The chromatograms generally showed large LS and UV signals but low DRI signals at the initial elution volume (6 mL). This could be due to the presence of a small amount of protein-pectin aggregates, which were eluted first. At elution volumes of 7–12 mL, the DRI signals of purified MHF pectin showed about four wider peaks, whereas EHF pectin had about five narrower peaks. The DRI signals for EHF pectin and MHF pectin were distinctly different, which could indicate that different molecular fractions were present in the purified pectins.
The results for weight-average molecular weight (Mw), polydispersity index (Mw/Mn) and root mean square (RMS) radius are shown in Table 3. The incremental refractive index (dn/dc) value used for the Mwcalculation was determined experimentally (0.189 ± 0.002 mL/g). Generally, the EHF showed lower Mwacross all the three extraction methods. For both EHF and MHF, pectin obtained using the enzymatic extraction method resulted in the lowest Mw of 2.10 × 105 and 1.65 × 106 g/mol, respectively. The enzyme used appeared to cause some hydrolysis of the larger molecular weight fractions. This finding is consistent with previous studies ( Panouille et al., 2006) on pectin extraction from chicory roots using commercial enzymes (Celluclast 1.5L and Cellulyve TR 400) and from pumpkin using an enzyme from the fungusBacillus polymyxa ( Ptitchkina et al., 2008). These researchers reported that the Mw of pectin isolated by enzyme treatment was relatively lower than that of pectin recovered using acid (0.05 M HCl). The Mw of the pectins obtained from pumpkin and chicory root by enzymatic extraction was approximately 2.0 × 105 and 3.0 × 105 g/mol respectively. In contrast, the Mw of pumpkin and chicory root pectins obtained by acid extraction was 7.0 × 105 g/mol and 5.0 × 105 g/mol respectively.
The chromatograms generally showed large LS and UV signals but low DRI signals at the initial elution volume (6 mL). This could be due to the presence of a small amount of protein-pectin aggregates, which were eluted first. At elution volumes of 7–12 mL, the DRI signals of purified MHF pectin showed about four wider peaks, whereas EHF pectin had about five narrower peaks. The DRI signals for EHF pectin and MHF pectin were distinctly different, which could indicate that different molecular fractions were present in the purified pectins.
The results for weight-average molecular weight (Mw), polydispersity index (Mw/Mn) and root mean square (RMS) radius are shown in Table 3. The incremental refractive index (dn/dc) value used for the Mwcalculation was determined experimentally (0.189 ± 0.002 mL/g). Generally, the EHF showed lower Mwacross all the three extraction methods. For both EHF and MHF, pectin obtained using the enzymatic extraction method resulted in the lowest Mw of 2.10 × 105 and 1.65 × 106 g/mol, respectively. The enzyme used appeared to cause some hydrolysis of the larger molecular weight fractions. This finding is consistent with previous studies ( Panouille et al., 2006) on pectin extraction from chicory roots using commercial enzymes (Celluclast 1.5L and Cellulyve TR 400) and from pumpkin using an enzyme from the fungusBacillus polymyxa ( Ptitchkina et al., 2008). These researchers reported that the Mw of pectin isolated by enzyme treatment was relatively lower than that of pectin recovered using acid (0.05 M HCl). The Mw of the pectins obtained from pumpkin and chicory root by enzymatic extraction was approximately 2.0 × 105 and 3.0 × 105 g/mol respectively. In contrast, the Mw of pumpkin and chicory root pectins obtained by acid extraction was 7.0 × 105 g/mol and 5.0 × 105 g/mol respectively.
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