SUSFOOD2: Extraction and characterisation of BIOactives and CARBohydrates from seaweeds and seagrasses FOR FOOD-related Applications

Current industrial procedures for carbohydrate extraction from seaweeds are well established. They have remained relatively unchanged for many decades in terms of their efficiency, water and energy requirements. There is also a large amount of side-stream waste. In this European research project, we evaluate novel and environmentally friendly processing techniques such as ultrasound, microwave, enzymes, and combinations of these, for extraction of food carbohydrates (principally polysaccharides) from selected commercially harvested or cultivated seaweeds. Our focus has been on the red seaweed Gelidium sesquipedale, a major source for agar, which grows along the Atlantic coasts of France, Spain, Portugal and Morocco, and the brown seaweeds Alaria esculenta and Saccharina latissima (seaweeds commercially farmed in Norway). Nofima?s main role in the project is analytical characterisation as a tool in evaluating the effectiveness of the new evaluated processes. A second task was for us to evaluate the potential for food applications of semi-refined agars and alginates produced by novel and environmentally friendly processing techniques. In the first project year we established methods for physical and chemical characterisation of G. sesquipedale agar. Its carbohydrate composition has been obtained via reductive hydrolysis and GC-MS and its molecular weight (size) has been measured by size-exclusion chromatography with light scattering. We obtained new and updated knowledge on the carbohydrate structure of this economically important agar which has been used to evaluate the novel processing parameters (partners in Spain and Ireland). A research manuscript was published in the journal Carbohydrate Polymers in 2020. For the brown Norwegian seaweeds A. esculenta and S. latissima we have extracted, and characterised its alginate. The insoluble material remaining following alginate extraction has been prepared and its cellulose characterised by the partner in Spain. The suitability of this side stream as a constituent in alternative food packaging has been evaluated and found to be very promising. Two industrial site visits were made: one to agar production facilities in Spain (Hispanagar) and one to the alginate production site at Dupont, Norway. In year two of the project we conducted further characterisation of agars and alginates extracted by ultrasonication and microwave by the partner in Ireland. The results of the agar part of this work are now published in the journal Algal Research (2021). Interestingly we found that agars generated by ultrasonication appear to have slightly different conformation properties in dilute solution. For alginates we have validated a colorimetric method to quantify it in semi-refined form. Further we determined molecular weight and mannuronic/guluronic acid ratio with 1HNMR. In the final project year, we assessed a series of semi-refined agar and alginate samples made in the project at pilot scale as potential food ingredients. These were benchmarked against commercial food alginate and agar samples. All samples assessed displayed inferior properties in terms of their gelling strength, colour and taste compared to more pure commercial counterparts. We prepared, for example, raspberry agar jellies as model foods. In most samples a strong seaweed taste was evident and a brown-green colour prominent. We conclude that semi-refined agars and alginates assessed in this project are not suitable as food ingredients. Further work is needed to improve the novel and environmentally friendly production processes to make purer agar and alginates suitable for food applications. The results from this project have been disseminated through a project webpage (www.biocarb4food.eu) and via an on-line final project seminar with a large audience of invited stakeholders (industry, academic, regulatory etc).

BioCarb4Food has served to focus our attention specifically on the characterisation and application of seaweed hydrocolloids as potential food ingredients. During the project there has been significant knowledge transfer between project partners. International cooperation has been at the heart of the project. Nofima has established generic methods both for quality characterisation of agar and alginate. Further developments and understanding of innovative processing methods are totally dependent on such accurate quality evaluation of process conditions and products. We have had a full focus on industrial relevance of methods used as industry will be the ultimate end-user. Industrial site visits and building relationships with industry stakeholders between project partners has been important. Through the project website we have reached out a wide audience to explain the importance of our project and what we have learned in terms of significant results.

Carbohydrates are the most important source of food energy in the world being also key ingredients for food formulations, serving as thickeners, stabilizers and gelling agents or providing functional attributes. Functional and technological properties of polysaccharides depend on composition, structure and physicochemical characteristics, defined by source and extraction method employed. Seaweeds and seagrasses are a valuable and under-exploited source of carbohydrates, in particular cell wall polysaccharides (phycocolloids), and bioactive compounds such as polyphenols or carotenoids. Current industrial procedures used by European companies for carbohydrate extraction from seaweeds are highly inefficient in terms of processing time, water and energy requirements. Furthermore, the remaining biomass (generally much more than 50% of the initial material) is used as compost or simply disposedas organic waste. We propose to explore, in close collaboration with industry, novel, environmentally friendly and efficient extraction techniques (ultrasound, microwave, enzymes and their combinations), combined with the exploitation of the remaining biomass, rich in bioactive compounds, to sequentially obtain novel carbohydrate-based extracts and fibers (nanocellulose) from seaweeds and seagrasses. We will characterize structure technological properties, toxicity and bioactivity of the fractions obtained from the various extraction technologies and a life cycle assessment (LCA) will also be conducted for proving the sustainability of the procedures. The project is expected to contribute to improved process efficiency, development of ingredients with high added value from already commercialized seaweed species and from under-exploited sources (seagrasses) which can positively impact in the competitiveness of seaweed, food and non-food companies at EU scale by a better valorization of raw materials.