The Knowledge: How to Rebuild Our World From Scratch (10 page)

FOOD AND CLOTHING

Burg-places broken, the work of giants crumbled.

Ruined are the roofs, tumbled the towers,

Broken the barred gate: frost in the plaster,

Ceilings a-gaping, torn away, fallen,

Eaten by age . . .

U
NKNOWN
EIGHTH
-
CENTURY
S
AXON
AUTHOR

LAMENTING
R
OMAN REMAINS,
“The Ruin”

COOKING IS THE ORIGINAL CHEMISTRY
in our history—deliberately directing the transformation of the chemical makeup of matter. The crispy browning on the outside of a grilled steak and the golden crust of a loaf of bread are both due to a particular molecular change known as the Maillard reaction. Proteins and sugars in the food react together to create a whole host of new, flavorsome compounds. But cooking serves far more fundamental purposes than simply making food taste more appetizing, and it will form the crux of keeping the survivors healthy and well nourished after the apocalypse.

The heat of cooking kills any contaminating pathogens or parasites, preventing food poisoning from microbes or infection with tapeworm from pork, for example. Cooking also helps to soften tough or fibrous food, and breaks down the structures of complex molecules to release simpler compounds that are more easily digested and absorbed. This increases the nutritional content of much food, allowing our
bodies to extract more energy from the same volume of edible matter. And in some cases, such as taro, cassava, and wild potato, prolonged heat inactivates plant poisons, which in the extreme example of cassava would otherwise be lethal from a single meal.

Cooking is only one kind of processing that we apply to food before consumption. The capability to keep food safely for protracted periods beyond its immediate collection is a fundamental prerequisite for the support of civilization. It allows produce to be transported from the fields or slaughterhouses into cities to support dense populations, and enables the stockpiling of reserves for leaner times. Food is spoiled by the action of microbes—bacteria as well as molds—breaking down its structure and changing its chemistry, or releasing waste products distasteful or even outright toxic to humans. The purpose of food preservation is to prevent this microbial spoilage occurring, or at least to delay the process for as long as possible. You pull this off by deliberately modifying the conditions in the food to push them outside the sweet spot for microbial growth. We’ll come in a second to a more detailed explanation of how this is actually achieved, but you are essentially trying to exert control over the food’s microbiology: preventing any microorganism growth, or even employing some microbes to block other, undesirable strains from gaining a foothold. In some cases, fermentation from microbial growth is encouraged to decompose the complex molecules in food and make nutrients more readily accessible for our own consumption. Biotechnology, therefore, is far from a modern innovation; it is, in fact, one of humanity’s oldest inventions.

The development that first endowed us with all of these capabilities—cooking food thoroughly by boiling or frying, fermentation processing, and long-term preservation—was the innovation of firing clay into earthenware pots. This had profound ramifications for us as a species. The human digestive system, unlike the multiple stomachs of ruminants like cows, for example, is unable to break down many food types particularly well, and so we have applied technology
to supplement what our bodies can naturally do. Pottery vessels, used as receptacles for food during fermentation or cooking to release further nutrients, therefore serve as additional, external “stomachs”—a technological pre-digestive system.

Modern cuisine—the height of civilized sophistication with all its marinades, confits, and drizzles of reductions—is no more than a superficial adornment upon these fundamental necessities of stopping food from poisoning you and unlocking as much of its nutritional content as possible. This isn’t a cookbook, so we won’t go into recipes or detailed instructions, but the general principles behind preservation and processing methods are crucial knowledge for a post-apocalyptic recovery.

Preserving food takes into account the environmental conditions that microbes, and indeed all life, need to thrive. But the traditional techniques we’ll look at were all developed over long periods by trial and error, long before the discovery of invisible microorganisms causing decay (even the modern practice of canned food was adopted before the demonstration of the germ theory). These techniques were found to work, but without any underlying theory as to why. Retaining this kernel of understanding after the apocalypse (see
here
for how to build a microscope capable of revealing these microbes) will be enormously beneficial to maintaining a reliable food supply and avoiding infectious disease—both critical to sustaining a population increase after a cataclysm.

