Myeolchi-aekjeot (Korean anchovy fish sauce)

A sauce of salted anchovies

Myeolchi-aekjeot is the liquid that comes from salting whole anchovies (myeolchi, Engraulis japonicus) and leaving them to ferment for a long time before the solids are filtered out. It is one of the two aekjeot, the fish sauces of Korea; the other is the sand-lance sauce kkanari-aekjeot. A Korean food review lists both beside red pepper powder, garlic, ginger, radish and glutinous rice paste among the seasonings of kimchi.

The Korean word aekjeot (액젖) marks the liquid branch of a wider family of salted seafood, jeotgal. A jeotgal keeps recognisable fish, shrimp, roe or viscera and is often eaten in small portions as a side dish or used to season other foods. An aekjeot is the filtered liquid and is used only as a seasoning.

How it differs from jeotgal

The review gives different curing conditions for the two. Jeotgal is brined at about 20% salinity for 2 to 3 months at room temperature and ends up resembling the seafood it began as. Aekjeot is submerged in brine of 20 to 30% for 1 to 2 years, after which particles are filtered off, so the seafood is no longer served as seafood.

The documented laboratory batch sits at the top of that range: about 25% sodium chloride. The traditional description in the same research is a highly salted anchovy ferment of more than six months, left outdoors without temperature control.

What happens in the container

In the PLOS ONE experiment, twelve containers each held 1.0 kg of anchovies, 270 g of solar salt and 400 ml of 25% salt solution. Three containers were held at each of 15, 20, 25 and 30 degrees C. Salinity stayed nearly constant at about 24.7% (w/v) throughout. The pH began near 6.0, began to rise after about 42 days and, at 15 degrees C, fell again to below 5.8 after about 200 days.

Free amino acids rose rapidly in every container early on, and their totals were a little higher at higher temperatures. Trimethylamine and dimethylamine increased as trimethylamine oxide fell; the authors link these methylamines to the characteristic odour of fermented fish sauces.

The bacterial community depended on temperature. Tetragenococcus, a salt-tolerant genus, was the major genus at 20, 25 and 30 degrees C and was most abundant at 30 degrees C. It was not detected at 15 degrees C. The communities and metabolites developed differently at the four temperatures, so a cooler or warmer place gives a different ferment even with the same fish and salt.

Use in kimchi

The review states that jeotgal and aekjeot contain flavour compounds that contribute greatly to ripening during kimchi fermentation. Myeolchi-aekjeot is widely used in kimchi seasoning. The same review traces part of kimchi's biogenic-amine load to fish sauces of this kind, which is the reason it treats them together.

Sand-lance sauce, a different base

Kkanari-aekjeot is made from sand lance instead of anchovy, and the two sauces are not one fish or one formula. A supplied Korean atlas notes western and northern associations for the sand-lance sauce. The review reports histamine in commercial kkanari-aekjeot from 183.4 to 1839.68 mg/kg and tyramine from 112.3 to 583.0 mg/kg across the surveys it compiles, in the same range as the anchovy sauce. The temperature experiment covered anchovy only and says nothing about sand-lance products.

Biogenic amines and what is not known

The review compiles six surveys of commercial myeolchi-aekjeot. Every product exceeded 100 mg/kg histamine; reported histamine ranged from 150 to 2070.58 mg/kg and tyramine from 77.5 to 611.3 mg/kg where it was measured. The review suggests the long fermentation as a possible cause.

In the laboratory batch, putrescine, histamine, tyramine and cadaverine were not detected in any container. That is one controlled experiment under its own preparation and sampling, and it neither represents the market products nor approves a household process. Household salt basis, pH, temperature, time, amine controls and storage are not validated by any source read here, and no universal birthplace, season or market-wide microbial profile is established. Smell and taste do not establish safety.