Discussion on the hottest active packaging materia

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Discussion on active packaging materials and Technology (Part 2)

2.5 carbon dioxide generators and removers

storage and packaging of fresh food often produce carbon dioxide, which can inhibit the growth of microorganisms. To control the content of carbon dioxide, a carbon dioxide generation system or a removal system can be installed in the packaging film. High carbon dioxide concentration (10% - 80%) is particularly important for the storage of meat and poultry. However, the transmittance of carbon dioxide to plastic film is 3-5 times that of oxygen, so carbon dioxide is needed. However, if the concentration of carbon dioxide is too high, the fruit will enter the glycolysis stage, resulting in a rapid decline in the quality of the fruit. At this time, it needs = carbon oxide remover

small bags containing iron powder and calcium hydroxide can be used for the packaging of newly processed coffee. It can control the content of oxygen and carbon dioxide in the package at the same time, and prolong the shelf life of coffee by 3 times

2.6 water absorbent

desiccant has been widely used in removing moisture in packages, reducing water activity on food surfaces, and prolonging the service life of germanium racks, mainly in the form of small bags, in which the matrix is lime, clay, calcium oxide, etc. A water absorbing film has been developed to reduce the water activity on the surface of frozen food and extend the shelf life. In this packaging film system, propylene glycol is sandwiched between two layers of polyvinyl alcohol (PVA) film, and then sealed around to form a wrapping film. Polyvinyl alcohol membrane has high water or water vapor permeability, but it has barrier to propylene glycol. For specific use, it is wrapped with a layer of cellophane. When it comes into contact with fresh meat or fish, due to the different water activities of food and propylene glycol (0.99 and 0.0 respectively), the water will quickly separate from the food surface. This kind of active packaging can prolong the shelf life of fish by 3-4 days. The water absorbing film can be reused for 10 times after drying

2.7 temperature monitoring system

temperature control system can reduce the quality deterioration of frozen food caused by improper temperature control during storage. When the temperature of frozen food increases by 10 ℃ during storage and transportation, its quality deterioration speed increases by 2-8 times. The shelf life of food refers to the quality retention time of food under certain conditions. In fact, the conditions of food will change during storage and transportation. Therefore, it is very important to equip the package with a device that can reflect the temperature change of food during storage and transportation. It can indicate to consumers whether the temperature control of food during storage and transportation is appropriate and how much shelf life there is. When the same temperature integral indicator (1tri) label is installed on the food package, it can be designed as a visible label that can be sent or not, and it can also be designed as a label that can be displayed by a scanner at the supermarket exit, so as to avoid selling expired food

2.8 consumer convenience technology

microwave cooking brings great convenience to consumers. However, microwave cooking is often uneven. If the cooking time is too short, it is easy to make fresh food still carry bacteria after cooking. The heating time marked on microwave food often refers to the time when the food is heated at the slowest speed under 800W power. If the power is not 800W, it is also heated according to the marked time, and the food is often overheated or underheated. The microwave cooking indicator, which has been successfully developed, can be installed outside the microwave food package when the food is cooked. Its temperature indicator will change color, and consumers can see it at a glance. Microwave susceptor is the most typical active packaging auxiliary material. It is made of juku film vacuum coated aluminum film. Its optical density is 0.18-0.28. At the same time, it can absorb microwave in the microwave oven and convert it into heat energy to raise its own temperature, so as to heat the food in the package. It is mainly used for microwave popcorn, and can also be used as crispy pizza, tart and French bread

3 application examples of active packaging

3.1 active packaging applied to take away pizza

pizza is a famous Italian take away food, which is not only convenient to carry, delicious, high nutritional value, but also affordable. It is generally sold at special sales locations, usually in the form of takeout. Therefore, packaging must ensure to prevent the rapid reduction of temperature and evaporation of water vapor. This purpose can be achieved by using polymer active packaging that absorbs water, so that pizza can guarantee its

3 to serve you sincerely before consumers use. 2 thermal protection of food by active packaging

double-layer packaging containers made of molecular alloy materials are recommended to be used as thermal protection packaging of liquid food products. This work leads commercial active packaging to store things effectively in an external environment of about 25~c, and these active packaging can cool beverage J

