Food Preservation and Effect of Temperature

After 14 years of trial and error, he developed a process he called Appertizing. Fruits, vegetables, fish, or meat was sealed in stoppered bottles and the filled bottles were immersed in boiling water; the heat sterilized the bottles and food alike. Appert knew nothing of enzymes or bacteria, nor did anyone else in his day. He did observe that when food was heated in the sealed bottles, the food remained good as long as the seal was not broken. The food remained edible until the bottles were opened. The process won him his prize in 1809; he started a canning factory and went on to found a family-canning dynasty that continued into the 20th century. Several problems associated with Appert’s process led to the refinement of his process. Appert's bottles were expensive, heavy and fragile; their airtight seals were uncertain. By 1810 others had produced more reliable containers made of tin. In 1847, the invention of mass-produced, stamped-out cans made large scale inexpensive canning possible. By the beginning of the American Civil War, canning was a major method of food preservation, widely used to feed the armies of both the Union and the Confederacy. Louis Pasteur, the most prominent person to influence food preservation, showed that certain microorganisms are responsible for fermentation and decay of organic matter. His studies on food preservation led to the process and term "pasteurization." Improvements in the 19th and 20th centuries have made canning cheaper and more popular. The U.S. alone now produces billions of cans and jars of food each year. Canning, when done correctly, is so safe that a four-pound veal roast, canned in 1824 and opened in 1938, was fed to 12 rats for ten days without ill effect. The process was perfected well enough by then to result in a safe product.

Why Food Is Preserved

Unless food is preserved, it spoils soon after harvest or slaughter. This spoilage is caused by: