From homemade plum wine to traditionally Sicilian Nero d’Avola, each wine is the result of chemical and biological reactions. The most important of these – the transformation of sugar into alcohol and carbon dioxide – is carried out by the yeast. The sugar content of the fermented juice is measured to determine potential alcohol. As the yeast eats sugar in the unfermented juice, which is called “must,” the sugar content falls until nothing is left, or until the winemaker stops the fermentation going residual sugar for sweetness. Throughout this process, the winemaker measures the sugar with a hydrometer, an instrument that measures the density of liquid crystal.
- Make a disinfectant solution by mixing 1 gallon of warm water, one tablespoon of citric acid, and three tablespoons of potassium metabisulfite in a 1-gallon glass or plastic container. This will make the disinfectant solution sufficient for 10 to 20 readings and will remain usable for more than a year, provided it is sealed when not in use.
- Disinfect the hydrometer, wine thief, a thermometer, and a glass cylinder. Then rinse and place on a hygienic surface to dry. Make sure your hands are clean too.
- Measure the temperature of the must by placing the thermometer in the wort and allowing it to float for 5 minutes. Record the heat and set aside the thermostat.
- Remove enough essential to fill the glass cylinder. Then allow the hydrometer to float freely by placing the end of the relieving valve of the thief came into the wort and sucking the other purpose. Empty, the thief came in the glass cylinder by gently pressing the thief’s relief tab that went against the inside of the cylinder.
- Place the large end of the hydrometer in the wort in the glass cylinder. Turn the hydrometer gently to release the clinging air bubbles. Gently release your grip on the hydrometer.
- Let the hydrometer to come to rest. Record the number on the hydrometer where they must meet the hydrometer. This number will be either a specific reading severity (for example, 1,060), a Brix-reading degree (15, for example), or an alcohol potential reading (5 percent, for example). The specific weight tells you the density of the liquid compared to pure water at 60 degrees Fahrenheit. The degree reading Brix-te shows you the percentage by weight of must that is sugar. The potential of reading alcohol – taken at the beginning of fermentation – tells you what percentage of drinking your wine will have if all the sugar is fermented out or converted into alcohol by yeast.
- Remove the hydrometer from the glass cylinder and pour the must from the glass cylinder back into its original container or into a tasting cup.
- Clean and disinfect wine thief, glass cylinder, thermometer, and hydrometer.
Tips and warnings
- Most of the supplies you will need are available at homebrew stores.
- Taste the must throughout the fermentation process to see how the wine is progressing.
- When the specific gravity reads 1,000 or below, all the sugar has been converted to alcohol. The same can be said for 0 degrees Brix and 0 percent of potential alcohol.
- Different strains of yeast die out at varying levels of alcohol, so make sure they match the alcohol potential from the alcohol tolerance of the enzyme.
- About 1 percent of people are sensitive to the sulfites used in the disinfectant solution. If you are among them, use a different disinfectant solution (not sterilization). Homebrew stores often have alternatives. (All wine contains sulfites, so if you drink wine, you will know if it is sensitive.)