3.3 application of active packaging in kimchi packaging

the packaging system with small holes in kimchi is used to mechanically improve the top air and improve the quality of products. In the active packaging system, people investigated the influence of the existence of small holes on the top air. Therefore, a prototype of this active packaging system was constructed to investigate its influence on improving product quality. These combined holes eliminate the pressure built up in the package by allowing restricted airflow into the atmosphere. The continuous Co: gas produced in lactic acid pickles displaces the top 0: and N. This improved air improves the growth of lactic acid bacteria. People use a well-designed combined microporous membrane to effectively extend the shelf life of kimchi l9j

3.4 reduce the bitterness in grapefruit juice through active packaging

grapefruit enzyme and citrin are the main components of bitter substances in citrus juice. Our purpose is to determine whether the perceptible bitterness in grapefruit juice can be reduced through the interaction with active packaging film during storage. When grapefruit juice with 10 Brix is stored at 7 ℃, the interaction between cellulose acetate film and immobilized citrus enzymes produced by fungi can make the bitterness of grapefruit juice below the perceptible level. The packaging film was hydrolyzed and adsorbed 6-halo-1 pomelo enzyme and limonin, respectively. The contents of naringinase and limonin in grapefruit juice through cellulose acetate film contain curing enzyme 600 ~ 400mg/L and 8.0-6.7 mg/L respectively. He and the driver contacted the cooperative enterprise mg/L in Linyi and found the decrease of bittern under the perceived level. As the ratio of film area (CM)/juice volume (ML) increased from 1.1 to

3.6, the level of pomelo enzyme will be doubled by 6. From this point of view, the direct interaction between bitter substances and active packaging can reduce the bitterness

4 the latest research on active packaging abroad

active packaging abroad is mainly used in the food industry. In recent years, according to the principle of the role of active packaging, we have focused on the study of active packaging materials, which can have a certain active function by improving the original ordinary packaging materials, The improved packaging material plays its active function in the process of use to extend the shelf life of food. For example, the research on materials with controlled release function can be used to control the release of CO produced by fresh fruits and vegetables to extend the shelf life of fruits and vegetables; Add vitamin E to polyethylene film and polypropylene film to resist oxidation, so as to prolong the shelf life of food; There are also active packaging materials to control the growth and reproduction of microorganisms; We have seen that the vehicles that are shipping products use packaging materials with water absorption function to pack takeaway pizza, which can keep its delicious taste for a long time. The packaging materials with thermal protection function studied can keep the temperature of the inner food unchanged with the change of the external temperature for a long time, The friction force of the force measuring piston in the oil cylinder increases or gets stuck, so that the drinks drunk in summer can maintain a low temperature for a long time; The oxygen concentration in the package during the early fermentation of yoghurt can be effectively reduced by adding deoxidizer to the high-density polystyrene film, thus extending the shelf life of yoghurt. The shelf life of kimchi can be extended by using microporous membrane with controllable gas transmission rate in the packaging of kimchi; There are also research on packaging materials with temperature control function. The research of these materials is the main research direction abroad in recent years

5 conclusion

with the development of food science and technology and the requirements of consumers for high-quality food, active packaging and its remarkable efficiency in prolonging the shelf life of food have become one of the main directions of food packaging development at present. Some active packaging technologies have been used in Japan, North America, Europe and Australia for many years, especially in Japan. Due to the progressiveness of the technology of active packaging itself and the high added value generated after packaging food, many food research institutions and food enterprises in the world are sparing financial and material resources to research and develop more active packaging technology, and make it more commercialized faster for the benefit of mankind. As Dr. Theodore labuza of the University of Minnesota declared: in the near future, the change of active packaging will not be a general progress, but a revolutionary change. As a kind of intelligent packaging, reactive packaging is regarded as a revolutionary change in the packaging industry and the hope of the new century. It has a very broad application prospect

yuan Xiaolin [1] Li Yan [2][1] Changzhou Light Industry Vocational and technical college, Changzhou 213164 [2] Jiangnan University, Wuxi 214122

source: Packaging Engineering

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