New packaging technology that can identify the freshness of food

It is generally believed that a packaged food should be safe and fresh as long as it is within its shelf life, but it is not always the case. In order to ensure food safety and prevent consumers from mistakenly eating spoiled foods, scientists have developed new packaging technologies that can indicate whether foods are deteriorating and can prolong the shelf life of foods. These technologies are collectively referred to as "active packaging technologies" or "smart packaging technologies." .

Food packaging researchers have discovered that some materials can absorb the oxygen in the bag; some materials can interact with the gas produced when food spoils, changing color; some materials will change color when the temperature changes. If such materials are used to package foods, it will help prevent food from oxidizing and deteriorating, or provide consumers with more information on the safety of foods.

In order to delay the deterioration of food due to oxidation, the current practice is to put an iron powder packet inside the packaging bag and use the oxidation process of iron to consume the oxygen in the packaging bag. However, it is often uncomfortable to see small packets printed with the word “Don’t Eat” in food packaging bags. A new type of packaging that adds a layer of “oxygen” material to the wrapper avoids the use of iron powder packets.

For another example, some preserved foods need to be kept at a low temperature, otherwise the bacteria inside will multiply and cause food spoilage. A new type of label, which can indicate time and temperature, is attached to the package and shows how long the food has been stored at a certain temperature. This kind of label is like a target for shooting, there are many rings of transparent rings, what kind of chemicals are contained in the center ring, this kind of chemical will produce polymerization reaction with time and temperature difference, and change from transparent to black. If the packaged food is kept at a low temperature, the polymerization of the chemical will be very slow. Once the temperature increases, the polymerization will accelerate and the chemical will change from transparent to black. As the bacteria in foods increase with temperature and time, the degree of darkening of chemical substances will become more and more serious. When the inner ring turns black, it means that the food is no longer fresh. Consumers can use this change in the color of the label to determine if the food has been stored at high temperatures for a long time. The use of such a label facilitates targeted selection of packaged foods by consumers and avoids disputes with merchants due to food spoilage requirements.

Another food safety indicator packaging technique that researchers studied is a plastic wafer that is doped with dyes. It interacts with the gas released from the food in the bag and shows whether the meat and vegetables are deteriorating. The consumer can know if the food is deteriorating according to the color of the plastic sheet.

This advanced packaging technology has been put into use in the United States, France and other places. Many companies realize that while the use of new technologies requires more investment, their potential commercial benefits are even greater. At present, a U.S. company is developing fresh food packaging for frozen foods. This package can monitor the release of gases from meat, fish, and vegetables that have deteriorated due to improper preservation. Another company is developing a packaging film that can change permeability with changes in temperature to meet the different needs of oxygen and carbon dioxide for different fruits and vegetables. In New Zealand, researchers are developing a fruit package that can indicate when ripe fruits like peaches are ripe for squeezing. (Liu Gonghua)

Reprinted from: Chinese Packaging