When people talk about processed food, they're generally referring to the various methods used to preserve foods for packaging and selling. The industry built up around those foods is known as the processed food industry. Companies package foods in a wide variety of different ways, including freezing, pickling, canning and other methods. Some people feel that additives used in the processed food industry might be unhealthy for human consumption, and there is also a concern that food processing may destroy too many important nutrients.
One of the main methods used in the processed food industry is freezing. Cold temperatures are generally a very effective way to store foods for a long period of time. In some cases, freezing can also destroy some of the flavor in foods, and for this reason, companies have to freeze foods in very particular ways. For example, sometimes they may freeze each ingredient separately and then add them to the container. This technique means that the foods actually mix together for the first time when they are being reheated, and this generally makes them taste fresher.
Another common method used by the processed food industry is canning. With this technique, foods are sterilized and then sealed inside the airtight can, usually with several preservatives. This generally protects the foods from bacterial assault, which is the main key to preserving foods. Canned foods are normally inexpensive and easy to cook, so they are fairly popular. They also tend to contain high quantities of salt, which can be a bad thing health-wise, according to some experts.
There are also some older methods of processed food preparation that have remained popular. For example, drying foods is still common and so is pickling. The drying of goods causes it to lose all moisture, which generally protects the food from bacteria. Pickling involves allowing foods to soak in vinegar until they are completely saturated with it. Another method that still exists, but is much less common, is smoke curing, which imparts the flavor of the burning wood used in the process.
There has been a struggle between nutrition experts and the processed food industry over the healthiness of processed meals. The industry argues that processing has allowed people to make better use of their food by rationing it for longer periods of time. Many health experts, however, complain that the food loses vital vitamins and is often full of chemicals that may be harmful.