Agar-agar is a jelly-likesubstance, obtained from red algae.The gelling agent in agar is an unbranched polysaccharideobtained from the cell walls of some species of red algae, primarily fromtengusa (Gelidiaceae) and ogonori (Gracilaria).
These gels are rigid, brittle, have well defined shapes,as well as sharp melting and gelling points. A 1.5% solution of agar-agar forms a gel on cooling to about 32º to 45º C that doesnot melt below 85º C. This hysteresis interval is a novel property of agar-agar that finds many uses in food applications.