Back in the days before a large majority of Brazilians had refrigerators in their home, people used other techniques for preserving foods. There are lots of ways to preserve food that don't involve cold temperatures - a good thing in a mostly-tropical country like Brazil. Smoking, pickling in vinegar or wine, preserving in sugar syrups, salting - all these techniques are important parts of traditional Brazilian cooking.
The technique is identical to the way that the inhabitants of southwestern France have always made their famous duck confit - the only difference is that the animal in question in Brazil is a pig whereas in France it's a duck. Both animals have large stores of body fat, so both are suitable for preserving in this manner.
Most of the production of carne em lata in Brazil historically was domestic - on farms where pigs were raised one was slaughtered every couple of months, the prime cuts were eaten fresh and the lesser cuts were preserved in fat. There were meat-processing companies that made canned meat on an industrial scale for people who didn't have their own animals to slaughter but who needed meat that could be stored at room temperature until consumed. Most of these companies were located in the states of Minas Gerais and São Paulo.
Recently there has been a surge in demand for carne de lata in Brazil. Just as in France, where duck confit has now found a place at the highest levels of gastronomy, Brazilian chefs are discovering just how good canned meat can be. Many of the chefs are making their own carne de lata, but others have gone back to the original industrial producers for the product. The result is that the original firms that made carne de lata, or at least those who survived the long drought during the second half of the last century, are now finding a renewed interest in their product and a large increase in consumption.
One of the best-known of these firms is named Xavante, from the city of Divinópolis in Minas Gerais. They sell carne de lata, in cans with appropriately retro labels, in sizes ranging from 500 gr (about 1 lb) to 3.4 kg (7.5 lb) behemoths. The product is even available for online purchase.
Here at Flavors of Brazil we find it comforting to learn about the return of carne de lata - it's honest food, made as it always has been (because of necessity originally, because of taste these days). It's just one more example of that truism - "Everything old is new again."