Preparation And Application Of Edible Polysaccharide Antibacterial Packaging Film

With the gradual increase of consumer safety awareness,edible degradable and safe antibacterial packaging has become a research hotspot in the field of food packaging.In this study,edible composite antibacterial film was prepared with chitosan and pullulan as substrate,?-polylysine was added acting as antibacterial agent and its application was investigated.First,the minimum inhibitory concentration of ?-polylysine aiming at Staphylococcus aureus,Bacillus subtilis,Escherichia coli,and Salmonella was determined,which was the basis for the addition amount in the solution system for preparing the composite antibacterial film.So as to select the best formula,the structure of the composite antibacterial film with different ratios was characterized,its physical properties and antibacterial properties were explored.The experimental results showed that the minimum inhibitory concentrations of ?-polylysine against Staphylococcus aureus,Escherichia coli,Salmonella and Bacillus subtilis were 1,4,2,and 0.5 mg/mL,respectively,which was used to decide an effective concentration of ?-polylysine subsequently into film-forming solutions.So the final addition of ?-polylysine was 4 mg/mL.The optimum ratio of chitosan to pullulan was 15:15 g/L.At this time,the composite antibacterial film has a smooth appearance without wrinkles and high transparency.The mechanical properties were improved compared with other groups,the tensile strength was 82.26± 11.89 MPa,the elongation at break was 5.59±11.89%,the thickness was 37.00±5.00 ?m,and the transparency was 1.45±0.23.The results of scanning electron microscopy showed that the surface of the composite antibacterial film was smooth and there were no obvious cracks.Fourier infrared spectroscopy supported that hydrogen bonds were formed between chitosan and pullulan.In addition,the combination of chitosan and ?-polylysine improved the bacteriostatic effect through the size of the inhibition zone.Secondly,the edible composite antibacterial film above-mentioned was applied to shrimp and fresh beef samples respectively,and the effect was studied by testing the changes of TVBN,pH,color and microorganism during storage time.The results about shrimp showed that the edible composite antibacterial film can effectively inhibit the growth of microorganisms,significantly reduce the values of physical and chemical indicators such as TVBN and pH values,delay its corruption speed,and improve its appearance quality.The refreshing effect of edible antibacterial film on chilled beef showed that the red index(a*/b*)and sensory quality of treatment group was significantly higher than that of the control group.And the edible antibacterial film slowed down the rate of TVBN and pH in beef,which slowed down protein degradation,and significantly inhibited E,coli 0157:H7,Listeria monocytogenes,and Salmonella in beef.In summary,the chitosan-pulllan edible antibacterial film developed in this paper exhibit good tensile strength,transparency and strong antibacterial properties.The application of fresh-keeping to shrimp and beef significantly improved the storage quality and food safety level and extend the shelf life.