Effects of bovine serum albumin on the ethanol precipitation of sugar beet pulp pectins

Abstract

Bovine serum albumin (BSA) was used as an auxiliary to improve the ethanol precipitation yield of sugar beet pulp pectin (SBPP). The adjunction of BSA reduced the zeta potential of SBPP solution to a certain extent, which indicated that they were related to each other by electrostatic interaction. The hydration radius (Rh) of SBPP molecules decreased with the addition of BSA, reflecting the decrease of hydration degree of SBPP molecules. The effect of BSA on the ethanol precipitation yield of SBPP at different ethanol concentrations and different pH values was studied. The results showed that the presence of BSA could significantly reduce the dependence of SBPP on ethanol during the precipitation process. The effect of BSA on the precipitation behavior of SBPP was also regulated by system pH. The results of pectin structural analysis showed that there was no significant difference between SBPPs precipitated along with BSA and the original pectin samples in terms of galacturonic acid (GalA), neutral sugar (NS) and degree of methylation (DM). The high-performance size-exclusion chromatography (HPSEC) analysis showed that BSA could precipitate together with SBPP, but did not contribute to the precipitation of small-sized pectic fractions in SBPP solution. SBPP-BSA co-precipitation products were used to stabilize oil-in-water emulsions, and the storage stability of the resulting emulsions was significantly higher than that of the SBPP-stabilized emulsions. This method provided a new idea for reducing the consumption of ethanol in pectin precipitation. Meanwhile, the pectin-protein complex product obtained by co-precipitation had a good performance at stabilizing emulsions.