Preserving is probably the oldest intervention humans have wanted to make to food. That is not to say that when man first donned a loincloth and dragged his nominal wife around by her hair he was wondering how to make the butchered elk leg go an extra day, but certainly historical evidence suggests it was a present and pressing concern at least as far back as the ancients. It does not have to be primarily a chemical process; it can be a physical one. For example, for the last several thousand years, several types of food have been dried in order to preserve them.
The drying process can significantly extend the life of vegetable and fruit foods as well as meats. In parts of the world they even dry out tarantula spiders in order to preserve them (Figure 1). There are several ways of drying foods. Sunlight can be used – we have all seen, if not bought, sun-dried tomatoes – but also wind. Carpaccio, although it sounds like a cheap fortified wine, drunk only as shots by pissed-up Australians, was originally wind-dried Italian beef1.
Probably the earliest attempts at chemical preservatives employed salt. Although later mined, this was first isolated from the sea using tidal flows that filled small pools at high or possibly spring tides, and the water evaporated in the sun. In Western Europe and other places, pork and beef were routinely packed into salt, which preserved them. In fact this was the chief method of preserving these meats until at least the end of the middle ages. The discovery of nutmeg as a meat preservative became more widespread in use from around this time, allowing meat to be eaten all year round, but also to be taken on sea voyages. In fact, the utility of nutmeg in particular in preserving meat was so keenly observed and was unique to it for many years that with a geographically limited supply, human conflict
resulted. The conflict between the Netherlands and Portuguese in the 18th Century was fought more or less directly over nutmeg. Although pork with nutmeg is a seemingly odd combination today, it is a delicious one.
What Does Drying Do, and Why Does it Work?
Drying, whether with salt or not, works in the same way that adding sugar and heating to make jam works as a method of preserving food. You will know from experience that eating salty or very sugary (rather than just sweet) food makes one thirsty. The same is true of microbes exposed to high concentrations of sugar or salt. The sugar and salt draw the water out from them, too. However when the sugar or salt content is sufficiently high, so much water is drawn out, it kills them. This is how to spot poor-quality jam: mould will grow on it. The same principle can be applied to dried beef: the salts and other things within the meat fibres have reached a concentration that prevents microbes from living on them.
There is a secondary reason why covering a pork joint in salt will preserve it. It also forms a barrier between the meat and the air. This prevents the air-borne bacteria and fungi from ever reaching the food in the first place – it is a barrier between the food and the outside world. Today the principle barriers in use are plastic films and canning, as part of sealed packaging, and so on for just this purpose.
Preservatives: The E Numbers’ Finest Hour
The E numbers we use to preserve foods are plentiful, in fact there are two groups for this job. There are the numbers E200-299 (general preservatives) and E300-399 (anti-oxidants). The E300s are perhaps the most interesting because of how they are misunderstood. ‘Anti-oxidants’ are, to a lot of people, something to do with hand cream and young-looking skin. Perversely, the same chemicals that give these creams their anti-oxidant (preservative) properties are often the same ones that appear in food. And while a bit of vitamin C (ascorbic acid, otherwise known as E300) is not going to turn a shrivelled apricot into a peachy baby’s bottom, it will delay the fats in that cream from going rancid.
If you want to test this experiment at home, take a bottle of lemon juice and a fresh apple. Halve said apple, put the face of one half in the lemon juice and the other on a windowsill and leave for a couple of hours. Compare the state of the two after this time.
References and Notes
1 A. de Conte, ‘Amaretto, Apple Cakes and Artichokes’, Vintage Books, 2006.
One response to “E Numbers: Preservatives”
You must log in to post a comment.