Characterisation of pectins extracted from fresh sugar beet under different conditions using an experimental design

An experimental design was used to study the influence of different parameters (pH, temperature, time, and type of acid) on extraction of pectins from fresh sugar beet. The extraction conditions have important effects on the features of extracted pectins. Their composition (neutral and acidic sugars, degrees of esterification, amounts of ferulic and diferulic acids) and some physicochemical properties (molar mass, intrinsic viscosity) were determined. The type of acid used (HCl or HNO3) had no effect on the characteristics of extracted pectins. Different kinds of pectins can be obtained with good yields at pH 1. Galacturonic acid amounts of the extracted pectins were nearly constant whatever the extraction conditions, whereas the degrees of methylation and acetylation showed large variations. At pH 1, the extracts were particularly rich in rhamnogalacturonan regions, the nature and the quantity of side chains differing according to extraction conditions. The molar masses of extracted pectins were higher than those obtained from sugar beet pulp; beside the sole impact of raw material, possible cross-linking of pectic molecules through diferulic bridges is discussed.