Hydroxypropyl Methyl Cellulose (HPMC) (464) & Methyl Cellulose (MC) (463) have unique gelling properties. Selecting the right grade will require technical input from Hawkins Watts.
Application
Hydroxy propyl methyl cellulose (HPMC) has very similar properties to methyl cellulose, although a smaller range of viscosity types are available. The gel point is higher for HPMC (between 60-70oC).
| Application | Function | |
|---|---|---|
| Deep fat fried foods | Improved Batter adhesion, reduced oil absorption, Thickener. | |
| Reduced fat dressings | Higher hot viscosity, Fat replacement and emulsification. | |
| Soups and sauces | Heat stability, Improved creaminess and reduced phase separation. | |
| Edible films and coatings | Reduced frying oil pick up, High elasticity, reduced crystallisation in sugar coatings. | |
| Extrusions and baked goods | Shelf life extension, Increase plasticity, Improved freeze-thaw stability. | |
| Bake stable fillings | Boil-out control, Control of depositing viscosity, emulsification. | |
| Whipped toppings & Mousses | Foam stabilisation. Syneresis prevention. Viscosity control. Protein replacement. |
Chemistry
Hydroxypropyl methylcellulose (HPMC) 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 hydroxypropyl groups on the monomeric unit. Methoxy group content is normally 22-30% whereas the dydroxy group content is around 6-10%.
Properties
| Ion activity | non-ionic |
| Surface activity | high |
| Solubility | soluble in cold water, but insoluble in hot |
| Water retention | very good |
| Effect of temperature on the solution | viscosity initially decreases with rising temperature, but then increases until a gel is formed; further heating causes flocculation; these processes are reversible |
| Effect of pH | high solubility in all pH ranges |
| Effect of monovalent metal ions | high salt concentrations may cause coagulation (reversible) |
| Effect of polyvalent metal ions | no complexation, therefore no flocculation |
| Film formation | good to very good film-forming properties |
HPMC is ideal for
- controlling the rheology of aqueous solutions;
- controlling the release of substances in pharmaceuticals;
- providing high water retention; and
- forming films such as for tablet coatings.