At 7:30 on the 17th, carrying the Shenzhou No. 11 manned spacecraft Long March II F-11 carrier rocket launched at the Jiuquan Satellite Launch Center, Jing Haipeng and Chen Dong to open the Chinese astronauts to date the longest space Resident. According to Cao Ping, deputy director of the Spaceflight Center for Spaceflight Nutrition and Food Research, the astronauts have more than 100 kinds of food, including staple food, non-staple food, ready-to-eat, drinks, condiments and functional foods, for the 33-day flight. Products. Preservation period is generally more than a year, but without preservatives, can be delicious at the same time for the astronauts to provide adequate energy and nutrition. So, preservatives do not contain the same as a year, so we ordinary people canned food shelf life is also very long, it contains preservatives?
Canned without adding preservatives
China Agricultural University, Dr. Fan Zhihong, food science, said aerospace food in addition to ensuring the convenience of eating in space conditions, but also very focused on avoiding pathogenic microorganisms, many food to go through high-temperature sterilization or radiation sterilization treatment, but also pay attention to no waste and Slag. Spacefood experts have repeatedly revealed that, in addition to the natural state of the original low moisture content of food and food, astronauts food also includes freeze-dried food, canned food. Many foods have a shelf life of more than one year. From astronauts food, people can clarify some of the rumors heard daily: a long shelf life, does not mean that food must be added preservatives.
In fact, the principle of making cans is very simple: the raw materials and containers were fully heated sterilization, the hot seal; reheat sterilization, cooling, the container inside the top of the air volume will shrink, resulting in negative pressure, so that the original seal Of the bottle will not open, and outside the bacteria can not go out. After these processes, food naturally does not corrupt, so no need to add preservatives.
Processing does not mean no nutrition
Produce a reasonable canned food is not nutritious waste, after irradiation of food will not affect the health of consumers.
General meat and seafood canned paste using pasteurization, so the processing temperature of 120 ℃ or so. And home processing program is also very simple to buy, just heating can be. Therefore, to a certain extent, the loss of canned nutrition than home cooking (cooking is easy to more than 200 ℃) is also less. The vegetables, fruits, canned food processing temperature will not exceed 100 ℃, nutrition is relatively well preserved.
In addition, the raw materials used in canned food are fresh. Canned, in order to pursue a lower cost and better taste, will be in the most suitable season to choose the freshest ingredients. And in order to save costs, regular canned manufacturers have their own raw material base, and the production line built in the base from the nearest place. In this way, the equivalent from their own backyard is now mining is done, greatly shortened from the picking, transport and then to the process of processing, generally not more than 6 hours. And high-temperature heat treatment will stop or slow down the chemical reaction of loss of nutrition to maintain food freshness and nutrition.