Unlocking the Biochemical Potential of Diadema setosum Tests: A Pathway Toward Circular Marine Bioeconomy

This study investigates the biochemical and elemental composition of the test of Diadema setosum (D. setosum), a sea urchin species increasingly processed in Turkey, where the shell is commonly treated as industrial waste. Specimens were collected from the Mediterranean and Aegean Seas, and the test material was subjected to amino acid profiling, protein quantification, and X-ray fluorescence (XRF) analysis. The results revealed a considerable protein content (8.03%) and a rich amino acid spectrum dominated by glycine, aspartic acid, and arginine, supporting the presence of residual structural proteins even after processing. Mineral analysis showed a high calcium oxide concentration (43.19%), alongside significant levels of magnesium, phosphorus, strontium, and trace elements such as zinc, copper, and molybdenum. Rare earth elements and radionuclides including neodymium, samarium, and uranium were also detected, suggesting sediment interaction. These findings suggest that D. setosum tests could represent a sustainable source of bioavailable minerals and proteinaceous material, with prospective applications in fish or livestock feed, hydroxyapatite synthesis, or calcium oxide production, pending further validation.