• 中文核心期刊
  • CSCD来源期刊
  • 中国科技核心期刊
  • CA、CABI、ZR收录期刊

2种提取工艺粗茶叶多糖组成及其抗氧化活性研究

Compositions and Antioxidant Activities of Oolong Tea Extracts Made by Two Processing Methods

  • 摘要: 以清香乌龙茶为原料,采用先65%醇洗+后水提和先水提+后65%醇沉等2种提取方式制得粗茶叶多糖(TPs-水提和TPs-醇沉)及相应的附属产物(TPs-A、TPs-B和TPs-C),分析比较其组成含量、还原力及DPPH清除活性变化。结果表明,先65%醇洗+后水提制得的粗茶多糖中多糖含量最高,可溶性蛋白含量最低。其他组分来看,乙醚浸提茶叶有助于茶多酚/儿茶素类、总黄酮类、咖啡碱等小分子物质的浸出,水提醇沉则对茶叶内含成分的分离富集效果较差。抗氧化活性试验表明,2种提取方式制备的粗茶多糖TPs-水提和TPs-醇沉的还原力及DPPH清除活性显著弱于附属产物TPs-A、TPs-B和TPs-C。相关性分析表明,粗茶多糖的抗氧化活性表达与茶多酚中的儿茶素类,尤其是酯型儿茶素呈显著正相关,而与茶多糖、总黄酮和咖啡碱则呈正相关。结果表明,茶多糖具有抗氧化作用,其活性弱于茶叶中的多酚类。

     

    Abstract: An aromatic oolong tea was used as the raw material to extract polysaccharides (TPs) and other constituents (TPs-A, TPs-B and TPs-C) using two processing methods. The chemical compositions, reducing power, and DPPH scavenging capacities of the extracts were determined. The results showed that the method applying 65% ethanol for pre-soaking followed by a water extraction (E-W) produced more TPs and less soluble protein than the process employing a water extraction before precipitation by 65% ethanol (W-E). E-W promoted the extractions of polyphenols, catechins, flavonoids and caffeine; while, W-E was less efficient in separating or concentrating the components. On the antioxidant activity, TPs obtained by both methods were significantly lower on the reducing power and DPPH scavenging capacity than those of TPs-A, TPs-B and TPs-C. The correlation analysis suggested that the antioxidant activity of TPs was significantly related to the contents of polyphenols, catechins, and particularly ester catechins in the extract.There was also a synergism among TPs, total flavonoid and caffeine. It appeared that as antioxidants, TPs exhibited significantly lower activity than the phenolic compounds in the tea.

     

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