SIK, The Swedish Institute for Food and Biotechnology, SE-402 29 Göteborg, Sweden.
Biomacromolecules. 2011 Jun 13;12(6):2235-42. doi: 10.1021/bm200320c. Epub 2011 May 16.
The morphology of β-lactoglobulin structures inside droplets was studied during aggregation and gelation using confocal laser scanning microscopy (CLSM) equipped with a temperature stage and transmission electron microscopy (TEM). The results showed that there is a strong driving force for the protein to move to the interface between oil and water in the droplet, and the β-lactoglobulin formed a dense shell around the droplet built up from the inside of the droplets. Less protein was found inside the droplets. The longer the β-lactoglobulin was allowed to aggregate prior to gel formation, the larger the part of the protein went to the interface, resulting in a thicker shell and very little material being left inside the droplets. The droplets were easily deformed because no network stabilizes them. When 0.5% emulsifier, polyglycerol polyresinoleat (PGPR), was added to the oil phase, the β-lactoglobulin was situated both inside the droplets and at the interface between the droplets and the oil phase; when 2% PGPR was added, the β-lactoglobulin structure was concentrated to the inside of the droplets. The possibility to use the different morphological structures of β-lactoglobulin in droplets to control the diffusion rate through a β-lactoglobulin network was evaluated by fluorescence recovery after photobleaching (FRAP). The results show differences in the diffusion rate due to heterogeneities in the structure: the diffusion of a large water-soluble molecule, FITC-dextran, in a dense particulate gel was 1/4 of the diffusion rate in a more open particulate β-lactoglobulin gel in which the diffusion rate was similar to that in pure water.
使用配备有温度台的共聚焦激光扫描显微镜（CLSM）和透射电子显微镜（TEM），研究了在聚集和胶凝过程中β-乳球蛋白结构在液滴内的形态。结果表明，蛋白质有强烈的驱动力向液滴内的油水界面移动，β-乳球蛋白在液滴内形成了一个从内部构建的密集外壳。在液滴内发现的蛋白质较少。在形成凝胶之前，让β-乳球蛋白聚集的时间越长，进入界面的蛋白质部分就越大，导致壳层越厚，液滴内的物质就越少。由于没有网络来稳定液滴，所以液滴很容易变形。当 0.5%乳化剂聚甘油聚蓖麻醇酸酯（PGPR）添加到油相中时，β-乳球蛋白位于液滴内部和液滴与油相之间的界面；当添加 2%PGPR 时，β-乳球蛋白结构集中在液滴内部。通过光漂白后荧光恢复（FRAP）评估了液滴中β-乳球蛋白不同形态结构控制通过β-乳球蛋白网络扩散率的可能性。结果表明，由于结构的不均匀性，扩散率存在差异：在密集的颗粒状凝胶中，水溶性大的分子 FITC-葡聚糖的扩散率是在更开放的颗粒状β-乳球蛋白凝胶中的扩散率的 1/4，而在纯水中的扩散率则相似。
