Optimisation of production yield by ultrasound-/microwave-assisted acid method and functional property of pectin from sugar beet pulp

Response surface methodology was used to optimise pectin recovery from sugar beet pulp using ultrasound-/microwave-assisted acid method (UMAAM). The independent variables were microwave heating temperature, microwave heating time and solid-to-liquid ratio. From the results, the selected optimal conditions were 92 degrees C, 37min, and solid-to-liquid ratio 1:30. Under these conditions, the yield and uronic acid content of the pectin (SBP1) was 26.16% and 75.38%, respectively. Compared with the sugar beet pectin (SBP2) extracted by traditional acid method, SBP1 showed a higher molecular weight, higher viscosity and emulsifying activity and stability. The possible reason was that the UMAAM could have had minimal change in the protein-polysaccharide complex structure of pectin, but significantly increased the length of polysaccharide chains compared with SBP2. These results suggested that UMAAM is an efficient method in extracting pectin and has the potential to be used in the sugar beet industry.