Some look at sweet potatoes and see pie, fries, or Thanksgiving side dishes. In the late 2000s, David Souza gazed out at his family’s 2,000-acre sweet potato farm in California’s San Joaquin Valley and saw vodka.
David is a fourth generation sweet potato farmer and the founder of Corbin Cash distillery. His great-grandfather started growing sweet potatoes almost a century ago, and today, the Souza family’s D&S Farms is a leader in the California sweet potato industry. David wanted to be part of the family business, but he also yearned to exercise his creativity—and, after a stint working in promotions in Las Vegas, harbored secret dreams of becoming a spirits mogul. “So I bought a book off the Internet, built a still, and started secretly distilling in my garage before I told anybody about my idea,”’ he says with a smile.
The Experimentation Begins
David says figuring out a workable sweet potato vodka recipe took a surprisingly long time, especially since few people in the United States or Europe have distilled sweet potatoes. Despite the similarities in their names, sweet potatoes and regular potatoes aren’t even in the same botanical family, so potato vodka recipes from Eastern Europe were of little use. And, while sweet potatoes taste sweet to our palates, they don’t actually contain much sugar, and the carbohydrates they do have are complex and hard to break down into the smaller molecules yeast can digest.
The yield on those initial batches was terrible. “Originally, it was taking 25 pounds of sweet potatoes to make one 750 ml bottle,” says David, a ratio that put profitability out of reach. He partnered with a commercial enzyme company, but since nobody had ever done anything like this before, even those experts were stumped about what to recommend. “They dropped a bunch of enzymes in my lap and said try these, we don’t know what will work for you,” laughs David. “I was like a mad scientist, trying all these different enzymes, and eventually I found a set that worked well.”
Yet another variable was variety. D&S Farms grows 10 different varieties of sweet potato, and not all of them work for distillation. After extensive tinkering, David found a combination of varieties that gave good yield and great texture, a secret the distillery closely guards.
Corbin Sweet Potato Vodka was officially launched in 2010, and it’s gone on to win a ton of awards and recognition. David says the sweet potatoes give the spirit an earthy, nutty flavor with almond undertones and a silky texture. “It’s so smooth, there’s no bite on it,” he says proudly. “It’s almost like wine.”
But that wasn’t the end of David’s distillation journey. Buoyed by his success, he turned his attention to another crop grown at D&S Farms: rye. The Souza family uses rye as a cover crop between sweet potato plantings to minimize dust, keep weeds down, and improve the quality of the soil.
In 1917, David’s great-grandfather discovered an heirloom rye variety called Merced Rye that tolerated the hot, dry conditions of the San Joaquin Valley with aplomb thanks to its extra-deep roots, which can stretch down up to 13 feet. That deep root system not only taps into hidden water, it also recovers runoff fertilizer that seeps below the reach of sweet potato’s more shallow roots, mining those nutrients and delivering them to the rye plant. At the end of the season, the Souzas plow the rye plants into the field, returning that recovered fertility right back into the top layer of the soil where the sweet potatoes can benefit from it.
But whiskey lovers everywhere know that rye has more to give the world than increased soil fertility, and David was excited by the possibility of creating a rye whiskey made entirely from the heirloom rye grown on his family’s farm.
Again, challenges arose in the distillery. One hundred percent rye grain mashes are notoriously tough to work with, because rye quickly becomes thick and sticky when mixed with hot water. During one of the initial large-scale test runs, David says he encountered that problem first-hand. “It literally turned to peanut butter on us,” he says, laughing. “Shoveling out a 500 gallon tank of solid peanut butter? It was nasty. It took three days.” Rye’s quirks don’t end once mashing is complete. During fermentation, rye tends to foam, and one morning, David entered the distillery to find “the rye monster,” a three-foot layer of foam carpeting the ground.
Undaunted, he and his team figured out a way to make the process work, and in 2014, they introduced Corbin Cash Rye to the world. Earthy and complex without being overwhelming, it’s a perfect combination of peppery spice and rich, sweet, chocolatey notes. Current bottlings are somewhere between five and six years old, aged in full-sized casks, and amazing served neat or over ice, perhaps with a little piece of lemon peel thrown in for good measure.
Waste Not, Want Not
There’s yet another feel-good angle to the Corbin Cash story: Nothing is wasted, not even the parts that other distilleries consider “waste products.” The spent mash is returned to the field as fertilizer, or transferred to a dairy down the road and used as a supplement to cattle feed. And all of the water used in the distillery is recycled as well, either as heating water, cooling water, cooking water, or irrigation for the family’s almond orchard. That no-waste approach is good for business, good for the environment, and good news for all of us who love whiskey.