Abstract Rutin is a dietary flavonoid and a potent antioxidant with clinically relevant functions. Hence, rutin-enriched food products can be used as functional foods. However, rutin has low bioavailability because of its low water solubility, poor stability and limited membrane permeability. We previously reported a casein‒rutin co-precipitate that significantly increased water solubility, compared with commercially available rutin powders. This work investigated the gastrointestinal behaviour of a yoghurt enriched with casein‒rutin co-precipitate (RuYO) and an unfortified yoghurt combined with powdered rutin in a vegetable-based capsule (CtYO + Ru). A semi-dynamic in vitro digestion protocol was followed; the gastric phase was simulated in a human gastric simulator. The physical properties and rutin content of digesta samples were determined at different digestion times. The solids retention of RuYO and CtYO + Ru in the gastric phase decreased with increasing digestion time, confirming that gastric emptying occurred at a constant rate. Confocal microscopy indicated that the protein network was increasingly hydrolysed during gastric digestion. The release and stability of rutin during the digestion of RuYO were dramatically different from those of CtYO + Ru. Although a significant amount of the flavonoid remained in the insoluble fraction during gastric digestion, it was more stable in RuYO than in CtYO + Ru (total cumulative recoveries of 98% and 61% respectively). Similarly, rutin degradation was lower in RuYO in the intestinal phase (total cumulative recovery: RuYO, 26%; CtYO + Ru, 17%). Overall, yoghurt fortified with rutin‒casein co-precipitate gives better in vitro rutin bioaccessibility than the same yoghurt co-digested with a rutin supplement capsule.

中文翻译：

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酸奶结构的消化动力学影响黄酮类芦丁的释放和生物可及性

摘要 芦丁是一种膳食类黄酮，是一种具有临床相关功能的强效抗氧化剂。因此，富含芦丁的食品可用作功能性食品。然而，芦丁由于其水溶性低、稳定性差和膜渗透性有限而具有低生物利用度。我们之前报道了一种酪蛋白-芦丁共沉淀物，与市售芦丁粉相比，它显着增加了水溶性。这项工作研究了富含酪蛋白-芦丁共沉淀物 (RuYO) 的酸奶和一种在植物基胶囊 (CtYO + Ru) 中与粉末芦丁混合的未强化酸奶的胃肠道行为。遵循半动态体外消化方案；在人胃模拟器中模拟胃相。在不同的消化时间测定了食糜样品的物理性质和芦丁含量。RuYO 和 CtYO + Ru 在胃相中的固体滞留量随着消化时间的增加而减少，证实胃排空以恒定速率发生。共聚焦显微镜表明蛋白质网络在胃消化过程中越来越多地水解。RuYO 消化过程中芦丁的释放和稳定性与 CtYO + Ru 的有显着差异。尽管在胃消化过程中大量黄酮类化合物保留在不溶性部分中，但它在 RuYO 中比在 CtYO + Ru 中更稳定（总累积回收率分别为 98% 和 61%）。同样，RuYO 在肠道阶段的芦丁降解率较低（总累积回收率：RuYO，26%；CtYO + Ru，17%）。全面的，