Origins and Inspiration
This delightful, bubbly beverage draws inspiration from two distinct traditions: the 'sweet potato fly,' a fermented drink historically enjoyed in South
American cultures, particularly in Guyana, and the more recent resurgence of sweet potato kvass championed by artisan fermenters in Australia. Kvass, in general, is known as a low-alcohol, probiotic-rich concoction characterized by its sweet-sour profile, refreshing taste, and often cloudy appearance, typically served chilled. The 'sweet potato fly' itself is crafted using grated sweet potatoes, a blend of spices, citrus elements, and water. Its popularization in Australia was significantly boosted by home brewers and artisanal producers, with notable coverage from media outlets like ABC Radio National in 2012 further cementing its appeal. This contemporary adaptation offers a pre-digested form of starch, making it potentially easier on the digestive system compared to cooked sweet potatoes, and has been met with enthusiastic reception.
Gathering Your Ingredients
To embark on your sweet potato soda creation journey, you'll need a few key components. The star ingredient is one large sweet potato, ideally an organic orange-fleshed variety. For the probiotic starter culture, incorporate 1/4 cup of liquid whey, which is most potent in its probiotic activity. Sweetness and a touch of fermentation fuel come from 1/2 cup of raw honey, with tupelo or gallberry varieties being particularly recommended. You will also require filtered water to form the base of your beverage. For optional flavor enhancements, consider having 1 teaspoon of ground cinnamon and a whole lemon, including its juice and zest, at the ready. These carefully selected ingredients form the foundation for a naturally fermented, vibrant drink.
Primary Fermentation Process
Begin the primary fermentation by thoroughly scrubbing the sweet potato under warm, soapy water. Next, chop the sweet potato into roughly 1-inch pieces, keeping the skin on, and then pulse these pieces in a food processor until they are coarsely shredded. Transfer the shredded sweet potato into a 1/2 gallon mason jar. Add 1 quart of filtered water to the jar, followed by the liquid whey, raw honey, and any optional cinnamon and lemon juice with zest. Stir the contents vigorously until the honey is completely dissolved. Top off the jar with additional filtered water, leaving about a 1-inch headspace at the rim to allow the fermentation microbes room to work. If you wish to keep the sweet potato pieces submerged, a fermentation weight can be employed. Cover the jar opening with a fine cheesecloth, securing it with a rubber band. Let the mixture sit at room temperature for 2 to 5 days, remembering to stir it daily. The beverage is ready when it exhibits a slight effervescence, a tangy taste, a mild sourness, and a hint of sweetness. Continue fermenting for an additional day or two if these characteristics are not yet pronounced.
Achieving Carbonation
For an extra delightful fizz, a secondary fermentation process is highly recommended. Once the primary fermentation is complete, carefully strain the liquid from the mason jar into glass bottles equipped with fliptop, wire cap lids. It's crucial to fill these bottles only up to the bottom of the neck to accommodate the pressure that will build from carbonation. Seal the lids tightly and allow the bottles to sit at room temperature for an additional 1 to 2 days; a single day is usually sufficient in warmer summer conditions. After this period, promptly transfer the bottles to the refrigerator to chill thoroughly. When you are ready to serve, open each bottle slowly and cautiously, preferably over a sink, as significant natural carbonation will be released. The sweet potato shreds remaining after straining can be repurposed for a second batch, which will naturally be milder in flavor. Alternatively, you can halve the quantities of water, whey, and honey for a second batch that aims to replicate the strength of the initial batch.
