Enhancement of phenolics extraction from red algae (Kappaphycus spp.) using solid-state fermentation

The effects of solid-state fermentation (SSF) on microbial growth contribute to the bio-enrichment and availability of phenolic compounds in different varieties of Kappaphycus spp. red algae through the action of hydrolytic enzymes produced are investigated. Three different red algae samples were used; K. striatum var. green flower (GF), K. alvarezii var. white giant (WG) and K. alvarezii var. purple giant (PG). SSF was performed using A. oryzae for 0 to 6 days at 30°C. Results obtained demonstrated that the highest (p<0.05) extraction of phenolics (10.022 mg GAE/g and 14.90 mg CE/g), and antioxidant properties (72.47% activity of DPPH radical scavenging and 18.23 mM/g FRAP value respectively) was obtained for GF sample at day 4 of fermentation. Cellulase, β-glucosidase, and xylanase were found to be responsible for enhancing phenolics and antioxidant activity of WG and GF varieties by releasing bound phenolics. However, for the PG sample, β-glucosidase showed a significant relationship with TPC and antioxidant activity.