Case Study 2 — The Strange Career of Roman Garum

In the year 79 CE, when Mount Vesuvius buried the Roman city of Pompeii under a layer of volcanic ash, the eruption preserved — among many other things — a fish-sauce factory at the edge of the city. Archaeologists excavating the site in the eighteenth and nineteenth centuries found rows of large clay vats, residues of fermented fish protein, and trade-mark amphorae stamped with the names of garum producers. Pompeii had been one of the centers of garum production for the entire Roman empire, and the eruption captured the operation mid-process.

The factory's vats had contained anchovies and similar small fish, layered with sea salt at concentrations high enough that the salt was visible as crystals throughout. The fish had been fermenting for months at the time of the eruption. The volcanic heat and ash had cooked the contents to a hardened residue that scientists in the twenty-first century could re-examine with chemical and microbiological tools, finding the chemical signatures of a long-fermentation salt-protein process closely related to modern fish sauces.

This case study reconstructs the Roman garum economy, traces what made it disappear from European kitchens by the medieval period, and asks what we can learn — about lacto-fermentation, about food-tradition continuity, about cultural transmission and forgetting — from the strange career of a sauce that fed an empire and then was largely lost.

What garum was

Garum (and its lower-grade cousins liquamen, muria, and allec) was the fermented fish sauce of the Roman culinary universe. It was used in the way salt and vinegar are used in modern Western cooking, and the way fish sauce is used in modern Southeast Asian cooking — as a seasoning, a flavor base, a soup ingredient, an emulsion base for sauces, a preservation aid. Apicius, the Roman cookbook attributed to a first-century food writer, includes garum or liquamen in roughly half of its recipes. It was, by some accounts, the most widely consumed sauce in the Mediterranean world.

The production process was essentially identical to modern Asian fish sauce. Small fish — anchovies, sardines, mackerel — were layered with sea salt at concentrations of roughly 30 percent salt to fish weight. The vats were left for three to twelve months, sometimes longer for premium grades. As the fish autolyzed (their own digestive enzymes broke them down) and salt-tolerant bacteria worked, the protein was hydrolyzed into amino acids, peptides, and small flavor compounds. The liquid that drained from the vats was the sauce. Different grades — flos garum (the first, finest pour), garum sociorum (the high-end imported version from Iberia), liquamen (a lower grade), allec (the residual paste at the bottom of the vat) — were sold at different prices.

The high-end version was famously expensive. Garum sociorum, made along the Iberian coast (modern Spain) from premium tuna and mackerel, cost as much as fine wines. It was traded in stamped amphorae across the empire. Pliny the Elder writes, in the first century, of garum sociorum being one of the most prized foodstuffs in Roman markets.

The umami chemistry

What modern food chemistry tells us, looking back at Roman garum, is that the Romans had stumbled onto one of the most efficient methods ever devised for liberating free L-glutamate — the molecule that produces umami taste — from bound protein. The combination of high salt (which selects for halotolerant bacteria and slows spoilage), the fish's own digestive proteases (which keep working at high salt long after the fish are dead), and the long timescale (months to years) is essentially a controlled enzymatic hydrolysis. The end product is a liquid extract of free amino acids, with glutamate at concentrations rivaling pure MSG in savoriness.

The Roman cooks did not know about umami receptors, free glutamate, or proteolysis. But they tasted what the sauce did to food, and they kept making it for centuries because the result was so good. A small amount of garum, added to meat stews, vegetable preparations, fish dishes, even sweet preparations, deepened the flavor in ways no other Roman seasoning could.

The chemistry is the same chemistry in modern Vietnamese nuoc mam, Thai nam pla, Filipino patis, Italian colatura di alici (the Cetara coast preparation that is, essentially, Roman garum still made), and Korean aekjeot. The Romans were one of multiple independent or semi-independent traditions of fish-sauce-makers around the world, all of whom had figured out, through long experimentation, how to get glutamate out of fish.

What happened to it

By the time the Roman Empire's western half collapsed in the late fifth century, garum production had begun to contract. By the early medieval period (roughly the seventh through the tenth centuries), large-scale garum-making had largely disappeared from Western Europe. The reasons are debated by historians, but several factors converge:

The collapse of Mediterranean trade networks. Garum production was concentrated in coastal facilities, especially along the Iberian and North African coasts. The product was shipped in amphorae across the empire. With the disruption of imperial trade routes, the supply chain that fed garum to inland Roman customers fragmented. Local production may have continued in coastal communities, but the empire-wide market vanished.

The rise of monastic food culture. Christian monastic traditions, which became central to early medieval European food preservation and transmission, did not generally inherit Roman fish-sauce practices. Monastic cookbooks emphasize wine, cheese, bread, and salted preserved foods, but garum (which Apicius's pagan-Roman tradition had treated as essential) drops out. Why is unclear — possibly the labor-intensiveness of garum production was inconsistent with monastic operations, possibly the smell was associated with paganism, possibly it was simply not transmitted in the manuscript tradition.

Changes in the dietary economy. The Roman use of garum was, in part, a response to a high-salt high-protein dietary pattern in which umami concentration was valued. Medieval European diets, dominated by grains, legumes, and modest meat, may have valued garum less — or may have substituted other umami sources (aged cheese, dried mushrooms, fermented dairy).

The rise of vinegar as a preservation acid. Medieval Europe heavily developed vinegar-pickling traditions. Vinegar replaces some of garum's culinary roles (as an acid, as a preservation aid for meat preparations, as a flavor base in sauces). The substitution may have been partial, but it shifted the economic-culinary niche garum had occupied.

