Recent events have lead me to have a close look at fermented fish products. In particularly I’ve been looking at a product called garum, which is the inspiration for Green Pasture's Fermented Cod Liver Oil. These products are made in a very unique way, and as a result have some very interesting properties. This research has taken me as far back as the Roman Empire and as far forward as modern research in food science. Throughout history, garum and similar fermented fish sauces have been hailed for their health benefits, although no one really knew why. Now, with modern understanding of biological systems we can start to understand what makes these products so beneficial for health. The subject is fascinating, complex and incomplete, which does allow for a degree of speculation and imagination to fill in the gaps.
A Brief History in Garum
There is evidence of fermented fish sauces like garum being consumed as far back as Bronze age (at least 2600 years ago), but because nothing was recorded then, the details are very scarce. As you move into the Iron Age, there is an increasing amount of evidence that fish sauces are an important part of life in Europe, particularly in the Celtic regions. In fact, the most Western part of France which was known as Armorica was renowned for producing a high quality garum which would ‘give you strength‘ (Interestingly, the fictional characters Astrix and Obelisk who fought the Roman Empire lived in this region. Perhaps the secret potion that gave them super-human strength was garum?).
Legends aside, fermented fish sauces were certainly consumed in Europe before the Roman Empire expanded into France and Britain, but it was the Romans who made it popular across the continent, and made it commercially.
Evidence of garum factories are found throughout the Roman Empire, and from these factories it is clear that they made 2 types. One was plain garum, which was made in vast quantities and was used regularly as a flavor enhancer for food. The other was made in much smaller quantities for medical purposes and was called garum armoricum (after the region in France). A popular fish used to make high quality garum armoricum was the tunny (or tuna), which could only be caught once a year during their migration to spawning grounds. The limited amount of tuna available year round combined with the high quality garum it produced made it a very expensive and sought after product. As tuna is a very oily fish the resulting garum would likely be high in omega-3 fats, which may well be one reason it was associated with promoting health.
This garum was used by the military, athletes and women/children considered to be ‘weak’, because it was associated with promoting strength and good health. It is clear that its benefits were well recognized throughout the Roman Empire. However, as the Roman Empire went into decline the price of salt (which was essential for garum) rapidly increased which meant that garum could no longer be made. After this point in Europe fish sauces were never made on the same scale and were largely forgotten about, aside from some small isolated communities.
Recipes for garum vary from region to region, but they all follow a basic blueprint. Small fish (or the organs of specific fish such as tuna) are layered in containers. Between each layer of fish/ fish organs is a layer of salt and sometimes herbs. This is then left to ferment (often in the sun) for 1-6 months. The liquid can then be removed and shipped all over the empire as a flavour enhancer or medicine.
Using the same basic recipe that the Romans did, Green Pasture created a garum-esque cod liver oil. Green Pasture mix cod livers with salt and a starter broth, then let it ferment for a number of months before the oil is filtered out. From speaking to David Wetzel of Green Pasture, the only real difference between what the Romans did and what they do is the use of a starter broth. Green Pasture save some of the brine from previous ferments to use for future production. This ensures that the same bacteria are doing the fermentation, and so keeps the end product consistent (similar to how cheeses are made). Aside from this, Green Pasture ferment their cod livers in the similar way the Romans did.
Production is simple and traditional, but to anyone familiar with lipid biochemistry this method doesn’t sound like it would produce a healthy oil. Fats in these fish are predominantly poly-unsaturated fats, which are extremely easily oxidised. Being left in these conditions for an extended period of time seems like it oxidation is inevitable, which would of course make these fats toxic.
Read the rest of the article, as it was provided to us to preprint with permission.