Check food fresh at a glance
At present, the main basis for determining whether packaged food has deteriorated is the shelf life marked on the outer packaging. People usually think that food is safe and fresh as long as it is within the shelf life, but this is often not the case.
First, the shelf life of food is related to environmental factors. Different temperatures, humidity, air circulation, etc. have a great impact on the shelf life of food. Secondly, the quality of packaging materials and the quality of packaging technology will also affect the shelf life. Third, the shelf life is not the food preservation period. Foods within the shelf life can only guarantee that the food has not deteriorated, but cannot guarantee the original freshness and flavor of the food.
In some countries and regions, a variety of smart packaging technologies are being used in food packaging. They can not only indicate whether food is spoiled, but also extend the shelf life of food, thereby effectively ensuring the safety and original flavor of food.
Some fresh-keeping foods need to be stored at a low temperature, otherwise the bacteria inside will multiply, causing the food to deteriorate. A new type of label that can indicate time and temperature is being used. It can show how long food has been stored at a certain temperature. This kind of label is like a shooting target. There are many transparent rings in the ring. The center ring contains a chemical substance. This chemical substance will undergo a polymerization reaction with time and temperature, and it will change from transparent to black. If the packaged food is kept at a low temperature, the polymerization reaction of the chemical substance will be very slow. Once the temperature increases, the polymerization reaction will accelerate and the chemical substance will change from transparent to black. Because the bacteria in food will increase with the increase of temperature and time, the degree of blackening of chemical substances will become more and more serious. When the inner circle turns black, it means that the food is no longer fresh. Consumers can judge whether the food is still edible through this change in label color.
