Abstract Sodium caseinate was hydrolyzed with the commercial enzyme preparation Sternzym BP 25201, containing a thermolysin-like peptidase from Geobacillus stearothermophilus as the only peptidase. The hydrolysis was carried out at 65 °C with an enzyme activity of 1 nkat mL−1 or 15 nkat mL−1, leading to various degrees of hydrolysis (DH) ranging between 0.1 and 8.5%. The hydrolysates obtained were analyzed in a multi-scale approach, covering the hydrolysate properties (viscosity, hydrophobicity, peptide composition) and their interaction at oil–water (emulsion) and air–water (foam) interphases. The viscosity and surface hydrophobicity generally decreased with an increasing DH. Longer, more hydrophobic peptides, which self-assembled into network-like supramolecular particles, were detected up to a DH of 2.2%. Compared to untreated sodium caseinate, these structures could increase the half-life of emulsions (+400%) and foams (+31%). This was most probably caused by an increase in particle size (45.2-fold). By contrast, a higher DH led to a less hydrophobic product and smaller, spherical-shaped supramolecular structures. Foams and emulsions prepared with those hydrolysates were not stable and phase separated within minutes (for example, emulsion half-life = 5 min; foam half-life = 4.6 min at DH of 8.5%).

中文翻译：

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使用来自 Geobacillus stearothermophilus 的商业肽酶制剂改变酪蛋白酸钠的界面特性

摘要 酪蛋白酸钠用商业酶制剂 Sternzym BP 25201 水解，其中含有来自嗜热脂肪地芽孢杆菌的嗜热菌蛋白酶样肽酶作为唯一的肽酶。水解在 65 °C 下进行，酶活性为 1 nkat mL-1 或 15 nkat mL-1，导致不同程度的水解 (DH) 在 0.1% 和 8.5% 之间。以多尺度方法分析获得的水解产物，涵盖水解产物的性质（粘度、疏水性、肽组成）及其在油-水（乳液）和空气-水（泡沫）界面的相互作用。粘度和表面疏水性通常随着 DH 的增加而降低。检测到更长、更疏水的肽，它们自组装成网络状超分子颗粒，DH 高达 2.2%。与未经处理的酪蛋白酸钠相比，这些结构可以增加乳液 (+400%) 和泡沫 (+31%) 的半衰期。这很可能是由粒径增加（45.2 倍）引起的。相比之下，较高的 DH 导致疏水性较低的产品和较小的球形超分子结构。用这些水解物制备的泡沫和乳液不稳定，并在几分钟内发生相分离（例如，乳液半衰期 = 5 分钟；泡沫半衰期 = 4.6 分钟，DH 为 8.5%）。乳液半衰期 = 5 分钟；泡沫半衰期 = 4.6 分钟，DH 为 8.5%）。乳液半衰期 = 5 分钟；泡沫半衰期 = 4.6 分钟，DH 为 8.5%）。