Department of Food Science, University of Copenhagen, Frederiksberg C, Denmark.
Department of Food Science, University of Copenhagen, Frederiksberg C, Denmark.
Food Res Int. 2023 Feb;164:112415. doi: 10.1016/j.foodres.2022.112415. Epub 2022 Dec 27.
Calcium bioaccessibility depends on the amount of soluble calcium under intestinal digestion. The changes in calcium during in vitro static digestion of α-lactalbumin and β-lactoglobulin in presence of calcium chloride (0 mM, 20 mM and 50 mM) were followed by combining electrochemical determination of free calcium with the determination of soluble calcium by inductively coupled plasma optical emission spectroscopy. α-Lactalbumin and, more evident, β-lactoglobulin were found to increase calcium bioaccessibility with increasing intestinal digestion time by around 5% and 10%, respectively, due to the complex binding of calcium to peptides formed from protein hydrolysis by gastrointestinal enzymes. In vitro digested samples of β-lactoglobulin in presence of CaCl had nearly twice as much complex bound calcium as α-lactalbumin samples. The calcium bioaccessibility decreased significantly with the increasing concentration of added calcium chloride, although the amount of calcium chloride had little effect on the extension of digestion of α-lactalbumin and β-lactoglobulin. Simulated digestion fluids were found to have a negative effect on calcium bioaccessibility, especially the presence of hydrogen phosphate, and the amount of precipitated calcium increased significantly with increasing amount of added calcium chloride. Based on analysis and visualization by sequences of the peptides formed during digestion of α-lactalbumin and β-lactoglobulin, it was observed that peptides containing aspartic acid and glutamic acid acting as calcium chelators, may prevent precipitation of calcium in the intestines and increase calcium bioaccessibility. These results provide knowledge for the design of new dairy based functional foods to prevent calcium deficiency.
钙的生物可利用性取决于肠道消化下的可溶性钙的含量。在添加氯化钙（0 mM、20 mM 和 50 mM）的情况下，通过将游离钙的电化学测定与电感耦合等离子体发射光谱法测定可溶性钙相结合，研究了α-乳白蛋白和β-乳球蛋白在体外静态消化过程中钙的变化。结果发现，由于胃肠道酶水解形成的肽与钙形成复合物，α-乳白蛋白和β-乳球蛋白的钙生物可利用性随着肠道消化时间的延长分别增加了约 5%和 10%。在存在 CaCl 的情况下，体外消化的β-乳球蛋白样品中与肽结合的钙几乎是α-乳白蛋白样品的两倍。尽管添加的氯化钙浓度对α-乳白蛋白和β-乳球蛋白消化时间的延长影响不大，但钙的生物可利用性随着添加的氯化钙浓度的增加而显著降低。模拟消化液对钙的生物可利用性有负面影响，特别是存在磷酸氢盐时，随着添加的氯化钙量增加，沉淀的钙量显著增加。通过对α-乳白蛋白和β-乳球蛋白消化过程中形成的肽的序列进行分析和可视化，观察到含有天冬氨酸和谷氨酸的肽作为钙螯合剂，可能会防止钙在肠道中的沉淀并提高钙的生物可利用性。这些结果为设计新的基于乳制品的功能性食品以预防钙缺乏症提供了知识。
