PLA and PBAT are the mainstream raw materials in the current degradable plastics market. In order to further improve the performance of PLA and PBAT single films, many scholars have carried out research on PLA/PBAT composite films in recent years.
PLA/PBAT composite film has excellent mechanical strength, strong barrier, degradable and other characteristics, can be used as a new type of food packaging materials to replace polyethylene PE and other traditional food packaging materials, at the same time in the PLA/PBAT composite film to add the active factor, can be effective in extending the shelf-life of the food, to reduce the loss of nutritive value of food in the storage period.
At present, the application of PLA/PBAT composite film in food packaging research mainly focuses on gas selective permeability, antimicrobial properties and food storage and preservation and other related aspects.
gas selectivity
As consumers seek a high-quality food experience, food packaging films are being demanded for their barrier properties against oxygen and water vapor.
New Materials in Chemical Engineering Shankar et al. found that PLA/PBAT blended film containing 7% grape seed extract has good UV-blocking properties, and also applied the film to onion packaging, and found that the blended film has high moisture permeability and gas selective transmittance, which can effectively prevent the packaging film from fogging.
Jiang Jiannan from Tianjin University of Science and Technology, China, applied PLA/PBAT film with BHT (2,6-di-tert-butylhydroxytoluene, phenolic antioxidant) to freshly pressed rice, and found that the film had better mechanical properties, lower CO2 and water vapor transmission rates, and inhibited the oxidation of unsaturated fatty acids such as linoleic acid, which not only maintained the quality of freshly pressed rice but also delayed the decrease of its nutritional value. It not only maintains the quality of freshly squeezed rice but also delays the decrease of its nutritional value.
Packaging and Food Machinery Qian Zhang et al. added PBAT to the blended film of PLA/PHB, and the results showed that the tensile strength of the composite film decreased, but the elongation at break showed an increasing trend, and the oxygen and moisture permeability of the film was improved.
Based on the gas-selective permeability of PLA/PBAT composite membrane, it has good regulation of internal O2 and CO2. According to the addition of different components, the gas-selective permeability of PLA/PBAT composite film is different. For example, the PLA/PBAT composite film with grape seed extract has high moisture permeability and gas-selective permeability, which can effectively prevent the packaging film from fogging, so that it has a better application prospect in fruit and vegetable packaging. When BHT antioxidant is added to PLA/PBAT composite film, the film barrier performance is improved, and it can be considered to be applied in the future for the freshness packaging of grain to reduce the loss of nutritional value and extend the shelf life.
Antimicrobial performance
Good antibacterial and antimicrobial effect is the key factor to extend the shelf life of food.
Shankar et al. found that PLA/PBAT films containing zinc oxide nanoparticles exhibited strong antibacterial activity against Escherichia coli and Listeria monocytogenes, which effectively delayed the increase in the total number of colonies and were stronger against Gram-negative than Gram-positive bacteria.
Cardoso et al. found that PBAT films containing oregano essential oil possessed antimicrobial and antioxidant activities, and the films were effective in reducing the number of total coliforms, Staphylococcus aureus, and cryptophilic microorganisms, and had better antimicrobial efficacy against Gram-negative bacteria, and the antimicrobial and antioxidant activities of the films were enhanced with the increase in the concentration of oregano essential oil.
Raja Venkatesan et al. found that PBAT/silver oxide composite films prepared with different ratios of silver oxide had significant antibacterial properties against Staphylococcus aureus, and the antibacterial performance was proportional to the silver oxide content. At present, the studies on the antimicrobial activity of PLA/PBAT composite films are relatively few, mainly focusing on the application of PBAT as a single substrate cling film. Therefore, the research on the antimicrobial performance of PLA/PBAT composite films will receive more extensive attention.
