Impact of post-harvest processing on Alaria esculenta and its application in a model fish-based product

Alaria esculenta is a promising seaweed species for food applications due to its nutritional composition. However, its high content of iodine as well as its short shelf life after harvesting, makes post-harvest processing necessary. Processing of biomass may affect its functional properties, flavour, and nutritional contribution. This study evaluated the effects of four post-harvest processing methods: pulsed electric field (PEF), ultrasound (US), warm water treatment (WWT), and WWT combined with freezing and thawing (WWT-FT) on the nutritional value and safety of cultivated Norwegian A. esculenta. Processed seaweed was analysed for dry matter, ash, free and total amino acids, minerals and metals, and then incorporated into fish patties to assess sensory, textural, and nutritional impacts. Processing significantly reduced ash and iodine concentrations while increasing protein content and essential amino acid ratios. Free amino acids, including flavour-enhancing compounds such as glutamate and alanine, were reduced. Iodine concentrations were reduced by 68–85 %.The relative concentration of other PTEs incl. cadmium, mercury, and lead levels increased in most treatments, though remaining within acceptable limits. The inclusion of processed A. esculenta in fish patties had minimal impact on flavour, odour, and overall sensory profile, though WWT and US treatments increased rubbery texture. The sodium-to-potassium (Na/K) ratio in seaweed was reduced to below 0.60 in most treatments, supporting its potential use as a salt replacer. These findings suggest that post-harvest processing can improve the safety and nutritional quality of A. esculenta, enabling its integration into commonly consumed foods like fish patties.