Not only does all life on Earth require liquid water to grow and reproduce; organisms can also tolerate only a particular range of physical or chemical conditions. More specifically, the enzymes in a cell—the molecular machinery that drives the reactions of biochemistry and
coordinates the processes of life—are active only over particular ranges of temperature, salinity, and pH (how acidic or alkaline a fluid is). Preservation can be achieved by pushing any of these three factors away from the optimum for microbial growth.

The easiest method of preserving food is simply to desiccate it. Without much available water, microbes struggle to grow (this is why it’s also critical to dry your harvested grain before storing it in silos). The traditional technique is air- or sun-drying, suitable for fruit such as tomatoes as well as meat to make biltong or beef jerky, but it is a slow process and not suitable for large bulks of food.

Without being commonly considered as desiccated, many other foodstuffs are also preserved by low water availability. Large amounts of dissolved compounds like sugars make a solution very concentrated, which acts to draw water out of microbial cells and stop all but the hardiest strains from growing. This is exactly the principle behind jams: the saccharine fruitiness tastes great on toast in the morning, but the very reason for the creation of preserves in the first place is to protect fruit by the antimicrobial action of the concentrated sugar solution. Sugar can be extracted from tropical sugar cane or the root of the temperate-growing sugar beet by trickling water through the crushed plant to dissolve the sugar and then recovering the crystals of it by drying. Honey is extremely long-lasting for the same reason.

Salt is needed in small amounts for the healthy functioning of the human body—which is why our palate craves it—but a far greater quantity is used for preservation. Salted foods are protected in the same manner as preserves: concentrated briny fluids draw water out of cells and hamper growth. Fresh meat can be effectively preserved by packing it in dry salt for several days, or keeping it submerged in a heavy brine solution—about 180 grams of salt dissolved into every liter of water creates a brine solution roughly five times more concentrated than seawater. Salting has been a crucial preservation technique throughout history, so it is worth looking at in more detail.

In principle, producing salt is childishly simple, provided you’re anywhere near the coast. Seawater contains about 3.5 percent dissolved solids, the vast majority of which is common salt (sodium chloride), which can be extracted by evaporating off the water solvent. If you live in sunny climes, you can simply allow seawater to flood shallow pans and evaporate in the heat of the day to leave a crust of salt precipitated behind. In very cold temperatures, you can allow shallow ponds of seawater to freeze, leaving a concentrated brine solution at the bottom. But temperate conditions, as are prevalent across much of Europe or North America over the year, require burning fuel to heat cauldrons of saline to drive off the water. In the case of salt, then, the availability of a valuable commodity is not due to the rarity of the substance itself—three-quarters of the Earth’s face is sloshing with saline solution—but to the energetic costs of extracting it in large amounts, or of finding and exploiting minable deposits.
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Salting is often used in combination with another preservation technique, whereby naturally toxic antimicrobial compounds are generated and infused into the produce, often meat or fish: the process of smoking. As we’ll see in Chapter 5, the incomplete combustion of wood releases a broad suite of compounds, one class of which, creosote, is responsible for the distinctive flavor and decay-inhibiting effect of smoked food.
You can jury-rig a small-scale post-apocalyptic smokehouse very easily. Dig a pit for a small fire, with a metal cover, and a shallow trough leading a yard or two to the side, also covered on top with board and then soil, to channel the smoke. At the open end of the covered channel, where the smoke escapes, place a defunct fridge with a hole cut in the bottom. Stock the wire frame shelves with gutted fish, slices of meat, cheese, and so on, and smoke it for several hours.

