A homemade applejack recipe creates an apple-based liquor by freeze concentration. The recipe combines apple juice or cider with sugar, brewer's yeast and supplemental yeast nutrients. After initial fermentation, the mixture is frozen below 32 degrees Fahrenheit, where the water content turns to ice while the alcohol remains liquid. The two are separated and the alcohol is bottled, aged and enjoyed.
Generally, creating applejack starts by combining 5 gallons of apple juice and up to 2 pounds of sugar, dependent on how much fructose is already in the former. They are mixed in a sterilized container and warmed to approximately 75 degrees. Adding the brewer's yeast, available at homebrew shops, at this temperature ensures that the yeast activates immediately. Seal the container and add an airlock device that allows the carbon dioxide the yeast produces to escape.
After one to two weeks of fermentation, transfer the cider to a secondary fermentation vessel, leaving behind the yeast accumulation at the bottom of the primary container. Test the cider with a hydrometer to note the alcohol content. Allow the cider to ferment another one or two weeks, and then transfer again to a freeze-resistant plastic container. Freeze the cider with a large indoor freezer or, if in a region that experiences regular freezing temperatures, outdoors. Remove the ice that forms daily to concentrate the alcohol content up to 90 proof. After the majority of the water is removed, bottle the remaining applejack, and age it to mellow the flavor.