Food Quality and Design, Wageningen University, Wageningen, Netherlands.
Danone Nutricia Research, Utrecht, Netherlands.
Food Funct. 2022 May 23;13(10):5715-5729. doi: 10.1039/d2fo00542e.
Knowledge about how molecular properties of proteins affect their digestion kinetics is crucial to understand protein postprandial plasma amino acid (AA) responses. Previously it was found that a native whey protein isolate (NWPI) and heat denatured whey protein isolate (DWPI) elicit comparable postprandial plasma AA peak concentrations in neonatal piglets, while a protein base ingredient for infant formula (PBI, a β-casein-native whey protein mixture) caused a 39% higher peak AA concentration than NWPI. We hypothesized that both whey protein denaturation by heat as well as changing protein composition by including β-casein, increases the rate of intact protein loss, and that changing the protein composition (by including β-casein), but not whey protein denaturation, yields a faster absorbable product release. Therefore NWPI (91% native), DWPI (91% denatured) and PBI hydrolysis was investigated in a semi-dynamic digestion model (SIM). NWPI and DWPI hydrolysis were also compared in a dynamic digestion model with dialysis (TIM-1) to exclude potential product inhibition effects that may occur in a closed vessel digestion model as SIM. In both models, the degree of hydrolysis (DH), loss of intact protein, and release of absorbable products (SIM: <0.5 kDa peptides and free AA, TIM-1: bioaccessible AA) were monitored. Additionally, in SIM, intermediate product amounts and their characteristics were determined. DWPI showed considerably faster intact protein loss, but similar DH and absorbable product release kinetics compared with NWPI in both models. Furthermore, more, relatively large, intermediate products were released from DWPI than from NWPI. PBI showed increased intact protein loss, similar DH, and absorbable product release kinetics, but more, relatively small, intermediate products than NWPI. In conclusion, both whey protein denaturation and β-casein inclusion increased the rate of intact protein loss without affecting absorbable product release during digestion. Our results suggest that intermediate digestion product characteristics are important in relation to postprandial AA responses.
关于蛋白质分子特性如何影响其消化动力学的知识对于理解蛋白质餐后血浆氨基酸（AA）反应至关重要。此前发现，天然乳清蛋白分离物（NWPI）和热变性乳清蛋白分离物（DWPI）在新生仔猪中引起相当的餐后血浆 AA 峰值浓度，而婴儿配方奶粉的蛋白质基础成分（PBI，β-酪蛋白-天然乳清蛋白混合物）引起的峰值 AA 浓度比 NWPI 高 39%。我们假设，乳清蛋白的热变性以及通过包含β-酪蛋白改变蛋白质组成都会增加完整蛋白质损失的速度，而通过改变蛋白质组成（包括β-酪蛋白）而不是乳清蛋白变性，会产生更快的可吸收产物释放。因此，在半动态消化模型（SIM）中研究了 NWPI（91%天然）、DWPI（91%变性）和 PBI 的水解。在具有透析的动态消化模型（TIM-1）中还比较了 NWPI 和 DWPI 的水解，以排除 SIM 中可能发生的封闭容器消化模型中的潜在产物抑制作用。在这两种模型中，均监测水解度（DH）、完整蛋白质损失和可吸收产物释放（SIM：<0.5 kDa 肽和游离 AA，TIM-1：生物可利用 AA）。此外，在 SIM 中，还确定了中间产物的数量及其特性。与 NWPI 相比，DWPI 显示出相当快的完整蛋白质损失，但在两种模型中的 DH 和可吸收产物释放动力学相似。此外，DWPI 释放的中间产物数量更多，且相对较大。与 NWPI 相比，PBI 表现出更高的完整蛋白质损失、相似的 DH 和可吸收产物释放动力学，但更多的相对较小的中间产物。总之，乳清蛋白变性和β-酪蛋白的包含都增加了完整蛋白质损失的速度，而不会影响消化过程中的可吸收产物释放。我们的结果表明，中间消化产物的特性与餐后 AA 反应有关。
