A Roman Vegetarian Substitute for Fish Sauce

By Edith Evans

Roman cookery has been one of my research interests since the 1980s; I’ve accumulated a large repertoire of ancient recipes and usually do at least one live demonstration a year.  Most of the recipes include garum or liquamen – fish sauce – as a taste enhancer, providing salt and umami. Whilst finding fish sauce is fairly easy nowadays in Britain (the Romans used the same techniques to make it as the modern Thai and Vietnamese), using it at demonstrations disappoints vegetarians who would otherwise like to sample the plant-based dishes.

I found the answer to this problem in a Late Antique agricultural treatise:

Liquamen from pears: Ritually pure liquamen (liquamen castimoniale) from pears is made like this: Very ripe pears are trodden with salt that has not been crushed. When their flesh has broken down, store it either in small casks or in earthenware vessels lined with pitch. When it is hung up [to drain] after the third month without being pressed on, the flesh of the pears discharges a liquid with a delicious taste but a pastel colour. To counter this, mix in a proportion of dark-coloured wine when you salt the pears.
– Palladius: Opus Agriculturae 3.25.12

Liquamen castimoniale must have been required for people observing certain religious strictures (castimoniale means ‘to do with religious ceremonies’). Why would ordinary liquamen have been thought unsuitable? Was it the fish? (Pliny the Elder writes of a special fish sauce for Jews (Natural History 31.95) that he calls garum castimoniarum, although he’s obviously got the wrong end of the stick when it comes to Jewish food laws because he says it’s made using fish without scales). Alternatively, was it because liquamen was the product of fermentation? Fermentation was often considered a form of decomposition, which might have led it to be regarded as ritually unclean.

This has a bearing on how we interpret the recipe. Although Palladius tells us the ingredients to use (whole pears and salt, plus optional red wine) he does not give any information about the relative proportions. This leaves us with two possible techniques. Either you use a high proportion of salt and effectively create a brine utilising the juice of the pears, or you use a low proportion and promote a lactic fermentation by incubating the mix a suitable temperature (although Palladius doesn’t mention this). When used to flavour food, the product of the first method adds a strong taste of salt but no umami. The second would add some umami but also acidity, but a much lower amount of salt. However, if the problem was the fermentation itself, the second method would have been as unacceptable as standard fish sauce.

I’ve had a go at the lactic fermentation method, using 2% of the weight of the pears in salt, but when I tried it, the mix went mouldy before fermentation had a chance to take hold.  I’ve had much more success with the first method and have repeated it enough times to get a consistent product. The best pears to use are juicy varieties with very tannic skins, like Williams (also known as Bartlett) and Comice. I mash up the pears – stalks, skins, cores and all – mix them with 25% – 50% of their weight in coarse sea salt (I don’t bother with the wine), and leave them at the back of the fridge in a glass jar with the lid only lightly screwed on. At the end of two months (unlike us, the Romans counted inclusively), the pulp has started to separate out. The heavier elements form a pale layer at the bottom of the jar, whilst the top part of the mixture is more liquid and is a pale pinkish-brown. When drained through a nylon sieve, the colour of the resulting liquid is a very pale version of the colour of fish sauce. 

I’ve tried various proportions of salt, and found that, if you use 50%, you seem to get more liquid, probably because the mixture doesn’t draw in moisture from the air to the same extent.  But a smaller percentage of salt allows more of the delightful pear flavour comes through – I find it much more difficult to detect in the 50% version. Stored in a clean bottle it will keep for months without refrigeration.

Figure 1: The pear liqumen is in the flask with dark blue trim

I’ve only had a problem once, when spots of mould had appeared on the surface of a batch six months after I’d made it. As I was due to give a Roman cookery demonstration in a few days’ time I had to quickly rustle up something I could use, so I cored and cut up a pear, boiled it with 25% salt and a little water, removed the peel and pulped the flesh in the blender. It was much too pale, but the taste was the same and I decided it would be a useful method for someone who couldn’t wait two months – in fact that’s what I recommend for my Roman Cookery School videos (https://m.youtube.com/user/GGATArchaeology and https://en-gb.facebook.com/GGATarchaeology/).

