Biopolymers and Colloids Laboratory, Department of Food Science , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States.
J Agric Food Chem. 2019 Nov 6;67(44):12245-12254. doi: 10.1021/acs.jafc.9b04904. Epub 2019 Oct 24.
The pH-shift method is a simple approach for incorporating certain kinds of polyphenol-based nutraceuticals into already existing colloidal systems. The polyphenols can be loaded into hydrophobic particles due to the fact that their water-solubility is relatively high under alkaline conditions but low under acid or neutral conditions. In this study, it was demonstrated that bovine milk could be enriched with curcumin using this approach, without adversely affecting milk fat globule stability. The storage stability of the curcumin-enriched bovine milk was assessed when samples were incubated for 60 days at different pH values and temperatures. The pH-stability was determined by storing curcumin-enriched milk at 4 °C for 60 days at pH 6.5, 7.0, and/or 8.0. At this low storage temperature, all milk samples were stable to fat globule aggregation, creaming, curcumin degradation (<13% loss), and color loss. The temperature-stability was determined by storing curcumin-enriched milk at pH 7 for 15 days at 4, 20, 37, or 55 °C. Curcumin breakdown decreased with decreasing storage temperature: 55 °C (43%) > 37 °C (21%) > 20 °C (10%) > 4 °C (5%). Interestingly, the color of the curcumin-enriched milks incubated at 4, 20, and 37 °C remained similar to that of the initial samples, but the sample stored at 55 °C showed significant color fading. Curcumin bioaccessibility determined using an gastrointestinal tract was around 40%, which was attributed to some chemical degradation and binding of the curcumin reducing its stability and solubilization. This study shows that a hydrophobic nutraceutical (curcumin) can be loaded into dairy milk products using a simple method, which could facilitate the creation of novel functional foods and beverages.
pH 值迁移法是一种将某些多酚类营养保健品掺入现有胶体系统的简单方法。多酚类化合物可以负载到疏水性颗粒中，因为在碱性条件下它们的水溶性相对较高，但在酸性或中性条件下较低。在这项研究中，证明了可以使用这种方法将姜黄素掺入牛奶中，而不会对牛奶脂肪球的稳定性产生不利影响。当在不同的 pH 值和温度下孵育 60 天时，评估了富含姜黄素的牛奶的储存稳定性。通过在 4°C 下将富含姜黄素的牛奶储存 60 天，在 pH 值为 6.5、7.0 和/或 8.0 来确定 pH 值稳定性。在这种低储存温度下，所有牛奶样品均稳定，不会发生脂肪球聚集、乳脂上浮、姜黄素降解（<13%损失）和颜色损失。通过在 pH 值为 7 下将富含姜黄素的牛奶在 4、20、37 或 55°C 下储存 15 天来确定温度稳定性。姜黄素的分解随储存温度的降低而降低：55°C（43%）>37°C（21%）>20°C（10%）>4°C（5%）。有趣的是，在 4、20 和 37°C 下孵育的富含姜黄素的牛奶的颜色与初始样品相似，但在 55°C 下储存的样品则显示出明显的褪色。使用胃肠道模型确定的姜黄素生物利用度约为 40%，这归因于一些化学降解和姜黄素的结合，降低了其稳定性和溶解度。本研究表明，一种疏水性营养保健品（姜黄素）可以使用简单的方法负载到乳制品中，这有助于创造新型功能性食品和饮料。
