Study of the variability in time and space of the antioxidant activity and biochemical composition of Kappaphycus alvarezii at different stocking densities

Abstract

Kappaphycus alvarezii is a species of algae most cultivated in the world, due to its high content of bioactive compounds with reported antioxidant and biostimulant activities. The present study evaluated the effect of stocking densities on the biochemical and antioxidant composition of K. alvarezii cultivated in a long-line system, during the dry and wet seasons to provide a scientific basis for optimal harvesting. Moisture content, ash, fat, fiber, auxins, phenols, flavonoids, DPPH, and ABTS were measured. Data were analyzed using t-tests, Wilcoxon, Kruskal-Wallis, and one-way ANOVA. The results showed a higher fat content (2.01% P.s), crude fiber (5.21% P.s), total phenol content (324.09 μg GAE/g P.s), and ABTS (9.32 μg GAE/g P.s) during the dry season. Concerning the stocking density, a significant increase in the content of ash, total phenols, and ABTS was evidenced in the density of 10 lines.cell-1 at the same time. On the other hand, the content of flavonoids, DPPH, and auxins showed an opposite seasonal trend, reaching maximum levels in the wet season. This study provides new information on the environmental conditions that can lead to changes in the antioxidant activity and biochemical composition of this species to develop bioproducts for different industrial sectors such as food, pharmaceutical, and fertilizer in Ecuador.