Bubbly, tangy, and slightly sweet beverage inspired by sweet potato kvass from artisan fermenters in Australia and “sweet potato fly” traditionally enjoyed in South American cultures.
In traditional South American culture (modern-day Guyana), a fermented beverage called “sweet potato fly” is popular.
It is a type of kvass, which is a low-to-no alcohol, probiotic-rich drink with a sweet-sour, slightly malty, and refreshing taste. It has a cloudy appearance and is typically served cold.
Made from grated sweet potatoes, spices, citrus, and water, sweet potato fly became popularized in Australia by home brewers and artisan producers. Its fame further spread via coverage by Australian media (ABC Radio National) in 2012.
As my husband is from Australia and is re-introducing starch into his diet after a few years on GAPS, I thought I would try my hand at sweet potato kvass, since this would be a pre-digested form of starch and likely easier on the gut than cooked sweet potatoes.
It turned out spectacularly well! I recommend the optional, secondary fermentation to add extra carbonation.
Below is a photo of my secondary ferment in glass, fliptop bottles along with a secondary batch of sweet potato soda cultured with the shreds from the original ferment. This is similar to the two-batch method for beet kvass.
If you enjoy sweet potatoes and wish to try another fermented form, this cultured sweet potato mash is a tasty one that gets great reviews!
Sweet Potato Soda
Bubbly, slightly sweet and tangy beverage inspired by sweet potato kvass commercially available from artisan producers in Australia and “sweet potato fly” traditionally enjoyed in Guyana.
Instructions
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Scrub the sweet potato thoroughly in warm soapy water.
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Chop the sweet potato (skin on) into pieces about 1 inch in size. Pulse in a food processor to coarsely shred the pieces. Place the shredded sweet potato in a 1/2 gallon mason jar.
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Add 1 quart filtered water, liquid whey, honey and optional cinnamon and lemon juice + zest.
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Stir the mixture well until the raw honey is dissolved.
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Add additional filtered water to the lower edge of the jar rim, taking care to leave 1″ space at the top for the fermentation microbes to “breathe”. Add a fermentation weight to keep the sweet potato chunks submerged if desired.
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Cover the jar with a fine cheesecloth secured with a rubber band.
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Leave on the counter at room temperature for 2-5 days, stirring daily.
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Taste after 2 days. If it is slightly bubbly, tangy, slightly sour, and mildly sweet…it is ready! If not, leave it for another day or two and repeat the taste test until ready.
Optional Secondary Fermentation
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Strain the fermented sweet potato liquid from the mason jar into 8 or 16-ounce glass bottles with fliptop, wire cap lids. *Fill only to the bottom of the neck of the bottle to allow for pressure from carbonation.
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Close the lids tightly and leave on the counter for an additional 1-2 days (1 day in the summer).
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Place the bottles in the refrigerator to get cold. Open a cold bottle slowly in the sink, as there will be a lot of natural carbonation to release.
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*The sweet potato shreds can be reused to make a second batch that is slightly weaker in flavor. Alternatively, cut the amount of water, whey, and honey in half for a second batch that is similar in strength to the first batch.
Nutrition Facts
Sweet Potato Soda
Amount Per Serving (1 cup)
Calories 50
% Daily Value*
Potassium 150mg4%
Carbohydrates 12g4%
Protein 0.5g1%
Vitamin C 10mg12%
* Percent Daily Values are based on a 2000 calorie diet.
