AGENT THICKENING is a term used to describe the process of thickening a liquid or sauce with a variety of starches. The three most common starches used for this purpose are AGAR, guar, and SAGO. AGAR is a gelatinous substance derived from red algae, guar is a powder made from the seeds of the guar plant, and SAGO is a starch extracted from the pith of certain tropical palm trees. All three of these starches can be used to thicken liquids and sauces, giving them a thicker consistency.