A case study on Norwegian commercial harvesting and production of Saccharina latissima (Part 1): Effect of processing seaweed on chemical hazards, allergens, and microbiological hazards

When producing seaweed for human consumption, incorporating a “Food Safety-by-Design approach” can help protect human health and ensure the safety of future consumers. Post-harvest processing of seaweed is one strategy to reduce undesirable compounds. The study aimed to determine the effects of a commercial processing strategy (blanching and fermentation) of Norwegian-harvested Saccharina latissima (sugar kelp) on the presence of prioritized food safety hazards. We compiled and prioritized food safety hazards to be analyzed based on the current impact of the hazard, the analytical feasibility, and the fit of the hazard to the case study site. Twelve prioritized hazards were included in the case study analyses: arsenic (total and inorganic), iodine, cadmium, lead, mercury, copper, zinc, the allergen tropomyosin, Salmonella spp., Bacillus spp., norovirus, and Vibrio spp. We found that blanching was very effective in reducing iodine concentrations but mildly increased the zinc concentration. Fermentation of blanched seaweed further decreased iodine concentrations and had similar effects on inorganic arsenic, cadmium, and zinc. An unintentional increase in copper was observed. Bacillus cereus was detected in a blanched sample and fermented samples. Vibrio alginolyticus seemed to be introduced during blanching, yet fermentation greatly reduced the detection frequency. Our study illustrates the importance of clearly defining the goals of seaweed processing and optimizing the process for food safety hazards. Meanwhile, it is advised to monitor for unintended effects that may occur during processing, such as, in our case, the introduction of copper and pathogens like B. cereus and Vibrio spp. This study serves as an example for seaweed stakeholders on how to consider a Food Safety by Design concept and a risk-based approach during seaweed harvest and post-harvest processing.