Methods. Extraction of mucilage. The fresh leaves of A. barbadensis were taken and washed with water to remove dirt and debris. Incisions were made on the leaves, which were hung overnight.
The leaves were crushed and soaked in water for 5–6 h, boiled for 30 min, and left to stand for 1 h to allow complete release
of the mucilage into the water. The mucilage was extracted using an eight-layer muslin cloth bag to remove the marc from the
solution. Acetone (three times the volume of filtrate) was added to precipitate the mucilage. The mucilage was separated,
dried in an oven at a temperature of less than 500 °C, collected, ground, passed through a Number 80 sieve (nominal aperture
size is 180 μm) and stored in desiccators at 300 °C and 40% relative humidity before use (16).
Physicochemical and microbial properties of A. barbadensis mucilage. The dried mucilage was studied for percentage yield, chemical test, particle size, weight loss on drying, solubility, viscosity,
pH, swelling index, bulk and tapped density, angle of repose, compression properties, and microbial load.
Chemical test. The dried powder of mucilage was treated with Molisch's reagent and ruthenium red.
Weight loss on drying. Weight loss on drying was determined for an appropriate quantity of mucilage at 105 °C for 2 h (17).
Particle size. The particle size of the dried-powder mucilage was determined by the microscopic method, and the study was carried out in
pH of solution. The pH of the 1% solution was measured with a pH meter.
Density. A 0.5% weight/volume (w/v) solution of dried mucilage was prepared and transferred to a density-measurement bottle. An empty
bottle with distilled water was weighed. The density of the dried mucilage was calculated.
Charring. A few milligrams of dried mucilage were placed in a melting-point apparatus. The temperature was taken and recorded when
the material started to char.
Swelling ratio. The study was carried out using a 100-mL stoppered graduated cylinder. The initial bulk volume of 1 g of dried mucilage was
recorded. Water was added in sufficient quantity to yield 100 mL of a uniform dispersion. The sediment volume of the swollen
mass was measured after 24 h, stored at room temperature. The swelling ratio was calculated by taking the ratio of the swollen
volume to the initial bulk volume (18).
Bulk and tapped density. A preweighed, presieved quantity of dried mucilage was poured into a graduated cylinder, and the volume recorded. The cylinder
was tapped until the powder-bed volume reached a minimum value, and the tapped volume was recorded. The bulk and tapped densities
were calculated (19).
Carr's index and Hausner ratio. Carr's index and Hausner ratio were calculated from the bulk and tapped densities (20).
Viscosity. Rheological studies of dried mucilage were carried out using varying concentrations (0.1–0.5% w/v) prepared in distilled
water. The viscosities were measured using an Ostwald viscometer and compared with those of solutions of sodium CMC at the
same range of concentrations.
Angle of repose. The angle of repose was determined by the fixed-height funnel method and calculated using the following equation:
in which h is the height of the powder heap and r is the radius of the powder heap. Comparisons were made between dried mucilage, guar gum, and ispaghula husk.
Microbial count. The microbial count of the dried mucilage was performed as outlined in the Indian Pharmacopoeia for total aerobic microbial count of bacteria and fungi using the plate count method (21).