Biodegradable, additive-free gluten leather mimicking animal leather's mechanics and tactility via depth-specific thermal and UV programming.

The production of nitrogen-based nutrients is a major contributor to climate change, with industrial ammonia synthesis releasing over 500 million tonnes of CO₂-equivalents annually—more than 1.2% of global anthropogenic greenhouse gas (GHG) emissions. This is largely due to the fossil fuel–intensive Haber–Bosch process, which remains the dominant pathway for reactive nitrogen production in global food and feed systems. However, emerging alternatives such as marine biological by-products offer a fundamentally different nitrogen sourcing pathway. In this study, we conducted a comparative life cycle assessment (LCA) of greenhouse gas emissions for peptones derived from marine fish head waste (cutlassfish, salmon, tuna) and conventional land-based sources (soybean, skimmed milk). Marine-derived peptones exhibited substantially lower greenhouse gas emissions (GWP100) —9, 4.5, and 2.6 kg CO₂-eq, respectively—compared to 22 kg for soybean and 64 kg for skimmed milk. When weighted by global production volumes, the average greenhouse gas emissions (GWP100) were 5.8 kg CO₂-eq for marine-based peptones and 49.6 kg CO₂-eq for land-based peptones—an 88% reduction. Scenario-based analysis showed that marine systems, due to their centralized and energy-intensive nature, achieved up to 90.7% additional reductions in greenhouse gas emissions under renewable electricity substitution. To ensure methodological robustness, we applied the A–B comparison framework—which reduces attributional bias when comparing systems with differing co-product structures—and found that marine-based peptones consistently outperformed land-based alternatives across all simulation runs. These findings highlight the potential of fish-processing waste valorization as a low-impact nitrogen source and underscore its strategic role in developing climate-resilient biotechnologies and sustainable protein supply chains.

Fish waste disposal poses significant environmental and economic challenges, limiting sustainability in the marine food industry. Hence, sustainable valorization strategies are needed to enhance resource recovery while minimizing waste. As an approach, this study aimed to evaluate the potential of converting chum salmon (Oncorhynchus keta) head (CSH) waste into a high-value peptone for microbiological applications. Various proteolytic enzymes were screened for CSH hydrolysis, among which Protamex achieved the highest hydrolysis and recovery rates. The resulting chum salmon head peptone (CSHP) exhibited favorable characteristics, including a low average molecular mass (557 Da) and a high amino nitrogen content (4.9%), outperforming commercial animal (AP) and vegetable (VP) peptones. To assess its biotechnological potential, CSHP was evaluated as a nitrogen source for recombinant protein production and supported higher expression of human superoxide dismutase (hSOD) and human growth hormone (hGH) in Escherichia coli BL21(DE3), compared with AP, VP, and Luria–Bertani (LB) media. Furthermore, life cycle assessment revealed a substantially lower carbon footprint for CSHP production than that of conventional peptone sources. These findings suggest that CSHP is a reliable and sustainable alternative to traditional peptones, offering both therapeutic and industrial applications while contributing to marine waste reduction and circular bioeconomy strategies.