Anchovies - why do they have glutamate? And what about other fishies?

The reason anchovies are so glutamate-rich is fascinating, and it comes down to biology, behavior, and how they're processed.

Why are Anchovies So High in Glutamate

There are a few overlapping reasons:

1. Their Diet

Anchovies are filter feeders that consume a bunch of phytoplankton, zooplankton, and little crustaceans. These organisms are naturally high in glutamate and nucleotides, which accumulate in the anchovy's tissues over its life.

2. Their Muscle Biochemistry

Small schooling fish like anchovies are highly active swimmers that almost never rest. Their muscles are dense with mitochondria and metabolic enzymes — many of which are glutamate-dependent. This means their muscle tissue naturally contains high concentrations of glutamate.

3. The Curing and Fermentation Process

This is the big one. When anchovies are salt-cured (typically 12–24 months),  autolysis occurs — the fish's own enzymes break down its proteins into free amino acids, including massive amounts of free glutamate. This is almost identical to what happens in aged Parmigiano-Reggiano. The salt preserves the fish while allowing enzymatic breakdown to proceed slowly.

Fresh anchovies when cured creates the glutamate bomb that they become!

 

Other Small Fish — Do they have the good stuff too?

Yes, many small fish are naturally glutamate-rich. Sardines have similar biology to anchovies and canned sardines have significant free glutamate, just less than cured anchovies. Herring, Sprats, and Mackerel are also high in glutamate, especially when pickled or fermented.

And fermented Fish Sauces is where small fish really shine. Fish sauce, Garum (ancient Roman fish sauce) and Colatura di alici** (Italian anchovy drippings) are essentially liquid glutamate concentrates, sometimes reaching 1,000+ mg of free glutamate per 100g. The fermentation process is the same autolysis mechanism taken to its extreme.

 

What about the Big Fish like Tuna — What’s up with them?

Tuna has a different glutamate profile than small fish, for several reasons.

Fresh raw tuna actually contains meaningful free glutamate — around **140 mg/100g** — which is why good sashimi-grade tuna has a natural umami quality. It's less than anchovies but still significant.

Why does tuna not have it like anchovies?

Because tuna are apex predators with very different muscle biochemistry. Their muscles contain more slow-twitch endurance fibers vs. the fast-twitch fibers of anchovies. Thus they don't accumulate glutamate the same way in their tissues.

But, if Katsuobushi, dried, fermented, smoked skipjack tuna is one of the most glutamate-rich foods in the world! And the cornerstone of Japanese dashi broth!

And Italian Bottarga (cured tuna or mullet roe) is another example of curing and releasing the enormous umami of the fishy.

It’s all about the Enzymatic protein breakdown achieved via fermentation, curing, drying, or cooking to release the hiding umami. It is all about freeing the free glutamate from bound proteins.

 

Check out our hand selected anchovy collection!