Comparative studies of chemical composition of commercial and native edible macroalgae from Mar del Plata (Buenos Aires, Argentina): Mineral Content, lipids, and toxic metals

Macroalgae are recognized as a healthy food source due to their high content of minerals, lipids, and secondary metabolites. However, their ability to accumulate high concentrations of toxic metals, such as As, Cd, Cr, Hg, and Pb, among others, necessitates chemical studies to determine the benefits and risks associated with their consumption. The objective of this study was to analyze and compare the chemical composition of various macroalgae samples collected in Mar del Plata, Argentina, and commercial samples of Undaria pinnatifida. Mineral content was determined by ICP-MS, total polyphenols were measured using the Folin-Ciocalteu method in methanolic and aqueous extracts, and lipids were quantified gravimetrically. Significant differences were observed in the mineral composition between local samples of Ulva lactuca and U. pinnatifida. In U. lactuca, major metals included Ca, Fe, and Al, whereas Ca, Fe, and Sr predominated in U. pinnatifida. Notably, U. pinnatifida exhibited higher accumulation of Cr, As, and Pb. Commercial samples generally showed lower levels of toxic metals, with the exception of Cd and Hg. The Japanese Undaria sample presented elevated levels of As, Cd, and Pb, while the sample originating from China displayed high concentrations of Cr. Polyphenol extraction efficiency was greater with methanol. Lipid content was low (ranging from 3.4% to 4.3% of dry weight), with U. lactuca showing higher levels. These results highlight the chemical variability among macroalgae species and underscore the importance of conducting such studies to ensure safe consumption and promote the sustainable utilization of this resource.