Impact of a treatment with phospholipase A2 on the physicochemical properties of hen egg yolk.
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.
Daimer
Katharina
K
Technische Universitat Munchen, Chair for Food Process Engineering and Dairy Technology, Freising-Weihenstephan, Germany. katharina.daimer@wzw.tum.de
Kulozik
Ulrich
U
D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002645:Chickens; D004527:Egg Proteins / Q000737:chemistry / Q000187:drug effects; D004530:Egg Yolk / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D006358:Hot Temperature; D008246:Lysophospholipids / Q000378:metabolism; D054467:Phospholipases A2 / Q000378:metabolism / Q000494:pharmacology*; D010743:Phospholipids / Q000378:metabolism*; D011489:Protein Denaturation / Q000187:drug effects; D012995:Solubility
D004527:Egg Proteins; D008246:Lysophospholipids; D010743:Phospholipids; D054467:Phospholipases A2