Design and fabrication of thymol loaded antimicrobial film with zein-ethylcellulose for active food packagin
چکیده
tract:
Background and objective: Attention to the growing demand of the packaging industry to replace synthetic polymer films with natural polymers in order to protect the environment and also increase the safety and shelf life of food products, extensive research. The purpose of this study was to design and produce water-insoluble packaging film based on zein and ethyl cellulose and to investigate the effects of polymer concentration ratio, solvent type, hydrolysis treatment and plasticizer size on the filming properties of polymers and selecting the best treatment in terms of mechanical properties. And inhibit and study the effects of adding thymol and curcumin to the film on the antioxidant and antimicrobial properties of the films. .
Materials & Methods: First, the effect of variable concentrations of polymers, the use of different solvents and the effect of hydrolysis of polymers on the filmability of polymers were investigated to obtain the best film sample in terms of uniformity and apparent strength. For hydrolysis, zein and ethyl cellulose were treated separately at 75 ° C for two hours using acetic acid and ethanol solvents at a ratio of 30 to 70 for two hours. The best film was obtained and the optimized samples of thymol (25% by weight of dry matter) and curcumin (1% by weight of dry matter) were used as antimicrobial and antioxidant agents, after complete dissolution of these materials on the heater without heat. , Poured into Teflon containers. The produced films were evaluated to determine the film thickness, solubility, moisture content, water vapor permeability, mechanical, structural, morphological properties as well as antioxidant and antimicrobial properties.
Results: The best filmability for polymer mixture of ethyl cellulose zein with 2% and 1% by weight in acetic acid and 70% ethanol, respectively, with a ratio of 30 to 70 after hydrolysis for 2 hours at 75 ° C and use An equal percentage of plasticizers of glycerol and monoethylene glycol plasticizers, which were added to the mixture by 40% by weight of polymers, was obtained. According to the FTIR
results, more hydrogen bonds were formed after hydrolysis, which could be the reason for the improvement of the filmability index, as well as the indices of tensile strength and elongation to break point, compared to the non-hydrolyzed sample. Addition of curcumin and thymol created a spongy structure in the cross section of the packaging film and also improved the elasticity of the film. In films containing curcumin and thymol, increased swelling and solubility in water, as well as the degree of moisture permeability, confirmed the results of electron microscopy on the formation of a porous structure. The antimicrobial effects of thymol-containing films were slow-release and had a greater inhibitory effect on Staphylococcus aureus than Escherichia coli, as well as a significant inhibitory property against the growth of Aspergillus flavus mold. The measured antioxidant properties of curcumin-containing films were about 30% after four months, indicating the protective effects of the film matrix on curcumin retention and controlled release over tim
Conclusion: The filmability of the mixture of zein and ethyl cellulose was significantly improved after hydrolysis treatment and selection of glycerol and monoethylene glycol as plasticizers. The prepared film containing curcumin and thymol, in addition to having antibacterial and antifungal effects, showed acceptable and significant antioxidant properties during storage even after 4 months. Prepared films with acceptable mechanical and barrier properties have good potential in active food packaging with antimicrobial and antioxidant properties.
Keywords: tract:
Background and objective: Attention to the growing demand of the packaging industry to replace synthetic polymer films with natural polymers in order to protect the environment and also increase the safety and shelf life of food products, extensive research. The purpose of this study was to design and produce water-insoluble packaging film based on zein and ethyl cellulose and to investigate the effects of polymer concentration ratio, solvent type, hydrolysis treatment and plasticizer size on the filming properties of polymers and selecting the best treatment in terms of mechanical properties. And inhibit and study the effects of adding thymol and curcumin to the film on the antioxidant and antimicrobial properties of the films. .
Materials & Methods: First, the effect of variable concentrations of polymers, the use of different solvents and the effect of hydrolysis of polymers on the filmability of polymers were investigated to obtain the best film sample in terms of uniformity and apparent strength. For hydrolysis, zein and ethyl cellulose were treated separately at 75 ° C for two hours using acetic acid and ethanol solvents at a ratio of 30 to 70 for two hours. The best film was obtained and the optimized samples of thymol (25% by weight of dry matter) and curcumin (1% by weight of dry matter) were used as antimicrobial and antioxidant agents, after complete dissolution of these materials on the heater without heat. , Poured into Teflon containers. The produced films were evaluated to determine the film thickness, solubility, moisture content, water vapor permeability, mechanical, structural, morphological properties as well as antioxidant and antimicrobial properties.
Results: The best filmability for polymer mixture of ethyl cellulose zein with 2% and 1% by weight in acetic acid and 70% ethanol, respectively, with a ratio of 30 to 70 after hydrolysis for 2 hours at 75 ° C and use An equal percentage of plasticizers of glycerol and monoethylene glycol plasticizers, which were added to the mixture by 40% by weight of polymers, was obtained. According to the FTIR
results, more hydrogen bonds were formed after hydrolysis, which could be the reason for the improvement of the filmability index, as well as the indices of tensile strength and elongation to break point, compared to the non-hydrolyzed sample. Addition of curcumin and thymol created a spongy structure in the cross section of the packaging film and also improved the elasticity of the film. In films containing curcumin and thymol, increased swelling and solubility in water, as well as the degree of moisture permeability, confirmed the results of electron microscopy on the formation of a porous structure. The antimicrobial effects of thymol-containing films were slow-release and had a greater inhibitory effect on Staphylococcus aureus than Escherichia coli, as well as a significant inhibitory property against the growth of Aspergillus flavus mold. The measured antioxidant properties of curcumin-containing films were about 30% after four months, indicating the protective effects of the film matrix on curcumin retention and controlled release over tim
Conclusion: The filmability of the mixture of zein and ethyl cellulose was significantly improved after hydrolysis treatment and selection of glycerol and monoethylene glycol as plasticizers. The prepared film containing curcumin and thymol, in addition to having antibacterial and antifungal effects, showed acceptable and significant antioxidant properties during storage even after 4 months. Prepared films with acceptable mechanical and barrier properties have good potential in active food packaging with antimicrobial and antioxidant properties.
Keywords: Zine-ethyl cellulose-hydrolysis-thymol-curcumin