Green Extraction of Phenolic Compounds and Carrageenan from the Red Alga Kappaphycus Alvarezii

Kappaphycus alvarezii (KA) is a widespread worldwide alga, and one of the main industrial sources of carrageenan. Besides, KA biomass also contains other substances such as phenolic compounds and fatty acids that can be recovered by several methods. Then, this work aimed to investigate the eco-friendly methods, for the recovery of fatty acids, phenolics, and carrageenan fractions. The eco-friendly methods are faster, produce higher yields, and can be cost-effective in comparison with conventional methods. The performance of the eco-friendly methods (supercritical fluid, pressurized liquid, microwave assisted, and high-pressure carrageenan extractions) was compared with conventional techniques (maceration or Soxhlet) in terms of yield, chemical profile by gas and liquid chromatography, total phenolic content (TPC), antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) procedures, viscosity and gel strength of the carrageenan fraction. The results showed pressurized liquid extraction samples with the highest antioxidant potential and TPC (up to 2 to 4 times higher than conventional). Besides, the carrageenan fraction was efficiently recovered by microwave assisted extraction (MAE) and by pressurized-water carrageenan extraction (PWCE), and the samples presented viscosity and gel strength similar to that obtained by water maceration.