Nitrogen Fertilization Optimizes the Physicochemical Properties of Cactus Mucilage and the Biopolymeric Films Produced

In recent decades, increasing environmental concerns have driven interest in sustainable polymers, such as the mucilage derived from forage cactus (<i>Opuntia stricta</i>), which shows significant potential for food applications and the production of biopolymeric films. To expand its industrial use, improvements in synthesis methods, additive incorporation, and agronomic practices are necessary. However, studies on the use of <i>O. stricta</i> in films produced under nitrogen fertilization remain scarce, underscoring the need for further research to fully explore its potential in the bioplastics industry. Cladodes of <i>O. stricta</i> fertilized with 50, 150, 300, and 450 kg N ha^-1 were washed, peeled, and ground with ethanol (99.8% P.A.) at a 2:3 ratio (parenchyma/alcohol), resulting in a dried mucilage powder used for analysis and film formulation. Lower nitrogen supply resulted in the highest cladode yield and produced mucilage with lower electrical conductivity, reduced sodium and potassium content, and a higher concentration of phenolic compounds, making it more suitable for antioxidant food applications. Films made from this mucilage demonstrated greater transparency, higher luminosity, increased stiffness, and reduced moisture content and water solubility. XRD and SEM analyses revealed a more crystalline and homogeneous structure, resulting in improved mechanical resistance. These outcomes indicate that nitrogen availability directly modulates mucilage composition and, consequently, the structural integrity and barrier properties of the films. The findings identify low nitrogen fertilization as a cost-effective and environmentally favorable strategy for producing consistent, high-quality biopolymeric films with potential applications in sustainable packaging.