Effects of pH and high hydrostatic pressure on the structural and rheological properties of sugar beet pectin

• Sugar beet pectin (SBP) was treated by high hydrostatic pressure (HHP).
• Molecular mass of SBP at pH 3, 7 and 8 decreased significantly with increased HHP.
• A marked peak appeared at 1550 cm−1 in FTIR spectrum at pH 3 and 7 after HHP.
• The yield stress of SBP solutions increase after HHP treatment.
• The surface of SBP is broken by HHP treatment at pH 3, 7 and 8.

The objective of this study was to investigate the effect of high hydrostatic pressure (HHP) on the structural and rheological properties of sugar beet pectin (SBP) at pH 3, 7 and 8. The weight-average molar mass (M) of SBP at pH 3, 7 and 8 decreased significantly with increased HHP. The degree of esterification (DE) of SBP at pH 3 and 7 was unchanged by treatment with HHP; the degree of acylation (DA) was a little higher compared to the controls. Both DE and DA of SBP at pH 8, however, decreased significantly after treatment with HHP. There was a marked peak at 1550 cm−1 in FT-IR spectrum for SBP at pH 3 and 7 after treatment with HHP. The shear rate versus shear stress curves of SBP fit well with a Herschel–Bulkley model (R2 ≥ 0.99) and showed shear-thinning behavior. The yield stress (σ0) of SBP solutions at different pH values increased after treatment with HHP indicating the viscosity of SBP solutions was increased, perhaps because the protein in SBP was stretched.

Scanning electron microscopy of sugar beet pectin before & after 450 MPa treatment at different pH3, 7 and 8.Figure optionsDownload as PowerPoint slide