Fish sauce are made with anchovies, mackerel, scabbard fish and salt. The bigger the fish, the more mercury you might expect, especially if predator fish like scabbard fish. They do not have any additives like sugar, hydrolyzed protein, or preservatives. Vietnamese prefer sauces without a strong smell, and transparent with a deep golden amber color. "First press" fish sauce, meaning the sauce is bottled from the first time the fermenting barrels are drained, also indicates quality. Lastly, when measuring the nitrogen level of fish sauces (N), most fish sauce on the market falls within the mid 20N range. Anything over 30N is
Fish sauce briefly fermented has a pronounced fishy taste. Extended fermentation reduces this and gives the product a nuttier, richer and more savory flavor. An anonymous article, "Neuc-num", in Diderot and d'Alembert's 18th-century Encyclopédie, states: "It is said that Europeans become accustomed enough to this type of sauce". While there is no strict grading system for fish sauces, first-tapping, or first-pressing sauces are the most sought after. Some top brands are beginning to adopt the "Extra Virgin" designation and tout more artisan processes. Second-pass or volume sauces are easily identified as they have a thin, very watery consistency. Southeast Asian fish sauce