Hydrocolloids (e.g., agar and alginate) are substances that form gels or provide viscous dispersion in water, and are found in the cell wall of seaweeds. Seaweeds are known for a range of food applications and for their multiple biological properties, including antibacterial, antioxidative, anti-inflammatory, antitumour and antiviral. From an industrial application point of view, hydrocolloids exhibit the ability to be employed as gelling, stabilising, thickening and emulsifying agents, or for water-holding purposes. Among all the polysaccharides present in seaweeds, agar and alginate are two of the most commercialised compounds. Red seaweed species (i.e., Gelidium sesquipedale, Gelidium amansii) are commonly used for agar extraction since sulfated galactans (e.g., agar and carrageenan) are the most abundant compounds in the cell walls.