Production and characterization of smart and active food packaging based on sumach extract and fiber reinforced starch

The use of food packaging is of great importance to ensure the quality and safety of food. Due to its biodegradability, availability, and low cost, starch is one of the most widely used polymers in the production of food packaging. In this thesis, starch-based films were produced using the casting method and reinforced with sumac (Smk) extract and bamboo fiber (BL). The antibacterial nature of packaging can extend the shelf life of food and reduce fatalities caused by foodborne illnesses. Since starch alone does not exhibit antibacterial properties, this study aimed to impart this characteristic by incorporating sumac (Rhus coriaria L.) extract, which has been reported in the literature to possess antimicrobial properties, into starch films. Moreover, plant-based fibers can be used to reinforce starch, which is mechanically a weak polymer. Within the scope of the study, pure starch (5% w/v), starch with Smk (5% v/v), and starch films containing varying amounts of BL (5%, 10%, 15% w/w of starch) in combination with Smk were produced. The thickness, density, optical properties, swelling, solubility, moisture content, water vapor permeability, pH sensitivity, antibacterial and antioxidant activity, and mechanical properties of the obtained films were determined. In addition, SEM and FTIR analyses were performed. Finally, biodegradability tests were conducted using the soil burial method. Films containing Smk and BL showed significantly increased thickness and opacity compared to Smk-only films, while their density decreased. As the BL content increased, a significant reduction was observed in the films' moisture content and solubility values, whereas no significant difference was found in swelling values. While there was no statistical difference in water vapor permeability between Smk and Smk+BL films, all showed a significant decrease compared to the pure starch film. Mechanical testing indicated that as the BL ratio increased, tensile strength improved while elongation at break decreased. The antibacterial activity of the films was tested using the disk diffusion method against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Bacillus subtilis. The films were found to be effective against both Gram (+) ve Gram (-) bacteria. The DPPH assay showed that films containing Smk exhibited good antioxidant activity, and this activity did not change significantly with the addition of BL. After 12 weeks of soil burial, all films degraded by more than 70% in mass and were incorporated into the soil. These findings suggest that biocomposite starch films incorporating Smk extract, and Smk+BL additives have the potential for application in food packaging. A review of the existing literature revealed no prior studies investigating starch-Smk extract-BL formulations. This thesis study is the first to produce films with this specific composition, thereby contributing novel insights to the field.