豌豆种皮水溶性多糖的提取优化、动力学与分子特征

The optimization of the extract condition,kinetics,and molecular characteristics of water-soluble polysaccharides from Pisum sativum L.seed pericarp

旨在探讨豌豆种皮水溶性多糖的最佳提取工艺条件,解析提取动力学参数并鉴定单糖组成与分子特性,为制备多糖提供理论基础并了解潜在应用性。结果显示,热力提取多糖的最佳提取条件为:液料比25∶1(mL∶g),提取温度91℃,提取时间1.5 h。最大得率为4.4%。在90℃下,多糖得率与提取时间的关系可以两阶段的一级扩散动力学模式来描述,前期与后期的提取速率常数k 1分別为0.0288和0.0907 min-1;也可以一阶段的伪一级(n=0.81)动力学模式来描述,提取速率常数k n=0.0237 min-1。该多糖的主要单糖组成为阿拉伯糖、木糖和半乳糖醛酸(摩尔比1∶0.55∶0.45),显示含有聚阿拉伯糖、聚木糖和果胶。分子特性方面,其重均分子质量(M w)=338.9 kDa;多分散系数(PDI)=3.67;均方根回旋半径(R g)=46.8 nm;流体力学半径(R h)=33.8 nm;R g/R h=1.38;固有黏度[η]=85.8 mL/g;马克-霍温-樱田关系式([η]=K×Mαw)参数[α]=0.372,可推知其分子链构象呈柔软无规则卷曲松散的球状。豌豆种皮水溶性多糖适合用来制备高附加值的聚阿拉伯糖和聚木糖。

The aim of this study was to investigate the optimum extract condition for water-soluble polysaccharides from Pisum sativum L.seed pericarp,elucidate extraction kinetic parameters,and identify the monosaccharide compositions and molecular characteristics of the polysaccharides.Seventeen extraction conditions designed by Box-Behnken experimental design were applied.After response surface statistical analysis,the optimal extraction condition was:liquid-material ratio 25 mL/g;extraction temperature 91℃for 1.5 h.Under this condition,the maximal yield was 4.4%.The given multiple regression model could describe very well for yield variations in terms of extraction factors.The increase in polysaccharide yield with extraction time at 90℃could be closely explained by two-stage first-order diffusion kinetics with the early-and late-stage extraction rate constant(k 1)of 0.0288 and 0.0907 min-1,respectively.Alternatively,it could also be explained by one-stage pseudo-first-order kinetics(n=0.81)with an extraction rate constant k n=0.0237 min-1.The polysaccharides were mainly composed of arabinose,xylose,and galacturonic acid(molar ratio=1∶0.55∶0.45),implying the presence of arabinans,xylans,and pectins.Moreover,for molecular characteristics,the polysaccharides showed a weight-averaged molecular weight(M w)=338.9 kDa;polydispersity index(PDI)=3.67;mean-square radius of gyration(R g)=46.8 nm;hydrodynamic radius(R h)=33.8 nm;R g/R h=1.38,intrinsic viscosity[η]=85.8 mL/g,and the exponentαfor Mark-Houwink-Sakurada relationship[η]=K×M wα)=0.372.These results suggested that the chain conformation of the polysaccharides adapted flexible random-coil sphere.Conclusively,water-soluble polysaccharides from Pisum sativum L.seed pericarp would be suitable for the production of valorized arabinans and xylans.