Preparation And Properties Of Composite Coating By Incorporation Of Cinnamaldehyde And Lysozyme

With the rise of green foods,the safety of chemical preservatives has gradually become a question.The development and application of biopreservatives and natural degradable active edible film materials have become hotspots in the field of aquatic product preservation.In this paper,hydroxypropyl-β-cyclodextrin and Acacia senegal were used as composite wall materials,and a natural plant essential oil-cinnamaldehyde was used as the core material.Cinnamaldehyde was embedded by spray drying method to prepare hydroxypropyl-β-cyclodextrin-cinnamaldehyde inclusion complex.The lysozyme-pululan-gelatin edible film was prepared to study the effects of cinnamaldehyde inclusion complex on the physical and chemical properties of lysozyme composite coating film.The main results are as follows:1.Hydroxypropyl-β-cyclodextrin-cinnamaldehyde inclusion complex was prepared by spray drying method,the embedding rate was determined,and the microstructure of the inclusion complex,mixture,core material,and wall material was studied by scanning electron microscopy(SEM),differential scanning calorimetry(DSC),Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA)and other means.The sustained release properties of the inclusion compound in simulated seawater and pure water medium were compared.The results showed that the entrapment rate of the obtained inclusion complex reached 77.6%.The SEM results confirmed the formation of cinnamaldehyde inclusion complex.The DSC,FT-IR and TGA results showed that the inclusion complex was more stable than the mixture at high temperatures.After embedding,cinnamaldehyde entered the interior of the hydroxypropyl-β-cyclodextrin(HP-β-CD)cavity and the microstructure of HP-β-CD was changed.The release amount of the cinnamaldehyde in the inclusion complex increased with the increase of time,and the release rate in the simulated seawater was smaller than that of the pure water.2.The effect of cinnamaldehyde inclusion complex on the physicochemical properties of lysozyme-pululan-gelatin edible film was investigated.The effects of cinnamaldehyde inclusion complexes on the physicochemical properties and microstructure of lysozyme composite coating were determined by measurement of tensile strength,elongation at break,gas permeability and light transmission,DPPH radical scavenging rate,and SEM,X-ray diffraction(XRD),FT-IR and TGA analysis.The results showed that when the content of cinnamaldehyde was 0.2%,the tensile strength of the cinnamaldehyde-lysozyme composite coating film reached 21.13 MPa,and the elongation at break reached 3.1%.With the increase of cinnamaldehyde content,the gas permeability of the film increased.The lysozyme composite coating film has the best light transmittance and gradually decreased as the cinnamaldehyde content increased.With the increase of cinnamaldehyde content,the oxidation resistance of the composite coating film also increased,the thermal stability decreased slightly,the oxygen barrier performance creased,and the addition of cinnamaldehyde had no significant effect on the microstructure of the composite coating film.3.The effect of cinnamaldehyde inclusion complex on the preservation properties of lysozyme composite film was studied.The effects of four kinds of coatings on the shelf life of red drum(Sciaenops ocellatus)were studied by determining the total number of colonies,water holding capacity,volatile base nitrogen(TVB-N),thiobarbituric acid value(TBA),K value and odor.The results indicated that the preservation effect of single cinnamaldehyde coating,lysozyme coating and composite coating was obviously better than that of the control group.The composite coating was found to be the most effective in maintaining the quality of red drum fillets by significantly inhibiting the growth of bacteria during the cold storage,and effectively slowing down the TVB-N content,TBA value and K value,and extending the shelf life of fillets 5 to 10 days compared with the control group,and 5 days compared with that of the single cinnamaldehyde or lysozyme coating.Electronic nose analysis showed that the odor components of fish sample treated by lysozyme coating was significantly different from those of the control group within 15 days of storage.The odor of the sample treated with the single cinnamaldehyde coating was significantly different from that of the control group.