Abstract
The aim of the study was to evaluate how controlled laboratory addition with Pb, Cd, and Cu affects the fatty acid profile of milk and acid-coagulated cheese from three geographical regions (R1, R2, R3), considering the influence of regional characteristics and the March–April 2025 harvesting period. Comparative analysis of the lipid profile (SFA and UFA) and the ratios between fatty acids showed that region R2 displayed the most balanced nutritional structure, followed by regions R1 and R3. The lipid indices (IA 2.5–4, IT 3–4.4, HH 0.4–0.6, HPI 0.2–0.4) confirmed this pattern across all regions, indicating that R2 is characterized by a favorable, antiatherogenic, and antithrombotic lipid profile, whereas R1 exhibits an intermediate profile and R3 a markedly unbalanced profile. The same trend was observed for the lipid composition of the blank cheese samples. Heavy metal fortification produced major shifts in fatty acid composition and lipid indices. At the maximum level permitted by legislation, the changes were moderate, with SFA increasing from 71% to 77% and essential ω-3 and ω-6 PUFA decreasing, resulting in increased IA and IT and reduced HH and HPI. At 10× the maximum limit, the lipid profile became severely unbalanced: SFA increased to 81%, UFA dropped to 17%, ω-3 fatty acids were nearly absent, and ω-6 levels declined sharply, amplifying their imbalance. These changes were accompanied by a substantial deterioration in all lipid indices. These findings demonstrate that fatty acid composition (SFA, MUFA, PUFA) and lipid parameters (IA, IT, HH, HPI) serve as highly sensitive markers of heavy metal-induced oxidative stress in dairy products. Overall, the study shows that while the fatty acid profiles of milk from different regions reliably indicate both geographical origin and nutritional quality, exposure to heavy metal addition profoundly disrupts these profiles, together with their lipid indices, producing changes significant enough to signal compromised safety and diminished functional value of the resulting cheese.