The preservation of food in cans is now mainly carried out on a commercial scale. It is not recommended for home use due to health and hygiene concerns, and also because specialized equipment is required. Instead, home canning is typically done using jars.
This passage is describing a process for preserving food by killing or stopping the growth of microorganisms like molds, yeasts, enzymes, and bacteria that are typically found in food. This is done by subjecting the food to sterilization and then preventing any new microorganisms from getting in. Once the food is sterilized and sealed in airtight containers, like cans, it can be stored for a very long time without spoiling. This allows people to enjoy fresh-tasting produce even during the winter months.