OPTIMIZATION OF EXTRACTED CALCIUM FROM HELENCHA (Enhydra fluctuans) USING RESPONSE SURFACE METHODOLOGY

Abstract

Optimum extraction conditions of calcium from Helencha (Enhydra fluctuans) using hydrochloric acid as the solvent were evaluated. The extractions were carried out using three process parameters such as hydrochloric acid concentration, temperature and time ranging from 1 to 2 M, 50 to 100 °C and 60 to 180 minutes respectively. Box–Behnken statistical design was applied as the response surface method using Design Expert DX11 to determine the optimum extraction parameters. The extracted calcium was measured using a modified UV/Visible spectrophotometric method. The highest response experimented in the study was 190.95 mg calcium per 100 g powder. Though changing any parameter significantly (p < 0.05) affect the extraction of calcium, the temperature is the most significant factor (F = 1054) among others. A quadratic regression equation describing the effects of independent process variables on calcium extraction can be used for finding optimum conditions to achieve desired extraction yield in similar conditions. Applying the equation, the processed parameters (concentration, temperature and time) were optimized within the experimental range respectively as 1.97683 M, 98.2929 °C and 167.617 minutes and the predicted yield increased from 88.48 to 91.50 % with the extraction of 196.49 mg calcium per 100 g powder.