Spirulina-Incorporated Biopolymer Films for Antioxidant Food Packaging

Growing environmental concerns and the need for sustainable materials have accelerated the search for biodegradable alternatives to food packaging. Since nearly half of global plastic production is dedicated to food packaging, and less than 5% is recyclable, developing eco-friendly solutions is urgent. Biopolymeric films enriched with microalgae and cyanobacteria have emerged as promising options due to their bioactive properties. This study screened 38 film-forming formulations combining different biopolymers with varying concentrations of Spirulina (0–5%) to identify the most suitable candidates based on physical and visual characteristics. Films produced with pectin and hydroxypropylmethylcellulose (HPMC) matrices were selected for detailed characterization, including physicochemical, optical, mechanical, thermal, barrier, surface, and functional group analyses, as well as antioxidant activity. The highest elongation at break (%) was observed in the control HPMC film (16.5 ± 3.85), whereas the lowest value was recorded for the pectin film containing 1% Spirulina (2.75 ± 0.49). In parallel, the highest thickness (mm) was found in the pectin film with 5% Spirulina (0.153 ± 0.018), while the lowest thickness occurred in the HPMC film incorporating 1% biomass (0.076 ± 0.004). The incorporation of Spirulina decreased solubility and moisture content while increasing opacity. HPMC-based films demonstrated superior mechanical strength, thermal stability, barrier performance, and significantly higher antioxidant activity compared to pectin films. Antioxidant activity increased with biomass concentration, peaking at 5% (HPMC: 320.08 ± 35.7 µmol TE/g; pectin: 36.92 ± 7.63 µmol TE/g). Overall, the HPMC film containing 1% Spirulina showed the best balance of properties, including mechanical behavior and antioxidant performance, indicating strong potential for food packaging applications, particularly for protecting light-sensitive and oxidation-prone foods.