How Fish Sauce is Made
by Kasma Loha-unchit
Made From Fresh Fish From the Sea Fish Sauce Does Wonders for Thai Food
They say curiosity kills the cat, and I certainly do get my share of curious students, who wish to know how just about every bottled sauce from across the Pacific is made, including fish sauce.
In case you are not yet familiar with fish sauce, it is that salty, smelly brown liquid made from fish that is the single, most important flavoring ingredient in Thai cooking (also well-loved in Laos, Cambodia, Vietnam, Burma and the Philippines). Used like salt in western cooking and soy sauce in Chinese cooking, good-quality fish sauce imparts a distinct aroma and flavor all its own. It is indispensable in the Thai kitchen as Thai food wouldn't be quite the same without it.
Called "nam bplah" in Thai, or literally "fish water," genuine fish sauce is the water, or juice, in the flesh of fish that is extracted in the process of prolonged salting and fermentation. It is made from small fish that would otherwise have little value for consumption. This can either be freshwater or saltwater fish, though today, most fish sauce is made from the latter as pollution and dams have drastically reduced the once plentiful supply of freshwater fish in the heartlands of Southeast Asia.
Among marine fish, anchovies and related species of small schooling fish from two to five inches in length are commonly used, as they can be found in bountiful supply in the coastal waters of the Gulf of Thailand and the South China Sea. Larger varieties of fish, such as mackerel and sardines, also make good fish sauce, but because they are relatively more expensive due to their value as a food fish, they are seldom used in the commercial production of fish sauce.
For fish sauce to develop a pleasant, fragrant aroma and taste, the fish must be very fresh. As soon as fishing boats return with their catch, the fish are rinsed and drained, then mixed with sea salt – two to three parts fish to one part salt by weight. They are then filled into large earthenware jars, lined on the bottom with a layer of salt, and topped with a layer of salt. A woven bamboo mat is placed over the fish and weighted down with heavy rocks to keep the fish from floating when water inside them are extracted out by the salt and fermentation process.
The jars are covered and left in a sunny location for nine months to a year. From time to time, they are uncovered to air out and to let the fish be exposed to direct, hot sunshine, which helps "digest" the fish and turn them into fluid. The periodic "sunning" produces a fish sauce of superior quality, giving it a fragrant aroma and a clear, reddish brown color.
After enough months have passed, the liquid is removed from the jars, preferably through a spigot on the bottom of the jars, so that it passes through the layers of fish remains; or by siphoning. Any sediments are strained out with a clean cloth. The filtered fish sauce is filled into other clean jars and allowed to air out in the sun for a couple of weeks to dissipate the strong fish odors. It is then ready for bottling. The finished product is 100-percent, top-grade, genuine fish sauce.
Second and third grade fish sauces are made by adding salt water to cover the fish remains, letting sit for 2-3 months each time, then filtering before bottling. Finally, the fish remains are boiled with salt water, then strained out and discarded, to produce the lowest grade fish sauce; or they may be added to other fish remains from the first fermentation in the process of making second-grade sauce. Because flavor is substantially reduced with each fermentation, top-grade fish sauce is frequently added to the lower grades to improve their flavor. In fact, many manufacturers do not market top-grade, 100-percent fish sauce, saving it instead to mix with second and third grade sauces in order to produce larger quantities to sell that can still qualify as genuine fish sauce.
Because natural fish sauce requires time to make and very fresh, good quality fish, substantial investment is necessary for large-scale production. This has resulted in the proliferation of a number of less-than-pure products. Some are made by the process of hydrolysis in which some kind of enzyme or acid is added to hasten fermentation, while others are made by diluting natural or hydrolyzed fish sauce with salt water flavored and colored with sugar, caramel, monosodium glutamate (m.s.g.), by-products from the production of m.s.g., saccharin, and other natural or artificial flavorings and coloring.
How to tell which brands are good or not? Check the labels, though unfortunately, the certification of quality is not always clearly translated into English; and nutritional analyses cannot be relied upon, as they are outside the scope of many manufacturers who quickly slap these on just to meet U.S. import requirements. Short of being able to decipher or trust the labels, look for fish sauce with a clear, reddish brown color, like the color of good whisky or sherry, without any sediments. If the color is a dark or muddy brown, the sauce is likely to be either a lower grade, or one that is not properly or naturally fermented; it may also have been sitting on the shelf a bit too long. Good fish sauce also has a pleasant aroma of the sea, not an overwhelming smelly fishiness, and should not be overly salty. If the bottle you have been using makes the dishes you cook taste too fishy, try a new brand.
My favorite brands are Tra Chang (meaning "weighing scale") and Golden Boy. The latter is favored by my students for its endearing label – showing a baby boy sitting on a globe, cradling a bottle on the left arm with right thumb up. Both are excellent, adding a superb flavor to Thai dishes, but they are a bit harder to find than other brands, though well worth the effort of any search. Golden Boy is also available online from several online markets. Reasonably good are the King Crab and Anchovy brands. (Note: Kasma does not receive nor has she ever received any kind of remuneration from the manufacturers of these products. She recommends them because she thinks they are good products. Period.)
I do not personally recommend Three Crabs Brand, which several Asian cookbook authors recommend, mainly because it does not appear to be a naturally fermented fish sauce but is, rather, a flavor-enhanced, processed food product. According to the label, hydrolyzed wheat protein and fructose are among the ingredients – both are additives that have not been adequately time-tested for their potential long-term effects on health. Their inclusion suggests that the sauce is made through the process of hydrolysis, whereby a catalyst (sometimes from chemical sources) is added to hasten fermentation, allowing the company to produce large quantities of the product in shorter periods of time than would be required in natural fermentation.
It also appears suspicious that the label states that the fish sauce is a product of Thailand but is "processed in Hong Kong," further indicating that it is more highly processed than naturally fermented fish sauce. When compared with high-quality, naturally fermented fish sauces, the additives in Three Crabs Brand, to the discerning palate, gives this fish sauce a somewhat metallic, artificial after-taste. Since there are a number of excellent natural fish sauces, produced as has been traditionally done for generations, on the market, my preference is to stay with the traditionally made and time-tested products.
Now that you know how fish sauce is made, I hope it has not killed your appetite for good Thai food. Not my students – rotten fish or not, they can't wait to get their own bottle of the Golden Boy.
For your information, good quality fish sauce not only works wonders on Thai food, it is also good for you. It is high in protein (as much as ten percent for top grade), and this protein is a complete one containing all the essential amino acids that the body requires for growth and regeneration. It also contains a rich supply of B vitamins, especially B 12 and pantothenic acid, riboflavin and niacin. Other beneficial nutrients include calcium, phosphorous, iodine and iron.
Now, aren't you ready to seek out the Golden Boy? As for ideas of what to do with it once you have a bottle in your possession, tune below for some recipes and guidelines. Meanwhile, use your golden sauce in the place of salt or soy sauce in stir-fried vegetable and seafood dishes, or mix it with chopped Thai chillies and substitute for salt and pepper at the dinner table.
See Also: A Seafood Culture.
Here's an interesting blog entry (offsite) by Mary Dan Eades, M.D. titled Garum (Fish Sauce) The Ketchup of Antiquity.