Separation method of fat and protein in eggs and egg products

Abstract

A method of separating protein and fat from an egg or egg product. According to the disclosed method, proteins and fats are separated from a mixture containing egg white and egg yolk.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 322,436, filed on March 22, 2022, the contents of which are incorporated herein by reference in their entirety for all purposes. Technical Field

[0003] The present disclosure relates to a method for separating protein and fat from egg products. More specifically, the present disclosure relates to a method for preparing a protein composition from an egg product. Background Art

[0004] Eggs are a complex mixture of many ingredients. The most abundant ingredients in eggs are protein and fat.

[0005] Egg white or albumen accounts for about 66% of the liquid weight of the egg, 90% of which comes from water, while the rest of the weight of the egg white comes mainly from protein (10-15%) and small amounts of fat (less than 0.4%), minerals, vitamins and glucose. The most common proteins in egg white are ovalbumin, ovotransferrin, ovomucoid, globulin, lysozyme, ovomucin and avidin.

[0006] The yolk is about 33% of the liquid weight of the egg and is high in fat. As used herein, the term "fat" refers to lipids. The most common lipids in the yolk include: unsaturated fatty acids (oleic acid, linoleic acid, palmitoleic acid, and linolenic acid) and saturated fatty acids (palmitic acid, stearic acid, and myristic acid). The yolk also contains some protein, which usually accounts for about 10-20%.

[0007] Egg protein and egg fat can be used in various applications, such as food and feed applications, either for their nutritional content or for their functional properties, such as emulsifier (fat), gelling agent (protein), foaming agent (protein), etc. Depending on their different uses, it is usually necessary to separate egg fat and egg protein from each other.

[0008] A variety of systems and methods have been developed for separating eggs into yolk and egg white. The separation of yolk and egg white of whole eggs can be done at high speed under automated conditions, and it can separate yolk and egg very effectively.

[0009] However, there exists a need for a method to further separate the various components of eggs into more individual components, such as proteins and lipids.

[0010] The protein and fat in the egg can act as an emulsifier. The cracked whole eggs used in industry are usually in a stable mixture state, which makes it difficult to separate the egg protein from the lipids.

[0011] US 11 / 971,802 discloses a method in which lipids are separated from an egg mixture by using a cross-linking agent. A cross-linking agent (e.g., β-cyclodextrin, silicon dioxide, colloidal silicon dioxide materials, fumed silica materials, and synthetic calcium silicate hydrate) is added to the egg mixture, and the cross-linked lipids thus obtained can be separated from the protein. However, the use of a cross-linking agent is undesirable for a number of reasons.

[0012] Another method is disclosed in US 14 / 070,120, in which egg fat and egg protein are separated by using microfiltration.

[0013] There exists a need for alternative and efficient methods and apparatus for separating the various components of eggs into protein and fat. Summary of the invention

[0014] The approach disclosed herein overcomes the above-mentioned problems by providing a method for separating protein and fat in egg products.

[0015] As used herein, the term "protein" refers to an organic compound composed of amino acids (polypeptides), and includes, but is not limited to, proteins such as ovalbumin, ovotransferrin, ovomucoid, globulin, lysozyme, ovomucoid, and avidin. As used herein, the term "fat" is used interchangeably with "lipid" and refers to water-insoluble components such as fatty acids, steroids (e.g., cholesterol), glycolipids, lipoproteins, and phospholipids.

[0016] In certain embodiments, a method for separating protein and fat from a starting material comprising egg protein and egg fat is disclosed, comprising:

[0017] (a) adjusting the pH of the starting material to between pH 5 and 7,

[0018] (b) adding an effective amount of lipase to the starting material to form a mixture,

[0019] (c) incubating the mixture of step (b) at a temperature between 30° C. and 60° C. for a period of at least 10 minutes to obtain a digested mixture,

[0020] (d) subjecting the digested mixture to a separation process to form at least two phases, the at least two phases comprising a protein phase and a lipid phase, and

[0021] (e) collecting the protein phase and the lipid phase separately to obtain a protein composition and a lipid composition.

[0022] The starting material is prepared from or derived from eggs. The term "egg" refers to any bird egg, preferably a poultry egg. In one aspect, the starting material is a liquid mixture. In another aspect, the starting material comprises egg protein and egg fat.

