The rising global population necessitates increased urbanization and food waste management. Eggshells, a significant portion of this waste, present an opportunity for sustainable resource recovery and value-added product development. This research aims to mitigate global food waste by utilizing poultry eggshell waste from chickens, ducks, and ostriches as a cost-effective source of calcium chloride (CaCl۲). The eggshells were treated with hydrochloric acid and subjected to different drying methods—spray, freeze, and oven drying. This study evaluates the efficacy of the extracted CaCl۲ in the cheese-making industry, specifically for Iranian high-fat white cheese, and compares its performance to a standard Merck sample. The highest yield of CaCl۲ (۹۲.۴۶%) was achieved from chicken eggshells using the oven drying method, while the lowest yield (۷۵.۴۶%) occurred with ostrich eggshells via spray drying, with the purity of extracted CaCl۲ comparable to the Merck standard. Maximum cheese yield (۱۲.۶۹%) was obtained using unpasteurized milk with Merck CaCl۲, whereas the lowest yield (۱۱.۰۲%) was observed with pasteurized milk without it. The purity of CaCl۲ significantly influenced lipolysis and proteolysis during cheese-making. While no significant pH differences were noted among cheeses made with eggshell-derived CaCl۲, the NCaCl۲-NP sample exhibited the highest pH, resembling the Merck sample. Moisture content variations aligned with pH trends, whereas syneresis exhibited an inverse relationship, highlighting the role of poultry eggshell-derived CaCl۲ in cheese texture and quality. Despite no significant differences in the L index or whiteness among cheeses produced from different drying methods, those made with chicken eggshells, particularly via oven and freeze drying, exhibited the lowest color quality. The textural properties of high-fat white cheese made with poultry eggshell-derived CaCl۲ were generally comparable to the control (Merck-P), suggesting its viability in maintaining cheese texture. This study underscores sustainable waste management and promotes a circular economy through effective utilization of eggshell waste.
