Is Australian seaweed worth eating? Nutritional and sensorial properties of wild-harvested Australian versus commercially available seaweeds

This study aimed to determine the nutritional composition, perceived quality and palatability of nine Australian seaweeds (wild-harvested species not yet exploited for human consumption; Laurencia filiformis, Codium galeatum, Cystophora polycystidea, Cystophora torulosa, Phyllotricha decipiens, Durvillaea potatorum, Hormosira banksii, Phyllospora comosa, Ecklonia radiata), and compare them to four of the commonest commercially available species (Pyropia tenera, Sargassum fusiforme, Saccharina angustata, Undaria pinnatifida). Nutritional value varied amongst species and inconsistently with time. Four Australian species had higher total lipids than all commercial products in this study and amongst the highest values reported in the literature for seaweeds. Moreover, nine out of 13 species had an omega-6 and omega-3 fatty acid ratio favourable for human health (≤ ~ 1). Eicosapentaenoic acid (EPA) was present in higher concentrations than docosahexaenoic acid (DHA) in all species. Highest DHA concentrations were found in Australian species, whilst EPA was very much higher in Pyropia tenera (nori) than all other species. Crude-fibre and protein contents were high for most Australian and commercially available species on a dry weight basis. A subset of Australian and commercially available seaweeds was prepared and cooked as soup or salad for sensorial (organoleptic) evaluation. There were no significant differences in consumer acceptance of any seaweeds when prepared in the soup, but acceptance of the salad dishes differed significantly, influenced primarily by a preferred texture of commercial hijiki (S. fusiforme) over the Australian species. This study identifies specific Australian seaweeds that may be viable as commercial foods. Regular consumption of 10 g (dwt) of a mixture of the seaweeds tested in this study may improve human health by contributing health-promoting fatty acids, fibre and protein to an omnivorous diet, with higher levels of consumption required for vegetarians and vegans to meet daily requirements of favourable fatty acids and protein from non-animal sources. However, further research must also examine potentially toxic effects of regularly consuming seaweeds in these quantities.