Construction And Application Of Zein Active Composite Films Doped With Eugenol-Loaded Modified Mesoporous Silica Nanoparticles

Food packaging plays a vital role in ensuring the quality and safety of food.Nowadays,traditional petroleum-based plastic packaging materials have caused many environmental problems due to their non-renewable and non-degradable nature,and there is an increasing interest in the development and utilisation of biodegradable packaging materials.Among these,green,natural and environmentally friendly biopolymer films have been widely researched as an alternative packaging material to traditional synthetic plastics.Many natural biopolymers,such as proteins,polysaccharides and lipid-based biobases,have been shown to possess potential in the preparation of food packaging films to maintain or improve food quality.One of these is zein,a vegetable protein with good alcohol solubility and hydrophobicity,with molecules linked by hydrophobic,hydrogen and disulphide bonds,which can be used in the preparation of edible films.However,the preservation effect of single zein films and their mechanical properties are weak,limiting their further application.By compounding functional nanoparticles,it is expected that maize alcoholic protein-based packaging materials with synergistic properties can be developed.This has important implications for the study of green and natural food packaging.In this study,eugenol/caffeic acid-mesoporous silica nanoparticles（EG/CA-MSN）were prepared by covalently grafting caffeic acid with amino-mesoporous silica nanoparticles（NH₂-MSN）as a carrier loaded with eugenol,and then blended with zein solution to prepare a excellent performance eugenol/caffeic acid-mesoporous silica nanoparticles/zein（EG/CA-MSN/Zein）composite film and applied to the preservation of crucian carp fillets,as follows:Firstly,two new mesoporous silica nanoparticle carriers were prepared and obtained.The NH₂-MSN was prepared by bonding the hydroxyl group on the surface of the mesoporous silica nanoparticles（MSN）with 3-aminopropyltriethoxysilane（APTES）to introduce amino groups,and then the NH₂-MSN was physically modified and chemically modified by caffeic acid to produce two types of eugenol-loaded nanoparticle carriers（CA/MSN and CA-MSN）,respectively.The results showed that the CA-MSN carriers could significantly improve the thermal stability of eugenol and increase the volatile temperature of eugenol from 185℃to between 200～300℃;the cumulative release of eugenol in CA-MSN was 48.92%at a constant temperature of 25℃for 90 h,which was lower than the cumulative release of eugenol in CA/MSN and MSN,slowing down the release of eugenol and achieving the effect of prolonged inhibition.The CA-MSN carrier could play a synergistic role with eugenol in inhibiting bacteria,showing stronger inhibition effect on E.coli and S.aureus.At the same time,CA-MSN and CA/MSN loaded eugenol showed higher free radical scavenging rate compared to free eugenol.This suggested that CA-MSN was a suitable carrier for loading eugenol.The effect of EG/CA-MSN addition on the physicochemical and functional properties of zein films was investigated.The film was prepared by flow casting using zein as the film-forming matrix and EG/CA-MSN as the functional filler.The SEM and FTIR results showed that EG/CA-MSN and zein had good biocompatibility and intermolecular interactions.The addition of EG/CA-MSN improved the barrier properties and mechanical properties of the films,therefore,the composite films presented better mechanical properties and barrier properties than Zein film.When the amount of EG/CA-MSN was 9 wt%,the tensile strength of the composite films could reach 18.86 MPa,and the water vapour transmission rate and oxygen transmission rate were 23.58%and 21.29%lower than those of the control group,respectively.The addition of EG/CA-MSN further enhanced the antioxidant properties of Zein film and increased the scavenging rate to 78.28%and 85.49%for DPPH and ABTS radicals,respectively.In addition,the synergistic effect of eugenol and caffeic acid improved the antibacterial effect of the composite films on E.coli and S.aureus,with the diameter of inhibition zone against E.coli and S.aureus reaching 13.57 mm and 12.38 mm,respectively.Finally,EG/CA-MSN/Zein composite film was applied to the preservation of crucian carp fillets,and the effects of PE film,Zein film and EG/CA-MSN/Zein composite film on the quality of fish were investigated.The results showed that the EG/CA-MSN/Zein composite film could well block the oxygen and inhibit the growth of microorganisms on the surface of the fish.At the end of storage,the total bacterial count of fish in EG/CA-MSN/Zein group were2.04 lg CFU/g lower than the control group.The EG/CA-MSN/Zein composite film had better barrier properties and antibacterial and antioxidant properties than the Zein film,which could further delay lipid oxidation and protein decomposition,inhibit water loss and extend the shelf life of fish.The EG/CA-MSN/Zein composite film had great potential as a nano-active packaging material for food preservation.