Characteristics and application of the most popula

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The characteristics and application of several active materials for food packaging

Europe has been arguing about "active packaging" for more than 10 years. Japan has been debating this topic for more than 25 years

however, despite a variety of research activities on active packaging, it is still impossible to find traces of active packaging on supermarket shelves. Except for some applications, common products in the European market are trays for Italian dumplings and PET beer bottle caps

the concept of "active packaging" comes from the opposite of the commonly used "inert" packaging materials. In particular, it refers to the packaging materials with "shielding" function approved by European regulations for food packaging. In other words, this kind of packaging product can maintain the characteristics of the packaging contents, so that it will not be affected by environmental factors. It also contains some functional packaging materials that can break through the relevant European laws and regulations and improve the characteristics of the packaging contents. The legal rules implemented in the United States and Japan are not as strict as those in Europe

the European Commission recently proposed the 2002/72/CE decree, allowing some antibacterial agents to be used in plastic food packaging. In the food packaging industry, the definition of active packaging is mainly based on the system proposed by the European special research center that can improve the conditions of packaging (by releasing substances, eliminating or inhibiting), which can prolong the service life of packaging; Improve health safety; Improve the odor and taste characteristics while maintaining the same quality

dehumidifier and anti-corrosion agent

small bags containing silica gel (or other dehumidification substances) in the packaging products of electronic and communication devices are generally considered as an early form of active packaging. As these are not plastic packaging materials, they will not be discussed here. Another example of active packaging, whether film or paper, belongs to anti-corrosion packaging materials. Sometimes it is used as the protective outer layer of electronic and mechanical components, and even as the anti-collision protective sleeve of the whole mechanical equipment. Among them, it plays a role through special volatile substances, known as VCI (volatile CORROSIONINHIBITORS). VCI is usually incorporated into the packaging materials, so as to obtain anticorrosive paper or plastic film that can release VCI. The VCI slowly seeps from the surface of the packaging layer and fills the internal space of the packaging layer, so as to protect the metal parts. Different VCI formulations can be selected according to climatic conditions, holding time and the type of metal to be protected. A special film has been developed in the United States to protect silver or other precious metal parts. It is said that it contains an undisclosed substance, which can inhibit the corrosion of gas to metal and avoid blackening on the metal surface

however, the VCI film has different action principles. It passivates the metal surface according to the electro-chemical action, which is better than only absorbing oxygen or other gases in the packaging layer

oxygen inhibitor

although the technology of using plastics with high oxygen barrier and packaging has been very mature, which can minimize the oxygen content (such as vacuum or modified gas packaging), the requirements for reducing the oxygen content in the packaging are still very strong. In fact, oxygen is absorbed by food and the concentration in the package is diluted. In addition, high barrier plastic products are very expensive and often difficult to process. When the medium barrier composite plastic system is used in packaging, its effect of inhibiting oxygen concentration in a variety of application fields is much better than the glass and metal packaging used at present

another popular development project is beer bottle cap coated with oxygen inhibitor. With this kind of oxygen inhibitor, PET bottles can be used instead of glass bottles to fill beer, and the original flavor and taste of beer will remain unchanged for about 9 months after bottling. In fact, natural nonmetallic compounds or simple substances, which are generally crystalline, have started to use "oxygen suppression" packaging many years ago, including the packaging system to reduce the changes in chemical and biological properties caused by gas in the packaging, and are constantly improving and developing. The research direction of "active packaging" is a packaging system that has specificity and can be transformed into a huge commercial application market. At present, the popular trend is to separate active agents from real packaging materials

it is better for the packaging system containing oxygen inhibitor to work through an activation stage. The composite film with this oxygen inhibitor can be widely used in various packaging occasions, and its activation needs to be stimulated by certain factors. The following describes three kinds of oxygen suppressants for special plastics sold on the market

(1) shelfplus O2 series oxygen inhibitors produced by Ciba/Ciba can be activated by the humidity of food or by the combination of humidity and temperature in the pasteurization process

(2) the enzymatic series of oxygen inhibitors produced by bioka company of Finland have strong activation through humidity

