Comparison of alcohol precipitation and membrane filtration effects on sugar beet pulp pectin chemical features and surface properties

Two different procedures, alcohol precipitation with washing (APW) and a 10 kD MWCO membrane ultrafiltration with diafiltration (UF-DF), for pectin recovering and purification from crude aqueous extracts were investigated. The results showed that the yield, purity, chemical, and physicochemical features of isolated pectins depended upon the type of procedure used. The APW technique gave a higher pectin yield, and the isolated pectin contained more neutral sugars, more proteins, and more ash but less galacturonic acids than the 10 kD membrane UF-DF one. The weight-average molar mass of the APP was lower and its emulsifying properties slightly better than those of the UFPR10. Molar mass distribution of APP or UFPR10 showed two distinct pectin fractions peaks, which were separated in high-MW and low-MW pectin fractions using a 50kD MWCO membrane. The high-MW fractions exhibited poor emulsifying and emulsion stabilizing abilities whereas the low-MW fractions displayed a much higher emulsifying ability than the initial pectin fractions. Therefore, it was inferred that the ability of beet pectin to be an effective emulsifier and/or emulsion stabilizer was greatly dependent on its weight-average molar mass. (c) 2006 Elsevier Ltd. All rights reserved.