At the beginning, the inventor birdsay only found the freezing technology from a fish. Today, more than 80 years later, the freezing technology has been applied to almost any field of society in the world. Now in people's life, the dependence and demand of frozen food even exceeds that of fresh food.
As early as the 17th century, Francis Bacon, an English writer and philosopher, tried to put snow into a chicken to freeze it and keep it fresh. Unexpectedly, he got cold and soon fell ill. Even before Bacon's unfortunate experiment, it was known that extreme cold prevented eating meat from "going bad.".
China has a long history of eating frozen food. The Zhou Dynasty knew how to store the ice in winter in the basement for the next summer. Qu Yuan's evocation of spirits refers to the frozen sweet wine in the pre Qin period. Huang Xian of the Han Dynasty wrote an external history of tianluge, which contains: "the king of Han asked for frozen food in the heat of summer. The son of a generation used his private wealth as an ice room to collect soup and food. If it's frozen, it's up to the king. " Put food into the ice room to make frozen dishes. It's a bit like our family use today
The way the refrigerator works.
These early attempts to freeze food, whether with ice or cold water, failed to grasp the crux of the problem - for freezing, the most important thing is not so much the degree of freezing as the speed of freezing. The faster the food freezes, the less damage it will cause. The first person to realize this was Clarence birdsay, an American inventor. Therefore, he was regarded in history as the man who invented the technology of refrigeration - the greatest invention of food in the 20th century.
In the years after World War I, birdsay conducted a wildlife survey while traveling on the Labrador Peninsula in Canada. He noticed that the weather was so cold that after catching a fish, the fish soon froze. He wondered if this was the key to food preservation. When he got home, he experimented with a refrigerator in his kitchen. He uses two methods, both of which need to wrap the food in advance. The first method is to press the food tightly between two frozen metal plates and use calcium chloride solution to freeze it at about - 40-45 ℃. Another and more popular method is to press the wrapped food tightly between two hollow frozen metal plates and freeze it to about - 25 ℃ under the volatilization of ammonia. With this method, a piece of meat wrapped two inches thick can be frozen to 0 ℃ in 90 minutes, while fruits and vegetables only take 30 minutes.
In 1924, he set up a company to sell frozen fish in the market. Soon frozen food became a big business. After that, the invention of rapid freezing produced 168 patents, which not only covered the field of refrigeration technology, but also included technology in the additional field such as food packaging. For a long time, the famous red, white and blue packaging of birdsay has become a familiar sight in many stores around the world, even conveying a special American flavor. Since then, the name of birdsay has become a family language and changed the American way of life.
It may be that people will not immediately accept fresh food, or doubt whether the food after physical processing is safe and reliable. At the beginning, the impact of frozen food on social life was not obvious. Until the 1950s and 1960s, when the household refrigerator was in good time, frozen food began to be sold in large quantities.
Over the past few decades, food consumption in the United States has shifted from cooking at home to eating fast food in restaurants, from time-consuming food production to
Convenience foods such as frozen dinners and prepackaged foods. Today, almost half of Americans don't eat at home. They eat fast food, prepackaged food, and frozen food. Even at home, they rely on semi-finished ready to eat foods like frozen, prepackaged and canned foods.
However, it was nearly half a century later that the Chinese people really accepted the great invention of birdsay. According to Professor Zhang kunsheng of the Food Engineering Department of Tianjin Business University, frozen food began to appear in the Chinese market around the end of the 1970s. In the past, in China, most people still like to eat fresh food, not many people have freezers (or freezers), frozen food is not popular. In recent years, with the increase of income, the number of owners of freezers (or freezers) is increasing, and the frozen food and sales in the market have increased significantly.
However, at present, there is still a lack of in-depth research on the changes of frozen food quality in China; the standardization of frozen food is not mature enough, and the product quality is unstable. These two aspects are the gap between China's frozen food level and the developed countries such as Europe, America and Japan. *