Development of Biodegradable Straws Using Spent Coffee Grounds

The aim of the work was to innovate in the field of biodegradable straws by valorizing waste materials, specifically spent coffee grounds (SCG), in combination with food-grade biopolymers. Biodegradable straws were produced using pork gelatin and three starch types (corn, rice, and potato) via a dipping technique designed to ensure reproducible layer formation and structural stability. The prepared straws were analyzed for their physicochemical, antioxidant, textural, and solubility properties. Antioxidant potential was assessed using multiple assays (FRAP, ABTS, and CUPRAC), along with determinations of total polyphenol and flavonoid contents. Texture analysis was conducted to evaluate hardness, fracturability, and compression in comparison with commercial paper and plastic straws. Biodegradability was examined through solubility tests in distilled and seawater. The addition of SCG markedly enhanced antioxidant capacity and increased polyphenol and flavonoid contents, while starch type influenced mechanical performance, with rice starch-based straws showing the highest hardness values. All straws demonstrated complete dissolution in both distilled and seawater within 24 h, confirming rapid biodegradation. The results highlight the dual advantage of SCG incorporation: improving functional properties through antioxidant enrichment and reinforcing environmental sustainability by valorizing food industry waste. This study demonstrates the potential of SCG-enhanced straws as a scalable and eco-friendly alternative to conventional single-use plastics.