Effect of Molecular Size on Rheological and Film Properties of Polysaccharides

• Main Authors: Lin, Chengyi, 林晟毅
• Other Authors: Chang, Yungho
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/52509777529553303236

碩士 === 靜宜大學 === 食品營養學系 === 101 === Agarose (AGA), carrageenan (CAR), guar gum (GG) and konjac glucomannan (KGM) were treated in acid-methanol at 25 oC for 1-240h. The recovery, molecular weight distribution, degradation rate, sulfate content of CAR, acetyl content of KGM, rheological properties, and film properties were investigated. The results indicated that recovery of all polysaccharides was over 90% and the molecular weight was decreased with increasing treatment duration. AGA and CAR showed higher degradation rates than GG and KGM, it may be related with α- or β- linkage of polysaccharide structure. The sulfate content of CAR and acetyl content of KGM were decreased with increasing treatment duration. Gelling temperature, G' and tan δ of AGA were decreased with decreasing Mw. On the other hand, tensile strength (TS), elongation at break (EB) and moisture uptake (MU) of AGA films were increased with decreasing Mw, but decreased with decreasing Mw when Mw ≤ 116.8 kDa. However, the water vapor permeation (WVP) of AGA film was observed the reverse trend with TS, EB and MU of AGA films. Gelling temperature, G' and tan δ of CAR were decreased with decreasing Mw. In addition, TS, EB, MU and WVP of CAR films were decreasing with decreased Mw. G' of GG were decreased with decreasing Mw, but tan δ of GG had a reverse trend with G'. On the other hand, TS, EB and MU of AGA films were increased with decreasing Mw. The MU and WVP of GG films were decreased with decreasing Mw. G' of KGM were decreased with decreasing Mw, but increased with decreasing Mw when Mw ≤ 501.0 kDa. However, the tan δ of KGM was observed the reverse trend with tan δ. In addition, TS, EB, MU and WVP of CAR films were decreased with decreasing Mw. Result the rheological and film properties of polysaccharides change may related with AGA bundles amount, sulfate content of CAR, GG galactan side chains ratio and acetyl content of KGM. AGA, CAR, GG and KGM could decrease their molecular weight, enhance molecular mobility and achieved high recovery by acid-methanol treatment. The polysaccharide film of lower molecular weight may be provided with higher TS and EB, furthermore delivered lower MU and WVP. The observed properties of polysaccharides are expected of widely application in food preservation.