Acidity is another great ally in resisting the hordes of invading microbes. Vinegar is a weak solution of acetic acid (which we’ll come back to later in this chapter) and is very effective as a preservative in pickling. The opposite approach, preserving food with alkalinity, is much less prevalent because it saponifies the fats—see soap-making in Chapter 5—and so grossly changes the flavor and texture of the food.
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Rather than adding acid from elsewhere to preserve by pickling, food can also be protected by encouraging the growth of particular bacteria that excrete acidic waste products—allowing food to generate its own preservative. Sauerkraut, Japanese miso, and Korean kimchi are all produced by first using salt to draw out moisture from the vegetables and then allowing fermentation by salt-tolerant bacteria to increase the acidity naturally, transforming the food into an extreme environment and so blocking colonization by other microbes that may cause spoilage or food poisoning.

Yogurt is produced in a similar way, by allowing a culture of lactic acid–releasing bacteria to sour the milk (in general, acids are perceived by the tongue as sour-tasting) in a controllable way. This again creates an internal environment with enhanced acidity that resists colonization by other microbes and so prolongs the consumability of the nutrients by several days. With milk being such a useful source of key nutrients, its preservation is key for survivors of the apocalypse.

Vitamin D is essential for preventing the bone-degradation disease rickets, since it aids the absorption of calcium from food. This vitamin is manufactured by the body when skin is exposed to sunlight, but at
northern latitudes, with long, dark winters when people have had to wrap up against the cold, rickets plagued humanity for centuries. Milk is a wonderful source of both vitamin D and calcium, and so being able to reliably preserve the nutrients in milk will be crucial for the healthy inhabitation of the north.
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Butter is a good way of preserving the energy-rich fats of milk by removing much of its water. The essence of butter making is to first extract the fat-rich cream; you can either allow it to naturally rise to the top for a day or so in a cool container, or accelerate the process with a centrifuge (a whirling bucket will do the trick). The process of churning is simply to get the droplets of fat to stick together and exclude the remaining fluid, or buttermilk. This can be achieved by rolling a jar back and forth across the floor, or shaking it, but a more effective post-apocalyptic makeshift solution would be to use an electric drill with a paint-stirring paddle. Strain the butter out of the buttermilk, add salt for preservation, and then knead it until all the water has been squeezed out and the salt mixed throughout.

Yogurt and butter are stable for a few days to around a month, respectively, whereas cheese can safely preserve the nutrients of milk for many months: it is the perfect rickets-busting storage medium. Cheese making is more involved, but the crucial point is to preserve the nutrients in milk by removing its water component. Rennin, an enzyme from the first stomach of a calf, is used to break down the proteins in milk and so curdle it. The curds are strained off and pressed into a solid lump, which is then allowed to mature; it’s the action of various fungi that gives different cheeses their characteristic appearance and flavor.

Let’s turn our attention now to the preparation of cereal crops. The prehistoric domestication of wheat, rice, corn, barley, millet, and rye represents one of the crowning glories of human accomplishment. The reproductive strategies of these cultivated strains have been reprogrammed through artificial selection to bear easily recoverable grain—they are the solution that we found to the challenge of consuming grass species without the biological benefit of a ruminant digestion like that of the cows and sheep we husband.

Corn can be cooked and eaten as corn on the cob,
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and rice can be dehusked and simply boiled or steamed for eating. But the small, hard kernels of most cereal crops cannot be eaten as is, unlike many cultivated fruits or vegetables; they have to be technologically prepared for consumption.

The grain must be pulverized into a fine powder: flour. The simplest method is to place a handful of grain onto a smooth, flat rock on the ground, and then lean forward and use your body weight to crush and grind it beneath a handheld pestle stone. But this is backbreaking and enormously time-consuming labor: a far better system is to mill it between two squat cylindrical stones or steel disks, with the grain introduced (grist for the mill—another common phrase with ancient agricultural roots) into the sandwich through a hole in the middle. The weight of the top millstone provides the crushing pressure, and its rotation works the flour outward to be collected. In this way, the millstone represents a technological extension of our molar teeth, crushing and grinding hard foodstuffs to render them more digestible. You can
ease your own manual toil by yoking a draft animal to drive this slow rotation, or even better, harnessing water or wind energy (we’ll see how in Chapter 8). Even so, the pulverizing of a harvest’s worth of grain will represent an enormous expenditure of energy for a recovering society.

