Effect of drying biomass protocols on bioactive compounds, antioxidant and enzymatic activities of the red macroalga Kappaphycus alvarezii

Abstract Kappaphycus alvarezii is a red seaweed widely used throughout the world, with applications in various biotechnological processes. In this sense, the contents and stability of bioactive compounds of interest synthesized by this seaweed species must be guaranteed in post-harvest, by adopting suitable drying protocols of biomass (e.g.) that allow furnishing high-quality raw material for industrial usage. This study aimed to analyze the influence of commonly used drying methods, i.e., freeze-drying and oven-drying, on the total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (FRAP and DPPH assays), total carotenoid content (TC), and lipase (LA) and protease activities (PA) of K. alvarezii samples collected over the seasons in sea farms in southern Brazil. The freeze-drying technique showed to be more effective regarding superior contents of TPC and TC, besides antioxidant activity (DPPH assay). In its turn, oven-drying proved to be the best method regarding the TFC and PA, with better performance in the FRAP assay. In this way, it appears that the drying process of the algal biomass can be selected depending on the required traits of the biomass for the intended industrial application.