超声辅助提取刺梨果渣多糖及其抗氧化活性的研究

目的 采用超声辅助提取刺梨果渣多糖,探究不同超声时间(30, 45, 90 min)对刺梨果渣多糖化学组成、官能团、分子量及抗氧化活性的影响。方法 通过高效凝胶色谱、高效液相、傅里叶红外光谱等方法探究超声对刺梨果渣多糖结构的影响。以还原力及自由基清除率为指标,对刺梨果渣多糖的抗氧化活性进行研究。结果 刺梨果渣多糖是由葡萄糖醛酸、半乳糖醛酸、甘露糖、核糖、鼠李糖、葡萄糖、半乳糖、木糖、阿拉伯糖、岩藻糖组成的酸性多糖。相比传统热水提取,超声对多糖的单糖组成及官能团的特征吸收无明显影响,但可有效降解多糖高分子量的组分。短时间超声辅助提取(30,45 min)可提高刺梨果渣多糖对DPPH?、ABTS+?的清除能力以及对Fe3+的还原能力,这是由于分子量降低,多糖分子中的游离羟基及还原端含量增加,使得多糖抗氧化活性增强。但随着超声时间的增长(90 min),多糖抗氧化活性不再上升,可能是由于多糖双螺旋结构发生改变,供氢能力减弱。结论 超声辅助提取工艺可有效提高多糖提取率,短时间的超声辅助提取可通过降低多糖分子量从而提高其抗氧化活性。本研究可为超声辅助提取技术在刺梨果渣高值化利用中的应用提供理论参考。

Ultrasound-assisted extraction of Rosa roxburghii Tratt pomace polysaccharide and its antioxidant activity

Objective Ultrasound-assisted extraction was applied to extract polysaccharides from Rosa roxburghii Tratt pomace (RRTP). The influence of ultrasonic duration (30, 45 and 90 min) on chemical composition, functional group, molecular weight and antioxidant activity of the polysaccharides was investigated. Methods High-performance gel permeation chromatography, high-perfomance liquid chromatography and Fourier transform infrared spectroscopy were applied to illustrate the influence of ultrasound on RRTP structures. Antioxidant activity of RRTP was determined based on reducing ability and scavenging ability on free radicals. Results RRTP was an acidic polysaccharide consisted of glucuronic acid, galacturonic acid, mannose, ribose, rhamnose, glucose, galactose, xylose, arabinose and fucose. Compared to the traditional hot water extraction, ultrasound-assisted extraction did not result in obvious changes in the monosaccharide composition and functional groups of RRTP, while it could effectively degrade the high-molecular weight fractions in RRTP. Ultrasound-assisted extraction with short duration (30, 45 min) improved the ability of RRTP to reduce Fe3+ and scavenge DPPH? and ABTS+?. This was because that the lower the molecular weight RRTP had, the more the free hydroxyl groups and reducing ends existed in RRTP, which contributed to the stronger antioxidant activity. However, with the extending of ultrasonic duration (90 min), antioxidant activity of RRTP did not continue to be enhanced. This was probably due to the changes in regular helical conformation of RRTP, thus resulting in the reduced hydrogen donor capability. Conclusion Ultrasound-assisted extraction was an efficient method to increase polysaccharide extraction yield. Ultrasound with short extraction duration could improve antioxidant activity of polysaccharide by lowering its molecular weight. This study would provide a theoretical reference for the application of ultrasound-assisted extraction in reutilization of Rosa roxburghii tratt pomace.