Soy sauce is one of the oldest manufactured foods on earth. For most of its history, it was made one way: soybeans, wheat, salt, water, and time. The method was worked out in China, refined over centuries in Japan, and handed down through families who treated it as a trade rather than a recipe.
We brew ours with the same time-honored method, all except for one major difference. We brew it here in Louisville, Kentucky. Our Bluegrass Soy Sauce follows the traditional Japanese approach of five ingredients, all sourced in the United States, and it takes a year from start to bottle. Here's what happens during that year.
Five Ingredients, and That's the List
Spring water, non-GMO soybeans, wheat, sea salt, yeast.
The water comes from the same spring in Bardstown that distilleries use for some of Kentucky's finest bourbon. Limestone filtration pulls the iron out and leaves calcium and magnesium behind, and that mineral content gives the yeast something to adhere to. Water chemistry isn't a footnote in fermentation. It's closer to the foundation.
The soybeans are non-GMO, grown in Marion County. The wheat is Kentucky soft red winter wheat. The salt is solar evaporated. Nothing on the list is there to adjust color or stretch shelf life, because in a naturally brewed sauce there's nothing to adjust. The flavor either develops during fermentation or it doesn't arrive.
Koji Does the First Half of the Work
Naturally brewed soy sauce starts with koji.
The soybeans are cooked and the wheat is roasted and cracked. The two get combined and inoculated with a culture that spends several days growing through the grain. That culture produces enzymes that break soy protein down into amino acids, and amino acids are where savory flavor comes from. Only two strains are capable of making soy sauce, and both have been kept alive and propagated for generations.
The finished koji then goes into a brine of sea salt and limestone spring water. That's the mash, and it's where the sauce spends the rest of its time.
Twelve Months of Sitting Still
Bluegrass Soy Sauce ferments and ages for a full twelve months.
There's no way to speed that up and still get the same result. Enzymes work at their own pace, and the compounds that give an aged sauce its depth show up late. A year in, the mash has gone from salty and raw to something layered.
The finish is the part that makes ours specific to Kentucky. We age the soy sauce in bourbon barrels sourced from local distilleries. Federal law allows a bourbon barrel to be used only once for bourbon, which means the state produces a steady supply of charred oak that has already spent years holding whiskey. What's left in that wood is caramel, vanilla, and toasted oak, and the soy sauce pulls it out. If you want the longer version of what happens inside the barrel, we covered it in what "barrel aged" actually means.
Then It Meets KenZilla
Once the mash has fully fermented, it goes into our custom-built press to separate the solids from the liquid.
The press is named KenZilla, after Matt's dad, who built our first three. Small detail, but it's a fair illustration of how the operation came together. Most of what we use, somebody here made.
What Umami Actually Means
Umami is the Japanese name for the fifth flavor sense, alongside sweet, salty, sour, and bitter. Translated loosely, it means deliciousness.
Bluegrass Soy Sauce tastes meaty, brothy, and briny, with a leathery quality and a subtle sweetness underneath, plus the oak and light smoke from the barrel. It works anywhere you'd use soy sauce, and it holds its own on sushi and sashimi where the sauce has nowhere to hide. It also does quiet work in places you might not expect: a spoonful in a pan sauce, a splash in a vinaigrette, a little stirred into a braise.
One Base, Four Sauces
Bluegrass is the original, and it's the foundation for the rest of the barrel-aged soy sauce collection.
Imperial Double Fermented Soy Sauce takes eighteen months. Instead of a salt brine, the second fermentation starts with finished Bluegrass Soy Sauce, gets a fresh koji, and ferments another six months. Deeper and rounder, with the same range of uses.
Bourbon Smoked Soy Sauce is Bluegrass carried over to our smoker. Smoke is umami, so the two compound each other. Matt's daughter tasted it at eleven and called it a country ham sandwich, which is now how we describe it during tastings. Good in soups and ramen, and a few drops go a long way.
Small Batch Bourbon Ponzu is our take on a citrus soy. Traditional ponzu uses yuzu, which isn't grown much in the States, so ours is built on cold-pressed lemon juice. Traditional ponzu also uses sake. Ours uses 100-proof Old Forester.
The full four-bottle set is the shortest route to tasting them side by side.
Come Watch It Happen
We're on Story Avenue in Louisville, and the tour ends in a tasting where you can try each sauce in the line. If you'd rather see the barrels and the press than read about them, come visit.