This formula for citrus stock, which extends the life of fresh citrus and helps to eliminate waste, was created with plenty of wiggle room in mind, and Iain Griffiths, who founded the pop up and online forum, Trash Tiki, with Kelsey Ramage, suggests adjusting your recipe based on the type of citrus you are using, as well as the drink you hope to make.
In certain recipes, this stock can be used on its own as an ingredient or in place of fresh juice; it can also be combined with fresh citrus juice in a 1:1 ratio for use in highballs and frozen cocktails.
1 kilogram citrus husks (split in half and juiced)
citric acid (see Editor's Note)
malic acid (see Editor's note)
Bring the water to a boil and add the citrus husks. Allow the mixture to boil for five minutes.
Using tongs, remove the husks, then remove the liquid from the heat.
Allow the liquid to cool, and measure it by volume (it should be about 1,300 milliliters)
Transfer the liquid back to the stockpot and place it over high heat.
Bring to a boil, and reduce the liquid by half.
Add in white sugar (see Editor's Note) to stabilize, and adjust with citric and malic acids (see Editor's Note).
All citrus stocks can be fortified with sugar; the Trash Tiki team recommends adding an amount equal to 8 percent of the total weight (1 milliliter of water is equal to 1 gram, so 8 percent of a 650 milliliter solution would be equal to 52 grams).
Depending on which kind of stock you're making, the Trash Tiki team recommends adjusting the stock with citric and malic acids as follows:
• For lemon and lime stocks, add in 3 percent citric acid and 2 percent malic acid (for a 650 milliliter solution, this amounts to 19 1/2 grams of citric acid, and 13 grams of malic acid).
• For orange and grapefruit stocks, add in 2 percent citric acid and 1 percent malic acid (for a 650 milliliter solution, this amounts to 13 grams of citric acid and 6.5 grams of malic acid).
• For a mandarin stock, add in 1 percent citric acid and 2 percent malic acid (for a 650 milliliter solution, this amounts to 6.5 grams of citric acid and 13 grams of malic acid).