PhD defence by Cecilie Bay Wirenfeldt "Processing of Seaweed and the Effects on Food Quality and Safety"

Principal supervisor:

• Associate Professor Susan Løvstad Holdt, DTU

Co-supervisors:

• Professor Turid Rustad, NTNU
• Associate Professor Aberham Hailu Feyissa, DTU
• Senior Researcher Grethe Hyldig, DTU
• Professor Jens Jørgen Sloth, DTU
• Professor Lisbeth Truelstrup Hansen, DTU

Examiners:

• Senior Scientist Claus Heiner Bang-Berthelsen
• Professor Ingrid Undeland, Chalmers University of Technology
• Researcher Inger Aakre, University of Bergen

Chairperson at defence:

• Researcher Betül Yesiltas, DTU

A copy of the PhD thesis is available for reading at the department

Resume

Seaweed is gaining attention as a sustainable food source due to its ability to grow fast and the potential to be cultivated in the sea without requiring land or freshwater. However, new challenges come with seaweed as a food product, such as the processing of the seaweeds after harvest and ensuring food safety for consumers.

This PhD project has investigated post-harvest processes, such as drying, blanching, and washing of commercially available European seaweeds, to ensure safe seaweed food products. The work focuses on sugar kelp, winged kelp, bladderwrack, sea lettuce, and dulse, examining their vitamin C content, washing, blanching, and drying effects on quality as well as extension of their shelf lives.

It was found that blanching and washing can increase the food safety of seaweed products by reducing microbial load and potential toxic elements. However, it would also influence the nutrients, taste, and texture. Regarding shelf life extension, it was found that refrigerated sugar kelp always had a 7 days shelf life even if the kelp had been washed or blanched. Additionally, the research showed that microwave-vacuum drying was a promising alternative to freeze drying, maintaining similar quality and nutrient composition.