部分酸水解对桃胶多糖结构和乳化功能的影响

为探讨桃胶多糖(peach gum polysaccharide,PGP)发挥乳化作用的关键活性结构特征，采用0.1 mol/L三氟乙酸对PGP进行部分酸水解，通过控制水解时间制备得到不同水解度的PGP样品30P、60P、120P和180P，采用高效阴离子交换色谱和高效分子排阻色谱串联多角度激光光散射分析部分酸水解对PGP单糖组成和分子质量的影响，通过水包油(O/W)乳液体系探讨部分酸水解对PGP乳化功能的影响。结果表明：PGP是由阿拉伯糖、半乳糖、木糖、甘露糖、半乳糖醛酸和葡萄糖醛酸组成的一种酸性阿拉伯半乳聚糖，结合有少量蛋白质，重均分子质量为10 980 kU，在0.1 mol/L NaNO₃溶液中呈宽分布的柔性卷曲链状；随着酸水解的进行，PGP的糖醛酸和蛋白质含量逐渐升高，分子质量逐渐减小，支化度降低，水解产物的分子构象由柔性线团结构向刚性棒状转变；研究表明，60P O/W乳液较PGP及其他水解产物形成的乳液稳定性明显提高，由此推测60P是PGP发挥乳化功能的关键活性结构特征，即分子质量为1 188 kU，支化度部分降低，糖醛酸和蛋白质缀合物含量较高的柔性链...

Effect of Partial Acid Hydrolysis on the Structure and Emulsifying Function of Peach Gum Polysaccharide

In order to investigate the key structural features of peach gum polysaccharide (PGP) responsible for its emulsifying function, partial acid hydrolysis of PGP with 0.1 mol/L trifluoroacetic acid was conducted, yielding hydrolysates 30P, 60P, 120P and 180P with different degrees of hydrolysis at different hydrolysis times. The effects of partial acid hydrolysis on the monosaccharide composition and molecular mass of PGP were analyzed by high performance anion-exchange chromatography (HPAEC) and high performance size-exclusion chromatography with a multi-angle laser light scattering detector (HPSEC-MALLS) and the effect of partial acid hydrolysis on the emulsifying function of PGP was investigated by using an oil in water (O/W) emulsion system. Results showed that PGP was an acidic arabinogalactan composed of arabinose, galactose, xylose, mannose, galacturonic acid and glucuronic acid conjugated with a small amount of protein. PGP, whose average molecular mass of 10 980 kU, presented a flexible coil-like chain in 0.1 mol/L NaNO3 solution. As acid hydrolysis progressed, the contents of uronic acid and protein in PGP gradually increased, the molecular mass and degree of branching gradually decreased, and the molecular conformation of the hydrolysates changed from a flexible coil-like to a rigid rod-like structure. The stability of the O/W emulsion prepared using 60P as an emulsifier was significantly improved compared to the other hydrolysates. It was speculated that 60P, whose molecular mass was 1 188 kU and which had reduced degree of branching and higher contents of glycuronic acid-protein conjugate and exhibited a flexible chain-like structure, may be the key structural feature responsible for of the emulsifying function PGP. This study will be helpful to further explain the mechanism action of PGP as an emulsifier.