A crude, alginate-rich product from Alaria esculenta and Saccharina latissima – process development and exploration as texture ingredient

Abstract

Development of functional ingredients from cultivated brown seaweed may promote broader use in food products and meet a growing demand for cleaner labels. This study presents a simple, cost-effective method to produce a crude alginate-rich product from Saccharina latissima and Alaria esculenta. Instead of extracting alginate, the process retains it within the seaweed matrix by washing the biomass at low pH to release crosslinking ions, followed by neutralization to convert alginic acid into Na- or K-alginate. Gelation could be controlled by reintroduction of Ca²⁺. Through demineralisation, alginate junction zones were exposed and made available for crosslinking when Ca²⁺ was reintroduced. Hydrogels prepared from acid-washed products demonstrated similar strength to gels from Laminaria hyperborea stipe alginate. The gels were elastic and synergetic (37.2–48.6 %), attributed to more MG sequences and low alginate concentrations (<5 g/L). A correlation was observed between reduced Ca content after treatment and increasing gel strength. To explore clean-label ingredient alternatives and increase consumer acceptability, selected products were tested as binders in plant-based patties. The patties were easily shapable and held structure during cooking but had less hardness, springiness, and cohesiveness than a commercial patty with methylcellulose as binder. However, low cooking losses demonstrated high water-holding capacity of acid-washed products.