Research On The Properties Of PLA Antibacterial Packaging And The Migration Regularity Of Thymol

Antibacterial packaging is an effective way to reduce foodborne pathogen contamination and prolong food shelf life,through the release of antimicrobial agents to extend the food storage period,to ensure food safety and health.There are lots of chemical additives in food packaging materials,which may migrate into food when they are in contact,and some of additives lead to food contamination and change the original flavor of food,even endanger humans' health.The ordinary packaging substrate is difficult to degrade which causing great pollution to the environment.Polylactic acid(PLA)is biodegradable and has good biocompatibility.It is a kind of biodegradable material and a polymer which is the most promising alternative to traditional packaging materials.In this paper,PLA composites containing thymol were prepared via cast blending.The physical properties and antibacterial properties of PLA composites were studied;The migration of thymol from PLA films to food simulants were analyzed,The two factors of the temperature and food simulants affecting the migration are dicussed;The migration modeling and its influencing factors(diffusion coefficient and partition coefficient)were analyzed.And setting up migration model of thymol in food simulants,then analyze and compare the migration modeling and experimental date.The safety of the antimicrobial packaging film was evaluated by mouse acute toxicity test.The main findings are as follows:(1)Fourier transform infrared spectroscopy analysis showed that there was no covalent bond between thymol and polylactic acid,both of which belonged to simple physical blending.Scanning electron microscopy(SEM),Scanning differential calorimeter(DSC)and mechanical properties analysis found that.Thymol enhanced the tensile strength,ductility,flexibility and morphological stability.And with the addition of thymol content,the nature of antimicrobial packaging film also changes.Bacteriostatic experiments showed that when the content of thymol was 5 %,it could inhibit the growth of Escherichia coli,Staphylococcus aureus.When the content of thymol was 7 %,it showed inhibitory effect on Canidia Albicans.The sample containing 7 % thymol obtained the film higher mechanical properties.(2)The migration of thymol in the antimicrobial packaging film showed a nonlinear relationship with the time.With the increase of migration time and the migration temperature,the content of thymol in food simulants increased gradually,and finally became balanced.Temperature has a decisive effect on dynamic process and partition equilibrium of migration,the higher the temperature,the more of the migration and less time needed to reach equilibrium.The nature of food simulants also affects the migration of thymol.The migration of thymol in four kinds of food simulants was n-hexane solution> 10% ethanol solution> 4% acetic acid solution> distilled water The(3)There was a positive correlation between temperature and diffusion coefficient DP,and negatively correlated with the distribution coefficient KP / F.The food simulants also has an effect on the partition coefficient and the diffusion coefficient.The migration behavior of thymol is consistent with the second law of Fick diffusion.Based on the experimental data,the Piringer equation is used to establish the migration model.Contrast model migration value and actual migration value.It is found that the migration model equation can predict the migratory behavior of thymol.(4)Mouse systemic toxicity test showed that the experimental group of antimicrobial membrane extract on mice without irritation,Mice weight,physiological activity,physiological status were normal.At this time,the antibacterial packaging film conforms to the biomaterial standard.