The simplest, but least appetizing, way to consume ground flour is to mix it with a little water into a thick porridge or gruel. But there is a far more tasty, and versatile, starch-delivery mechanism that requires just a little more preparation. Bread is essentially no more than a cooked gruel, but as an effective pathway for nourishment it has underpinned civilization since its very birth. The basic recipe is ludicrously simple: grind some grass seeds into a powdery flour, mix with water into a pasty dough, then roll out and cook slowly, perhaps even just on a hot stone by the fire. This makes an unleavened flatbread, which is still exceedingly common today as chapati, naan, tortilla, khubz, and pita bread.

The type of bread we are most familiar with in the Western world, though, is risen bread, and this requires one further ingredient. Yeast is a microbe, a single-celled fungus not far removed from the toadstools sprouting from a rotting tree trunk, that is applied to the fermentation of flour dough, breathing out carbon dioxide that gets trapped in bubbles to produce a light, fluffy loaf. One particular strain of yeast,
Saccharomyces cerevisiae
, is used for producing almost all leavened bread today. Indeed, you’d do very well to have the presence of mind to rescue a starter stock of this organism, as vital and hard-working in its own way as the ox or horse, before it is lost in the turmoil of the apocalypse; it can be found in supermarkets dried, in packets, but won’t persist indefinitely. How might you go about re-isolating bread-making microorganisms from scratch if you have to?

The yeast required for raising bread, as well as other fermentation bacteria, are naturally present on cereal grain and thus also in milled flour. The trick is to isolate these beneficial bugs among all the others
that might do you harm: you need to play primitive microbiologist and create a selection process that favors the desired bugs.
The guide given here is for isolating the correct microbes for baking a sourdough, the first leavened bread to be baked, around 3,500 years ago in ancient Egypt, and still popular today among craft bakers.

Make up a mixture of one cup of flour (whole-grain is best for this initial process) and half to two-thirds of a cup of water; cover and allow it to sit in a warm place. Check after twelve hours for signs of growth and fermentation, such as bubbles forming. If none are apparent, stir and wait another half day. Once you get fermentation, throw half of the culture away and replace with fresh flour and water in the same proportions, repeating this refill twice a day. This gives the culture more nutrients to reproduce and continually doubles the size of the microbial territory to expand into. After about a week, once you have a healthy-smelling culture reliably growing and frothing after every replenishment, like a microbial pet thriving on the feed left in its bowl, you are ready to extract some of the dough and bake bread.

By running through this iterative process you have essentially created a rudimentary microbiological selection protocol—narrowing down to wild strains that can grow on the starch nutrients in the flour with the fastest cell division rates at a temperature of around 20°–30°C. Your resultant sourdough is not a pure culture of a single isolate, but actually a balanced community of lactobacillus bacteria, able to break down the complex storage molecules of the grain, and yeast living on the byproducts of the lactobacilli and releasing carbon dioxide gas to leaven the bread. Such a mutually supportive marriage between different species is known as a symbiotic relationship and is a common feature of biology from nitrogen-fixing bacteria hosted in the roots of legume plants, to the bacterial digestion assistants in our own gut. The lactobacilli additionally excrete lactic acid (just as in yogurt production), which gives this bread its tasty sour tang, but also act to exclude
other microbes from the culture, keeping the symbiotic sourdough community wonderfully stable and resilient against incursion.

Not all flours can be used for leavened bread, however, as it requires the presence of gluten to create a malleable dough able to trap the bubbles of carbon dioxide breathed out by the growing yeast. Wheat grain contains lots of gluten and so makes a divinely light-textured loaf, whereas barley flour has barely any. Barley has a far more pleasing application than daily bread, however.

