Hydroxypropyl methylcellulose (HPMC) and guar gum are both commonly used in the food and pharmaceutical industries, but they have different chemical structures and functional properties that make them different from each other.

HPMC is a water-soluble polymer derived from plant cellulose that has been modified with various chemical groups to improve its properties. It is commonly used as a thickener, stabilizer and emulsifier in food and pharmaceutical formulations such as sauces, dressings, coatings, pills and tablets. HPMC offers many advantages over traditional thickeners such as gelatin and starch, including better stability, clarity, viscosity and flow, as well as pH and temperature tolerance.

Guar gum, on the other hand, is a water-soluble polysaccharide extracted from the guar bean. It is a natural thickener, binder and emulsifier commonly used in food and industrial applications such as dairy products, baked goods, beverages, paper and textiles. Guar gum has many advantages over other thickeners such as carrageenan, xanthan gum, and gum arabic, including high viscosity, low cost, and natural origin.

Although HPMC and guar gum differ in origin, structure, and function, they also share some similarities. Both are tasteless, odorless and non-toxic, making them safe to eat. Both are water-soluble, meaning they can be easily mixed with other ingredients and dissolved in water. Additionally, both are used in similar applications such as sauces, dressings, and baked goods to improve their texture, appearance, and shelf life.

However, there are some key differences between HPMC and guar gum that make them better suited for some applications than others. For example, HPMC is more commonly used in pharmaceutical formulations such as pills and tablets because it has better compression and binding properties than guar gum. It also has better film-forming and coating properties than guar gum, making it suitable for manufacturing capsules and pills.

Guar gum, on the other hand, is more commonly used in food formulations such as ice cream, yogurt, and salad dressings because it has better viscosity and stability than HPMC. It also has better water retention and freeze-thaw properties than HPMC, which makes it suitable for making frozen and refrigerated foods.

HPMC and guar gum are two commonly used hydrocolloids with different properties and applications. HPMC is more commonly used in pharmaceutical formulations due to its better binding and coating properties, while guar gum is more commonly used in food formulations due to its better viscosity and stability. However, both have advantages and disadvantages depending on the specific application, and choosing the appropriate hydrocolloid will depend on many factors, including cost, functionality, and compatibility with other ingredients.