Enhanced Carrageenan Extraction from Chondrus crispus Using Pulsed Electric Field Pretreatment

Chondrus crispus is a major commercial source of carrageenan, a sulfated polysaccharide widely used in food and biotechnological applications. However, conventional hot water extraction methods often require prolonged heating and intensive processing, which can reduce extraction efficiency, increase energy consumption, and partially degrade carrageenan structure, thereby compromising functional properties and overall product quality. Improving extraction efficiency while preserving carrageenan structural integrity therefore remains a key challenge for sustainable macroalgal processing. In this study, pulsed electric field (PEF) pretreatment was evaluated as a non-thermal strategy to enhance carrageenan extraction from C. crispus harvested from the Norwegian coast. Biomass was subjected to PEF treatment at electric field strengths of 2.5 and 3.0 kV cm⁻¹ using pulse numbers ranging from 100 to 1500, followed by aqueous extraction. The results were compared with conventional hot water extraction (HWE). PEF pretreatment significantly influenced polysaccharide recovery, with the highest yield obtained at 3.0 kV cm⁻¹ and 1500 pulses, exceeding that of the HWE (p < 0.05). Protein content in the solid residues was not significantly affected by PEF intensity, indicating minimal protein solubilization or degradation. Monosaccharide analysis revealed galactose as the dominant sugar in all extracts, consistent with carrageenan-rich polysaccharides, with enhanced galactose recovery under optimized PEF conditions. Structural characterization by ¹ H and ¹³ C NMR spectroscopy confirmed the presence of mixed κ- and ι-carrageenan motifs across all treatments, with no evidence of major structural degradation. Overall, PEF-assisted extraction represents an effective and mild approach to improve carrageenan recovery from C. crispus while preserving polysaccharide structure, highlighting its potential for application in sustainable macroalgal biorefineries.