Physical properties of decolorized Hsian-tsao leaf gum / polysaccharide gum mixed systems

• Main Authors: Lin, Pin-Chih, 林品緻
• Other Authors: Lih-Shiuh Lai
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/40193931369599201402

碩士 === 靜宜大學 === 食品營養學系 === 90 === Abstract The polysaccharide extract of hsian-tsao leaves was treated with 10%, 5%, and 2% active carbon consecutively, followed by ethanol precipitation. Physical properties of the mixtures of decolorized hsian-tsao leave gum (dHG) and xanthan gum (XG), locust bean gum (LBG), propylene glycol alginate (PGA), gellan gum (G), or κ-carrageenan (κ-CA) were monitored as a function of mixing ratios (0/4, 1/3, 2/2, 3/1, 4/0), types of polysaccharide, addition of sodium chloride (0 or 0.1M), and total solid contents (1, 1.5, 2%). Except for the mixed systems of PGA/dHG, the storage modulus (G’), loss modulus (G”), and creep compliance (J) of all other mixed systems were between those of the single polymer systems, no matter with or without sodium chloride addition. G’ and G” of these mixed systems increased, but J decreased with increasing total polysaccharide concentration or decreasing dHG ratio in the mixture. Such results implied that instead of synergistic effect, phase separation may occur between dHG and other polysaccharides. The physical behavior of PGA/dHG mixed system was more complicated. The G’ and G” of PGA/dHG mixed system without sodium chloride addition were generally lower than those of the single polymer system, indicating antagonistic effect between these two types of polymers. However, the incompatibility between dHG and PGA could be significantly reduced by sodium chloride addition. With the presence of 0.1M sodium chloride, PGA even showed synergist effect with dHG under a total polysaccharide concentration of 1.5% and 2%. Among the mixed systems studied, only G/dHG andκ-CA/dHG mixed systems with sodium chloride addition could form thermal-reversible macroscopic gels. Differential scanning calorimetry results showed that the gel-sol transition temperatures and transition enthalpy of the mixed gels increased with increasing total polysaccharide concentration. However, as decreased the dHG ratio in the mixture, though the microstructure of the mixed gels (observed through scanning electron microscopy) became more orderly, the gel-sol transition temperatures only increased forκ-CA/dHG system, and remained relatively unchanged for G/dHG system.