Pectin Extraction from Opuntia spp. Cladodes: Process Optimization, Characterization and Films Development for Food Packaging

This study investigated the extraction and characterization of pectin from the peel and the pulp of Opuntia ficus-indica (OFI) cladodes, aiming to define sustainable and optimized extraction conditions and to evaluate the applicability of the extracted pectin in film development for food packaging. Cladodes were chemically characterized, confirming their richness in sugars, dietary fiber, and bioactive compounds. Different solvents (citric acid, acetic acid, and acidified water) and pH values (1.5–7) were evaluated, with citric acid (1% w/v) selected as the most suitable solvent due to its extraction efficiency and food-grade nature. Process optimization was performed using response surface methodology (RSM), considering liquid-to-solid ratio (5–15 v/w), extraction time (40–60 min), and temperature (70–90 °C). The regression models showed good fit, with R2 values of 88.79% for peel and 89.20% for pulp. Extraction yield was mainly influenced by liquid-to-solid ratio, time, and temperature, with optimal conditions defined as 10 v/w, 40 min, and 80 °C. Pectin obtained under optimized conditions was characterized by Fourier-transform infrared (FTIR) spectroscopy, showing functional groups consistent with commercial citrus pectin, while galacturonic acid content and degree of esterification confirmed its purity and classification as low-methoxyl pectin, supporting its suitability for further film production. Additionally, the extracted pectin was successfully incorporated into blended films with commercial pectin, resulting in films with improved water resistance and water vapor barrier performance. Overall, OFI cladodes represent a promising and sustainable source of pectin for biodegradable food packaging applications.