Journal of Colloid and Interface Science ( IF 9.9 ) Pub Date : 2018-05-23 , DOI: 10.1016/j.jcis.2018.05.080 Birgitta I. Zielbauer , Andrew J. Jackson , Sania Maurer , Gustav Waschatko , Marta Ghebremedhin , Sarah E. Rogers , Richard K. Heenan , Lionel Porcar , Thomas A. Vilgis
Hypothesis
Oleosomes are stabilized by a complex outer phospholipid-protein-layer. To improve understanding of its structure and stabilization mechanism, this shell has to be studied in extracellular native conditions. This should be possible by SANS using contrast variation. Oleosomes are expected to be highly temperature stable, with molecular changes occurring first in the protein shell. Direct measurements of changes in the shell structure are also important for processing methods, e.g. encapsulation.
Experiments
Extracted soybean oleosomes were studied directly and after encapsulation with pectin by SANS using contrast variation. In order to determine structure and size, a shell model of oleosomes was developed. The method was tested against a simple phospholipid-stabilized emulsion. The oleosomes’ temperature stability was investigated by performing SANS at elevated temperatures.
Findings
Size (Rg = 1380 Å) and shell thickness of native and encapsulated oleosomes have been determined. This is the first report measuring the shell thickness of oleosomes directly. For native oleosomes, a shell of 9 nm thickness surrounds the oil core, corresponding to a layer of phospholipids and proteins. Up to 90 °C, no structural change was observed, confirming the oleosomes’ high temperature stability. Successful coavervation of oleosomes was shown by an increase in shell thickness of 10 nm after electrostatic deposition of pectin.
中文翻译:
小角度中子散射(SANS)研究大豆油质体
假设
脂质体由复杂的外部磷脂蛋白层稳定。为了更好地了解其结构和稳定机制,必须在细胞外天然条件下研究该壳。SANS使用对比度变化应该可以做到这一点。预计脂质体是高度温度稳定的,首先在蛋白质壳中发生分子变化。直接测量外壳结构的变化对于加工方法(例如封装)也很重要。
实验
直接对提取的大豆油质体进行研究,并在使用果胶通过SANS用对比剂将其包封后进行研究。为了确定结构和大小,开发了脂质体的壳模型。该方法针对简单的磷脂稳定乳液进行了测试。通过在高温下进行SANS研究油质体的温度稳定性。
发现
已经确定了天然和封装的脂质体的大小(R g = 1380Å)和壳厚度。这是第一个直接测量油质体壳厚度的报告。对于天然油质体,油核周围有9 nm厚的壳,对应于一层磷脂和蛋白质。在高达90°C的温度下,未观察到结构变化,从而确认了油质体的高温稳定性。果胶静电沉积后,外壳厚度增加10 nm,表明脂质体成功共均化。