Effect of processing conditions on phytochemical constituents of edible irish seaweed himanthalia elongata

Seaweed is well recognized as an excellent source of phytochemicals. This study was a preliminary screening to investigate the effects of various food processing methods on the phytochemicals of Himanthalia elongata. Hydrothermal processing was carried out until an edible texture was achieved. The total phenolic content (TPC) of fresh H.elongata was 175.27mg gallic acid equivalent (GAE)/100g fresh weight (FW) while boiling significantly reduced the TPC to 25.4mg GAE/100g FW (P<0.05). A drying pretreatment before boiling reduced the cooking time therefore leading to less leaching of antioxidants upon boiling. In terms of extract, drying of H.elongata followed by boiling had the most significant effect on the phytochemicals as TPC increased by 174%. Boiled extracts had the most effective 2, 2-diphenyl-1-picrylhydrazyl scavenging activity (EC ₅₀ of 12.5μg/mL). As a comparison, seaweed subjected to the same treatments was studied in terms of antimicrobial activity. Overall, extracts from fresh H.elongata achieved the highest inhibition.