Recipes for Glauber salt and the serendipity of research

Johan Rudolf Glauber (1604-1670)
Johan Rudolf Glauber (1604-1670)

By Marieke Hendriksen

The German apothecary and alchemist Johan Rudolf Glauber (1604-1670) spent much of his working life in Amsterdam. There, he used the facilities of a commercial glasshouse–“The Two Roses”–on the Rozengracht for some of his experiments.[1] By extracting the colours of metals by melting them into glass, Glauber hoped to come closer to the unveiling of the Philosopher’s Stone.[2] Although he never achieved this, his experiments proved highly relevant for understanding a number of chemical substances and compounds. The reason Glauber’s name still sounds familiar to us today is that he discovered how to artificially create hydrate sodium sulfate, a compound highly relevant for glassmaking, which Glauber called sal mirabile.[3] This white crystalline solid is still commonly known as Glauber salt, and can be bought from online chemists to intensify the colours of textile dyes.[4]

Frontispice to the English translation of Glauber's work, containing a recipe for sal miracle: "The works of the highly experienced and famous chymist, John Rudolph Glauber," transl. Christopher Packe, London: Thomas Milbourne, 1689
Frontispice to the English translation of Glauber’s work, containing a recipe for sal mirabile.

Glauber salt was, and is, of great use in the making of glass, where an alkaline is necessary to lower the melting point of the ingredients for glass and to obtain good results. Before the discovery of Glauber salt, or soda ash (sodium carbonate) that had been extracted from the ashes of plants, was commonly used. The downside of using soda ash though, as Herman Boerhaave (1668-1738) put it in his Theory of Chemistry, was that ‘the ashes of plants us’d herein, also vary the goodness of glass.’[5] The relative ease with which Glauber salt could be made (Glauber’s own recipe!) requires nothing more than plain salt, water, a retort and a fire. Its purity ensured a more stable glass quality than soda ash. But Glauber and his contemporaries thought that his newly discovered salt was miraculous for another reason: its perceived therapeutic qualities. Glauber salt was long used as a laxative and a styptic.[6]

Sodium sulfate or Glauber salt
Sodium sulfate or Glauber salt

These useful applications meant that the popularity of Glauber salt in the eighteenth and nineteenth century was enormous, as also shown by the numerous recipes for it in medical and chemical handbooks. In a manuscript with lecture notes, a student of the Leiden professor of chemistry Gaub (1705-1780) devoted almost ten pages to the description of three processes to create Glauber Salt.[7] Reversing these recipes, the Dutch apothecary Petrus Johannes Kasteleyn (1746-1794), who aimed to stimulate the public’s interest in chemistry in the eighteenth century, wrote in his Chemical exercises for the lovers of chemistry in general, and the apothecaries, producers, and dealers in particular that through chemical analysis he had found that  ’16 ounces of pure Glauber salt consist of 2 ounces of vitriolic acid, and 3.5 ounces of pure alkali.[8]

From the early twentieth century onwards, the use of Glauber salt in medicine declined as safer alternatives were discovered, but it is still widely used industrially today. The story of the recipe for Glauber salt shows us the serendipity of research: while looking for something entirely different–the Philosopher’s Stone–Glauber discovered a substance that would become widely used in medicine, crafts and industry for centuries to come.


[1] AAR (Amsterdamse Archeologische Rapporten) 61, 2011, p. 44. The glasshouse was housed at the Rozengracht 1657 and 1679.

[2] D. Von Kerssenbrock-Krosigk, Glass of the alchemists : lead crystal-gold ruby, 1650-1750 (Corning, NY: Corning Museum of glass, 2008), p. 17.

[3] For Glauber’s recipe for sal mirabile, see The works of the highly experienced and famous chymist, John Rudolph Glauber, trans. Christopher Packe (London: Thomas Milbourne, 1689), p. 225.

[4] http://www.stoftotverven.nl/Glauberzout-500-gram; http://www.dharmatrading.com/chemicals/glaubers-salt.html

[5] H. Boerhaave, Elementa chemiae, quae anniversario labore docuit in publicis, privatisque scholis. 2 vols, vo.l. I, Leiden: Isaak Severinus, 1732, p. 183.

[6] Pinkhof, ‘Glauberzout als Bloedstelpend Middel,’ Nederlands Tijdschrift voor Geneeskunde, 1897, 41, pp. 297-8.

[7] H.D. Gaub, “Chemiae praxis. Notes of lectures by an unnamed student. Produced in Leyden.”, z.d. WMS 4  MS.2479, Wellcome Library, London, pp. 67-79.

[8] P.J. Kasteleyn, ‪Chemische oefeningen voor de beminnaars der scheikunst in ‘t algemeen, en de apothekers, fabriekanten en trafiekanten in ‘t bijzonder, vol. 2 (Amsterdam: ‪A. J. van Toll, 1872), p. 83. For more on Kastelyn’s educational purposes, see L. Roberts, ‘P. J. Kasteleyn and the “Oeconomics” of Dutch Chemistry,’ Ambix 53, 3 (2006): 255-272.