How we tested
Packed with flavor-enhancing umami, soy sauce is one of the oldest food products in the world. It originated in China about 2,500 years ago and made the leap to Japan around the seventh century. Over time, it’s been produced in a variety of styles and become a pantry staple worldwide; in fact, it’s the third best-selling condiment in this country after ketchup and mayonnaise. We feature it in all kinds of Asian dishes, but we also harness its savory flavor in recipes as diverse as barbecue, burgers, fried chicken, corn on the cob, vegetable soup, and lamb chops.
That said, we’ve learned over the years that not every bottle delivers the kind of nuance and balance that good soy sauce should, so we rounded up 10 top-selling nationally available products made in the United States, Japan, and China to zero in on a soy sauce worthy of being both a condiment and a staple cooking ingredient. Three were tamari, a close relative that’s made just like soy sauce but contains little to no wheat. We tasted them plain (with rice to cleanse the palate between samples) and cooked in a teriyaki sauce brushed over broiled chicken thighs.
Tasters reported that they could not only taste but also smell distinct differences among the samples. Some boasted sweet-savory aroma and nuances like “caramel,” “vanilla,” “molasses,” and “honeysuckle,” while others not only lacked complexity but actually deterred us because they tasted “metallic,” “musty,” and “fishy.” Cooking them with strong aromatics like garlic and ginger muted those off-flavors enough that the sauces were passable, though ultimately they fell near the bottom of the rankings. As for the tamaris, two of the three were true failures; they tasted so harshly salty that we couldn’t recommend them. The third was an outlier that balanced salt and sweet better than many of the other soy sauces.
We needed to look only as far as the processing methods for soy sauce to understand where those variations in flavor and complexity came from. Our results show a clear divide between those that were made according to a slower, more traditional method and those produced by a shortcut approach.
The six top-ranking sauces we tasted are made the old-fashioned way: fermented, or “brewed.” The process starts by culturing boiled soybeans and roasted wheat with a mold that creates a mixture called koji, which functions like a sourdough starter: It begins to break down the carbohydrates and proteins and provides a sauce’s unique flavor profile. (Some manufacturers have used the same koji for decades or even centuries; Kikkoman, for example, claims that its koji dates back 300 years). From there, salt and water are added, and the mash, now called moromi, is left to ferment for anywhere from a few months to years. During that time, lactic acid bacteria work with yeasts to further break down proteins and carbohydrates into a mix of flavorful compounds (alcohols, esters, peptides, and acids), including glutamic acid (a major source of umami), and the clear-colored mash darkens to a deep reddish brown. Finally, when the manufacturer decides it’s ready—in our lineup, this period ranged from four months to two years—the mash is pressed to extract soy sauce, which is then pasteurized. The heat kills bacteria, stops fermentation, and launches the Maillard reaction, breaking down the proteins into hundreds of new compounds that give soy sauce rich caramelized flavor and aroma.
The two lower-ranking soy sauces are made by hydrolysis, a process that takes just two to three days and involves no wheat or even soybeans, per se. Instead, defatted soy flour (or other flours, such as corn) is boiled with hydrochloric acid to separate the amino acids, which are then neutralized with sodium carbonate. The resulting hydrolyzed vegetable protein is doctored with caramel color, corn syrup, and salt to make it look and taste more like fermented soy sauce.
We found these two hydrolyzed sauces, from La Choy and Crystal, passable—or at least pleasantly familiar—in the teriyaki sauce, where their “intense,” “deep and dark” flavors were not out of place and were balanced by the other ingredients. But when we tasted them plain, we picked up on “odd” flavors “like powdered beef soup”—not surprising, since hydrolyzed vegetable protein is used to create the savory, brothy flavor of bouillon cubes—that gave us reservations about recommending them as all-purpose sauces that might also be used as condiments.
Against the Grain
But what about hydrolysis makes it yield a less balanced and complex product than fermentation does? For one thing, the rapid and thorough protein breakdown. Research has shown that fermentation slowly breaks down proteins and thus allows them to develop multiple types of flavor compounds, whereas hydrolysis quickly converts all of the protein to amino acids, so the end result is relatively one-dimensional.
The other major difference is the absence of wheat, which contributes sweetness and favorable aromas that balance the salt in fermented soy sauces. Without it, the hydrolyzed products tasted “harsh” and “salty” and reminded tasters of “Gravy Master.”
The absence of wheat is also likely what accounted for the overly salty flavors we detected in the tamaris, all three of which are fermented products. We noticed that two of the tamaris contain an added sweetener to help balance the salt, though the evaporated cane juice in the losing sample couldn’t compensate for a saltiness so harsh that tasters’ mouths were “burning.” Fortunately, the sugar in the better tamari, from Kikkoman, made for a much more balanced product.
Kikkoman is also the maker of our favorite soy sauce, which achieves good salty-sweet balance and plenty of complexity from its six to eight months of fermentation, one of the longer spans of our lineup. What’s more, it does so with just four ingredients—wheat, soybeans, water, and salt—whereas other recommended sauces add flavor enhancers and sugar to achieve a similar effect. Bottom line: You can’t go wrong as long as you buy a soy sauce that’s labeled “fermented” or “brewed,” but we’ll stick with Kikkoman’s simpler approach.
We sampled 10 top-selling nationally available supermarket varieties of soy and tamari sauce, selected from sales data gathered by Chicago-based market research firm IRI, in two blind tastings: plain and in our recipe for Chicken Teriyaki, where the sauces were combined with ginger, garlic, sugar, and mirin and reduced on the stove to concentrate flavors. We rated them on aroma, flavor, saltiness, and overall appeal. All products were purchased at Boston-area supermarkets or online. Sodium levels (per 1-tablespoon serving) and ingredients were taken from product labels. We averaged tasting results; products appear in order of preference.