An efficient method for producing polysaccharides with high antioxidant activity from Caulerpa lentillifera and evaluating their stability

Algal polysaccharides are widely utilized in various industries due to their functional and bioactive properties. However, commercial-scale polysaccharide production requires simple, efficient, and low-cost processes. This study developed a practical and scalable method for producing polysaccharides from Caulerpa lentillifera. Given its high moisture and polysaccharide content, a squeezing method followed by spray drying was evaluated. The squeezed fresh polysaccharide (SFP) exhibited higher levels of bioactive compounds and stronger antioxidant activity than the polysaccharide extracted at 90 ◦C (90-FP). Similarly, the spray-dried polysaccharide (SDP), obtained from squeezing and spray drying, showed superior bioactive compound content and antioxidant activity compared to the ethanol-precipitated polysaccharide (EPP). The SDP extract contained 51.25 % total sugars, 7.33 % sulfates, 2.62 % uronic acid, 7.99 % protein, and 8.64 mg GAE/g total phenolic content. It exhibited strong antioxidant activity, with 50 % inhibitory concentration (IC50) values of 0.73 mg/mL for 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, 9.57 mg/mL for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 26.96 mg/mL for lipid peroxidation (LPO) inhibition, and 0.88 mg/mL for ferrous ion-chelating (FIC) ability. Its ferric-reducing antioxidant power (FRAP) was 7.49 mg Fe2+/g extract. Additionally, the SDP extract demonstrated high stability suitable for industrial application, with a shelf life of 8.78 months and a half-life of 57.76 months at room temperature.