Based on PLA/PBAT blends can be mixed with silver oxide, zinc oxide and other metal particles or plant essential oils and other raw materials to prepare active composite film, the composite film has good antimicrobial activity, which can effectively delay food spoilage, reduce the loss of its nutritive value, improve the quality and safety of food in the storage period, is a green food preservation technology, the application of cold meat and aquatic products in the cold meat and aquatic products will be a future development trend, in the It is a green food preservation technology, and its application in cold meat and aquatic products will be the future development trend, which has great application potential in extending the shelf life of cold meat and aquatic products and improving the quality and freshness.
Storage and freshness properties
PLA/PBAT composite film has good UV shielding function, at the same time can reduce the water content and water activity in food, in fresh fruit and vegetable storage can effectively reduce water and nutrient loss, extend shelf life, improve the sensory quality.
WANG et al. found that PLA/PBAT blended film has high UV shielding function and can effectively prevent greening of potato.
Zhang Peiyu et al. from Zhejiang University, China, found that PLA/PBAT biodegradable material bags have better storage effect on Chinese cabbage, because there are microporous areas in the structure of the composite film, which can promote the diffusion of water from the inside to the surface of the film, thus appropriately reducing the water content and water activity in the foodstuffs, and at the same time, the composite film can effectively inhibit the degradation of chlorophyll and ascorbic acid during the storage period of the Chinese cabbage. The composite film can effectively inhibit the degradation of chlorophyll and ascorbic acid during storage.
Jiu-Tian Zhang of Jilin Agricultural University, China, used PLA/PBAT to prepare food preservation bags, and found that the higher the PLA content in the co-mingled preservation bag, the lower the sealing strength of the bag, and the addition of PBAT can improve the sealing strength of the bag, and the bag is easy to be degraded, and it is safe and non-polluting.
In the future, we can utilize the advantages of PLA/PBAT composite film preservation, according to the types of fruits and vegetables, physiological differences, etc., the development of different fruit and vegetable varieties of PLA/PBAT composite film with superior performance. In addition, a variety of freshness preservation technology has developed into an effective strategy to extend the shelf life of food, the future can be PLA/PBAT composite film preservation and physical preservation and other preservation technologies used jointly to give full play to the synergistic effect of a variety of preservation technologies.
Based on the PLA/PBAT active composite membrane has a good gas regulation, according to the different additives can realize high barrier or good gas permeability. At the same time, the composite film has a certain bacteriostatic effect, effectively extend the shelf life of food, in fresh fruit and vegetable storage medium food to play a good role in preserving freshness, can be used as fresh food in long-distance transportation, deep-sea voyage and other scenarios of packaging materials to ensure the quality and taste of fresh food. Therefore, PLA/PBAT active composite film will play an important role in the field of food packaging.
concluding remarks
Compared with traditional food packaging materials, PLA/PBAT active packaging materials are environmentally friendly, biodegradable and safe, and can play a certain role in preserving freshness as packaging materials for fresh food, which can not only be used in daily scenarios such as supermarket sales, but also in military applications such as escorting convoys, plateau border defense, and deep-sea voyages in an attempt to maximize the guarantee of the original flavor of food to provide the freshest food for the army officers and soldiers. Meanwhile, in the future, PLA/PBAT composite film preservation can be used in conjunction with other preservation technologies, such as physical preservation, to give full play to the synergistic effect of multiple preservation technologies. Since one of the prerequisites for the large-scale application of PBAT/PLA is to regulate and modify its properties during processing according to different practical use requirements, the degradation ability of PLA/PBAT composite food packaging materials can be fully utilized. However, at present, the research on the degradation ability of PLA/PBAT composite food packaging materials is relatively small, and the subsequent research on the degradation environment, degradation time and degradation principle can be deepened, so as to avoid degradation of the products in the course of service, which is unable to meet the requirements of actual use.
With the continuous maturity and development of PLA/PBAT composite film preparation technology, these biodegradable food packaging materials are expected to be industrialized and widely used in daily life, food packaging and medical devices.
