Freezing is amidst the oldest and most generally used approaches of food preservation which allows the retention of taste, texture, and nutritional value in foods better than in every other method. The freezing process is an amalgamation of the favorable effects of low temperatures at which microorganisms cannot grow, chemical reactions are reduced, and cellular metabolic reactions are delayed.
People have been freezing foods as a means of preservation from as early as 1000 B.C, when they stored food in ice cellars. Freezing food using mechanical refrigeration began 124 years ago, becoming commercial on a small scale in 1890. Prior to 1920, meat and some fruit, primarily strawberries were the main frozen foods.
Products other than fruits were frozen in one of two ways. In ‘ordinary freezing’, the food was frozen in large rooms with ceiling-hung ammonia pipe coils that used gravity air circulation. In ‘sharp freezing’, food was frozen in small freezer rooms specifically designed for freezing food that had wall- and ceiling-hung pipe coils. Most of these rooms were -15oC (5oF) or above, although in some situations the temperatures would go as low as -18oC (0OF). In Europe, -10oC(14oF) was deemed satisfactory as a distribution temperature and suitable for storage for frozen meat.
Strawberries were frozen using ‘cold packing’ where the berries were put in paraffin-lined barrels, placed in cold storage rooms at -10oC and rolled in periodically to mix the berries with sugar. Scientific work between 1907 and 1916 demonstrated that quick-freezing food would provide a major quality advance and eliminate the disadvantages of slow freezing, namely the loss of taste and juice leakage when the product was thawed. Developing the methodology and equipment to achieve quick-freezing economically and on a repeatable basis was the challenge. By the early 1920s scientists were trying several methods of quick freezing. They used calcium chloride brine, usually at -42oC.
In 1924, Clarence Birdseye invented the quick-freeze method which facilitates for the production of the frozen foods we know of today. While he was working in Labrador, an eastern province in Canada, Birdseye often froze his catch a day after as he was taught by Inuit. He noticed that the fish was not mushy and tasted really good after being thawed. One day he froze the fish immediately after removing it from the water. He was ecstatic to discover that the fish was just as delicious when it was thawed several months later. From this, he theorized that food must be frozen quickly in order for it to retain its texture and taste.
Birdseye was correct. Before quick-freezing, foods were frozen at a fairly slow rate which caused large ice crystals to develop. This formation ruptured the cell membranes of the food hence when the food was defrosted, the ice crystals melted and the water would leak out causing the taste and the texture of the food to go with it. It was not until 1927 that Birdseye applied to patent a multi plate freezing machine. According to the Handbook of Frozen Foods, he would place food in between two metallic plates that were chilled at low temperatures against a low convection tunnel in order to flash-freeze the product.
Two methods of quick-freezing food were therefore developed. In the first technique, the food was held between two metal belts that were chilled at -40oF and -45oF using a calcium chloride solution. In the second technique which is the more popular one, food was held between two hollow metal plates that were chilled by the evaporation of ammonia to -25oF. However, before freezing the food, packaging was required beforehand.
In 1930, the first line of frozen food went into the public through Birds Eye Frosted Food Company. Birdseye’s company quickly ran out of money but he then relocated to Gloucester, Massachusetts, a center of the fishing industry at the time and established a new company known as General Seafoods. He developed equipment and packaging and invented his freezing process. The Birdseye Frosted Food Company is currently identified as Pinnacle Foods Inc.
Frozen food still took time to gain its popularity among the people. A Large number of Americans tasted their first frozen food in the 1940s during World War II, when a shortage of tin caused a scarcity of canned food. Along with the growth of supermarkets and advancements in refrigeration and freezing, frozen foods had become a staple in the American diet by the 1950s. Today, the frozen food industry is valued at quarter trillion USD globally.
For those of you who prefer visual content you can look at this video of frozen food history.