Abstract Lotus leaf flavonoids (LLF) are a group of bioactive natural substances. In this study, the structure, thermal properties, rheology behaviors and in vitro digestibility of cooked LLF-starch complex were investigated. Differential scanning calorimetry (DSC) analysis showed the shift in gelatinization peak to a higher temperature and the decrease in gelatinization enthalpies in the complexes significantly. The short-term retrogradation was retarded either. The flow behaviors of starch pastes changed with adding LLF. Scanning electron microscope (SEM) images showed a less compact structure in LLF-starch complex and laser confocal scanning microscope (CLSM) images detected that LLF mostly distributed around starch granules, which further prove the binding between LLF and starch. Moreover, fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) elucidated LLF probably interacted with starch by non-covalent bond especially hydrogen bond. In addition, LLF-starch complex exhibited inhibitory effect on starch digestion compared to pregelatinized starch, and the reasonable content of LLF-starch complex was (0.7 g/100 g). Thus, LLF-starch complex can be potentially used as a functional additive for high resistant starch (RS) and low glycemic index (GI) diets.

中文翻译：

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莲藕（Nelumbo nucifera Gaertn.）叶黄酮复合物的理化性质、结构和体外消化率

摘要 荷叶黄酮（LLF）是一组具有生物活性的天然物质。在这项研究中，研究了熟 LLF-淀粉复合物的结构、热性能、流变行为和体外消化率。差示扫描量热法 (DSC) 分析表明，糊化峰向较高温度移动，复合物中的糊化焓显着降低。短期回生也被推迟。淀粉糊的流动行为随着LLF的加入而改变。扫描电子显微镜 (SEM) 图像显示 LLF-淀粉复合物的结构不太紧密，激光共聚焦扫描显微镜 (CLSM) 图像检测到 LLF 主要分布在淀粉颗粒周围，进一步证明了 LLF 与淀粉之间的结合。而且，傅立叶变换红外 (FTIR) 光谱和 X 射线衍射 (XRD) 阐明 LLF 可能通过非共价键特别是氢键与淀粉相互作用。此外，与预糊化淀粉相比，LLF-淀粉复合物对淀粉消化具有抑制作用，LLF-淀粉复合物的合理含量为（0.7 g/100 g）。因此，LLF-淀粉复合物有可能用作高抗性淀粉 (RS) 和低血糖指数 (GI) 饮食的功能性添加剂。