From Agro‐Industrial Waste to Functional Packaging Using Antimicrobial and Mechanically Reinforced Starch Foams With Melon Seed and Rosemary

ABSTRACT The demand for sustainable alternatives to petroleum‐based packaging has promoted starch‐based materials; however, low mechanical strength and limited functionality restrict their application. Expanded starch foams were developed from agro‐industrial by‐products by combining melon seed flour as reinforcement and rosemary ( Salvia rosmarinus ) flour as a source of antimicrobial compounds. Five formulations were produced: a starch control and composites containing rosemary flour (25%), melon seed flour (25%), or combinations of melon seed (15%) and rosemary (15%–25%) flours. Materials underwent thermal compression molding and were characterized for mechanical, physical, thermal, and color properties, as well as antibacterial, antifungal, and biodegradation performance. Compared with the starch control, the incorporation of rosemary flour increased hardness (up to 26.5 Shore D) and contributed to higher tensile strength (up to 1.60 MPa), while formulations containing melon seed flour improved the flexural mechanical performance (Young's modulus 879 MPa). The combined system exhibited selective antibacterial activity against Bacillus cereus , Salmonella enteritidis , and Pseudomonas aeruginosa , with inhibition zones up to 13 mm, and antifungal activity against Penicillium roqueforti . Biodegradation tests showed 70%–80% disintegration within 5 weeks in a composting environment. These findings demonstrate a viable strategy for valorizing agro‐industrial waste into functional packaging materials, with potential applications for low‐moisture foods.