Tragacanth gums hydrate in water to give viscous, slightly long solutions and pastes.

Hydroxypropyl methylcellulose (HPMC) has very similar properties to methylcellulose, although a smaller range of viscosity types is available. The gel point is higher for HPMC (between 60-70°).

ApplicationFunction
Deep fat fried foodsImproved batter adhesion, reduced oil absorption, thickener.
Reduced fat dressingsHigher hot viscosity, fat replacement and emulsification
Soups and saucesHeat stability, improved creaminess and reduced phase separation.
Edible films and coatingsReduced frying oil pick up, high elasticity, and reduced crystallisation in sugar coatings.
Extrusions and baked goodsShelf life extension, increase plasticity, improved freeze-thaw stability.
Bake stable filingsBoil-out control, control of depositing viscosity emulsification.
Whipped toppings and moussesFoam stabilisation. Syneresis prevention. Viscosity control. Protein replacement.

Hydroxypropyl methylcellulose (HPMC) (E464) is a methylcellulose modified with a small amount of propylene glycol ether groups attached to the anhydroglucose units on the cellulose backbone. HPMC is characterised by its monomeric chain length, degree of substitution and content of methoxy and hydroxypropoxy groups on the monomeric unit. Methoxy group content is normally 22-30%, whereas the dydroxy group content is around 6-10%.

Properties
Ion activitynon-iconic
Surface activityhigh
Solubilitysoluble in cold water, but insoluble in hot
Water retentionvery good
Effect of temperature on the solutionviscosity initially decreases with rising temperature, then increases until a gel is formed, further heating causes flocculation, these processes are reversable
Effect of pHhigh solubility in all pH ranges
Effect of polyvalent metal iconsno complexation, therefore no flocculation
Film formationgood to very good film-forming properties