It is well known that both protein and iso-humulone, originating from barley malt and hops respectively, play important roles in beer foam stability. In this study, we hypothesize that the interaction of iso-humulone and different beer proteins will give rise to adsorbed layers with different characteristics at hydrophobic surfaces. The properties of these adsorbed layers are likely to play a crucial role for beer foam formation and stability.Beer protein and iso-humulone were extracted based on the brewing process from barley malt and hop respectively. The proteins were fractionated into two fractions (lipid transfer protein (LTP) and a mixed fraction of LTP and protein Z) and their interfacial properties as well as interaction with iso-humulone in solution and at hydrophobic surfaces were investigated by surface rheology and ellipsometry. The results show that the composition and properties of the adsorbed layers depend on how the layer is formed and that iso-humulone plays an important role for the characteristics of the adsorbed protein layers. The interaction between iso-humulone and protein Z is found to have pronounced effects of yielding a coherent and elastic adsorbed layer and, thus, for beer foam stability.

中文翻译：

---

啤酒麦芽汁蛋白质组分与异葎草酮之间的界面特性和相互作用

众所周知，分别来自大麦麦芽和啤酒花的蛋白质和异葎草酮在啤酒泡沫稳定性方面起着重要作用。在这项研究中，我们假设异葎草酮和不同啤酒蛋白的相互作用将在疏水表面产生具有不同特性的吸附层。这些吸附层的性质可能对啤酒泡沫的形成和稳定性起着至关重要的作用。啤酒蛋白质和异葎草酮分别从大麦芽和啤酒花的酿造过程中提取。蛋白质被分成两个部分（脂质转移蛋白 (LTP) 和 LTP 和蛋白质 Z 的混合部分），通过表面流变学和椭圆光度法研究它们的界面特性以及与溶液中和疏水表面的异葎草酮的相互作用。结果表明，吸附层的组成和性质取决于层的形成方式，异葎草酮对吸附蛋白层的特性起着重要作用。异葎草酮和蛋白质 Z 之间的相互作用被发现具有显着效果，可产生连贯的弹性吸附层，从而对啤酒泡沫稳定性产生影响。