Methods of egg yolk fractionation
Liquid egg yolk can be fractionated into water soluble and precipitated lipophilic fractions without the need to freeze or add carbohydrate(s). A composition that includes egg yolk and an excess of water has its pH downwardly adjusted before being gravitationally separated into low and high density fractions, with the former including no more than 5% of the granules from the egg yolk.
1. A method for fractionating liquid egg yolk into water soluble and precipitated lipophilic fractions, said method comprising:
a) introducing to a composition that comprises liquid egg yolk and purified water, the volume of said water being from 1 to less than 5 times the volume of said liquid egg yolk, food grade acid so as to decrease the pH of said composition to a target pH of from 4 to 6 , thereby providing a pH-adjusted composition, and
b) without freezing or adding carbohydrate to said pH-adjusted composition, gravitationally separating said pH-adjusted composition into water soluble and precipitated lipophilic fractions, wherein less than 5% (w/w) of the granules from said liquid egg yolk are present in said water soluble fraction,
each step of said method being conducted at a temperature of from 0° C. to 60° C.
2. The method of claim 1 , wherein said liquid egg yolk comprises raw egg yolk or reconstituted egg yolk.
3. The method of claim 1 , wherein said purified water has a metal ion concentration no greater than 50 ppm.
4. The method of claim 1 , wherein said composition is agitated prior to and during introduction of said food grade acid.
5. The method of claim 1 , wherein the target pH of said pH-adjusted composition is from 5.0 to 5.6.
6. The method of claim 1 wherein each step of said method is conducted at a temperature of from 0° C. to no more than 30° C.
7. The method of claim 1 , wherein said gravitational separation involves centrifugation.
8. The method of claim 1 , wherein the composition is not exposed to a temperature of less than 0° C. or greater than 60° C.
9. A method comprising:
mixing a volume of water with a volume of liquid egg yolk to form a composition comprising liquid egg yolk and water, wherein the volume of water is from 1 to less than 5 times the volume of the liquid egg yolk;
decreasing the pH of the composition by introducing an acid to the composition to form a pH-adjusted composition; and
without adding carbohydrate to the pH-adjusted composition, gravitationally separating the pH-adjusted composition into a water soluble fraction and a precipitated lipophilic fraction,
wherein less than 5% (w/w) of granules from the liquid egg yolk are present in the water soluble fraction.
10. The method of claim 9 , wherein separating the pH-adjusted composition into the water soluble fraction and the precipitated lipophilic fraction does not involve a freezing step.
11. The method of claim 9 , wherein the liquid egg yolk comprises raw egg yolk or reconstituted egg yolk.
12. The method of claim 9 , wherein the composition is not exposed to a temperature of less than 0° C. or greater than 60° C.
13. The method of claim 1 , wherein the volume of water is from 1 to 2 times the volume of the liquid egg yolk.
14. The method of claim 1 , wherein the volume of water included in the composition is in excess of a volume of water equivalent to the volume of the liquid egg yolk, and wherein the excess volume of water is 2 times the volume of the liquid egg yolk.
15. The method of claim 1 , wherein a ratio of the volume water to the volume of egg yolk comprises 3 parts water for every 1 part liquid egg yolk.
16. The method of claim 9 , wherein the volume of water is from 1 to 2 times the volume of the liquid egg yolk.
17. The method of claim 9 , wherein the volume of water included in the composition is in excess of a volume of water equivalent to the volume of the liquid egg yolk, and wherein the excess volume of water is 2 times the volume of the liquid egg yolk.
18. The method of claim 9 , wherein a ratio of the volume water to the volume of egg yolk comprises 3 parts water for every 1 part liquid egg yolk.
19. The method of claim 9 , wherein the target pH of the pH-adjusted composition is from 4 to 6.