SOLUTION AND COLOR STABILITY OF THE BARK EXTRACT OF BRIDELIA-FERRUGINEA BENTH

A solvent system consisting of water: propylene glycol: ethanol (2:2:1 ) was found suitable for diluting the ethanol bark extract and for rec onstituting the freeze-dried extract of Bridelia ferruginea Benth for preparation of a gargle formulation. Such solutions remained clear whe n subjected to high storage temperatures and eight freeze-thaw cycles. The wine colour of Bridelia bark extract solution darkened on storage . Darkening was accelerated by heat while light had minimal effect. In clusion of certain antioxidants-sodium metabisulphite, ascorbic acid a nd citric acid, reduced the colour change. Heating the freeze-dried ex tract at 115 degrees C for 4 h and at 130 degrees C for at least 1 h a rrested the colour change. When lime juice was added to the solution o f the heated powder, the colour of the resulting solution became unsta ble implicating a pH effect on colour stability. The colour of bottle and use of carton for storage had no appreciable effect on colour stab ility.