| With the development of society, people are focus on the shortage of resources, the quality of food and the green environmental biodegradable plastic, which is made of natural polymer. This study combined with the advantages of the antibacterial activity of cinnamon cinnamaldehyde, select chitosan as main film matrix, glycerol as plasticizer, Tween-80 as the emulsifying agent, chitosan/cinnamaldehyde antibacterial film was made by casting method. A series of experiments were carried out on the optimized preparation, performance testing, release experiment of cinnamaldehyde, the application of real food, specific study content and results are as follows:(1) Preparing and optimizing process of cinnamaldehyde/chitosan antibacterial film.Tensile strength and elongation at break as the evaluation index.. Chitosan concentration, acetic acid concentration, and glycerol concentration as three factors,each factor was taken 3 levels, conduct L9(33) orthogonal test, evaluate the index comprehensively, and obtain the optimal ratio of cinnamaldehyde/chitosan antibacteerial film as follwow: glycerol concentration was 3%(v/v), chitosan concentration was 1.5%(w/v), acetic acid concentration was 0.75%(v/v). According to the single factor analysis, the concentration of Tween-80 was 0.5%.(2) Properties and structure characterization of cinnamaldehyde/chitosan antibacterial film were detected. The properties of the chitosan films and its four different concentrations(0.5%、1%、1.5% and 2%)(v/v) of cinnamaldehyde antibacterial film were evaluated and compared. The results showed that: with the increase of the concentration of the cinnamaldehyde, the thickness of the film increased(0.091 ± 0.0064 mm, 0.096 ± 0.0031 mm, 0.106 ± 0.0029 mm and 0.125 ± 0.0032mm), water vapor permeability coefficient increased, color difference of the film increased, and the transparency decreased. Add cinnamaldehyde reduced elongation at break(14.70±1.76%、10.83±2.75%、8.30±1.65% and 7.75±0.85%), but increased the tensile strength of the film, and the maximum of 15.77 ± 1.13MPa; According to Fourier transform infrared spectroscopy, the results showed that the antibacterial films has good biocompatibility; with the increase of the concentration of the cinnamaldehyde, degree of crystallinity, cracked, rough surface was increased, meanwhile, enhanced thermal stability of antimicrobial film and have antibacterial effect significantly.(3) The release of cinnamaldehyde from antimicrobial film was researched. Cinnamaldehyde content was detected by GC-MS and its releasing regularity to air and to isooctane was investigated. The results showed: the release ratio of cinnamaldehyde to air in the 2% concentration chitosan antibacterial film increased with time and increased(40℃, at a balance of 59.53%) with the temperature(4℃、25℃ and 40℃). The release rate decreased with the increased of the initial concentration of cinnamaldehyde; the release of isooctane was decreased with the increase of the initial concentration of the cinnamon aldehyde, and increased with the increase of the temperature. The cinnamaldehyde partition coefficient KP, F values and diffusion coefficient DP values of antibacterial film were calculated. Partition coefficient KP, F values was decreased with the increase of temperature. Diffusion coefficient DP values was increased with the increase of temperature. The range of DP value was 9.39×10-12~1.64×10-10cm2/s. Under the same temperature, KP values between cinnamaldehyde and isooctane was less than in the air. DP values of release to isooctane was greater than in the air.(4) Application of cinnamaldehyde/chitosan antibacterial film on fresh pork preservation was studyed, pH value, total volatile basic nitrogen(TVB-N) content, total bacterial count and sensory evaluation as evaluation indicators. The results showed that: wrapping package as a form of packaging fresh pork could extend the shelf-life of fresh pork from 4-5 days to 8 days; in the form of the padded,the upper and lower double layer padded was best, and could make the shelf life of fresh pork extended to 7 days. Under the form of padded, the contact area(cm2) of the 2% antimicrobial film with the pork and the pork weight(g) ratio should be greater than 2:3. |
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