Study On Preparation Of High Barrier Unsaturated Poly(Lactic Acid) Composite Film And Its Preservation Properties For Chilled Meat

Chilled meat is tender,juicy,and rich in nutrients,but it is highly perishable.Currently,the packaging of chilled meat generally uses high barrier packaging materials,combined with vacuum and gas-filled packaging technologies to extend its shelf life.In this study,polylactic acid-itaconic acid butanediol ester copolymer（P（LA-co-IA））was synthesized in one step,and chitosan（CS）and graphene oxide（GO）were attached to its surface via layer-by-layer assembly to improve the material’s barrier properties and endow the film with antimicrobial properties.This research aims to develop green,biodegradable,high-barrier packaging materials for preserving chilled meat and extending its shelf life.Film performance test results show that the P（LA-co-IA）film has excellent mechanical properties,with a fracture elongation of 186.1%.After attaching CS and GO,the deformation resistance of the P（LA-co-IA）composite film is improved.As the number of attached layers increases,the stress and Young’s modulus of the P（LA-co-IA）composite film are also enhanced.In addition,the oxygen barrier properties of the P（LA-co-IA）composite film are significantly enhanced,with the oxygen transmission rate（OTR）of the multilayer-deposited P（LA-co-IA）/CS/GO₁₀film being 1.6 cm³/m²·d,meeting the international standard for high barrier materials.The film also possesses certain ultraviolet barrier properties.PA/PE films,P（LA-co-IA）films,and P（LA-co-IA）composite films with different numbers of attached GO layers were made into bags and used for the sealed packaging of chilled meat.The quality changes during cold storage of fresh meat were assessed by measuring physicochemical indicators such as total bacterial count,volatile base nitrogen,and the degree of fat oxidation.Test results showed that as the number of assembled layers increased,the preservation effect of the P（LA-co-IA）composite film on chilled meat improved.The P（LA-co-IA）/CS/GO₁₀group effectively inhibited the growth of microorganisms in chilled meat and the production of nitrogenous volatile substances.Due to the ultraviolet barrier properties and high oxygen barrier properties of the P（LA-co-IA）/CS/GO_Xfilm,the degree of fat oxidation in the packaged chilled meat was significantly reduced.On the 12th day of storage,the degree of fat oxidation in chilled meat in all packaging groups except the P（LA-co-IA）/CS/GO₁₀group reached the spoilage range.The microbial growth of chilled meat in the P（LA-co-IA）/CS/GO₁₀group was slow,reaching the spoilage level on the 16th day of storage.The degree of tissue damage in chilled meat was relatively low,with less loss of meat juice and stronger water-holding capacity.In summary,the self-assembled composite film effectively slowed down the decline of various indicators during the storage of chilled meat,extending its shelf life to 16 days.