(3) OSP series oxygen suppressors produced by CPChem company (formerly Chev Ron Phillips) are activated by ultraviolet radiation

all the above oxygen inhibitors shall be made into composite films with the following typical structures, including the inner layer to the outer layer, with a layer of medium or high barrier polymer (such as PA), oxygen inhibitor, and a layer of low barrier polymer (such as PE or EVA). Among them, oxygen suppressants can isolate oxygen in the air and usually cannot directly contact food

wipak walsrode company used shell to provide the possibility of reduction. US type additives were used to produce combitherm 23115/408 film. The appearance was silver gray. It is most suitable to be used in the environment with saturated humidity in the package. It must be placed in a dry environment (relative humidity lower than 40%) when winding and collecting

bioka's products are currently under development. Its commercialized packaging is in powder bags and is being recommended to professional manufacturers for the production of laminated products

cryovac uses the OSP oxygen inhibitor of CPChem to produce OS 1000 thin films. This kind of film has excellent performance. Nestl, a subsidiary of Nestl, Switzerland, can compare the protection methods of the hydraulic jaws of the above tensile testing machine: e buitoni company selects it for packaging various flour foods and putting it on the American market. The wall of this packaging box is a thermoformed EVOH barrier structure layer, and the upper part of the box is sealed with OS 1000 film with an oxygen inhibitor layer, which can reduce the oxygen content in the food packaging box to less than 0.1% and prolong the shelf life of the product by 50%. Therefore, it won the "Gold Award for technicalinnovation" issued by the American flexible packaging Association

ethylene trapper

ethylene trapper is a very interesting point of view for the plastic industry. Ethylene is a carbon hydrogen phase monomer extracted from petroleum to realize industrial production. It is mainly used in the production of polyethylene plastics. Surprisingly, ethylene can also be produced in the metabolism of plants. It acts as a catalyst to ripen and soften fruits. Therefore, especially when ethylene accumulates in the packaging materials, the fresh fruits and vegetables sold in sealed packaging in stores will soon rot and deteriorate

the main countermeasure is to use a small bag of ethylene capturing agent placed in the package to remove oxygen first. Potassium permanganate is very effective in this step, but it is harmful to human body, so it can not be directly used in food packaging

other minerals that are very effective in removing ethylene monomers are zeolite, cristobalite and some kinds of carbonates. These ores may also play a key role in the production and application of thin films. The Austrian EIA warenhandels company uses zeolite to produce the profresh brand additive, which can be directly used in the production of ordinary polyethylene film. It can also obtain good fresh-keeping effect without using multi-layer composite film, and has obtained the food certification issued by the US FDA and German officials. However, up to now, all the above-mentioned additives will have a negative impact on the beauty of packaging products, because the film made with them is easy to distort and translucent

other substances that need to be eliminated in the packaging are the malodorous smell emitted from the oil after being stored for a period of time. They are called aldehydes in chemistry, and the most representative is hexanal. Removing aldehydes does not prevent food from further oxidation. In any case, this is a practical technology to prolong the service life of products, because the taste of such chemicals is easy to be smelled before the nutritious components of food are seriously rotten

the United States approved the application for protection of the patent right of acetaldehyde elimination film in 1994. At present, DuPont/DuPont is carrying out the commercial development of acetaldehyde elimination film. The additive used is ethylene capture agent, but the chemical mechanism is still unclear. Several Italian university researchers are conducting special research on this. Today, it is generally recognized that how to eliminate other unpleasant odors in film packaging (especially the amine gas emitted when storing fresh fish) and carbon dioxide gas generated during the breathing of fresh vegetables, but so far there has been no report on commercial development and application

antimicrobial agents

food deterioration is mainly caused by microorganisms. Adding fungicides to food can play a good role. It has been proved that the addition of antibacterial agents to plastics, especially for PVC products used in humid environments, has achieved good results. This kind of plastic is required to have the function of inhibiting microorganisms. Therefore, a large number of biodegradable plasticizers are included in the production formula to make the plastic surface easy to flow and form and kill bacteria

the original intention of developing and using antibacterial agents for sterilization is to kill the bacteria with positive Gram staining. At present, nisine is a widely used food fungicide, and some organic acids (such as sorbic acid, propionic acid, benzoic acid derivatives) have also been proved to be used as food preservatives

the above-mentioned active packaging is used more and more, and the effect of extending the shelf life of food is also expanding. However, the requirements of food hygiene and safety standards cannot be ignored in application

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