بررسی خصوصیات فیزیکوشیمیایی و مکانیکی فیلمهای فعال خوراکی بر پایه ژلاتین حاوی اسانسهای آویشن، پونه و مریم گلی.

Background and objectives: To minimize the use of antibiotics, additives, and chemical preservatives, it is possible to incorporate natural antimicrobial substances into packaging. Recent studies focusing on developing and evaluating edible films have highlighted the effectiveness of essential oils in protecting against microbial growth, preventing food spoilage (both chemical and microbial), and reducing food waste. Films containing gelatin display impressive mechanical strength, making them suitable for edible film production due to their ability to form a gel-like structure, which is attributed to the presence of certain amino acids like proline and hydroxyproline. Taking into account the plentiful availability and affordability of thyme, oregano, and sage essential oils in our country, as well as the low cost of gelatin, this particular composition of film could serve as a model for widespread implementation in the food packaging. Materials and methods: In this study, the impact of various concentrations of thyme, oregano, and sage essential oils on gelatin based films properties was investigated. The study examined different concentrations of essential oil ranging from minimum 0% to highest 4% as the independent variable. The dependent variables included a range of physicochemical tests ( solubility, water permeability, thickness, opacity, and color parameters), as well as mechanical tests (elongation at the break point, tensile strength, and Young's model). The study utilized a mixed experimental design known as simplex lattice and employed Design Expert13 software. Results: In this research, the highest tensile strength (12 MPa), elongation at break point (26%) and Young's modulus (80 MPa) were found in high concentrations of oregano essential oil (4%). Among the treatments, the lowest solubility was in the highest concentration of oregano essential oil in the mixture (4% area) and the lowest water vapor permeability(WVP) was obtained in the lowest concentration of oregano essential oil in the mixture. The difference among the amount of turbidity of the films was not significant. The highest turbidity was indicated in film with the lowest concentration of oregano essential oil. The highest amount of film thickness was obtained in the present of 4% concentration of oregano essential oil, which was statistically significant. By increasing the concentration of thyme essential oil in the mixture, the hue angle, whiteness index and saturation decrease, and its highest amount was in the area of 4% oregano and sage. The changes of a* and b* parameters was similar, but the concentration of essential oils has no effect on the changes of L* parameter. Conclusion: The results of this research showed that adding a high concentration of oregano essential oil to the gelatin film compared to thyme and sage essential oils produced films with sufficient strength that have the highest efficiency and desirable characteristics. It can be used as a suitable coating for food protection by delaying the oxidation of lipids, mechanical properties and favorable color changes. [ABSTRACT FROM AUTHOR]