Daimer Katharina, Kulozik Ulrich
Technische Universitat Munchen, Chair for Food Process Engineering and Dairy Technology, Freising-Weihenstephan, Germany.
J Agric Food Chem. 2008 Jun 11;56(11):4172-80. doi: 10.1021/jf703641e. Epub 2008 May 20.
Changes in physicochemical properties of egg yolk were investigated after a treatment with phospholipase A 2 (PLA 2), where phospholipids are converted in lyso-phospholipids. Protein solubility and protein denaturation before and after modification by PLA 2 was monitored as well as the functionality of egg yolk by means of interfacial tension. Enzymatic treatment showed a significant impact on the properties of egg yolk with regard to protein solubility and denaturation behavior. To gain a closer insight, egg yolk was separated in its water-soluble fraction called plasma and the insoluble granules. Both fractions were separately modified by PLA 2. The granule fraction shows a higher protein solubility, and the plasma proteins show very high heat stability after modification by PLA 2. Hypotheses regarding related changes in the low-density lipoprotein (LDL) particles are discussed. Results suggest that significant differences in the functional properties of untreated and PLA 2-modified egg yolk do not primarily result from the existence of lyso-phospholipids but from structural changes in egg yolk granules and LDL particles.
在用磷脂酶A2（PLA2）处理后，研究了蛋黄理化性质的变化，在该处理中磷脂会转化为溶血磷脂。监测了PLA2修饰前后的蛋白质溶解度和蛋白质变性情况，并通过界面张力测定了蛋黄的功能特性。酶处理对蛋黄的蛋白质溶解度和变性行为特性有显著影响。为了更深入了解，将蛋黄分离成其水溶性部分（称为血浆）和不溶性颗粒。这两个部分分别用PLA2进行修饰。颗粒部分显示出较高的蛋白质溶解度，而血浆蛋白在经过PLA2修饰后显示出非常高的热稳定性。讨论了关于低密度脂蛋白（LDL）颗粒相关变化的假设。结果表明，未处理和PLA2修饰的蛋黄功能特性的显著差异主要不是由溶血磷脂的存在引起的，而是由蛋黄颗粒和LDL颗粒的结构变化导致的。
