Antioxidative activities, phenolic compounds and marine food allergens in the macroalgae Saccharina latissima produced in integrated multi-trophic aquaculture systems

The concept of "Integrated Multi-Trophic Aquaculture" (IMTA) is considered one of several strategies to increase biomass production from the sea by combined culture of different organisms, such as low-level trophic macroalgae, profiting from and reducing the environmental impact of fish farming. However, due to lack of data and scientific evidence, appropriate food regulations are lacking for IMTA to guide the production of macroalgae and their application as food products. Macroalgae are reported to be nutritious and to have valuable bioactivities including antioxidative activity. Besides valuable compounds, macroalgae can also contain elements with unwanted effects such as allergens. Thus, there is a growing concern from the food industry and food safety authorities regarding the potential occurrence of contaminating marine allergens in seaweed food products. As seaweed is produced in the ocean, allergens of marine species, such as crustaceans, molluscs or even fish might find their way into the production line and these hazards must be monitored to evaluate the risk for allergenic incidents and the need for appropriate labelling for future food products. To date, there is little data in this aspect on seaweed production in IMTA systems, where especially the occurrence of contaminating allergens could be increased due to close contact with cohabitant species. Hence, the occurrence of marine food allergens (fish parvalbumin, mollusc and crustacean tropomyosins), as well as total phenolic compounds and antioxidant activity have here been assessed in S. latissima produced in three different locations in 2020 in the vicinity of salmonids farms in Norway. We confirm the presence of phenolic compounds and antioxidative activity in S. latissima, produced in IMTA systems, in a similar range for all assessed locations and comparable to previous studies. Of the tested allergens, only crustacean tropomyosin could be detected in all locations of this study up to 1 mg/kg dry weight, however not representing a critical level for consumption.