Food "smart" packaging

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 packaging technologies that extend the shelf life of foods. These technologies are collectively referred to as "active packaging technologies" or "smart packaging technologies." .

■ “Smart” foods come from “positive” packaging. To delay the deterioration of food due to oxidation, it is now common practice to put a small packet of iron powder on the packaging surface and use the iron oxidation process to consume oxygen from the packaging. However, some customers find it difficult to find a small bag with the word “Don't Eat” printed in the food. The new packaging adds a layer of “oxygen” material to the packaging paper, which can make them feel more comfortable. . For another example, some fresh-keeping foods need to be kept at a low temperature, otherwise the bacteria inside will become active and cause food spoilage. A new type of label that can indicate time and temperature is attached to the package. The chemical composition of the label will polymerize when the temperature rises. The color of the label will have a change of brightness and darkness. Customers can know at what temperature the food is stored and stored. How long has the freshness been?

According to the British "New Scientist," this type of technology, known as "positive packaging," has been put into use in the United States, France and other places. Many companies realize that satisfying customers with the freshness of products and their potential business benefits are huge, and the extra cost of developing and using new technologies is nothing more than a “little surprise”. At present, some companies in the United States are developing fresh food packaging for frozen foods. The new packaging can monitor the release of gases from meat, fish, or vegetables that have been improperly rotated and deteriorated due to freezing. Concentrations of oxygen and carbon dioxide required for the preservation of different fruits and vegetables are different. Packaging technology for this characteristic is also under development. A California company is developing a packaging film that can change its permeability with temperature to meet the different oxygen and carbon dioxide needs of different fruits and vegetables. Food technology researchers estimate that the next 20% to 40% of food packaging will use "active packaging" technology.

â–  Indication of whether the food is deteriorating. Food Packaging Researchers have found that some materials can absorb the oxygen in the bags; some materials interact with the gases produced when the food is spoiled and change color; some materials change color when the temperature changes. If such materials are used to package foods, it will help prevent food from oxidative deterioration or provide consumers with more information on the safety of foods.

Since these active material packages have the function of demonstrating food safety, many companies are cooperating in various forms to study such "active packaging." French "non-price" supermarket chains are using a packaging technology called "time temperature indication" on many fresh foods. It's actually a label that shows how long food has been stored at a certain temperature. This kind of label is like a shooting target. There are many rings of transparent rings. The center ring contains a chemical substance. This chemical will polymerize with time and temperature 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 on foods increase with temperature and time, the degree of darkening of chemicals becomes 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.

Another food safety indicator packaging technology that the researchers studied is a kind of plastic wafer that is doped with dyes. It interacts with the gas released from the food in the packaging bag to show if the meat and vegetables are deteriorating. After the plastic piece is put into the food packaging bag, if the food in the packaging bag is rotted, gas will be released and the plastic piece will change color. Consumers can know if the food is deteriorating based on the color of the plastic sheet.

â–  Extend the freshness of fruits and vegetables that need to be kept at a certain concentration of oxygen and carbon dioxide. Such oxygen and carbon dioxide concentrations are difficult to control in sealed bags. Because when the temperature is high, the fruits or vegetables in the package will consume more oxygen and release more carbon dioxide. Therefore, if no adjustment is made, the preservation period of food is bound to be affected.

To solve this problem, a company in Menlo Park, Calif., is working on a packaging film called Intelimer. When the temperature changes, the membrane will change its permeability so that different foods are kept at the optimal oxygen and carbon dioxide concentration ratio.

Another way to slow down the rate of deterioration of foods is to use an oxygen scavenger to remove oxygen and control the air inside the package to avoid oxidative deterioration of the food. At present, a common method is to put a small sachet containing iron powder in the food packaging bag, and consume the oxygen in the packaging bag through the iron powder. However, this method has obvious deficiencies because the “inedible” warning signs on small sachets are likely to cause consumers to resent. For this reason, a sealed gas company in New Jersey, USA, is producing a bag material that can remove oxygen itself. This material has an inner layer of oxidizable polymer that traps and consumes oxygen inside the package like iron powder.