Incorporation of safflower extract into sodium alginate and polyvinyl alcohol films: impact on physicochemical properties and food packaging applications

This study investigated the physicochemical, mechanical, and antioxidant properties of sodium alginate (SG) and polyvinyl alcohol (PVA) films with safflower extract (SF) for food packaging. Three formulations were developed: a control (SG/PVA) and two experimental films with SF at 3% (SG/PVA/SF1) and 5% (SG/PVA/SF2) of total polymer weight. The films were evaluated for physical properties, colour, mechanical performance, total phenolic content (TPC), and antioxidant activity (DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-azino-bis(3-etilbenzotiazolin-6-sulfonic acid) assays). SF significantly enhanced antioxidant properties, with SG/PVA/SF2 showing the highest TPC (62.03 mg/100 g) and antioxidant activity (30.75% DPPH, 45.91% ABTS), compared to SG/PVA (15.39 mg/100 g, 3.80% DPPH, 11.56% ABTS). In storage tests, SG/PVA/SF2 reduced weight loss after 14 days (6.23%) versus unwrapped dates (12.87%) and improved colour retention (L = 66.46, a = 12.69, b = 52.53) and firmness (21.02 N vs. 12.63 N). X-ray diffraction analysis revealed that SF disrupted crystallinity, resulting in flexible, amorphous structures. SF-enriched SA/PVA films reduced weight loss in Barhi dates, from 12.87% (unpackaged) to 10.17% (SA/PVA), 6.42% (SF1), and 6.23% (SF2), while SF2 preserved higher firmness (21.02 N) than the control (12.63 N). These results demonstrate the films' potential to enhance antioxidant and barrier properties, extend fruit shelf life, and serve as sustainable packaging.