Effect of drying treatment on the extractability and anti-inflammatory function of photosynthesis-related components in dulse Palmaria palmata and their efficient recovery from dried thallus

In manufacturing industries that use seaweeds containing high moisture as raw materials, the volume reduction of seaweeds is a basic requirement for their efficient storage, transport, and processing. In this study, fresh red algae, dulse Palmaria palmata was hot air–dried at 30 and 60 °C with or without pre-freezing for 1 week, and anti-inflammatory components, phycobiliprotein (P) and chlorophyll a-related compounds (C) were extracted together using water from the dried thalli. The water extractability of each was diminished by pre-freezing and markedly impaired by hot-air drying of the raw dulse. In contrast, the anti-inflammatory activity of thermolysin digested P and C mixtures, which was evaluated using lipopolysaccharide-stimulated murine macrophages, persisted despite exposure of the raw materials to the freezing and hot-air-drying processes. In addition, the deterioration in the extractability of P caused by hot-air drying was recovered by the enzymatic degradation of the cell wall hardened by drying, and the water extract showed strong anti-inflammatory activity. These results indicated that hot-air–dried dulse can be used as an anti-inflammatory material by utilizing the appropriate physicochemical procedure for restoring the extractability of the anti-inflammatory components, and enzymatic algal cell degradation is one such practical countermeasure.