Standardisation and physicochemical characterisation of the extracts of seeds of Glinus lotoides

Extraction methods were standardised for saponin-containing extracts from the seeds of Glinus lotoides and the effects of some extraction process variables, such as the extracting solvent (various concentrations of methanol in water) and method of extract drying (freeze-drying and vacuum oven-drying), on the physical properties of the extracts were investigated. Physicochemical properties, namely particle size and size distribution, morphology, water uptake profiles and sorption isotherms, densities, flow properties and compaction profiles, of the crude dry extracts of 60% methanol (extract A), 70% methanol (extract B) and 80% methanol (extract C) were investigated. The average particle sizes (X50) of extracts A, B and C were found to be 68.4, 92.1 and 68.5 microm, respectively. Scanning electron micrographs of freeze-dried and vacuum oven-dried extract A showed that the particles are irregular in shape and are compact masses with sharp edges. The percent water uptake by the crude extracts was found to increase with an increase in relative humidities, while the hygroscopicity increased with decreasing methanol ratio of the extracting solvent. The bulk and the true densities of the three extracts (A, B and C) ranged from 0.66 to 0.67 and 1.49 to 1.50 g/ml, respectively. The tapped density (0.94 g/ml) and hence the porosity (56.0%), Carr's index (29.8%) and Hausner ratio (1.42) of extract A were greater than those of extracts B and C. Measurements of angle of repose indicated that all of the extracts exhibit poor flow properties. Compaction studies revealed that extract C has higher compactibility than extracts A and B.