New Worlds: Food Preservation

When the covid pandemic sent us all into lockdown, I, like many people, became extremely leery of leaving the house. In fact, for a while there the only reason I walked past my front door was to visit the grocery store, which I did as infrequently as I could get away with. I was very proud that I generally managed to go about three weeks between trips. We achieved this feat partly through ordering from a restaurant once a week, but the rest of the time — and for the first time in my life — I had to devote serious thought to the issue of food perishability.

Sure, I’ve had food go bad on me before. But until spring of 2020, my reaction to floppy carrots or milk that had gone off was to shrug and make a quick trip to the store. Now, suddenly, I had to plan out meals with an eye toward what would keep indefinitely, what would stay good for a while, and what had to be used as soon as possible. Dinners involving more immediately perishable produce became a special treat, something we had in those first few days after a supply run. By the end of a given span, we were subsisting mostly on frozen lasagna and similarly durable options.

But at least we had the option of frozen food. When I think about the logistics of keeping people fed in a world without ready access to fridges and freezers, I wonder how our species has managed to avoid wholesale starvation.

After all, not all kinds of food are available year-round. (Even now, good luck finding things like fresh cherries out of season.) Depending on where you live, very few foods will be available at certain times of year. But while I’ve seen the importance of the planting and harvesting seasons show up occasionally in fiction, I feel like vanishingly little attention gets paid to the question of what happens to that food after the harvest — how people ensure there will still be something to eat months later. My understanding is that the leanest time of year was not usually the depths of winter; it was the spring, when stores had run short but the new growth had not yet produced much you could eat.

To avoid the aforementioned wholesale starvation, we’ve poured huge amounts of effort and creativity into figuring out how we can prevent food from becoming inedibly rotten, moldy, or stale. The earliest method is probably drying, using air and sun to dessicate various products and thereby inhibit the growth of bacteria and mold. You can dry meat, fish, some kinds of fruit and vegetable, or mushrooms, providing for a variety of foods in the off season; we also dry out grains for improved long-term storage. Along with increasingly longevity, removing water tends to make things lighter and more compact, which makes dried rations very useful for travelers, especially armies on the move.

Of course, nature gives us another easy way of preserving food — depending on where you live. The Year Five essay on keeping ourselves cool already touched on a number of methods that can be used to chill good and drink, but if you’re in a part of the world where the temperature goes below freezing in the winter and stays there pretty reliably, you can go a lot farther than just chilling. Mind you, freezing can significantly change the texture and palatability of some items, especially if they stay frozen for a long time . . . but the same is true of drying. And then you’ll need to warm your food up again before you eat it, since few of us particularly enjoy trying to gnaw bits off a frozen hunk of meat, or chowing down on icy peas.

In some cases you can let nature take its course, so long as you do it in a controlled manner. Fermentation involves letting some micro-organisms hold other, less desirable micro-organisms at bay. Alcohol is probably our most famous deployment of this technique, though we probably don’t think about it primarily in terms of preservation anymore; for the most part, it’s a recreational product now. But grains and fruit for booze are far from the only things we’ve fermented: we’ve used this process on everything from olives to milk to fish, producing some incredibly pungent results.

Other methods involve adding something to the material you want to keep for later. Smoking on its own won’t preserve meat or fish — though it can make them quite tasty! — but if you combine it with drying, salting, or both, it can produce better results than either of the latter processes on their own. You do need fairly ample sources of fuel, though, and while you can smoke things over pretty much any burnable substance (including dung), when fuel is in short supply, you may not want to spend it for this purpose. Meanwhile, the importance of salt for curing and brining is so great that during the endemic warfare of the Sengoku period in Japan, the lord Uesugi Kenshin defied a boycott and sent salt to his landlocked enemy’s domain, saying, “I do not fight with salt, but with the sword.”

Salt is often one of the key components of pickling as well, but that term actually encompasses a range of possibilities other than a brine solution. Other antimicrobial fluids you can immerse your food in for preservation include vinegar, alcohol, oil, and honey — all of which can be adulterated with flavorings to produce a tastier product on the far side. Confits are meats cooked and then stored immersed in fat, while jellying involves encasing the material in a gel. Lye, while not (I think) technically a pickling agent, finds employment especially in regions where salt is not easily available.

Finally, sometimes the preservation is more about the container than the material inside. If you can keep oxygen and microbes away, food will last a good deal longer. Canning is the most common approach to this in modern times, but it wasn’t invented until the Napoleonic Wars, when the French government offered a reward to anyone who could develop some better method of preservation — especially one that would allow them to campaign in the winter and spring, when food supplies were scarcer. Before that we had jugging, where you stew meat or fish in a tightly sealed earthenware container, and even burial. That last is more generally a method of achieving cooling, drying, or fermentation, but archaeologists have dug up caches that suggest Irish peat bogs may have served as effective food storage sites.

It’s telling how many of these methods are involved in producing the infamous “traditional foods” of various cuisines that become the butt of innumerable jokes. A good portion of my ancestry is Scandinavian, so I grew up making cracks about lutefisk, even though I’ve never tried it. We still use many of these techniques, of course — sometimes in better form, like freeze-drying that is less detrimental to the texture and nutrititive content of food than pre-industrial methods — but we no longer rely on them to the extent that we once did. And thus many foods which are diplomatically referred to as “an acquired taste” recede into the background: I can have fresh fish instead of dried, lye-treated fish that requires approximately two weeks of careful reconstitution before it becomes theoretically fit for human consumption.

When hardship strikes, though, we may remember why these techniques exist.