61A-27 |
Solubilization of pectic polysaccharides from ginseng fiber by extrusion |
M. Choi1, K. Na, T. S. Lim, J. M. Yun, and J. K. HWANG1. (1) Bioproducts Research Center, Yonsei University, B138A Yonsei Engineering Complex, 134 Shinchon-dong Sudaemun-ku, Seoul, 120-749, South Korea Ginseng fiber (GF) produced after hot water or alcohol extraction of red ginseng is discarded or simply used as a feed. The insoluble structure of GF can be successfully disintegrated and solubilized by the shearing force generated during extrusion. This research was performed to elucidate the relationship between extrusion conditions, especially specific mechanical energy (SME), and the yield and uronic acid content of water soluble polysaccharides (WSP) from GF and to investigate the physicochemical properties of the resulting WSP. GF was extruded with a twin-screw extruder under different conditions of screw speed, 250-350 rpm; feed rate, 20-30 kg/hr; moisture content, 20-25%. The extruded GF was solubilized in distilled water at 85oC for 1 hr to recover water soluble fractions. Ion exchange chromatography was performed on DEAE Sepharose Fast Flow with sodium acetate buffer (pH 4.5) and a linear gradient of NaCl. Galacturonic acid contents and neutral sugar contents were measured by m-hydrodiphenyl method and phenol-sulfuric method, respectively. Neutral sugar composition of WSP was analyzed with HPIC (high performance ion chrpmatography). Yield, free neutral sugar content and uronic acid yield of WSP increased with increasing SME with R2 of 0.92, 0.80, and 0.76, respectively. Uronic acid content of WSP decreased with increasing SME with R2 of 0.74. WSP, extracted from GF, contains arabinose, galactose, rhamnose and glucose as major constituting neutral sugars. The severe extrusion conditions resulted in increasing the release of neutral polysaccharides from ginseng fiber. The ion exchange chromatograms imply the structure of pectin, isolated from GF, could be modified by changing SME. These results suggest that extrusion, providing mechanical shearing force, is a potential tool to effectively disintegrate the rigid cell wall of GF, and thus to facilitate extraction of anionic pectic polysaccharides using water.
Session 61A, Carbohydrate
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