Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
Molecules. 2022 Apr 6;27(7):2358. doi: 10.3390/molecules27072358.
Screening proteins for their potential use in foam applications is very laborious and time consuming. It would be beneficial if the foam properties could be predicted based on their molecular properties, but this is currently not possible. For protein-stabilized emulsions, a model was recently introduced to predict the emulsion properties from the protein molecular properties. Since the fundamental mechanisms for foam and emulsion formation are very similar, it is of interest to determine whether the link to molecular properties defined in that model is also applicable to foams. This study aims to link the exposed hydrophobicity with the foam ability and foam stability, using lysozyme variants with altered hydrophobicity, obtained from controlled heat treatment (77 °C for 0-120 min). To establish this link, the molecular characteristics, interfacial properties, and foam ability and stability (at different concentrations) were analysed. The increasing hydrophobicity resulted in an increased adsorption rate constant, and for concentrations in the protein-poor regime, the increasing hydrophobicity enhanced foam ability (i.e., interfacial area created). At higher relative exposed hydrophobicity (i.e., ~2-5 times higher than native lysozyme), the adsorption rate constant and foam ability became independent of hydrophobicity. The foam stability (i.e., foam collapse) was affected by the initial foam structure. In the protein-rich regime-with nearly identical foam structure-the hydrophobicity did not affect the foam stability. The link between exposed hydrophobicity and foam ability confirms the similarity between protein-stabilized foams and emulsions, and thereby indicates that the model proposed for emulsions can be used to predict foam properties in the future.
筛选具有潜在泡沫应用潜力的蛋白质非常费力且耗时。如果能够根据蛋白质的分子特性来预测泡沫特性，那将是有益的，但目前这还无法实现。对于蛋白质稳定的乳液，最近引入了一个模型，可以根据蛋白质的分子特性来预测乳液的性质。由于泡沫和乳液形成的基本机制非常相似，因此，确定该模型中定义的与分子特性的联系是否也适用于泡沫，这一点很有趣。本研究旨在使用经过控制的热处理（77°C 下 0-120 分钟）获得的疏水性改变的溶菌酶变体，将暴露的疏水性与泡沫能力和泡沫稳定性联系起来。为了建立这种联系，分析了分子特性、界面性质以及泡沫能力和稳定性（在不同浓度下）。疏水性的增加导致吸附速率常数增加，对于蛋白质贫相浓度，疏水性的增加增强了泡沫能力（即，形成的界面面积）。在相对暴露的疏水性较高（即比天然溶菌酶高约 2-5 倍）时，吸附速率常数和泡沫能力与疏水性无关。泡沫稳定性（即泡沫塌陷）受初始泡沫结构的影响。在蛋白质富相区域-具有几乎相同的泡沫结构-疏水性不会影响泡沫稳定性。暴露的疏水性与泡沫能力之间的联系证实了蛋白质稳定的泡沫和乳液之间的相似性，从而表明，未来可以使用针对乳液提出的模型来预测泡沫特性。
