Greenland seaweeds for human consumption

Abstract

Seaweeds, i.e., marine macroalgae, have gained increasing interest as food in the Nordic countries in recent years. Greenland, geopolitically a part of Europe as a self-governing region within the Kingdom of Denmark, currently imports most if its food. Locally harvested and produced seaweed could contribute to a more sustainable food landscape, and open new possibilities for export. Seaweed is a part of the traditional Greenland Inuit diet, though not widely consumed any more. Furthermore, knowledge on the nutritional composition and possible harmful compounds of Greenlandic seaweeds is scarce. The overall aim of this PhD study was to characterise seaweed species from Greenland regarding their potential use as food items. The aim was therefore to determine the nutritional composition, contaminants, and anti-nutritional factors. Furthermore, the influence of anthropogenic microbial and chemical contamination was investigated. The influence of processing in the form of washing and blanching on the shelf-life of fresh seaweed was also studied. Finally, this project aimed to quantify the impact of increased local seaweed harvesting and culture in Greenland within the framework of the United Nations Sustainable Development Goals (SDGs). The nine brown and one red seaweed species investigated had different nutritional profiles considering elemental composition (As, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Se and Zn), iodine, proteins, fatty acids, amino acids, antioxidants. However, they shared some similarities within groups: the fucoids (Ascophyllum nodosum, Fucus distichus and Fucus vesiculosus) and the kelps (Hedophyllum nigripes, Laminaria solidungula, Saccharina latissima and Saccharina longicruris), except for the kelp Agarum clathratum, which had a vastly different profile from the other kelps. The red seaweed Palmaria palmata also showed a different profile compared to the brown seaweeds investigated. High iodine content was identified as an issue in all brown seaweeds, but none of the common contaminants typically associated with seaweed (arsenic, cadmium, lead, and mercury) were at concerning levels. However, due to high potassium concentrations, patients on low potassium diets would obtain a significant part of their recommended daily intake from the consumption of H. nigripes, L. solidungula or S. longicruris. Kainic acid was detected in P. palmata but was not evaluated to be a hazard. Anthropogenic contamination was both evident in elemental profiles as well as through microbial contamination. Therefore, it is recommended to avoid harvesting close to, and downstream from, wastewater discharge into the sea. A shelf-life study of Danish S. latissima washed or blanched in either potable or seawater suggested a maximum refrigerated shelf-life of 7 days, stored at 3 ℃. Bacterial spoilage was driven by Pseudomonas spp. and Shewanella spp. Blanching successfully increased some posivitive odour attributes and changed the colour of the seaweed from brown to green, making it an interesting tool for culinary experiments, and product development. This study serves as an important contribution to the understanding of food quality and storage life in general and should be repeated with Greenlandic seaweed to validate the findings. An increased seaweed harvest and cultivation in Greenland would most positively impact SDGs 8 (Decent work and economic growth), 12 (Responsible consumption) and 14 (Life below water), and most negatively SDG 13 (Climate action). Reducing energy consumption and shifting to renewable energy sources for harvesting, culture and processing could mitigate some of this negative impact. In summary, the overall evaluation of the chemical, nutritional and microbial assessment shows that all ten species investigated are suitable for human consumption, when harvested away from contamination sources. It is therefore recommended to promote seaweed consumption through the public health program Inuuneritta III, and the SDG agenda of Greenland. The results from this project can be directly used to inform consumers about the nutritional properties of Greenlandic seaweeds, and as a basis for future research of further interesting components.