Abstract Pumpkin has human nutritional benefits, arising from its high content of starch and of dietary fibres such as pectins. Pectin has been found to slow starch digestion in digesta, which is related to the reduction of propensity towards diet-related diseases such as diabetes, but whether un-extracted pectin could influence in vitro digestibility of in situ starch in vegetable is unknown. In this paper, the molecular structures of pectin and starch from 13 commercial pumpkin varieties were characterized (using HPLC and size-exclusion chromatography), and the in vitro digestion kinetics of the boiled flour measured. The structural and kinetic data were fitted to models, and correlation analysis applied to the resulting parameters to find the factors influencing the digestibility. It was found that (1) a particular structural feature of pumpkin starch was the high proportion of long amylopectin chains, (2) pumpkin pectins exhibited wide diversity in molecular structure, (3) the in vitro digestibility of pumpkin flour parameters correlated with structural parameters of both pectin (degree of esterification) and starch (average hydrodynamic radius). These results showed that both macromolecules affect pumpkin flour digestibility, and the presence of pectin as a key component of cell wall materials contribute to the provision of a barrier between amylase and starch. Unlike the digestion of pure starch, where the starch structure is the major determinant in digestibility, the digestion of pumpkin flour depends also on the complex network of pumpkin polysaccharides.

中文翻译：

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南瓜淀粉和果胶消化率与结构的关系

摘要 南瓜富含淀粉和果胶等膳食纤维，对人体具有营养价值。已发现果胶可减缓食糜中淀粉的消化，这与降低糖尿病等饮食相关疾病的倾向有关，但未提取的果胶是否会影响蔬菜中原位淀粉的体外消化率尚不清楚。在本文中，对来自 13 个商业南瓜品种的果胶和淀粉的分子结构进行了表征（使用 HPLC 和尺寸排阻色谱），并测量了煮沸面粉的体外消化动力学。将结构和动力学数据拟合到模型中，并将相关分析应用于所得参数以找出影响消化率的因素。发现（1）南瓜淀粉的一个特殊结构特征是高比例的支链淀粉长链，（2）南瓜果胶在分子结构上表现出广泛的多样性，（3）南瓜粉的体外消化率参数与结构参数相关果胶（酯化度）和淀粉（平均流体力学半径）。这些结果表明，这两种大分子都会影响南瓜粉的消化率，果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。(2) 南瓜果胶在分子结构上表现出广泛的多样性，(3) 南瓜粉的体外消化率参数与果胶（酯化度）和淀粉（平均流体力学半径）的结构参数相关。这些结果表明，这两种大分子都会影响南瓜粉的消化率，果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。(2) 南瓜果胶在分子结构上表现出广泛的多样性，(3) 南瓜粉的体外消化率参数与果胶（酯化度）和淀粉（平均流体动力学半径）的结构参数相关。这些结果表明，这两种大分子都会影响南瓜粉的消化率，果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。(3) 南瓜粉的体外消化率参数与果胶（酯化度）和淀粉（平均流体动力学半径）的结构参数相关。这些结果表明，这两种大分子都会影响南瓜粉的消化率，果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。(3) 南瓜粉的体外消化率参数与果胶（酯化度）和淀粉（平均流体动力学半径）的结构参数相关。这些结果表明，这两种大分子都会影响南瓜粉的消化率，果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。果胶作为细胞壁材料的关键成分的存在有助于在淀粉酶和淀粉之间提供屏障。与纯淀粉的消化不同，淀粉结构是消化率的主要决定因素，南瓜粉的消化还取决于南瓜多糖的复杂网络。