of the potassium metabisulphite and forcing the precipitation of the tartaric salts, resulting in a total reduction of the acidity.
- Thirdly, another important action of the alcohol is the determination of the bouquet of the wine.
- Lastly, the alcohol has an action on maceration and on the determination of the color of the wine.
We can distinguish between three types of alcoholic content, actual alcoholic strength, potential alcoholic strength, and total alcoholic strength.
The actual alcoholic strength represents the number of the milliliters of alcohol contained in 100 milliliters of wine, measured at 20°C or 68°F, which actually gives the percentage by volume of the alcohol concentration of wine. This measurement is usually helpful in the winemaking process to understand if it is the time to start bottling or not.
The potential alcoholic strength represents the amount of ethyl alcohol that can still be obtained by the fermentation of all the sugar remaining in the wine. It can be calculated by multiplying the grams of sugar contained in 100 milliliters of wine with a factor of 0,6 that is the alcoholic yield. For example, if there are still 100 grams of sugar in 100 milliliters of wine, you would still be able to obtain 60 milliliters of alcohol through a secondary fermentation.
The total alcoholic content is the sum of the actual alcoholic strength and the potential alcoholic strength and it can be determined either by distillation or by ebulliometry.
How Much Alcohol Is In Wine
In winemaking, the most important is the determination of the actual alcoholic strength. The actual alcoholic strength is usually measured through pycnometry or ebulliometry. However, these scientific methods are hard to use at home and usually, only the industrial wine producers use them.
To measure the actual alcoholic strength at home, the simplest way is with the help of a hydrometer.
How Much Alcohol Is In Wine
Determining The Actual Alcoholic Strength With A Hydrometer
A hydrometer is a simple instrument. Essentially it is a long glass tube with a weight fixed on one end and with various gradations on the length of the tube.
To use it, you have to literally drop the hydrometer in a glass full of wine and observe how high or low it floats, then read the gradation to determine the actual alcoholic strength.
To do this accurately, you must take two readings, one at the beginning of the fermentation process and one when the fermentation process has ended.
The first reading should be taken at the same time when you add the yeast to the wine. At this stage, the instrument should indicate a reading of about 10 to 13%. This reading is not the actual value of the alcohol concentration but rather an indicator of how much alcohol you can obtain if all the sugars are fermented completely.
Make sure to write this number down and keep it in a safe place as you will need it in future.
When the fermentation stopped and right before bottling the wine, take another reading with the hydrometer. At this stage, the instrument should indicate a value of around – or + 1.
To determine how much alcohol is in wine, subtract the second number from the first one and you will have the exact concentration of your beverage.
There is to say that a hydrometer cannot determine the potential alcoholic strength as it doesn’t actually measure how much sugar there is left in your wine. For this reason, if you are planning to begin a secondary fermentation, maybe to produce a sparkling wine, you should use other instruments to determine the potential of a new fermentation.
Determining The Actual Alcohol Strength With A Pycnometer
A more scientific way of determining the actual alcoholic strength is with the use of a pycnometer. A pycnometer is a small narrow-necked flask with a sign engraved on it. Before using the instrument, it is necessary to calibrate it.
For the calibration, fill the pycnometer with water up to the sign and measure its weight. Empty the instrument and fill it with wine, then measure its weight again. The ration between the two weights is the density.
For accuracy of the calibration, both liquids have to be at the same temperature.
To determine the actual alcoholic strength, the wine sample must be distilled to a volume equal to two-thirds of the initial volume. The hydro-alcoholic solution is then poured into the pycnometer and diluted with distilled water up to the sign placed on the neck of the instrument.
Mix thoroughly and measure the weight. The number obtained corresponds to a specific actual alcoholic strength and there are many tables you can use to find out the actual alcoholic strength of your wine.
Knowing how much alcohol is in wine is important from many points of view. Most importantly, you will be able to determine the quality of the wine you produced and decide whether you have to improve your brewing technique or not.
You will also be able to determine if and how much sugar you have to add to your wine if you want to start a secondary fermentation. All this will help you achieve a better wine every time.