Proximal Composition of Undaria pinnatifida from San Jorge Gulf (Patagonia, Argentina)

Undaria pinnatifida is a brown macroalga considered a high quality natural food because of its numerous health benefits. The aim of this paper is to provide seasonal information on the chemical content of blades and sporophylls of U. pinnatifida from San Jorge Gulf (SJG, Chubut, Argentina) in order to evaluate their different uses. Moreover, samples of algae deposited on the beach are also studied. A multi-elemental analysis is made by Total Reflection X-ray Fluorescence (TXRF). Sixteen elements are quantified: As, Br, Ca, Cr, Cu, Fe, K, Mn, Ni, P, Pb, Rb, S, Sr, V and Zn. The results reveal that the mineral content in blades of U. pinnatifida is high, especially in autumn. Some elements show an important seasonal variation, such as: K (14-54.8 g kg^-1), P (2.7-7.0 g kg^-1), Sr (361-569 mg kg^-1), Fe (62-140 mg kg^-1), Zn (8-103 mg kg^-1), Br (45-94 mg kg^-1) and Rb (4-24 mg kg^-1). In the case of potentially toxic elements, a variation was seen mainly in arsenic, with higher values during summer and autumn. The concentrations of nickel and lead are below the limit of detection (0.9 mg kg^-1). Sporophylls contain high concentrations of macro and micronutrients, with maximum values in spring. Besides, reproductive structures showed higher total arsenic values than blades. This could indicate that arsenic is mainly accumulated in sporophylls. Algae deposited on the beach are considered a waste; but they show a similar elemental composition to the samples extracted from the sea. We concluded that all samples analyzed could be used as food or fertilizers by local populations.