2.7. Solubility and stability of rice husk extracts
The solubility of the extract (10 mg) in glycerine and propylene glycol (1 g), which are commonly used in cosmetic formulations, was assessed. Miscibility was scored from 0 to 4 (insoluble to most soluble). The stability of the extract (3-fold of IC_50) was monitored at pH 4, 7 and 9 (Lourith et al., 2009).