The various plastic materials used by people for food packaging today are inert. They only use physical means to block the outside air from entering the interior of the packaging container, so that the packaged food remains unimpaired. However, they are incapable of holding oxygen or other harmful gases in the food due to flashes or encapsulation inside the package. Therefore, they are called passive packaging.
Some of the world's major additive manufacturers and packaging manufacturers are developing a new type of active packaging material, which is made by adding new oxygen-absorbing agents to traditional plastic films. This new film absorbs oxygen, ethylene, and other gases that are deteriorating from the food in the container. The new film is made of composite materials with other films with good barrier properties, which can greatly extend the shelf life of the packaged food. Food processors and packaging manufacturers are very interested in this kind of packaging material, but it has not been applied on a large scale. The main reason is that the cost is more than 10% higher than that of conventional packaging materials, and the benefits of extended food shelf life are difficult to estimate. . This is Active Packaging.
The so-called positive packaging means that the packaging food and the environment are coordinated with each other to produce the desired effect, and its role is to maintain the quality of the packaged food and hope all improvements. According to expert analysis, the prospects for the replacement of this material are very broad. For example, naringinase is immobilized on a polymer and used as an inner wall coating for grape juice packaging. The enzyme can make flavonones in fruit juices. Hydrolysis, which tends to result in bitterness, therefore, this packaged beverage can maintain a sweet flavor for a long period of time.
The growth of microorganisms on the surface of foods is the main cause of deterioration. Antimicrobial packaging materials are now being developed. This kind of package can slowly release a kind of anti-microbial ingredients, which can greatly improve the food storage period and improve food quality. The packaging containers are generally sterilized prior to packaging and self-sterilizing packaging (self-sterilizing packaging) has now taken place. For example, the nisin that is being studied is produced by Lactococus lactis, and it is coated on low-density polyethylene film with methyl cellulose as a carrier, which has a very good antibacterial effect. Other antibacterial agents such as benzoic acid, sodium benzoate, salicyclic acid, potassium sorbate and propionic acid have been studied, some of which have been applied in edible coatings.
In 1997, a new generation of active packaging materials has been used for packaging containers in the inner layer, outer layer and lid and other parts. The new oxygen-absorbing agent it uses mainly contains metal oxides, supplemented with various oxidation promoters and fillers. All components are harmed to the requirements of food hygiene, and are made into the form of masterbatch. They can be directly added into the resin and extruded or made into composite materials. Australian Southcorp packaging Pymble Co., Ltd. uses organic oxygen absorbers such as ethylene glycol and phenol to copolymerize with packaging resin monomers to produce oxygen-absorbing copolymers.
Amoco has developed various Amosorb Series Oxygen Absorption Masterbatches for PP, PE, PET and Elastomers, both for heating and hot-fill food packaging materials and for frozen food packaging. All kinds of hard bottles, films, cap liners, etc. can be used.
At present, the market capacity of this new active packaging material is only 50 million US dollars per year. According to optimistic estimates of relevant people, by the year 2000, it will reach 1 billion U.S. dollars a year. It will face the competition of low-cost, high-performance traditional inert packaging materials, but the advantages of these two materials can complement each other and develop together.
Food is more and more complex and has many colors, and packaging must adapt. There are now "system integration" packages that use several packaging technologies simultaneously, such as modified atomsphere packages that can be sterilized by microwave ovens. Radiation disinfection, and can extend the storage period. Other new technologies for food processing and disinfection, such as high pressure, ultrasonic and magnetic processing, can be applied in packaging. Research work in this area is currently under way.