Method of separating components of technical eggs, edible eggs, yolk and whites and products therefrom
The present invention relates to methods for the separation of various components from eggs. More particularly, the present invention relates to methods for the separation of proteins and lipids from eggs, including technical eggs (inedible) or edible eggs, yolks or whites, which comprises cross-linking the lipids of eggs with a cross-linking reagent. In an embodiment, the method includes separating the proteins from the cross-linked lipids. In an embodiment, the method includes the separation of various components associated with the cross-linked lipids. The methods disclosed herein allow for the isolation of multiple different components from the egg in an efficient, cost-effective manner without compromising the recovery process of the components or their subsequent utility in various applications or compositions. The compositions and isolated components obtained by the methods of the invention can be used in pharmaceutical, medical, nutritional, cosmetic or health applications.
1. A method of separating protein from an egg mixture, wherein the egg mixture comprises lipids and solubilized proteins, the method comprising the steps of:
(a) adding a cross-linking reagent to the egg mixture comprising lipids and solubilized proteins to obtain cross-linked lipids;
(b) adjusting the pH level of the egg mixture to a pH at which the cross-linking reagent is functional so that cross-linking of lipids occurs; and
(c) separating the proteins from the cross-linked lipids to provide a separated protein fraction.
2. The method of claim 1 wherein the suitable pH for cross-linking to occur is from about 6.0 to about 8.0.
3. The method of claim 1 wherein the egg mixture comprises a technical egg, an edible egg, an egg yolk, or an egg white, or combination thereof.
4. The method of claim 1 wherein the cross-linking reagent is selected from the group consisting of beta-cyclodextrin, silicon dioxide, colloidal silica material, fumed silica material, and synthetic calcium silicate hydrate.
5. The method of claim 4 wherein the colloidal silica material is an acid stabilized dispersion of colloidal silica particles.
6. The method of claim 4 wherein the fumed silica material is selected from the group consisting of synthetic amorphous silicon dioxide, crystalline-free fumed silica, crystalline-free precipitated silica.
7. The method of claim 1 , wherein the separating step of (c) comprises dialysis, precipitation, sedimentation, centrifugation, decantation, particulate filtration, membrane filtration, temperature modification, extraction, desalting, chromatography, chemical precipitations, chromatofocusing, electrophoresis, or combinations thereof.
8. The method of claim 1 , further comprising the step of centrifuging the protein fraction made in step (c) and recovering a supernatant that comprises solubilized proteins.
9. The method of claim 8 wherein separating the proteins from the supernatant is performed using membrane filtration to obtain a retentate protein mixture.
10. The method of claim 9 wherein the membrane used to recover the proteins from the supernatant has a molecular cut off weight of at least 0.8 micron.
11. The method of claim 1 wherein the proteins comprise ovotransferrin, albumin, beta-livetin (alpha-2-glycoprotein), gamma livetin (IgY), insulin-like growth factor-1 (IGF-1), or phosvitin or combinations thereof.
12. The method of claim 1 , wherein the separated protein fraction comprises proteins of greater than 100 kDa in molecular weight.
13. The method of claim 12 wherein proteins greater than 100 kDa in molecular weight are separated using a membrane that has a molecular weight cutoff of at least 100 kDa to obtain a retentate protein mixture comprising proteins that are greater than 100 kDa in molecular weight and a permeate protein mixture comprising proteins that are less than 100 kDa in molecular weight.
14. The method of claim 13 further comprising separating proteins that are less than 100 kDa in molecular weight obtained from the permeate protein mixture but greater than 1 kDa in molecular weight by subjecting the permeate to a membrane that has a molecular weight cutoff of at least 1 kDa.
15. The method of claim 1 , further comprising drying the separated protein.
16. The method of claim 15 , wherein the drying step is selected from the group consisting of spray-drying, freeze-drying, spray-freeze drying, paddle-drying, drum drying, lyophilization, vacuum drying, or air drying.