Loss of texts and tacit knowledge. Apicius's cookbook survives because monastic scribes copied it through the medieval period. Many Roman cookbooks did not survive. The tacit knowledge of how to set up and operate a garum factory — which involved subtleties of fish selection, salt grading, vat design, temperature control, and timing that no cookbook fully captured — was held in workshop traditions that did not survive the disruption of Roman commerce.

By the time European Renaissance food writers in the sixteenth century encountered Asian fish sauces brought back by traders, they recognized the family resemblance to Apicius but treated the products as exotic. The connection to a continuous European tradition of the same chemistry had been broken. There were tiny survivals — the Cetara coast of southern Italy continued producing colatura di alici into the modern day, and similar fish-essence preparations persist in pockets of Iberia and southern France — but as a major ingredient in European cooking, garum was gone.

The chemistry, of course, did not disappear. It moved: it lived continuously in Asian fish-sauce-making, where the same proteolysis-driven free-glutamate liberation continued in nam pla, nuoc mam, patis, and the rest. When Western chefs in the late twentieth century rediscovered fish sauce — first through Vietnamese restaurants, then through cookbooks, then through chefs like David Chang who built American restaurants around fish-sauce-driven flavors — they were essentially reconnecting with a chemistry their own ancestors had used for centuries and forgotten.

What the case teaches us

Several generalizable lessons.

Food traditions can be lost

It is tempting to think that a food technology, once developed, persists. Most do — bread, cheese, beer, wine, sauerkraut, and dozens more have continuous traditions stretching back thousands of years. But not all of them. Garum is a major counterexample, and there are others: Mesoamerican pulque (an agave-fermented beverage) collapsed in scale during Spanish colonization and never fully recovered; certain North African fermented grains (kishk) shrank to small regional practice; the Japanese kusaya (a strongly fermented dried fish) is now made in only a handful of small island operations.

Cultural disruption — through trade-network collapse, religious change, colonization, war, displacement — can interrupt the transmission of food traditions. The chemistry survives in physical principle; the human practice does not survive automatically. People keep food traditions alive. When the people are gone, or moved, or converted, or killed, the traditions can vanish even when the substrates are still abundant.

Convergent chemistry is real

The fact that fish sauce was independently developed in the Mediterranean (Roman/Greek), Southeast Asia, and East Asia, with closely matching production methods and product profiles, is striking. It is one of the best examples of convergent food technology — different cultures, in different climates, with different fish, arriving at essentially the same chemical solution to the same problem (how do we preserve fish protein and concentrate flavor?).

This is the chapter's recurring theme #4 made concrete: food traditions are accumulated scientific knowledge. Different humans, doing the same kind of long observation, found the same chemistry. The chemistry is what unifies them. The cultural specifics (fish species, salt grade, vat materials, accompanying flavors) are local optimizations of a universal underlying solution.

Rediscovery is a thing

The reintroduction of fish sauce to Western Europe via twentieth-century Asian immigration and food culture is an example of a tradition that disappeared, persisted elsewhere, and returned. The Roman use of garum was, in some ways, a forerunner of the modern Western cook's use of fish sauce — same chemistry, similar culinary logic, separated by 1,500 years and a Eurasian travel route.

A modern chef using fish sauce in a Western kitchen is connecting to an ancestral chemistry that the chef's culture knew, then forgot, then was retaught by another culture. That cycle — knowledge originating, propagating, decaying, and being relearned — is one of the larger patterns in human culinary history.

Modern kitchens are richer for the recovery

Western food writing in the early twenty-first century has spent considerable energy on umami — its receptors, its sources, its synergies. This conversation has been led by Asian-American writers (David Chang, Dale Talde, others) who treated Asian fish sauces as primary ingredients in a way Western cookbooks had not.

The recovery of umami as a central concept has, paradoxically, also been a recovery of Roman culinary thought. Apicius's free use of garum — in roughly half of recipes — looks much less strange to a modern cook who routinely reaches for fish sauce, miso, soy sauce, or aged cheese as flavor bases. The connection has been re-established, partly. The vocabulary has caught up.

A coda on cultural transmission

The chapter's emphasis on cultural sensitivity has a sharp edge here. Roman garum is a Western European tradition that was lost. Asian fish sauces are continuous traditions practiced by Asian cultures today. Calling Asian fish sauces "the Asian version of European fish sauce" is historically backwards — it suggests the Asian traditions are derivative, when in fact they are continuous and the European tradition is the one that broke.

The honest framing is that there are multiple lineages of fish-sauce-making, separately developed across the world, of which the Roman one is the most prominent example of a major lineage that did not survive. The currently-living traditions — Vietnamese, Thai, Korean, Filipino, Indonesian, Italian (Cetara) — are the inheritors of an ancient global practice, not the borrowers of a European one.

Roman cooks would have recognized modern fish sauce as a familiar tool. Modern Western cooks are, often without knowing it, returning to a flavor profile their own forebears used heavily. The chemistry was always universal. The practice has been geographically variable. The recovery is recent.

Analyze This

You are writing a short essay (or designing a class presentation) on the disappearance of garum from medieval European cooking. Choose two of the following framings and explain which is more compelling, with at least three pieces of evidence each:

1. The economic explanation. Garum disappeared because the trade networks that supported it collapsed. Specialized industries cannot survive disruptions of their supply chain.

2. The cultural explanation. Garum disappeared because Christian European culture devalued or stigmatized it (associations with paganism, with Roman luxury, with "smelly" foods).

3. The substitution explanation. Garum disappeared because vinegar, aged cheese, and other umami sources took over its functional role; the niche it occupied was filled by other ingredients.

4. The information-loss explanation. Garum disappeared because the tacit knowledge of how to make it well was held in workshop traditions that did not survive the medieval transition; cookbooks alone could not transmit it.

Pick two, weigh them, and conclude. What does your conclusion suggest about which other food technologies are most vulnerable to disappearance today?