Yeasts growing in an environment with plenty of oxygen, such as in a dough, are able to break down their food molecules all the way to carbon dioxide (just as human metabolism does). But culture yeasts under anaerobic conditions, with restricted oxygen, and they can only partially decompose sugars, instead releasing ethanol (alcohol) as a waste product: this is the essence of brewing. Since its discovery, alcohol has been helping revelers have a good time, but it has a myriad other uses and is well worth the effort of purifying in the interests of rebuilding civilization. Concentrated ethanol is valuable as a clean-burning fuel (such as in a spirit burner or biofuel car), a preservative, and an antiseptic. It is also a versatile solvent for dissolving a variety of compounds insoluble in water, such as in the extraction of chemicals from plants for perfumery or creating medical tinctures. And when alcohol is exposed to air for a while it turns vinegary, as any wine drinker is surely familiar with after a bottle has been open for a few days. New bacteria colonize the fluid and convert the ethanol into acetic acid: cooking or table vinegar is commonly between 5 and 10 percent acetic acid diluted in water, and more concentrated solutions can be used for pickling, as we have seen.

Unlike the mixed microbial community of a sourdough, the pure yeast culture used in brewing cannot itself break down the complex starch molecules in the grain, which must therefore first be converted into fermentable sugars. The biological function of starch is as an
energy source to support the young sprouting plant until it has become established with leaves, and so the grain’s own mechanisms are activated to disassemble the starch. The barley grains (or indeed those of any other cereal) are steeped in water and encouraged to germinate for a week in a warm damp room, and thereby break apart their starch into accessible sugars (the starch molecule is a long chain of sugar subunits linked together), before being dried or partially roasted—to vary the color and flavor of the final brew—in a kiln. This malt is then mashed with hot water to dissolve out all of the sugars, and filtered to produce a sweet-tasting wort. The wort is first boiled, both to evaporate off some of the water in order to concentrate the sugars, and also to sterilize it and so offer a blank slate for adding the desired fermentation microbes afterward. Finally the wort is cooled and inoculated with yeast from a previously brewed batch, and then fermented for around a week.

One exceedingly useful item to scavenge from the supermarket shortly after the Fall would be a bottle of craft ale that contains a sediment of live yeast at the bottom, so as to save this handy bug for posterity. But yeasts suitable for brewing are also prevalent in the environment and can be re-isolated using a selection technique similar to that described above. In fact, the pure-culture yeasts used for commercial bread making today are descended from cells originally found in the froths of beer-brewing fermenters, and were isolated using the microbiological tools of agar plates and microscope that are described in Chapter 7. So next time you’re warmly tipsy, remember that your brain has been mildly poisoned and impaired by the excrement of a single-celled fungus. Cheers!

Pretty much any sugar source (or starch disassembled back into sugar) can be fermented into an alcoholic product: honey, grapes, grain, apples, and rice are transformed into mead, wine, beer, cider, and sake, respectively. But regardless of the nutrient source, alcohol from fermentation can only reach a concentration of around 12 percent before
the yeast cells essentially poison themselves with their own ethanol excretion. The process of purifying alcohol to higher concentrations, by separating ethanol from the water and everything else in the messy ferment, is known as distillation and is another truly ancient technology.

As with extracting salt from saline solution, separating alcohol from the watery soup of the ferment exploits a difference in the properties of the two components—in this case the fact that ethanol has a lower boiling point than water.
At its simplest, a still need be no more complicated than that used by Mongolian nomads to make their hooch. A bowl of the fermented mash is held over a fire, with a collection vessel on a ledge above it, and then a third, pointy-bottomed pot full of cold water positioned directly above both; a hood is then draped over the entire arrangement. The fire heats the mash, and the ethanol is driven off first, the vapor condensing on the cool underside of the water pot and running down to drip into the middle dish. Modern laboratories merely replicate this basic setup with dedicated glassware, a thermometer to check that the steam boiling off the mash doesn’t exceed 78°C (the boiling point of ethanol), and a gas burner with a controllable air inlet. The efficiency of the process can be improved by using a fractionating column, an upright cylinder packed with glass beads, so that the vapor coming off the mash repeatedly condenses and re-evaporates, further concentrating the alcohol relative to water each time, before a final condenser with a water-cooled jacket collects the distillate.