🏭 Making and preserving food

Cheese starts with milk, which gets a special ingredient added, either a bit of acid or a natural substance called rennet, that causes the milk to separate into thick clumps called curds and a watery liquid called whey. The curds get drained, pressed, and often salted, then left to age for anywhere from a few days to several years, depending on what kind of cheese it will become. Different cheeses come from different milk, different ageing times, and sometimes even different moulds added on purpose, which is why cheese can taste so different from one kind to the next.

Canning seals food inside an airtight container, then heats it enough to kill off germs that would otherwise cause it to spoil, and that airtight seal stops new germs from ever getting back in. A properly canned food can safely last for a year or more sitting on a regular shelf, no fridge needed at all, which is a huge help for storing food long term. Canning was actually invented specifically to help feed soldiers on long journeys, back before refrigerators or freezers existed at all.

Freezing works by turning the water inside food into ice, which slows germs down so much they practically stop growing, and that is really what causes food to spoil in the first place. Because everything happens so much more slowly at freezing temperatures, food can stay safe to eat for months, sometimes even a year or more, tucked away in a freezer. Freezing does not kill every germ completely, though, which is why frozen food still needs proper cooking once it thaws out and warms back up.

Long before fridges, freezers or cans existed, people discovered that removing water from food, by leaving it in the sun, wind or smoke, stopped germs from growing and let food last for months instead of days. Dried fruit, dried meat and dried grains could be carried on long journeys or saved through a whole winter when fresh food was hard to find. Many traditional foods eaten today, like raisins, jerky and dried pasta, actually started out purely as clever ways to preserve food long before anyone had a fridge.