What You Need to Know
Agar agar is composed mainly of agarose, a linear polysaccharide of alternating 1,3‑β‑galactopyranose and 1,4‑α‑galactopyranose units. Upon heating to 85–95 °C the chains unwind, and as the solution cools to 32–40 °C the chains re‑associate into double helices that aggregate into a rigid, transparent network. The gel strength increases roughly linearly with concentration and the gel remains stable up to 80 °C, allowing reheating without loss of firmness.
The Science
Primary Reaction
Helix formation and aggregation of agarose chains leading to gelation