Jonas Steenholdt Sørensen1, Aurora Luiza Cardoso1,2, Turid Rustad2 and Lisbeth Truelstrup Hansen1
1 National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark, 2 Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway.
Brown seaweed (Alaria esculenta and Saccharina latissima) can potentially be the future North Atlantic Ocean crop. One of the main bottlenecks in upscaling seaweed production is the need to stabilise the annual harvest before it spoils. We investigated the microbial quality changes during chilled storage of brown seaweeds and subsequent stabilization by either convection or ambient atmospheric drying. The quality of the dried seaweeds was determined by the swelling, water-, and lipid-binding capacity. Microbial loads (3M Aerobic Count Plate) were 4.0-4.5 log(CFU/g) at the time of harvest for the two species. The microbial numbers increased to 5.9-6.1 log(CFU/g) after seven days of storage at 2-3 °C. For fresh seaweed, the drying process had limited impact on the bacterial load, with reductions of 0.1 to 2.9 log(CFU/g) during the process. In contrast, the same drying process resulted in reductions of 4.2 to 5.8 log(CFU/g) for seaweed, which had been stored for 7-days prior to the drying. Dried S. latissima showed higher swelling and water-binding capacities compared to A. esculenta regardless of the drying method. Drying at the ambient atmosphere yielded a higher lipid-binding capacity for both species than convection drying. Based on the bacterial concentrations, the seaweed should be stabilised within the first five days of chilled storage post-harvest. Convection drying inactivates more bacteria and has a shorter process time. However, if the seaweed is intended for use in a lipid-rich product, such as pesto, the use of ambient atmospheric drying might be beneficial.