紫薯多酚的提

发布时间：2019-05-18 12:00

【摘要】：紫薯(Purple sweet potato)属旋花科,多分布于中国南方大部分地区。紫薯所含营养成分丰富,块茎除含有植物多糖、蛋白质、维生素等多种营养成分外,还富含花色苷、绿原酸、类黄酮等多酚类物质,这类物质是天然的抗氧化剂,具有降血脂、抗肿瘤、有效清除自由基、抗衰老等增强机体免疫的功能。目前关于多酚的研究主要是对某种原料的游离酚进行的提取测定,而自然界的各类物种,尤其是在植物原料中,除了游离酚外,还有一部分酚类物质是以结合态的形式存在的,这部分酚类物质即为结合酚。目前国内外对植物中结合酚提取纯化及活性研究方面的系统报道较少,本文以"辽薯20"这一品种的紫薯冻干粉为原料,对其游离酚和结合酚分别进行提取和纯化,采用高效液相色谱技术、液质联用技术对其酚酸类物质组成进行了分析,采用DPPH自由基清除法和α-葡萄糖苷酶活性抑制法初步研究了其抗氧化活性和降血糖活性,并利用体外模拟消化试验研究了其体外模拟消化释放和在胃肠道消化过程中的稳定性,研究结果如下:1、经筛选后采用体积分数为60%的乙醇水溶液提取紫薯游离酚,在单因素试验的基础上,利用响应面分析法优化相关参数,得出了紫薯游离酚提取的最优预测值,即当提取温度50.12℃,液料比55.43:1(mL/g),提取时间2.12h时,提取率可达到1.08g/100g,结合实际操作,优化工艺参数确定为温度50℃,液料比55:1(mL/g),提取时间2h.在此参数下,提取率为(1.06±0.001)g/100g,达到了预测值的98.88%。用碱水解法对充分提取游离酚后的紫薯渣中结合酚进行水解提取,单因素试验基础上采用响应面分析法优化工艺参数,得出紫薯结合酚提取的最优预测值为:液料比32.2:1(mL/g),NaOH浓度1.87mol/L,水解时间5.22h时,多酚提取率达到0.58g/100g.结合实际操作优化工艺参数为液料比30:1(mL/g),NaOH浓度2mol/L,水解时间5h,结合酚提取率为(0.57±0.008)g/100g,达到预测值得97.34%。2、AB-8型大孔树脂纯化紫薯游离酚较为理想,吸附时最适上样浓度是1.0mg/mL,上样液pH为3.0,最大上样体积120mL即5.4BV,此时的吸附率可以达到(80.29±0.44)%,解吸时最适洗脱剂为pH为7.0的体积分数为50%的乙醇水溶液,洗脱体积150mL即6.8BV,此时的解吸率达到(85.59±0.38)%;结合酚的纯化使用的是HPD-100型号的大孔树脂,吸附时最适上样浓度是0.25mg/mL,上样液pH为3.0,最大上样体积80mL即3.6BV,此时的吸附率可以达到(73.88±0.40)%,解吸时最适洗脱剂为pH为5.0的体积分数为50%的乙醇水溶液,洗脱体积150mL即6.8BV,此时解吸率可以达到(84.64±0.10)%。酚类化合物在纯化前后含量差异显著,说明大孔树脂对紫薯多酚的纯化效果较好。3、液质联用鉴定结果表明紫薯游离酚由单咖啡酰奎宁酸(绿原酸)、甲基化咖啡酰奎宁酸、二咖啡酰奎宁酸和甲基化二咖啡酰奎宁酸的同分异构体构成,紫薯结合酚主要包含羟基苯甲酸和咖啡酸,进一步利用高效液相色谱对照法确定了游离酚中二咖啡酰奎宁酸为绿原酸、异绿原酸A、异绿原酸B和异绿原酸C和结合酚中对羟基苯甲酸的存在。对树脂纯化后的紫薯多酚样品进行体外清除DPPH自由基及抑制α-葡萄糖苷酶活性的检测,结果表明,游离酚和结合酚清除DPPH自由基的半数抑制浓度(IC50)分别为0.014mg/mL和2.02mg/mL;α-葡萄糖苷酶活性抑制的IC50分别为0.16mg/mL和0.98mg/mL,说明紫薯的多酚清除DPPH自由基的能力和抑制α-葡萄糖苷酶活性的能力总体来说较好。4、通过体外模拟机体消化方式来研究紫薯消化过程中多酚的释放量、吸收量及多酚的稳定性,结果表明:紫薯在体外模拟消化过程中,多酚释放的最佳时间为:胃消化1h、肠消化2h.总酚、黄酮、花色苷和酚酸的生物利用率分别为(18.42±0.33)%、(15.00±0.21)%、(0.46±0.006)%和(12.87±0.12)%。游离酚在消化过程中除酚酸外,总酚、黄酮和花色苷的浓度持续降低,但结合酚在肠消化时黄酮、花色苷和酚酸的含量升高,由此说明结合酚稳定性好于游离酚;经过体外模拟消化的紫薯,其游离酚各物质的浓度均明显下降,但在结合酚中总酚、黄酮和酚酸的浓度明显上升,说明在体外消化过程中有一部分游离酚与大分子结合,转化成结合酚。
[Abstract]:Purple sweet potato is a kind of spinning machine, which is mostly distributed in most parts of the south of china. The purple sweet potato contains rich nutrient components, and the tuber is rich in various nutrient components such as plant polysaccharide, protein, vitamin and the like, and is rich in polyphenol substances such as flower color, chlorogenic acid, and flavonoid, And has the functions of resisting aging and the like and enhancing the immunity of the body. At present, the research on polyphenol is mainly the extraction and determination of the free phenol of some kind of raw material, and the various species of the natural world, in particular in the plant raw material, in addition to the free phenol, a part of the phenolic substance is present in the form of the bound state, and the phenolic substance is the combined phenol. At present, there are few systematic reports on the extraction and purification of the combined phenol in plants and the research on the activity of the combination of phenol in plants, and the free phenol and the combined phenol are respectively extracted and purified by using the purple sweet potato freeze-dried powder as the raw material, and the high-performance liquid chromatography technology is adopted. The composition of phenolic acids was analyzed by liquid-mass spectrometry, and the anti-oxidative activity and the hypoglycemic activity were studied by the method of DPPH free radical scavenging and the inhibition of the enzyme activity of the yeast-grape. The results of this study were as follows:1. The free phenol of purple sweet potato was extracted with 60% ethanol aqueous solution after screening, and on the basis of single factor test, The optimum predicted value of the extraction of the free phenol of purple sweet potato was obtained by using the response surface analysis method, that is, when the extraction temperature is 50.12 鈩，

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