The Joy of Soy

If you need to stock a Chinese kitchen， you might start with a good bottle of soy sauce. But in order to understand why this ingredient is so critical， you’ll have to first look at the role of another essential commodity： salt.

Salt’s ability to preserve food to last far out of season must have made it seem almost mystical C if very taxable C to the ancients. From the dawn of the first Chinese empire， the state held a monopoly over salt sales as a way of raising state revenue. Remarkably， it still does. State control made salt a rare， expensive commodity， and regular Chinese needed a way to make the little they could get their hands on last a long time.

One of the most common ways to stretch salt was through brewing fermented sauces. Enter soy sauce. Over two thousand years ago， Chinese would make a particularly pungent condiment， known as jiang， by layering fish with salt and soybeans until they fermented into a thick ooze C very much like the garum of ancient Rome， or the fermented fish sauces found in modern-day Southeast Asian cuisine.

Earthen jars packed tightly with this pungent mixture were household treasures， carefully managed for months or sometimes years. The soybeans both sped up fermentation and were noticeably cheaper than the fish， making them useful enough that the fish component was eventually ditched altogether. It’s said that this sauce is the ancestor of today’s soy sauce， while its fishier cousins endure from Korea to Indonesia.

To get sauced these days， soybeans are soaked， boiled and let to sit with a particular strain of fungus， Aspergillius oryzae， in brine. The fungus consumes and breaks down the starches in the soybeans， a process which leaves a dark brown liquid behind. The mixture is then pressed to extract every last morsel of flavor before bottling.

Each batch of this brew has varying levels of quality， and variance in water content and length of fermentation affect the taste. Like olive oil， the first pressing of the soybeans is considered to have more flavor， and is reserved for dipping. This， and everything after， is called “light”or “fresh” soy sauce. Light soy sauce is the standard cooking variety， available under dozens of brands and primarily used for flavoring， finishing and seasoning due to its delicate nature. It’s thinner， saltier and has a less bombastic influence than its heavier alternatives， making it better for vegetables and table-side dipping.

Light soy sauce can be aged， which thickens the consistency and darkens the color enough to be called， fittingly， “dark” soy sauce. The more robust， rich taste of this mixture makes it better for more intense cooking， as the flavors hold up and even improve at high temperatures. Some regions fiddle with the recipe， including additives such as mushrooms or starch to give the brew its distinctive heavy texture.

At least in China， both of these varieties are used to alter food in the kitchen and on the plate. Saltiness is one of the cornerstones of Chinese cuisine and probably its most common flavor （though spicy is a strong contender）. Since the Chinese mindset holds that the saltiness of the food is the responsibility of the chef C you won’t find a salt shaker on a Chinese dining table C getting the balance right is crucial.

Why is soy sauce still so popular when salt is now so cheap？ For one， soy sauce is a potent source of umami. A dash of soy sauce can easily lend an extra boost of that meaty， mushroomy， savory quality that is so appealing to the palate. There’s a lot of chemistry involved here， but the gist of it is that soy and other fermented sauces are an easy way to get that extra push that ramps up Chinese cooking.

That taste， combined with the industrial-scale production of soy sauce， available in every supermarket and corner store in a bewildering smorgasbord of variety， make soy sauce a given for any chef. The side effect of this is that Chinese now have one of the highest intakes of salt per person in the world. Modern soy sauces are saltier than traditionally brewed and homemade alternatives， and table salt is now a standard weapon in the cook’s arsenal， meaning many restaurant dishes get a double dose. Rural Chinese， especially in the north， add so much salt to their food during cooking that it has become a public health problem， turning many regions into stroke and hypertension hotspots. What was once a problem of scarcity is now a problem of abundance.

Beware， gentle reader. And if you think you’re getting real soy sauce when you’re eating Chinese takeout， think again. Those little transparent packets aren’t necessarily the real thing C in fact， they’re typically filled， according to The Atlantic， with a cheap， saccharine mixture of “water， salt， food coloring， corn syrup， MSG， and preservatives.”Head to your nearest Asian market to try the real thing for yourself， and even ancan taste the difference. The wise soy saucer shops carefully.