[0023] In one embodiment, the starting material is substantially free of crosslinking agents (eg, beta-cyclodextrin, silica, colloidal silica materials, fumed silica materials, and synthetic calcium silicate hydrates). In fact, the present invention does not require any crosslinking agents.

[0024] The starting material includes an egg product. In certain embodiments, the starting material consists of an egg product. Advantageously, the egg product can be a mixture of egg white (egg albumen) and egg yolk. In certain embodiments, the egg product can be only egg white or only egg yolk, even if these embodiments are not preferred embodiments of the present invention.

[0025] In one embodiment, the starting material does not contain any (added) water. In another embodiment, the starting material contains water. For example, the starting material contains 20 to 95 weight percent, or 50 to 90 weight percent of water of the total weight.

[0026] In certain embodiments, the starting material is a stable mixture of egg protein and egg fat, or an emulsion of egg protein and egg fat. In a stable mixture (e.g., an emulsion), it is difficult to separate protein and fat only by mechanical separation. In certain embodiments, the starting material is an aqueous mixture of egg protein and egg fat.

[0027] The protein and fat contents of egg white and yolk (if both are present) vary depending on the starting material and the source of the eggs: sources with a high egg white content (e.g., spun eggs from shell eggs) will be high in protein; whereas those with more yolk-based material (e.g., whole eggs from a hatchery or breakers) will have relatively high fat levels and relatively low protein levels.

[0028] In one embodiment, the starting material is prepared from eggs that have been graded as unfit for direct human consumption. For the purposes of this disclosure, the phrase "unfit for direct human consumption" as applied to eggs refers to eggs that cannot be consumed by humans without some additional biochemical treatment, such as eggs that cannot be boiled and served directly to humans or eggs that cannot be cracked and added directly to a cooking or baking process.

[0029] In one embodiment, the starting material is prepared from eggs that have been subjected to an incubation process without hatching or from liquid eggs from an egg factory.

[0030] As described above, the starting material may comprise egg yolk alone or a mixture of egg yolk and egg white. The starting material may contain greater than 0.2 weight percent, or greater than 0.3 weight percent, or greater than 0.5 weight percent, or greater than 1 weight percent, or greater than 2 weight percent, or greater than 5 weight percent, or greater than 10 weight percent, or greater than 20 weight percent, or greater than 30 weight percent, or greater than 40 weight percent of egg yolk of the total solids.

[0031] The starting material may contain less than 70 weight percent, or less than 60 weight percent, or less than 55 weight percent, or less than 50 weight percent, or less than 45 weight percent egg yolk of total solids.

[0032] As described above, the starting material may contain egg white alone or a mixture of egg white and egg yolk. The starting material may contain greater than 45 weight percent, or greater than 50 weight percent, or greater than 60 weight percent, or greater than 70 weight percent, or greater than 80 weight percent, or greater than 90 weight percent of total solids.

[0033] The starting material may contain less than 99.5 weight percent, or less than 99 weight percent, or less than 98 weight percent, or less than 97 weight percent, or less than 96 weight percent, or less than 95 weight percent, or less than 90 weight percent, or less than 80 weight percent, or less than 70 weight percent egg white of total solids.

[0034] The starting material may contain greater than 40% or greater than 45% protein (% based on total solids).

[0035] The starting material may contain less than 85% or less than 80% protein (% based on total solids).

[0036] The starting material may contain from 40% to 85%, or from 45% to 80% protein (% based on total solids).

[0037] The starting material may contain greater than 8%, or greater than 10%, or greater than 15% fat (% based on total solids).

[0038] The starting material may contain less than 40% or less than 35% fat (% based on total solids).

[0039] In certain embodiments, the pH of the starting material is measured before the above-mentioned step (a). The pH of the starting material may be between 7 and 9, or between 7 and 8. In step (a), the pH of the starting material is adjusted to between pH 5 and 7, or between 5 and 6.5, or between 6 and 6.5, or about 6 or about 6.5. Typically, the pH of egg white is slightly alkaline (between 7.5 and 9), while the pH of egg yolk is typically acidic (between 6 and 7). It is typically difficult to separate fat and protein, for example in a mixture of egg white and egg yolk (which tends to form a very stable mixture). Surprisingly, it was found that when lipase is used at this pH, the resulting digested lipid component is easily separated from the protein component (even if this is not the recommended optimal pH for lipase).

