Patience is a key ingredient when making homemade wine, a hobby that can take months to reach the payoff: a sip of your own creation. Because the process differs according to the type of grape you use and your tastes, it isn't possible to pinpoint a single recipe or formula that will work every time you try your hand at making wine. Still, some general steps and factors to consider apply no matter what materials you start out with.
Go through the grapes, throwing out any that are rotten, bug-eaten or unripe. Rinse the grapes with clean water and remove the stems if you're using red grapes. White grape stems don't need to be removed.
Sanitize any equipment you'll be using to process your grapes, including crushing implements, vessels, siphon tubes and other essentials. Make a sulfite solution with 3 tablespoons of potassium metabisulfate and 1 gallon of water. Spray the solution on or dip the equipment in it; there's no need to rinse.
Use your feet, your hands or a potato masher to crush the grapes, producing both pulp and juice. If you're processing a large batch, you may want to invest in a crusher or crusher/destemmer. If you are making white wine, put the crushed grape pulp in a mesh fermenting bag and press it, squeezing out as much juice as possible. Discard the pulp.
Test the acidity of the "must," as the grape mixture is called, using a titration kit. Dry red wine should have a reading between 0.60 percent and 0.70 percent, and dry white wine should have a reading of 0.65 to 0.75 percent. To raise the acid content of the must, add a mixture of fruit acids, referred to as acid blend; 1 teaspoon of acid blend added to each gallon of must will raise the reading 0.15 percent. To reduce the acid content, dilute the must with water and test again.
Test the sugar level of your must with a tool called a hydrometer. Sugar feeds the yeast in fermentation, producing alcohol. The "potential alcohol" reading on the hydrometer should be 9 to 13 percent. Add sugar, if necessary, in small amounts – about 1 tablespoon at a time per gallon – making sure it dissolves. You can dissolve the sugar in water before adding if you like.
Place the juice in a fermentation vessel; white wine makers will have only juice to add to the vessel, but red wine makers will have both juice and pulp. Put the pulp in a mesh fermenting bag and submerge it in the juice. For both white and red wine, add any ingredients called for in your recipe, except for the wine yeast. Add water to bring the batch to the desired number of gallons.
Drop in one crushed Campden tablet, which contains potassium metabisulfite to sterilize the must, for each gallon of liquid. Cover the fermentation vessel with a lightweight cloth or towel and let sit for 24 hours.
Add one package of wine yeast per 5 gallons of must and cover the vessel again with a lightweight cloth or towel. You must add the wine yeast after the Campden tablets have had 24 hours to work. The fermentation process will start within a day, appearing as a foam on top of the must. Stir the must once per day.
Transfer the must to a clean fermentation vessel with an air lock on the fifth or sixth day. The air lock allows gases to escape while protecting the must from contaminants. Use a food-safe plastic tube to siphon the must into the clean vessel, leaving any sediment behind. If you are making red wine, press the pulp in the fermenting bag, getting out as much juice as possible, and discard the pulp. Add water to bring the liquid back up to the desired number of gallons if necessary.
Let this secondary fermentation continue for up to six weeks, until the foaming has ended and the fermentation has stopped. Use the "specific gravity" scale on the hydrometer to verify that fermentation is over; it should read between 0.990 and 0.998. Add one crushed Campden tablet for every gallon of liquid.
Allow the wine to clear for several weeks up to several months. Siphon the liquid away from the sediment into clean vessels once a month while the liquid clears. When the wine is clear, siphon it through a wine filter and into bottles and then cork the bottles.