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.
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/).