[0040] The pH can be adjusted by adding one or more pH adjusting agents. In certain embodiments, a food grade pH adjusting agent is used. Examples of pH adjusting agents may include, but are not limited to, citric acid, acetic acid, phosphoric acid, potassium carbonate, and potassium citrate.

[0041] Step (a) can be carried out before and / or after step (b). In one embodiment, the above-mentioned step (a) is carried out before step (b), or in other words, the pH of the mixture is first adjusted to pH 5 to 7, or 5 to 6.5, or 6 to 6.5, or about 6.5 by adding one or more pH adjusting agents, and then lipase is added to the starting material to form a mixture. In another embodiment, the above-mentioned step (b) is carried out before step (a), or in other words, lipase is first added to the starting material to form a mixture, and then the pH of the mixture is adjusted to pH 5 to 7, or 5 to 6.5, or 6 to 6.5, or about 6.5 by adding one or more pH adjusting agents, and then the above-mentioned step (c) is carried out. In another embodiment, the above-mentioned step (a) is carried out before and after step (b), or in other words, the pH of the mixture is adjusted to pH 5 to 7, lipase is added to the starting material to form a mixture, and the pH is further adjusted to pH 5 to 7.

[0042] Any lipase can be used in the method, and can be derived from a microbial source, such as Mucor sp., Rhizopus oryzae, Candida cylindracea, Penicillium, or derived from an animal source, such as a pancreatic lipase from porcine pancreas. Preferably, the lipase is a microbial lipase, such as a microbial lipase isolated from a fungus. In one embodiment, the lipase is derived from a microorganism selected from Mucor javanicus, Rhizopus oryzae, Candida cylindracea, Aspergillus niger, Aspergillus oryzae, and is preferably derived from Mucor javanicus, Rhizopus oryzae, Candida cylindracea. In one embodiment, the term "lipase" encompasses phospholipases. In another preferred embodiment, the term "lipase" does not encompass phospholipases. In one embodiment, the lipase can be an alkaline lipase, or in other words, a lipase with optimal lipolytic activity when pH is 7 or higher. In an advantageous embodiment, the lipase is an alkaline lipase (having a pH optimum of 7 or higher as recommended by the manufacturer), but is used in the present invention at a pH between 5 and 6.5, or between 6 and 6.5, or about 6 or about 6.5.

[0043] In certain embodiments, only one lipase is used. In certain embodiments, no colipase is used.

[0044] In certain embodiments, the amount of the lipase used in step (b) is 0.01 to 0.3 weight percent, or 0.05 to 0.3 weight percent, or 0.06 to 0.3 weight percent, or 0.1 to 0.3 weight percent of the total starting material. On the one hand, the amount of the lipase used in step (b) is higher than 0.01 weight percent, or 0.05 weight percent, or 0.06 weight percent of the total starting material.

[0045] In some other embodiments, the starting material is desugared before or after step (b), for example, by a fermentation process or by an enzymatic reaction with an enzyme (such as glucose oxidase). In certain embodiments, the starting material is not desugared before or after step (b).

[0046] Due to the denaturation temperature of the enzyme, the temperature of the incubation step (c) is usually not higher than 60°C, and is usually 30 to 60°C, preferably 35 to 50°C, preferably 35 to 45°C, preferably 37 to 45°C.

[0047] The duration of the incubation step can vary widely depending on, for example, the specific lipase used, the concentration of the lipase, and the temperature. In certain embodiments, the incubation time in step (b) is at least 10 minutes. In certain embodiments, the incubation time in step (b) is 10-60 minutes, or 10-120 minutes, or longer.

[0048] In one aspect, during step (c), the pH and / or temperature of the material is monitored. In one embodiment, the pH is further adjusted during step (c). In one embodiment, no pH adjustment is performed during step (c), or between step (c) and step (d).

[0049] In some embodiments, the separation in step (d) can be achieved by centrifugation. This can be performed using any appropriate equipment, such as a centrifuge and / or a decanter. A centrifugal force between 5000 and 10,000G can be used. The separation temperature of step (d) can be between 1°C and 60°C. However, although literature (such as Stoke's Law) and experts recommend raising this temperature to achieve better separation, it is surprising that lower temperatures are found to advantageously enhance the separation of fat and protein. Therefore, the temperature of step (d) is preferably between 1°C and 40°C, or between 5°C and 25°C, or between 5°C and 10°C.

