Preparation,characterization Of Double Factors Collagen Active Films And Their Preservation Mechanism On Grass Carp Fillets

Traditional synthetic packaging materials only separate food from external contaminants,and their role in inhibiting food degradation is poor.Besides,the extensive use of synthetic packaging materials have been posed a huge threat to the environment.The packaging materials prepared by mixing bioactive macromolecules and natural active compounds are not only safe and environmentally friendly,but also have antibacterial and antioxidative activities,which can be used to delay food spoilage.In this paper,the hydrophobic antibacterial agent cinnamaldehyde was made into nanoparticles and nanoemulsions to improve its water solubility.Subsequently,the nanoemulsions with higher loading amount of cinnamaldehyde were mixed with vitamin C and collagen to prepare the antibacterial and antioxidant active films.Finally,the mechanism of antibacterial and antioxidant active coatings on the preservation of grass carp fillets was studied.The research contents were as follows:(1)Preparation of cinnamaldehyde/sodium alginate/chitosan nanoparticles(CA/SA/CS NPs).When the mass ratio of SA to CS was 5.5/1,SA to Ca Cl₂was 5/1,SA to CA was 1/2 and the p H value of CS solution was 5.0,the prepared nanoparticles had good stability and high encapsulation efficiency.The average particle size of nanoparticles was 455.2 nm,encapsulation efficiency was 72.92%,polymer dispersion index(PDI)was 0.189,and zeta potential was-40.8 m V.Electron microscopic images showed that the structure of nanoparticles was sphere or ellipsoid.In addition,nanoparticles had a certain sustained release effect in the hydrophilic and lipophilic simulation systems.(2)The oil in water cinnamaldehyde nanoemulsions were prepared by using tween 80 to emulsify cinnamaldehyde.The results showed that 10 m L of 2%(w/v)tween 80 solution,200 mg of cinnamaldehyde and magnetic stirring time of 24 h were more preferable.The average particle size of the nanoemulsions was 97.4 nm,PDI was 0.106,and zeta potential was-8.5 m V.Atomic force microscopy images showed that the nanoemulsions took on a uniform spherical structure.(3)The cinnamaldehyde/vitamin C/collagen composite films with antibacterial and antioxidant activities were prepared by combining silver carp skin collagen with cinnamaldehyde nanoemulsions and vitamin C.Subsequently,the microstructure,antibacterial and antioxidant properties of the films were studied.The results showed that when the film contained 100 mg of cinnamaldehyde and 50 mg of vitamin C(GL-100CA-50Vc),it had a good light barrier property and the elongation at break was 158%.In addition,the inhibition rate of GL-100CA-50Vc film against Pseudomonas aeruginosa was 55.97%,and the free radical scavenging rate of film to ABTS and DPPH was 96.26%and 95.74%,respectively,which indicated that the film had good antibacterial and antioxidant activities.(4)Using cinnamaldehyde/vitamin C/collagen active coatings to preserve grass carp fillets,and the changes of fish quality at 4°C were studied.The results showed that the grass carp fillets were well preserved when the active coating contained 100mg of cinnamaldehyde and 50 mg of vitamin C(GL-100CA-50Vc).At the end of the preservation period,the weight loss rate of fish fillets was 18.13%,and the TVB-N and TBA were 7.19 mg/100 g and 0.133 mg/MDA.kg^-1,respectively.What's more,the number of spoilage microorganisms and the degree of protein decomposition were relatively low.