Sustainable Synthesis of Calcium Propionate from Cockle Shell Biowaste for Food Additive Production

Calcium propionate (Ca(CH3CH2COO)2) was successfully synthesized from cockle shell biowaste through a reaction with propionic acid at concentrations of 80%, 90%, and 99%, valorizing seafood processing biowaste as a renewable calcium source in support of circular economy principles. The synthesis was conducted at ambient temperature with a fixed CaCO3: propionic acid molar ratio of 1:2, enabling rapid reaction completion without external heating or complex purification steps. The prepared samples were characterized by FTIR, XRD, TGA, and SEM techniques, which confirmed the formation of calcium propionate monohydrate (Ca(CH3CH2COO)2·H2O), while XRF confirmed more than 97 wt% CaO across all samples with non-toxic impurities corresponding to compositional requirements for food additive calcium propionate (E282). The sample prepared using 80% propionic acid exhibited the highest yield (90.24%) and soluble percentage (98.23%). The proposed approach demonstrates an effective valorization of cockle shell waste into a food additive, calcium propionate, offering advantages in terms of sustainability, cost efficiency, and scalability, and highlighting its strong potential for industrial food additive production within a circular economy framework.