How to Invent Everything: A Survival Guide for the Stranded Time Traveler

by Ryan North

If you have a surplus of vinegar, you can use that to preserve foods directly (see Section 10.2.5). Cheese is really just preserved milk, and you can make it by introducing vinegar (around 120mL of it) to 1L of boiling milk.* The vinegar curdles the milk, causing delicious cheese curds to separate out, leaving a yellowy liquid called “whey” behind. Drain and press your curds (wrapping them in fabric will do the trick there; see Section 10.8.4) and you’ll make a cheese that won’t spoil for weeks. Salt it, or soak it in brine to preserve it, and it’ll last even longer. By introducing specific bacteria to your cheese as it ages, you can control its flavor: the Camembert, Brie, Roquefort, and blue cheeses you remember were all made by introducing different strains of Penicillium mold (Section 10.3.1) to the curds—though the strains used in cheese making in the modern era aren’t the same as the ones used to produce penicillin.