Protein-based foams are potential sustainable alternatives to petroleum-based polymer foams in e.g. single-use products. In this work, the biodegradation, bioassimilation, and recycling properties of glycerol-plasticized wheat gluten foams (using a foaming agent and gallic acid, citric acid, or genipin) were determined. The degradation was investigated at different pH levels in soil and high humidity. The fastest degradation occurred in an aqueous alkaline condition with complete degradation within 5 weeks. The foams exhibited excellent bioassimilation, comparable to or better than industrial fertilizers, particularly in promoting coriander plant growth. The additives provided specific effects: gallic acid offered antifungal properties, citric acid provided the fastest degradation at high pH, and genipin contributed with cross-linking. All three additives also contributed to antioxidant properties. Dense beta-sheet protein structures degraded more slowly than disordered/alpha-helix structures. WG foams showed only a small global warming potential and lower fossil carbon emissions than synthetic foams on a mass basis, as illustrated with a nitrile-butadiene rubber (NBR) foam. Unlike NBR, the protein foams could be recycled into films, offering an alternative to immediate composting.

The proliferation of petroleum-derived plastics has led to environmental concerns, prompting the exploration of sustainable alternatives. This study deals with the development of natural polymeric composite materials that can be used as alternatives to conventional plastics. In particular, biocomposite films were prepared by hot pressing a blend of carrot pomace (CP) with 10, 30 and 50 wt% of two vegetable proteins: wheat gluten (Gn) and zein (Z), for the optimization of the final properties of the developed biomaterials. The resulting composites exhibit improved physicochemical, morphological, and thermal properties and provide enhanced water resistance compared to CP-only bioplastics, while in particular, the ones prepared with Gn, exhibited also improved optical and mechanical properties, making Gn composites best candidates for a larger number of applications. Further optimization was achieved by adding 10 wt % polyglycerol plasticizer to the CP-50 wt% Gn composites, resulting in even better mechanical and oxygen barrier properties. These biocomposites show great potential for food packaging, offering mechanical resistance (elastic modulus of 244.9 +/- 25.3 MPa and tensile strength of 10.1 +/- 0.7 MPa), flexibility (elongation at break of 24.7 +/- 5.7%), high transparency and optical clarity, effective UVblocking in the 200-350 nm range, excellent antioxidant activity (3.4 mu mol Trolox/g) and water vapor (1.3 x 10-9 g s-1 m- 1 Pa-1) and oxygen (296.1 +/- 1 cm3 mu m m- 2 day-1 atm- 1) barrier properties. Additionally, they exhibit low migration of components into food simulants (6.7 +/- 0.6 mg dm-2) and fast biodegradation in soil (83% after 30 days). The findings reported in this manuscript motivate the adoption of eco-friendly materials and represent a significant step towards a sustainable future.

The production of biodegradable gluten-based protein foams showing complete natural degradation in soil after 26 days is reported, as an alternative to commercial foams in disposable sanitary articles that rely on non- biodegradable materials. The foams were developed from an extensive evaluation of different foaming methodologies (oven expansion, compression moulding, and extrusion), resulting in low-density foams (ca. 400 kg/ m3) 3 ) with homogenous pore size distributions. The products showed the ability to absorb 3-4 times their weight, reaching ranges for their use as absorbents in single-use disposable sanitary articles. An additional innovative contribution is that these gluten foams were made from natural and non-toxic wheat protein, glycerol, sodium and ammonium bicarbonate, making them useful as fossil-plastic-free replacements for commercial products without the risk of having micro-plastic and chemical pollution. The impact of different processing conditions on forming the porous biopolymer network is explained, i.e., temperature, pressure, and extensive shear forces, which were also investigated for different pH/chemical conditions. The development of micro-plastic-free foams mitigating environmental pollution and waste while using industrial co-products is fundamental for developing large-scale production of single-use items. A sanitary pad prototype is demonstrated as an eco-friendly material alternative that paves the way for sustainable practices in manufacturing, and contributes to the global effort in combating plastic pollution and waste management challenges, Sustainable Development Goals: 12, 13, 14, and 15.