Function:

• Locust bean gum is a galactomannana similar to guar gum, but it is less soluble and lower viscosity than guar gum as it has fewer galactose branchpoints. It needs heating to dissolve but is soluble in hot water. Locust bean gum differs from guar gum in that it does form thermally-irreversible weak gels by association of the galactose deficient regions and therefore has poorer freeze thaw behavior. These unsubstituted areas also allow increased interaction with cellulose. Being non-ionic, locust bean gum is not affected by ionic strength or pH but will degrade at PH extremes at higher temperatures.
• Locust bean gum specifically retards ice crystal growth by forming structured gel at solid/liquid interface. This particularly occurs on freeze-thaw cycling, which encourages the frustrated crystallization of the galactomannan so causing the gel to form. It encourages phase separation with skimmed milk powder showing synergistic viscosity with casein and becoming slightly thixotropic on forming a biphasic system containing casein micelles within a polysaccharide continuous network. To aid this it may usefully be combined with xanthan, with which it shows viscosity synergy, and κ-carrageenan to super helices of which it adsorbs.