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首页> 外文学位 >Procyanidin oligomers and polyphenol oxidase: Methods for extraction optimization, enzymatic inhibition, and application as a natural inhibitor.
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Procyanidin oligomers and polyphenol oxidase: Methods for extraction optimization, enzymatic inhibition, and application as a natural inhibitor.

机译：原花青素低聚物和多酚氧化酶：提取优化，酶抑制和天然抑制剂应用的方法。

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摘要

The extraction of procyanidins from a food is influenced by food matrix, extraction solvent, sample particle size, sample to solvent ratio, as well as other factors. Many of these parameters can be controlled in a laboratory to improve or target the extraction of low or high molecular weight oligomers. This study first examines the influence of solvent polarity and composition, solvent-solute ratio and particle size on the extraction of procyanidin oligomers monomer through decamer. The solvents evaluated included dimethyl sulfoxide (DMSO), acetone and methanol. Reversed-phase high-performance liquid chromatography (HPLC) and a diol-stationary phase were used to qualitatively compare extraction efficiencies of the procyanidin oligomers. Results indicate that using 70% acetone, solute-solvent ratio 3g-15 mL, and particle size 0.99 mm optimized procyanidin extraction from cocoa beans, yielding 55.2mg/g procyanidins per gram defatted cocoa. These optimized extraction methods were used with cocoa hulls but resulted in roughly 5% of the amount of procyanidin oligomers extracted from the cocoa bean; when the solvent volume was doubled, 8.5% was recovered. However, the profile of oligomers extracted changed, as the hull provided a more uniform distribution of higher oligomers extracted than the cocoa bean. Oligomeric procyanidin extracts from cocoa pods and cocoa hulls were studied for their ability to inhibit polyphenol oxidase. Pentameric procyanidins from cocoa beans showed mixed, non-competitive inhibition with a KI of ∼0.1-0.3 mM. Cocoa hull extracts showed inhibition in a controlled assay, but did not show significant inhibition when applied to a food model. Upon re-extraction of the procyanidins from the food-model, it was discovered that the oligomers were no longer detectable by HPLC chromatography. While procyanidin oligomers can act as polydentate ligands and bind the enzyme at several sites on the protein surface, interactions between the oligomers and the food-matrix lead to loss of oligomeric structure, as well as loss of inhibition function.
机译：从食物中提取原花青素受食物基质，提取溶剂，样品粒度，样品与溶剂的比例以及其他因素的影响。这些参数中的许多参数都可以在实验室中进行控制，以改善或瞄准低分子量或高分子量低聚物的提取。这项研究首先研究了溶剂极性和组成，溶剂-溶质比和粒径对通过decamer提取原花青素低聚物单体的影响。评估的溶剂包括二甲基亚砜（DMSO），丙酮和甲醇。使用反相高效液相色谱（HPLC）和二醇固定相定性比较原花青素低聚物的提取效率。结果表明，使用70％丙酮，溶质-溶剂比3g-15 mL和粒径<0.99 mm，可可豆中原花青素的最佳提取工艺得到每克脱脂可可豆55.2mg / g原花青素。这些优化的提取方法用于可可豆壳，但可可豆中提取的原花青素低聚物的量约为5％；当溶剂体积加倍时，回收了8.5％。但是，提取的低聚物的轮廓发生了变化，因为船壳提供了比可可豆更均匀的更高提取的低聚物分布。研究了可可豆荚和可可豆壳的低聚原花青素提取物抑制多酚氧化酶的能力。来自可可豆的五聚体原花青素显示出混合的，非竞争性的抑制作用，KI约为0.1-0.3 mM。可可壳提取物在对照试验中显示出抑制作用，但应用于食品模型时未显示出明显的抑制作用。从食物模型中再次提取原花青素后，发现通过HPLC色谱不再可检测到低聚物。原花青素低聚物可以充当多齿配体并在蛋白质表面的多个位点上结合酶，但低聚物与食物基质之间的相互作用会导致寡聚结构的丧失以及抑制功能的丧失。

著录项

  • 作者

    Robertson, Danielle Lee.;

  • 作者单位

    University of California, Davis.;

  • 授予单位 University of California, Davis.;
  • 学科 Agriculture Food Science and Technology.;Chemistry Organic.
  • 学位 M.S.
  • 年度 2010
  • 页码 79 p.
  • 总页数 79
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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