Cheese

Cheese is a diverse dairy product made by the coagulation of milk protein, known as casein.

This process transforms liquid milk into a solid food with various flavors and textures. Most cheese is produced from the milk of cows, goats, or sheep, though water buffalo are also used.

People value cheese because it is more compact and has a longer shelf life than liquid milk. It is also a dense source of nutrition, providing high amounts of fat, protein, calcium, and phosphorus.

The production process begins with acidification, which makes the milk sour. This is often achieved by adding starter bacteria, such as those from the Lactobacillus or Streptococcus genera. These bacteria convert milk sugars into lactic acid.

To complete the curdling, makers add an enzyme called rennet. Traditionally, rennet was extracted from the stomach of young calves, but most modern cheesemakers use recombinant chymosin. The addition of rennet creates a strong, rubbery gel. This gel is then separated into solid curds and liquid whey. For many varieties, the curds are cut into small cubes to allow water to drain.

Different cheesemaking techniques create a wide range of styles. Some makers heat the curds to temperatures between 35 and 55 degrees Celsius. This process forces more whey out and changes the milk chemistry. Other methods involve stretching and kneading the curd in hot water, a technique used for Mozzarella. Salt also plays a vital role beyond flavor. It preserves the cheese, draws out moisture, and firms the texture. Some cheeses are salted by mixing it into the curds, while others receive a brine wash on the outside.

Cheesemaking is an ancient practice that likely began by accident. It may have occurred when milk was stored in animal stomachs, where natural rennet caused curdling.

Archaeological evidence shows cheesemaking in Poland dating to 5500 BCE. In the Mediterranean, evidence appears from 5200 BCE. In China, preserved cheese was discovered in the Taklamakan Desert, dating to 1615 BCE. Even ancient Egyptian tombs have yielded evidence of cheese from around 2000 BCE.

History shows that cheese has been a significant part of human culture for millennia. Ancient Greek mythology credits Aristaeus with its discovery, and Homer's Odyssey describes the Cyclops storing cheese in racks.

During the Roman Empire, cheese was a sophisticated enterprise. The writer Pliny the Elder documented the many varieties enjoyed by Romans, including hard cheeses from the Helvetii. In the modern era, industrial production changed how cheese is made. In 1851, Jesse Williams began using an assembly-line method in New York. This helped make cheese like Cheddar a major industrial food.

Today, there are over one thousand types of cheese produced worldwide. Their specific characteristics depend on the animal's diet, the milk's butterfat content, and how long they are aged. Some cheeses, like Brie, are soft, while others, like Parmesan, are hard. Harder cheeses generally last longer than soft ones. In 2022, global production of cheese from whole cow milk reached 22.6 million tonnes. The United States was a major producer, accounting for 28% of that total.

Cheese is also a global commodity with significant economic and environmental footprints. In 2014, countries like France, Iceland, and Germany were the highest consumers, averaging 25 kg per person annually. Modern storage has also evolved; while 19th-century makers used paper and twine, 21st-century producers use vacuum packaging and gas-flushing with carbon dioxide and nitrogen.

While cheese is a staple food, its production has a carbon footprint. In 2021, producing one kilogram of cheese resulted in 6 to 12 kg of CO2eq. This makes it higher in emissions than many other foods, though it remains lower than beef or lamb.