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Fish sauce is the mother of all condiments. Most prevalent today in Southeast Asian cuisines, 2,000 years ago it was the favorite condiment of classical Rome. Then and now, ﬁsh sauce is a strategy used in coastal areas to turn abundant small marine life into a nutritious, stable, and ﬂavorful food resource. Fish sauce is essentially liqueﬁed ﬁsh; the cells of the ﬁsh are transformed from solid to liquid state by enzymatic digestive processes described in the scientiﬁc literature as autolysis [self-digestion] and hydrolysis [digestion into water]. Reﬂecting on the fact that this process spontaneously begins in salted ﬁsh if not quickly dried, historian H. T. Huang writes that ﬁsh sauce “was an invention that was just waiting to happen.”
Use fresh whole small saltwater ﬁsh, mollusks, or crustaceans with their viscera (organs). “The enzyme or enzymes responsible for ﬁsh protein hydrolysis are chieﬂy located in the visceral organs,” reports Keith Steinkraus. According to a team of researchers investigating the production of Thai nampla ﬁsh sauce in the Journal of Agricultural and Food Chemistry, ﬁsh are left at ambient temperatures for 24 to 48 hours prior to salting. “This actually initiates the fermentation process.”
Next, add salt and stir thoroughly to evenly distribute it. Heavy salting is critical to protect the ﬁsh from rapid putrefaction and growth of potentially dangerous bacteria, including C. botulinum. Most contemporary styles of ﬁsh sauce incorporate salt at a proportion of no less than 25 percent (by weight); some use considerably more. Food historian Sally Grainger notes that ancient Roman recipes for ﬁsh sauce used much less salt, approximately 15 percent. She attributes the higher salt levels in modern ﬁsh sauce to “fear of dangerous bacteria such as botulism.” However, the International Handbook of Food-borne Pathogens states that 10 percent salt is enough to prevent the risk of botulism in ﬁsh in “the aqueous phase” at room temperature.
Typically no water is added to ﬁsh sauce. Salted ﬁsh are placed in a crock, barrel, tank, or other vessel, and weighted down — as is sauerkraut — to expel air pockets and keep solids from ﬂoating to the top. Initially, salt pulls water from the ﬁsh cells by the process of osmosis; then enzyme and microbial processes cause hydrolysis. Depending upon temperature, salt content, and tradition, ﬁsh sauces ferment for between 6 and 18 months, with periodic stirring. The recipe I followed, for a Filipino-style ﬁsh sauce called patis, sent to me by my friend Julian (whose mother was from the Philippines), instructed to ferment in a warm place until a “desirable aroma has developed.” The color also darkens as time passes, as more of the ﬁsh solids liquefy. I left mine to ferment for about six months. It tasted like ﬁsh sauce, though I cannot claim to be a connoisseur with a discerning palate. Keith Steinkraus reports on patis production that the fermentation time ranges from six months to a year.
In the Filipino tradition, the ﬁsh sauce is drained from the solids. The liquid sauce is patis; the residual solids, with remaining bones removed, are ground into a paste called bagoong, also used as a condiment. Fish sauce may be used raw after straining or is often pasteurized before bottling, sometimes with the addition of alcohol.
Microbiologists have debated the importance of fermentation in the production of ﬁsh sauce. “Generally, the number of bacteria steadily decreases in the ﬁsh following the addition of salt,” writes Steinkraus. Nonetheless, microbial analysis has established that salt-loving (halophilic) bacteria “are likely playing an important role in the maturation and development of typical ﬁsh sauce aroma and ﬂavor.” This is the basic process. A Roman cuisine enthusiast, Heinrich Wunderlich, suggests speeding fermentation of garum (classical Roman ﬁsh sauce) by using a yogurt maker that keeps the ﬁsh and salt at 104 degrees F/40 degrees C. With whole small ﬁsh, or just innards, 15 to 20 percent salt by weight, and stirring once a day, he writes that the ﬁsh liqueﬁes in three to ﬁve days, leaving a bare skeleton. Flavor develops more slowly, and is fully developed, even in the yogurt maker, only after a few months have passed. There are many variants on basic ﬁsh sauce, some using speciﬁc ﬁsh, mollusks, or crustaceans; others with added ingredients including sugar, tamarind fruit pulp, pineapple, and grains, either molded (such as koji or qu), malted, in the form of lees (the solid residue from making saké), or even outer husks. There are also hybrid ﬁsh-soy sauces incorporating soy koji into the fermenting mix.
More from The Art of Fermentation:
From The Art of Fermentation: An In-Depth Exploration of Essential Concepts and Processes from around the World by Sandor Ellix Katz, © 2012 by Sandor Ellix Katz. Reprinted by arrangement with Chelsea Green Publishing, White River Junction, VT.