Formulation of film prepared from Tamarind seed Xyloglucans containing Centella asiatica extract

Abstract

The process of defatting and sedimentation of xyloglucan from tamarind seed were investigated in order to select the appropriate method for xyloglucan extraction. The selected Method I was performed by soaking tamarind seed powder with hexane prior to mixing with water and then sedimentation by centrifugation. In addition, the optimized spraying condition was estimated by response surface methodology. The effect of two process parameters, inlet temperature and aspirator rate on yield and moisture content was studied. A face centered design showed a quadratic model fitted for %yield and a linear model for %moisture content (P < 0.05). The optimum region by overlay plot was carried out using the best condition to evaluate the repeatability of the spray-drying technique. The observed means obtained for %yield and %moisture content were in range of the prediction intervals at 95% confidence level as, 50.40±4.13% and 6.07±0.37%, respectively. The result clearly showed that the model fitted the experimental data well. The properties of xyloglucan spray dried powder were determined. The pH value of 1%w/v solution of xyloglucan in water was 7.83. The solubility in water of xyloglucan was 6.28 mg/ml. The solution of xyloglucan exhibited typical pseudoplastic flow. The film prepared from xyloglucan powder containing Centella asiatica extract in equivalent amount of asiaticoside at 1%w/w, from mechanical property evaluation, was hard and tough and had good adhesive property with adhesive force of 3.703±1.11 N/cmP2. Differential scanning calorimetry and powder x-ray diffraction studies revealed that Centella extract might molecularly disperse with film formulation and/or exist in an amorphous state as a solid dispersion. The release of asiaticoside more than 50% from film formulation was achieved at 8 hours. The analysis of release mechanism showed that the release of asiaticoside was proportional to the square root of time, indicating that asiaticoside might be released from the film formulation by diffusion. The skin permeation study using porcine skin as model membrane showed that asiaticoside permeated into skin approximately 1.30±1.28%. The detection of small amount of asiaticoside permeated might be due to hydrolysis of asiaticoside to Asiatic acid, one of active compounds of Centella extract.