Structural features and emulsifying stability of a highly branched arabinogalactan from immature peach (Prunus persica) exudates

An acidic polysaccharide was isolated from immature peach (Prunus persica) exudates (designated as PGP). The primary structure and conformational properties were characterized by methylation and GC-MS analysis, NMR spectra, and high performance size exclusion chromatography (HPSEC) coupled with multiple detectors. Results showed that PGP was mainly consisted of arabinose (48.5%, w/w) and galactose (33.8%, w/w), with small amount of xylose (4.0%, w/w), glucuronic acid (4.3%, w/w) and galacturonic acid (2.3%, w/w) as well as trace mannose. A beta-(1 -> 6)-galactan backbone with branches of long alpha-(1 -> 3)-arabinan at O-4 position of galactose, and alpha-(1 -> 5)-Araf at O-3 position of galactose terminated by alpha-Araf and occasionally beta-4-OMe-GlcpA was proposed to PGP. Conformational studies revealed that PGP presented as hyper-branched compact spherical conformation, with weight average molecular weight (Mw) of 1.40 x 10(4) kDa, radius of gyration (Rg) of 223.4 nm, and intrinsic viscosity ([eta]) of 2.76 dL/g in aqueous solution. High concentrations of PGP (5% and 10%, w/v) demonstrated good emulsifying stability on the O/W emulsion by inhibiting coalescence and flocculation, stabilizing the particle size, and increasing the zeta-potential of emulsion system, suggesting it could be an alternative material as emulsion stabilizer used in food industry.