[0050] The digested mixture forms at least two phases after separation in step (d): a protein phase containing at least protein and a lipid phase (or fat phase) containing at least fat. In certain embodiments, the digested mixture forms three phases after separation in step (d): a protein phase and two lipid phases, one of which has low-density fat and one of which has high-density fat.

[0051] Step (e) comprises collecting the protein phase and the one or more lipid phases separately, thereby separating the egg protein and the egg fat by obtaining a protein composition and a lipid composition.

[0052] In a preferred embodiment, the protein composition contains protein derived from egg yolk and egg white. In another embodiment, the protein composition contains protein derived from egg yolk only, especially when the egg product in the starting material consists of egg yolk. In another embodiment, the protein composition contains protein derived from egg white only, especially when the egg product in the starting material consists of egg white.

[0053] In certain embodiments, the protein composition obtained in step (e) comprises less than 20 weight percent, or less than 10 weight percent, or less than 5 weight percent, or less than 4 weight percent, or less than 3 weight percent, or less than 1 weight percent, or less than 0.5 weight percent fat of the total solids.

[0054] In certain embodiments, the protein composition obtained in step (e) comprises about 50 to 99 weight percent, or about 55 to 95 weight percent, or about 55 to 90 weight percent, or about 70 to about 90 weight percent, or greater than 70 weight percent, or greater than 80 weight percent, or greater than 90 weight percent protein of the total solids.

[0055] The fat phase can be collected for other commercial applications different from the protein phase. In one embodiment, the lipid composition contains fat derived from egg yolk and egg white. In another embodiment, the lipid composition contains fat derived from egg yolk only, especially when the egg product in the starting material consists of egg yolk. In another embodiment, the lipid composition contains fat derived from egg white only, especially when the egg product in the starting material consists of egg white. In one embodiment, the lipid composition can be obtained from one lipid phase. In another embodiment, the lipid composition can be obtained from two lipid phases.

[0056] In certain embodiments, the fat (lipid) phase obtained in step (e) comprises about 40 to 99 weight percent, or about 45 to 90 weight percent, or greater than 70 weight percent, greater than 80 weight percent, or greater than 90 weight percent fat of the total solids.

[0057] In certain embodiments, the fat (lipid) phase obtained in step (e) comprises less than 45 weight percent protein of total solids.

[0058] In certain embodiments, the fat (lipid) phase obtained in step (e) comprises less than 5 weight percent, or less than 1 weight percent, of egg impurities based on total solids.

[0059] The present invention also relates to a lipid composition obtained by the separation method.

[0060] The present invention also relates to a protein composition obtained by the separation method. The protein composition has excellent binding properties. The protein composition is a liquid protein composition. The protein composition can be further concentrated, for example by evaporation, by reverse osmosis (RO) and / or nanofiltration. In one embodiment, the protein solution is concentrated to contain about 15-35 weight percent protein. The protein composition can be further dried. The protein composition can be further heat treated to improve gel function.

[0061] Therefore, another aspect of the present invention relates to a method for preparing a protein composition from a starting material comprising egg protein and egg fat, the method comprising:

[0062] (a) adjusting the pH of the starting material to between pH 5 and 7,

[0063] (b) adding an effective amount of lipase to the starting material to form a mixture,

[0064] (c) incubating the mixture of step (b) at a temperature between 30° C. and 60° C. for a period of at least 10 minutes to obtain a digested mixture,

[0065] (d) subjecting the digested mixture to a separation process to form at least two phases, the at least two phases comprising a protein phase and a lipid phase,

[0066] (e) collecting the protein phase to obtain a protein composition,

[0067] (f) optionally, concentrating the protein phase to provide a concentrated protein composition,

[0068] (g) optionally, drying the high protein composition to provide a dried protein composition,

[0069] (h) optionally, subjecting the dried protein composition to a heat treatment, thereby obtaining a heat-treated dried protein composition.

[0070] The technical features listed above for the method of separating protein and fat are also applicable to the method of preparing the protein composition.

[0071] In certain embodiments, the concentration of step (f) is performed by filtration, more particularly by evaporation and / or reverse osmosis (RO) and / or nanofiltration.The protein composition may be deashed during this step (f).

[0072] In one embodiment, the protein composition obtained in step (e) or (f) is dried, preferably by spray drying.

