Optimization study on Extraction and Physicochemical Properties of Mhakjong’s Extract

Abstract

The purpose of this research was to optimize the extraction process and identify physicochemical properties of gel from Mhakjong’s extract. Mhakjong: water ratios in the extraction experiments were 1:25, 1:50, and 1:75. The extractions were carried out at 40, 60, and 80∞C for 60, 120, and 180 min using Central Composite Design (CCD). Optimized condition for the extraction of Mhakjong’s extract was using the 1:75 ratio of solid: solvent in distilled water at 66∞C, extraction time 60 minutes, and natural pH (6.5-7.0). With this condition, Mhakjong’s extract exhibited the maximum yield, viscosity, and gel strength. The major monosaccharide constituents of extract were arabinose, rhamnose, galactose, and trace amounts of other neutral sugars (glucose, xylose, and mannose). When the concentration of gel in Mhakjong’s extract increased higher than 0.75% (w/v), viscosity, and gel strength significantly increased. Mhakjong’s extract (0.5%w/v) also formed gel under neutral conditions (pH 6-7). The addition of NaCl and CaCl2 significantly decreased the Mhakjong’s extract viscosity. It was also observed that the addition of sugar increased the viscosity and gel strength of Mhakjong’s extract, the excessive amount of sugar (>30%) decreased the viscosity and gel strength. An increment of pH increased the viscosity and gel strength of Mhakjong’s extract and pH more than 7, which resulted in a decrease of viscosity and gel strength.