关键词: 红枣, 多糖, 动力学, 傅里叶变换红外光谱, 原子力显微镜

Abstract: The extraction of polysaccharides from Linze jujube fruit (LZJP) by hot extraction followed by ethanol precipitation was studied. The physicochemical properties and microstructure of LZJP were analyzed. Based on Fick’s first law of diffusion, the mass transfer kinetics of polysaccharides at different temperatures and solid to solvent ratios were investigated and a kinetic model was established for the extraction process. The key model parameters including rate constant, relative extraction rate, activation energy and half-life were calculated. The experimental data were found to be well fitted to the kinetic model and the extraction process obeyed first-order kinetics with an activation energy of 19.266 kJ/mol, indicating that hot water extraction could enable effective extraction of polysaccharides from Linze jujube fruit. Purification of LZJP by DEAE-52 cellulose and Sephadex G-100 column chromatography yielded homogenous polysaccharides LZJP3 and LZJP4, respectively. Fourier transform infrared spectra showed that LZJP3 and LZJP4 were acidic polysaccharides and β-pyran polysaccharides. Atomic force microscopy indicated that LZJP3 molecules were loosely arranged with uniform size and shape and that LZJP4 had a small amount of globular aggregates and a large number of dispersions with unequal sizes. Scanning electron microscopy showed that LZJP3 was flaky with a smooth but slightly damaged surface; LZJP4 was branched with a?wrinkled and dry surface.

Key words: Ziziphus jujuba Mill., polysaccharides, kinetics, Fourier transform infrared spectroscopy, atomic force microscope