2 replies to this topic

[hallucinogen]

Is Anyone aware of the approximate Temperature of when the Egg Lecithin phospholipid denatures in the egg when it is heated up ?

Will boiling an egg for 5-mins effectively denature all the Lecithin in it ?

I can't find the exact information on it's heat-stability anywhere...

[niner]

Does lecithin denature at all? Proteins denature, and DNA denatures, but lecithin is a pretty simple molecule. It's probably stable toward decomposition up to a pretty high temperature. I googled lecithin melting point and found this-

J Lipid Res. 1967 Nov;8(6):551-7.
Phase equilibria and structure of dry and hydrated egg lecithin.
Small DM.

The behavior of purified egg lecithin in water has been investigated in relation to the quantity of water present and the temperature. The complete binary phase diagram of egg lecithin-water is presented as well as X-ray diffraction data on selected mixtures. Dry egg lecithin is present in at least partially crystalline form until about 40 degrees C. Above this temperature it forms a "wax-like" phase up to about 88 degrees C. From 88 to 109 degrees C it forms a viscous isotropic phase which gives face-centered cubic spacings by X-ray analysis. Above 110 degrees C its texture is "neat" and the structure is assumed to be lamellar until its final melting point at 231 degrees C. Hydrated lecithin forms (except for a small zone of cubic phase at low water concentrations and high temperature) a lamellar liquid crystalline phase. This phase contains up to 45% water at 20 degrees C. Mixtures containing more water separate into two phases, the lamellar liquid crystalline phase and water. In the melting curve of hydrated lecithin a eutectic is noted at about 16% water and the cubic phase seen when less water is present disappears at this composition of the mixture. These facts, along with previous vapor pressure measurements, suggest that there is a structural change at about 16% water. X-ray diffraction studies of lecithin at 24 degrees C and calculations from these data suggest that the reason for this may be the presence of a "free water layer" when more than 16% water is present.

PMID: 6057484 Free full text

This deals with pure egg lecithin rather than the form in the egg, FWIW.

[hallucinogen]

What i am distinctly interested in is whether it's crystalline matrix is altered enough after being subjected to heat of 100C for 3mins for it to result in much diminished cholesterol emulsification and absorption within the digestive tract, as compared to its raw yolk liquid form where it's influence over cholesterol absorption is exerted at maximum level,

and to what extent exactly is the difference ?

Edited by hallucinogen, 02 October 2013 - 12:38 AM.