Preparation And Properties Of Xylan-based Antioxidant Active Packaging

Food packaging film plays an important role in ensuring that food is not affected by microorganisms,oxygen,and adverse factors in the process of food storage,transportation,and sales.Traditional packaging film derived from fossil energy is neither environment-friendly,nor helpful in aspect of extending the shelf life of food.Therefore,the development of degradable active food packaging film has became important item recently.In this paper,xylan,from by-product in dissolving pulp industry,was initially modified to prepare carboxymethyl xylan?CMX?through etherification.The obtained CMX was further used to prepare an active packaging film.The modification and material fabrication could provide basis for the application of industrial xylan in food packaging film.Industrial xylan were etherified by chloroacetic acid in ethanol under alkaline condition.CMX samples with various degrees of substitution have been prepared through different reactions.The optimum reaction condition was as follows:the molar ratio of xylanase unit:sodium hydroxide:chloroacetic acid was 1:2.5:1,the volume of ethanol was 25 m L,the alkalinization time was 30 min,the etherification temperature was 75°C,and the etherification time was 75 min.The results of fourier transform infrared spectroscopy?FT-IR?and nuclear magnetic resonance spectrum(¹³C-NMR)tests indicated that CMX was successfully prepared.It was found that the modified xylan had better water solubility,and the molecular weight of modified xylan decreased significantly.The composite film was prepared based on the CMX and gelatin-tannin nanoparticles?NPS?.It was found that when the content of NPS was 10%,the composite film exhibited the best mechanical properties.Compared with the composite film without NPS,the tensile stress increased from 28.5 MPa to 39.0 MPa.Ultraviolet-visible?UV?transmittance analysis showed that the incorporation of NPS could effectively block the UV radiation.The results of the anti-oxidation ability of the film indicated that the composite film had excellent anti-oxidation ability and could delay the oxidation of food.Cellulose nanofibrils?CNF?were obtained through the TEMPO oxidation.CNF was used as reinforcing agent to prepare CMX film,and the result showed that the mechanical properties of the films were the best with 20%CNF addition and the tensile strength is up to 62.5 MPa.Subsequently,tannin acid was added to prepare an active packaging film.The addition of tannic acid slightly reduced the tensile properties of the film,but it could meet the requirements of food packaging film.In addition,the composite film had excellent ultraviolet blocking performance,which could reduce the influence of ultraviolet light on food quality.