Esterification of sugar beet pectin using octenyl succinic anhydride and its effect as an emulsion stabilizer

Sugar beet pectin (SBP) was esterified using octenyl succinic anhydride (OSA) and potassium carbonate, as a catalyst, at 160 degrees C. The structure of the product, octenyl succinate sugar beet pectin (OS-SBP), was characterized by Fourier transform infrared (FT-IR), Raman and H-1 NMR spectroscopy, which demonstrated that OSA groups had been introduced into the SBP molecules and most OS substitution occurred at the C-3 position. SBP- and OS-SBP-stabilized oil-in-water emulsions prepared at a concentration of 1.0% (w/w) were compared using 20% middle-chain triglyceride (MCT) as the oil phase. The properties of emulsions stabilized by SBP and OS-SBP were evaluated via surface tensiometry, microscopy, determination of the creaming index (CI) and droplet size distribution. The results showed that emulsions stabilized by OS-SBP with a low degree of substitution (DS) possessed a smaller oil droplet size and improved storage stability compared with those of the emulsion generated using SBP. The decalcification could improve the emulsifying properties of OS-SBP. The results suggested that OS-SBP with a DS of 1.8 would be a strong emulsifying agent in acidic environments. (C) 2015 Elsevier Ltd. All rights reserved.