Explore the vast range of titles available.

Oyster shell waste has led to many problems, including displeasing odors, pollution of the seaside, and harm to the environment. Using calcined oyster shells as a natural preservative might solve the problem of oyster shell waste. We studied the use of calcined oyster shell powder (COSP) as a natural preservative for improving shrimp shelf-life over 12 days under refrigerated conditions. As compared with the control, COSP treatment effectively retarded pH change, reduced the formation of total volatile basic nitrogen, and inhibited bacterial growth during refrigerated storage. In addition, shrimp muscle lipid oxidation measured by peroxide value (PV) and thiobarbituric acid (TBA) was decreased during storage. The quality was preserved up to 12 days with 2.0–4.0% COSP treatment as compared with only 6 days for un-treated shrimp. The development of preservatives for aquatic products is expected to delay growth of and spoilage by microorganisms in the refrigerated state, thus providing more barrier protection for aquatic food safety.

The relationship between rheological properties and printability in 3D-printed recycled concrete incorporating calcined oyster shell powder (COSP) remains insufficiently understood. The unstable rheological behavior and insufficient buildability of 3D-printed recycled concrete limit its application in digital construction. In this study, the COSP, a marine solid waste-derived functional powder, was incorporated into 3D-printed recycled concrete to improve rheological behavior and printability. The effects of different COSP contents on rheological properties and structure build-up were assessed. In addition, MIP, XRD, and SEM analyses were used to clarify the underlying regulation mechanism. The results showed that COSP significantly improved the rheological properties of fresh paste. As the COSP content increased from 0% to 5%, the static yield stress, dynamic yield stress, and thixotropic recovery degree increased from 1703 Pa to 4561 Pa, from 92 Pa to 375 Pa, and from 56% to 87%, respectively. Meanwhile, the structural deformation rate decreased from 12.3% to 6.37%, corresponding to a reduction of approximately 48%. An appropriate COSP content also improved the mechanical properties, with the flexural strengths in the X and Y directions increasing to 5.17 MPa and 4.99 MPa, respectively, and the compressive strengths increasing to 26.04 MPa and 25.48 MPa, respectively. The microscopic performance results indicated that COSP refined the pore structure, promoted the formation of hydration products, and improved compactness. This study offers preliminary evidence for improving the printability of 3D-printed recycled concrete, while addressing the urgent environmental challenge of marine solid waste utilization and enhancing the economic feasibility and production efficiency of 3D-printed concrete.

Calcined oyster shell powder (COSP), a natural antibacterial agent derived from marine waste, was used in this study to treat postharvest green onions ( Allium fistulosum ), which are susceptible to microbial contamination during the washing process after harvesting. The green onions were dipped in COSP solutions of varying concentrations (0%, 2%, 4%, 6%, and 8%). This study investigated the effects of COSP treatment on the physicochemical properties and microbial activities of green onions. Compared to untreated green onions, COSP-treated green onions exhibited an extended shelf life to 28 days, evidenced by reduced weight loss by up to 9.84%, reduced the total bacterial count by up to 1.20 Log₁₀ CFU/g, stabilized pH level (5.28 ± 0.38–6.06 ± 0.20), preserved chlorophyll a and b content (0.40 ± 0.01–0.46 ± 0.01 and 0.17 ± 0.003–0.22 ± 0.007, respectively), enhanced antioxidant activity (DPPH scavenging activity up to 12.47%, ABTS value up to 82.94%), and better color appearance. Furthermore, COSP treatment was effective in preserving allicin (35.03 ± 0.77–45.07 ± 2.37%) content and inhibiting the degradation of cycloalliin (13.58 ± 0.08–16.48 ± 0.15 g/kg dry weight) and methiin (17.14 ± 0.10–19.41 ± 0.47 g/kg dry weight) in green onions, thereby preserving their fresh aroma. This study offers a novel postharvest preservation method for green onions using marine waste-derived COSP dipping, which helps reduce the loss of quality in postharvest products. Graphical abstract Highlights COSP-treated green onions exhibited longer shelf life and minimal microbial contamination. COSP maintained the overall quality of green onions under refrigeration. COSP inhibited the degradation of cysteine sulfoxides in green onions. COSP exhibited a cellular level benefit by maintaining vacuolar water content. Effective COSP concentrations ranged from 4% to 6%.

Marine fishery wastes such as bivalve shells, crab shells and cuttlebone are rich in calcium. Calcium carbonate derived from these materials can be transformed into calcium oxide by calcination, which is used in a wide variety of applications (e.g., biomaterials for bone and teeth implants and drugs). In this study we analyze the effects of calcination temperatures (550°C, 700°C and 900°C) on characteristics and elemental composition of calcium oxide derived from shells of four marine species collected in Thailand: oyster (Saccostrea cucullata), green mussel (Perna viridis), blue swimming crab (Portunus pelagicus), and cuttlefish (Sepia brevimana). The XRD patterns indicated the complete transformation of calcium carbonate into calcium oxide, observed by the changes of diffraction angles at 900°C for all calcined samples, except cuttlebone, which was calcined successfully at 700°C. Likewise, the FT-IR results revealed changes of functional groups at the same calcination temperatures. In addition, ICP-OES showed the effects of calcination temperature on elemental contents: major elements (Ca, P and K) increased in all samples, and some minor elements increased in blue swimming crab shell (Zn and Cu) and oyster shell (Fe) as a result of increasing the calcination temperature. This study demonstrates the optimum calcination temperature of calcium oxide production from four types of marine wastes that might be benefit for the chemical compound production industry.