Heat-Induced Changes in Avian (Cortical and Medullary) Bone Mineral Reactivity, Solubility, and Adsorption Capacity

Two types of bone tissue from laying henscortical and medullary bonewere selected to investigate how differences in structure, organization, organic matrix composition, mineral properties, and functionality, further potentiated following upon a thermal treatment (up to 800 °C), influence mineral reactivity, dissolution, and adsorption behavior, using Pb as a model adsorbate. At lower temperatures (<400 °C), water and organic components are progressively removed, resulting in a more porous mineral structure with increased surface area. At higher temperatures (>600 °C), sintering promotes the coarsening of apatite crystals, leading to a reduction in surface area. Simultaneously, the loss of organic matter and the diffusion of foreign ions (e.g., Mg and Na) from the apatite lattice to the crystal surface alter both surface chemistry and charge. Bone mineral solubility and adsorption were strongly influenced by both bone type and treatment temperature. Medullary bone exhibited significantly higher solubility than cortical bone, particularly at intermediate treatment temperatures. This behavior appears to be primarily controlled by the organic matrix (e.g., collagen and proteoglycans) and the manner in which these components interact with or adsorb onto crystal surfaces. Pb adsorption was governed by both surface area and chemical composition, and predominantly occurred via a coupled dissolution-precipitation mechanism. Specifically, the dissolution of Ca-apatite was accompanied by the formation of highly insoluble Pb-bearing mineral phases at the bone surface. This process was notably more efficient in thermally treated medullary bone. Overall, this study demonstrates how key bone properties can be tailored for specific applications, highlighting the potential for revalorizing bone waste from the meat industry.