Circular packaging solutions: Active films from food waste pigments and meat industry co-products

This study explored the valorisation of food waste-derived pigments from blackberry pomace, red cabbage, and beetroot peel for the development of smart, biodegradable packaging films based on blood plasma and gelatin biopolymers. Pigments (anthocyanins and betalains) were extracted using ultrasound-assisted techniques, where probe ultrasound yielded markedly higher pigment concentrations than bath ultrasound (Total Anthocyanin Content, TAC (2921 vs. 814 mg/L) and Betalain Content, BC (604 vs. 446 mg/L). Ethanol-assisted extraction significantly enhanced anthocyanin recovery (330 vs. 234 mg/L, P < 0.005), while BC was greater in beetroot peel than flesh (985 vs. 604 mg/L, P < 0.002). Incorporation of these pigments into plasma-based films substantially increased antioxidant activity with beetroot peel extract showing the highest activity (P < 0.0001). Shelf-life evaluation revealed significant film × storage time interactions for lipid oxidation (P < 0.0001), with TBARS values remaining as low as 1.5-2.4 mg MDA/g in pigment -infused films after 9 days of refrigerated storage compared with 7.1 mg MDA/g in the control. Total viable counts and pH remained stable across treatments and time (P > 0.05), indicating no adverse microbial or physicochemical effects. Although the influence of pigment addition on mechanical performance of the film is mixed between biopolymers, gelatin films generally exhibited superior tensile (9.55 vs 3.01 MPa, P < 0.0001) and seal strength (397 vs 209 N/m, P < 0.0001) compared to plasma-based films. Further analyses showed improved thermal stability and molecular integration upon pigment incorporation. Collectively, these results highlight the feasibility of upcycling food processing by-products into protein-based active films offering a promising pathway toward sustainable, circular food packaging systems.