Production and characterization of an active starch film using peanut skin extract, and its application to Parmesan cheese preservation

Peanut skin is an agro-industrial by-product rich in bioactive compounds and has considerable potential for the development of sustainable packaging materials. This study aimed to produce and characterize potato starch films incorporating peanut skin extract, and to evaluate their potential for preserving Parmesan cheese. The extract was obtained through alkaline extraction and incorporated into the starch matrix at four concentrations (0, 30, 60, and 90%, g of extract/100 g of starch). The films were characterized in terms of their mechanical, functional, bioactive, morphological, crystallinity, and thermal properties. Subsequently, the film exhibiting the best mechanical performance and highest water resistance was selected to evaluate its effectiveness in preserving Parmesan cheese. To this, cheese samples were placed in containers covered with the selected film, a starch film without extract (control), and a polyethylene film. The samples were then exposed to UV radiation (18 W) at 30 ± 2 °C for 30 days. During storage, pH, lipid oxidation, and cheese color were evaluated. All data were analyzed using analysis of variance (ANOVA) followed by Tukey's multiple comparison test at a 95% significance level. The film containing 60% extract exhibited the best overall performance, showing suitable mechanical properties (tensile strength of 3.6 MPa and elongation at break of 24.2%), lower moisture content (16.8%), lower water solubility (24.7%), a higher water contact angle (71.3°), and greater antioxidant capacity (579 μM Trolox/100 g) compared with the control film (tensile strength of 3.2 MPa, elongation at break of 14.3%, moisture content of 19.0%, water solubility of 30.5%, water contact angle of 50.6°, and antioxidant capacity of 197 μM Trolox/100 g). This film was used to preserve Parmesan cheese stored under UV radiation, demonstrating superior preservation over the 30-day storage period by maintaining a more stable pH, reducing lipid oxidation, and minimizing color variation compared with the control and the polyethylene film. The results demonstrated that peanut skin extract has the potential to be used as a bioactive agent in potato starch films, thereby adding value to peanut by-products.