Characteristics Requirements For Packaging

Film food packaging

The more important performance index of packaging materials is the air permeability. According to the different air permeability of materials, the application fields of this material in packaging can be determined.  Some packaging materials require oxygen permeability, in order to supply the product with enough oxygen;  Some packaging materials are required to have a barrier to oxygen in the material, such as the packaging of drinks, which can prevent oxygen from entering the packaging to achieve the effect of inhibiting mold growth.  PLA has gas resistance, water resistance, transparency and good printability. 

transparency

PLA has good transparency and gloss, and its excellent performance is comparable to that of cellophane and PET, which is not available in other degradable plastics.  The transparency and glossiness of PLA are 2~3 times that of ordinary PP film and 10 times that of LDPE film.  Its high transparency makes the use of PLA as packaging material beautiful appearance.  Such as for candy packaging, at present, many candy packaging on the market have adopted the PLA packaging film.

The appearance and performance of the packaging film is similar to the traditional candy packaging film, with high transparency, excellent kink retention, printability and strength, but also has excellent barrier, can better retain the candy aroma.  A Japanese company used the brand "RACEA" PLA of Kakir Dao Agglutinator of the US as the packaging material for its new product. The packaging has a very transparent appearance.  Toray Industries has used its proprietary nanoalloy technology to develop PLA functional films and slices.  The film offers the same heat and impact resistance as petroleum-based films, while providing excellent elasticity and transparency.  

PLA film has good transparency

Barrier property

PLA can be made into thin film products with high transparency, good barrier property, excellent processing and forming property and mechanical properties, which can be used for flexible packaging of fruits and vegetables.  It can create a suitable storage environment for fruits and vegetables, maintain the life activities of fruits and vegetables, delay aging, and maintain the color, aroma, taste and appearance of fruits and vegetables.  However, when applied to actual food packaging materials, some modifications are needed to adapt to the characteristics of food itself, so as to achieve better packaging effect.  

In practice, for example, mixed films have been found to be better than pure ones 

The broccoli was packed with pure PLA film and PLA composite film respectively, and stored at (22±3)℃. The changes of physiological and biochemical indexes of the broccoli during storage were tested regularly.  The results show that the PLA composite membrane for broccoli room temperature storage of preservation effect is good, can make the sack form is conducive to regulating the broccoli respiratory metabolism level of humidity successfuiiy environment, better maintain the appearance quality of broccoli, make its original flavors have got very good retention, so as to extend the shelf life of broccoli at room temperature for 23 days.  

Antibacterial activity

PLA can form a weak acidic environment on the surface of the product, which is based on antimicrobial and mildew prevention. If other antimicrobial agents are used, the antimicrobial rate can reach more than 90%, which can be used in the antimicrobial packaging of the product.  Yin Min took Agaricus bisporus and Golden Ear as examples to study the fresh-keeping effect of the new PLA nano-antibacterial composite membrane on edible fungi, so as to extend the shelf life of edible fungi and keep their quality status good.  The results showed that PLA/ Rosemary essential oil (REO)/ AGO composite film could effectively delay the reduction of vitamin C content in auricle auricum.

Compared with LDPE film, PLA film and PLA/REO/TiO2 film, the water permeability of PLA/REO/Ag composite film is obviously higher than that of other films.  It is concluded that it can effectively prevent the formation of condensed water and inhibit the growth of microorganisms.  At the same time, it also has excellent bacteriostatic effect, can effectively inhibit the microbial reproduction during the storage of golden ear, can significantly extend the shelf life to 16 days.