Abstract: 【Objective】 This study aimed to clear the effect of high hydrostatic pressure (HHP) on the structural and emulsifying properties of sugar beet pectin, and provide a theoretical basis for the applications of sugar beet pectin in food industry. 【Method】 1% (w/v) of sugar beet pectin solution was prepared, and treated under different pressures (0.1, 250, 350, 450 and 550 MPa) and pH 7 for 30 min; 450 MPa and pH 7 for different times (10, 20, 30 and 50 min); 450 MPa and different pH values (pH 3, pH 7 and pH 8) for 30 min. After that, the structural and emulsifying properties were compared with the untreated samples. 【Result】 When the sugar beet pectin solution was treated under different pressure conditions at pH 7, with the increase of pressure, the Mw of sugar beet pectin was reduced from 5.58×10⁵ Da (0.1 MPa) to 1.56×10⁵ Da (550 MPa), and the degree of esterification (DE) and acetylation (DA) were increased from 61.29% and 18.17% (0.1 MPa) to 68.24% and 21.72% (550 MPa), respectively. FT-IR spectra in 1 760-1 730 cm^-1 and 1 630-1 600 cm^-1 regions of SBP showed more clearly than untreated SBP, and FT-IR images spectra in 1 560-1 540 cm^-1 was appeared after the HHP treatment. After 250 MPa treated for 30 min, the emulsifying activity (EA) and the emulsifying stability (ES) of SBP were increased from 209 m²·g^-1 and 79 min to 230 m²·g^-1 and 97 min, the volume mean diameter (D_4,3) was decreased and the specific surface (Sv) was increased. However, the emulsifying properties of pectin were not significantly changed after continued to increase pressure. There were no significant differences in Mw, DA, DE and emulsifying properties between different processing times under 450 MPa. Mw of SBP under pH 3, pH 7 and pH 8 conditions were reduced from 5.88, 5.58 and 5.44×10⁵ Da to 2.38, 2.25 and 2.49×10⁵ Da after 450 MPa treated for 30 min; the DE of SBP did not change significantly under pH 3 and pH 7 conditions, the DA was increased from 19.35% and 18.17% to 21.70% and 24.84%, respectively; but the DA and DE were reduced from 70.13% and 19.53% down to 50.24% and 16.41% under pH 8 condition; the EA and ES of SBP were significantly improved after high pressure treatment at pH 3, pH 7 and pH 8, the EA was better at pH 3 and pH 7 conditions, and the ES was the best at pH 3. 【Conclusion】 These results suggest that HHP treatment reduced the molecular weight of sugar beet pectin, induced the protein exposure, and also improved the emulsifying properties of sugar beet pectin.

Key words: HHP treatment, sugar beet pectin, molecular weight, degree of acetylation, emulsifying properties