Cassia tora gum, also known as cassia gum, is a galactomannan polysaccharide derived from the endosperm of Cassia tora (also referred to as Senna tora) seeds. It is widely valued for its thickening, gelling, and stabilizing properties and is commonly used as a cost-effective alternative to guar gum and locust bean gum. 

Molecular Structure

Cassia tora gum consists of a linear backbone of β-(1→4)-D-mannopyranose residues with α-(1→6)-linked D-galactopyranose side chains attached approximately every 5–8 mannose units, resulting in a mannose-to-galactose ratio of about 5:1. The polymer exhibits a high molecular weight in the range of 200–300 kDa and is composed of approximately 75–84% polysaccharides, including mannose (77–79%), galactose (≈15%), and glucose (6–7%). This relatively low degree of branching, compared with guar gum (≈1:2 ratio), confers distinct rheological properties. The empirical formula is commonly expressed as (C₆H₁₀O₅)_n·H₂O, and its monosaccharide composition is typically confirmed by HPLC-based sugar analysis.

Extraction and Physicochemical Properties

Production involves seed dehulling, roasting, milling, and separation of the endosperm, followed by alcohol extraction and drying to obtain a pale yellow powder. Typical characteristics include a pH range of 5.5–8.0, bulk density of approximately 0.6 g/mL, and particle size below 250 µm. Cassia gum readily disperses in cold water to form high-viscosity colloidal solutions (generally >260 mPa·s at 1% w/v), displays pseudoplastic flow behavior, and maintains thermal stability during hydration above 80 °C. It shows good acid tolerance (pH 4–10) and can form gels at concentrations of 75% or higher. The polymer is insoluble in ethanol and contains low levels of chrysophanic acid, contributing to its toxicological safety profile.

Biomedical Applications

The biocompatibility of cassia gum supports its use in biomedical formulations, particularly in the development of hydrogel films for wound dressing and controlled drug delivery systems, where hydrogen bonding with plasticizers enhances mechanical stability and flexibility. In addition, its galactomannan structure suggests potential prebiotic activity by promoting microbial fermentation in the