Nanna Rhein-Knudsen, Anne S. Meyer*
*Corresponding author
Center for Bioprocess Engineering, Lyngby, Denmark

Abstract

The global production of seaweeds continues to grow for production of food hydrocolloids, i.e. carbohydrate polymers that form viscous suspensions and gels in water. Because of their unique gelling properties seaweed hydrocolloids are used in various food and pharmaceutical applications. Asian countries and Tanzania are currently the main producers of seaweed hydrocolloids based on cultivation of seaweeds such as Kappaphycus alvarezii, Gracilaria spp. and Laminaria spp. that hold carrageenan, agar, and alginate, respectively. In this review we summarize the chemistry, food uses, and gelling mechanisms of carrageenan, agar, and alginate, and describe the key techniques and principles for their extraction from seaweeds. We also discuss the options for local seaweed manufacturing as a business opportunity in countries along the West African coast

INTRODUCTION

Carrageenan, agar, and alginate are natural polysaccharides that function as hydrocolloids, i.e. substances that interact with water to form viscous suspensions and gels. These hydrocolloids are extracted commercially from certain seaweed (macroalgae) species. Due to their unique gel-forming abilities, the seaweed hydrocolloids are widely used as thickeners, fat replacers, and stabilizers in the food industry and also have numerous applications in biotechnology and in pharmaceutical products e.g. as wound dressings and matrices for control of drug release (1,2). The seaweed hydrocolloids differ in their chemical composition and thus have different gelling properties (ranging from increasing viscosity in solutions to producing very strong gels) and hence different applications. Table 1 highlights some commercial applications of the seaweed hydrocolloids.

Seaweed derived hydrocolloids offer several advantages over currently used gelling agents, e.g. gelatin obtained from animals and xanthan gum produced by fermentation of carbohydrate sources by Xanthomonas campestris, as they do not require land for cultivation, ...