Insights into the structuring ability of two brown seaweeds (Laminaria digitata and Saccharina latissima) for applications as natural texturisers

Abstract

Seaweeds represent a potential source of new food products with enhanced sustainability. However, in order to use seaweeds as ingredients more knowledge is needed regarding the impact of processing on their structuring ability and functionality. We report on the structure and rheology of aqueous dispersions of two species of brown seaweed, namely: Laminaria digitata and Saccharina latissima, prepared by different food processing techniques. High pressure homogenisation disrupted seaweed cell walls, leading to stable weak gels characterised by smaller particle size compared to untreated samples. Thermal treatment (70 °C 1 h), applied prior or during shear treatment, did not impact the particle size, however, it led to serum phases with higher viscosities. This was related to an increased solubilisation of polysaccharides from the cell walls into the serum, as reflected by chemical analysis and small angle X-ray scattering (SAXS). Furthermore, although in terms of rheological behaviour and particle size, both species showed similar response to food processing conditions, the cell wall nanostructure of L. digitata was modified to a larger extent compared to S. latissima, which was linked to a higher solubilisation of polysaccharides. These insights regarding functionalisation of brown seaweed dispersions provide the scientific knowledge to use whole seaweed as natural structurants for future food and other technological applications