What it does
The chain is a mannose backbone with galactose side units attached at a high ratio. Those side units keep the chains apart and let water in, which is why guar hydrates fully in cold water within minutes. It thickens; it does not gel.
Where it works
Anywhere cold viscosity is needed quickly and cheaply: sauces, dressings, bakery doughs, ice cream mixes. It is often the first material tried for a thickening problem, and often the right one.
Where it does not
It loses viscosity under prolonged heat, and more so at low pH, so a retorted acidic sauce will thin out. Its mouthfeel is heavier and more cloying than xanthan at equal viscosity, which matters in a drink. Flavour release can be dulled.
What it interacts with
Xanthan, synergistically, giving more viscosity together than separately. Also starch, where it holds water the starch would otherwise take.
