荔枝果渣可溶性膳食纤维去结合酚前后结构和功能性质的比较

Comparison of the Structure and Functional Properties of Soluble Dietary Fiber from Lychee Pomace before and after the Removal of Bound Phenolics

该研究以荔枝果渣中的可溶性膳食纤维(Soluble Dietary Fiber,SDF)为原料,探讨碱水解法去除其中的结合酚后SDF结构和功能性质的变化。结果表明荔枝果渣可溶性膳食纤维中结合酚含量为4.53 mg GAE/g。扫描电镜结果表明去除结合酚后的SDF结构变得较为松散;傅里叶红外光谱的结果表明SDF的主要成分为果胶和半纤维素,去除结合酚后的SDF未发生官能团上的转化。单糖组成和流变特性分析结果表明SDF和去除结合酚后的SDF单糖组成相同,且都为假塑性非牛顿流体;但相同剪切速率下,去除结合酚后的SDF表观黏度大为降低,这与其更加松散的结构有关。相同浓度下,去除结合酚后SDF的DPPH自由基清除能力降低了15.06%~29.02%,ABTS阳离子自由基清除能力降低了42.06%~78.98%。此外,去除结合酚后SDF对3种益生菌的体外增殖作用也显著降低。上述结果证实,结合酚与荔枝果渣可溶性膳食纤维的生物活性息息相关,为荔枝果渣的开发利用提供理论基础。

In this research,soluble dietary fiber(SDF)from litchi pomace was used as the raw material to study the changes in the structure and functional properties of SDF after the removal of the bound phenolics via alkaline hydrolysis.The results showed that the content of bound phenolics in SDF from litchi fruit residue was 4.53 mg GAE/g.The results of SEM examination showed that the structure of SDF became looseer after the removal of bound phenolics;the results of Fourier transform infrared spectroscopy analysis showed that the main components of SDF were pectins and hemicelluloses,and the removal of bound phenolics from SDF did not change the functional groups.The analysis results of monosaccharide composition and rheological properties showed that the monosaccharide compositions of SDF samples before and after the removal of bound phenolics remained the same,and both SDF dispersions were pseudoplastic non-Newtonian fluids;However,at the same shear rate,the apparent viscosity of the SDF sample after the removal of bound phenolics was greatly reduced,which was related to the looser structure of this SDF.At the same SDF concentration,the removal of bound phenolics led to the decreases of DPPH radical scavenging ability by 15.06%~29.02% and ABTS+radical scavenging ability by 42.06%~78.98%.In addition,the effect of SDF on the in vitro proliferation of three probiotics was also significantly reduced after the removal the bound phenolics.The above results confirmed that the bound phenolics were closely related to the bioactivities of soluble dietary fiber from lychee pomace,and provide a theoretical basis for the exploitation and utilization of litchi pomace.