Effect of extraction conditions on the yield, purity and surface properties of sugar beet pulp pectin extracts

Abstract

The extraction of pectins from sugar beet pulp was carried out in an aqueous acid medium under different conditions using a full two-state experimental design for three extraction parameters (pH, temperature and time). The yields of the extracted pectins ranged from 4.1% to 16.2%. Their contents in pectin constituents were 35.2–76.3% galacturonic acid, 6.8–32.9% neutral sugars, 2.0–4.2% methoxy groups, 0.8–3.8% acetyl groups, and 0.1–0.7% ferulic acid. Moreover, protein residues were present in all the extracts within the range of 0.9–6.8% and varied with the extraction conditions. On high performance size exclusion chromatography, the elution pattern of the acid-extracted pectins showed a wide molar mass distribution consisted of two relatively broad peaks. Their weight-average molar mass values determined by HPSEC-RALLS ranged widely from 20,200 to 90,100 g/mol. Most of the extracted pectins were surface-active, and some of them were quite able to produce and stabilize with effectiveness oil-in-water emulsions. Thus, it was inferred that yield, physico-chemical characteristics and surface properties of acid extracted pectins from sugar beet pulp were influenced by the extraction conditions.