Food Processing Technology History: From Canning to Refrigeration

Introduction: Food Before Modern Processing

Food processing, and the healthy, edible food it produces, is taken for granted in today's society. However, in the nineteenth century, fresh food was not the norm, and technologies were developed to preserve food so that more Americans could enjoy fresh, wholesome meals year round. It was one of the most important areas of technological development in history, and it changed the way people ate, drank, and enjoyed their meals.

Before the advent of food processing, fresh food simply spoiled. In medieval times, people attempted to cover up the smell and taste of tainted food by using fragrant herbs in cooking and serving. Even earlier, people used salt to preserve meats, and employed smoking and drying, especially for meat. However, none of these processes was entirely satisfactory, and there was still no way to preserve many fruits, vegetables, and baked goods. Therefore, Americans — and others around the world — relied on fresh food when it was available, usually during the warmer summer months. In winter, early spring, and late fall, most available food consisted of meat, freshly baked goods, and root vegetables that could survive the colder months.

The First Real Food Processing Technology: Canning

The development of food processing technology changed all of that, allowing the world to eat a wider variety of foods all year round. It was a breakthrough in technology, but it was also a breakthrough in the eating habits of Americans, because they could enjoy more food and more freshly processed food, creating variety in their diet while also expanding their healthy food options. In addition, even people in rural areas, far from the produce and food centers of the country, could eat the same foods as those in cities, despite their isolation.

The first canned food appeared in France in the early 1800s. Nicholas Appert, a chef and brewer, discovered that filling glass jars to the top with food and boiling them would preserve the food inside — it would not spoil until after the jar was opened. It took him fifteen years of experimentation before he got it right, but in the end, he made his findings openly available to the world. He never took out a patent on his process, because he hoped home cooks could use it for their own benefit.^[i]

In 1817, an Englishman named William Underwood brought the technology to America. He settled in New York and began a small business preserving pickles and fruits in glass jars. Food processing was still in its infancy at this point, and people like Underwood did not know precisely how long to boil the jars for the best results. One historian notes, "Processing foods had always been a matter of conjecture when glass containers were used."^[ii] By 1825, the term "canning" was applied to the process when Thomas Kensett patented his method of packing oysters and fruits in tin cans. Kensett actually patented the container itself, and after his innovation, canning grew tremendously in the United States.

Canning spread across the country, but it took until 1851 for the sterilization process to be perfected. An American named Winslow discovered how to sterilize effectively at high temperatures, making the process much more scientific and no longer dependent on chance and speculation.^[iii] By 1860, there were canning factories in California and across the nation, and canned food would play an important role in feeding soldiers during the Civil War.^[iv]

As important as the technology of canning was, it still needed refinement, and the problem of containers remained. Although Kensett had patented the canning process, it was not until the 1850s that machines were created to automatically stamp out lids and bottoms, which considerably sped up production. Lids were created with large holes through which food could be poured, and then a cover was soldered on to seal the contents. By 1876, the technology had improved even further. Historian Oliver describes the progression:

"In 1876 the Howe floater eliminated the tinner's soldering iron, since a machine rolled the cans at an angle in a bath of solder. The Tillery copper was even more efficient. It spread solder around the edge of the cap in one operation. In 1887 the Cox capper transformed the process into mass production by operating on six cans at once, completing a tray of twenty-four cans automatically."^[v]

As a result, can-making was transformed, and for the first time, canners did not have to make their own cans — they could buy them from other vendors and concentrate on the food side of the business. By 1900, the entire process was automated. In 1880, only three workers could turn out roughly 1,500 cans in a day, but by 1900, machines were producing 50 cans per minute.^[vi] Just before 1900, cans were redesigned so they no longer required solder; instead, lids were held on by crimping part of the can body over the lid to seal it. These were called "sanitary cans," and became the industry standard.^[vii]

Food Processing Develops: Pasteurization and New Methods

The right cans were just one part of the equation. As automation created more containers, more food was needed to fill them, and a variety of food processing equipment was invented in the mid-nineteenth century to keep up with demand. Several machines — from corn knives to scrape corn off the cob to pea shellers — were developed during the mid- to late-1800s to meet the growing need for canned food and greater variety. As the public became accustomed to canned food, demand rose, and so did the need for further technological innovation. By 1883, the first assembly lines in canning had been established, and automatic canning had begun in Indiana. The process was highly detailed; as historian Oliver notes, "the cans were filled and passed on a belt through a temperature of 250 degrees, then to a water cooler, and then to the warehouse without any stoppage in the process. During the operation, cans were not touched by hand."^[viii] Automation was one of the most important developments in canning, because it made more food available to the public, and because lower production costs were passed along as savings to consumers.

Canning is only one element of food processing, and broader progress could not have occurred without French scientist Louis Pasteur, who discovered pasteurization — another form of food preservation. Pasteur found that food did not spoil because of air, as most scientists and food packagers believed at the time. They thought that removing air from packages (cans and bottles) would prevent spoilage. Pasteur demonstrated that the real culprits were yeasts and bacteria that multiplied on food the longer it remained unprocessed. This discovery opened the way for many more food processing technologies, from pressure canning to the hot and cold pack methods.

The pressure method cooked food in a vessel using steam rather than water. In 1874, Andrew K. Shriver pioneered a closed steam-kettle cooker that cooked at high pressure and reduced cooking time considerably.^[ix] The cold pack method placed refrigerated food into jars and cans for packing, but this created longer cooking times because the food took longer to reach boiling temperature. Later, food was heated before being placed in packaging, reducing processing time. All of these innovations represented progress, but none was perfect. Canners still struggled with bursting cans — until a young scientist and professor named Henry L. Russell solved the problem of fermentation. Russell discovered that food inside sealed cans could still ferment, causing burst containers and spoiled contents. He found that if food was heated to 242 degrees Fahrenheit and cooked for an additional fifteen minutes, fermentation would not occur. He published a paper on his findings in 1895, and the canning industry went on to become one of the largest food processing industries in America, with numerous further advances throughout the twentieth century.