嗜热链球菌发酵辣椒产胞外多糖提取、结构特征及体外抗氧化活性研究

Extraction,Structural Characteristics and in Vitro Antioxidant Activity of Extracellular Polysaccharides from Peppers Fermented by Streptococcus thermophilus

为解析嗜热链球菌发酵二荆条辣椒后产胞外多糖(SR-EPS)的结构特征,同时探究其体外抗氧化活性,文章以水提醇沉法提取SR-EPS,经Sevage法除蛋白、透析截留去杂质后,测定了SR-EPS的基本成分,利用高效液相凝胶色谱仪、傅里叶红外光谱仪、离子色谱仪、扫描电镜等对SR-EPS的结构进行初步表征,同时考察了其在体外的抗氧化活性。结果表明,SR-EPS的得率为94 mg/mL,可溶性总糖、蛋白质和糖醛酸的含量分别为39.23%、0.88%、9.03%;SR-EPS由3个主要组分构成,包含α和β两种类型的糖苷键,是以甘露糖、葡萄糖和半乳糖为主的酸性杂多糖,表观结构为颗粒堆叠状、紧密且有规则;SR-EPS对ABTS^(+)·、DPPH·和羟基自由基的清除能力以及铁离子螯合能力均以剂量为依赖。综上,该研究可为了解乳酸菌发酵辣椒产胞外多糖的体外抗氧化活性提供参考,也为胞外多糖结构有序性理论提供数据支撑,同时为乳酸菌胞外多糖在功能性食品中的研发和应用提供一定的理论依据。

In order to analyze the structural characteristics of extracellular polysaccharides(SR-EPS)from Erjingtiao peppers fermented by Streptococcus thermophilus,and to explore its in vitro antioxidant activity,in this paper,SR-EPS are extracted by water extraction and alconol precipitation method.After the protein is removed by Sevage method and impurities are removed by dialysis and entrapment,the basic components of SR-EPS are determined,and the structure of SR-EPS is preliminarily characterized by high performance liquid gel chromatograph,Fourier infrared spectrometer,ion chromatograph,scanning electron microscope and so on.At the same time,its in vitro antioxidant activity is investigated.The results show that the yield of SR-EPS is 94 mg/mL,and the content of total soluble sugars,proteins and uronic acids is 39.23%,0.88%,9.03%respectively.SR-EPS are composed of three main components,including two types of glycosidic bonds such asαandβ.They are acidic heteropolysaccharides mainly composed of mannose,glucose and galactose.Their apparent structure is particle stacking,compact and regular.The scavenging capacity of SR-EPS on ABTS^(+),DPPH,hydroxyl radicals and iron ion chelation capacity are dose-dependent.In summary,this study can provide references for understanding the in vitro antioxidant activity of extracellular polysaccharides from peppers fermented by lactic acid bacteria,and provide data support for the theory of structural order of extracellular polysaccharides.At the same time,it can provide a certain theoretical basis for the research and application of lactic acid bacteria extracellular polysaccharides in functional foods.