[0073] In one embodiment, the protein composition obtained in step (e) or (f) is dried, preferably by spray drying, and further heat treated to obtain a heat-treated dry protein composition. For example, the dry protein composition can be placed in a hot and humid chamber at a temperature of 60° C. to 80° C. and a humidity of 30% to 40% for at least 3 days. Advantageously, the protein is denatured and the gel strength increases. In one embodiment, it has a gel strength of at least 100, or between 100 and 1500.

[0074] The present invention also relates to the protein composition obtained by the method, and / or the concentrated protein composition obtained in step (f), and / or the dried protein composition obtained in step (g), and / or the heat-treated dried protein composition obtained in step (h).

[0075] In one embodiment, the dry protein composition or the heat-treated dry composition comprises at least about 70 dry weight percent, or at least 80 dry weight percent protein. In one embodiment, the dry protein composition comprises less than about 20 dry weight percent, or less than 10 dry weight percent fat.

[0076] The protein composition obtained in any form can be used in food (eg human food or animal food).The protein composition can be used to fortify feed, for nutritional purposes or functional purposes (eg, for binding), or for both.

[0077] Therefore, another aspect of the present invention relates to a food product comprising a protein composition obtained by the method disclosed herein. The food product may be a human food product or an animal food product.

[0078] In one embodiment, food is animal food. The term "animal" may include, but is not limited to, cats, dogs, shrimp, pigs, fish. Animal feed may be in any form, including, but not limited to, liquid, wet, canned or dry forms. On the one hand, dry forms may include, but are not limited to, pellets, kibble, treats and chunks. In some embodiments, animal food comprises at least 0.1 weight percent, or at least 0.5 weight percent, or at least 1 weight percent, or at least 2 weight percent of a protein composition disclosed herein, such as a dry protein composition. DETAILED DESCRIPTION

[0079] The present disclosure provides a method for preparing a high-protein composition from an egg product. More specifically, the present disclosure relates to a method for separating protein and fat in eggs and egg products.

[0080] Several embodiments of the disclosed method are described below by way of example:

[0081] Item 1. A method for separating protein and fat in a starting material containing egg protein and egg fat, comprising:

[0082] (a) adjusting the pH of the starting material to between pH 5 and 7,

[0083] (b) adding an effective amount of lipase to the starting material to form a mixture,

[0084] (c) incubating the mixture of step (b) at a temperature between 30° C. and 60° C. for a period of at least 10 minutes to obtain a digested mixture,

[0085] (d) subjecting the digested mixture to a separation process to form at least two phases, the at least two phases comprising a protein phase and a lipid phase, and

[0086] (e) collecting the protein phase and the lipid phase separately to obtain a protein composition and a lipid composition.

[0087] Item 2. The method according to Item 1, wherein the starting material comprises egg white and egg yolk, and wherein the egg yolk in the starting material constitutes more than 0.2 weight percent of the total solids in the starting material.

[0088] Item 3. A method according to Item 1 or 2, wherein the starting material is prepared from eggs that have been classified as unsuitable for direct human consumption.

[0089] Item 4. The method according to any one of Items 1 to 3, wherein the starting material is prepared from eggs that have been subjected to an incubation process but not hatched or from liquid eggs from an egg-breaking factory.

[0090] Item 5. The method according to any one of Items 1 to 4, wherein the starting material prior to step (a) comprises greater than 1 weight percent of egg yolk based on total solids.

[0091] Item 6. The method according to any one of Items 1 to 5, wherein a food grade reagent is used to adjust the pH in step (a).

[0092] Item 7. The method according to any one of Items 1 to 6, wherein the amount of lipase used in step (b) is 0.01 to 0.3 weight percent of the total starting materials.

[0093] Item 8. The method according to any one of Items 1 to 7, wherein the starting material is not subjected to a fermentation process before or after the addition of the lipase.

[0094] Item 9. The method according to any one of Items 1 to 8, wherein the protein phase obtained in step (e) comprises less than 20 weight percent fat of the total solids.

[0095] Item 10. The method according to any one of Items 1 to 9, wherein in step (a) the pH is adjusted to between 5 and 6.5.

[0096] Item 11. A protein composition obtained according to the method of any one of Items 1 to 10.

[0097] Item 12. A lipid composition obtained according to the method of any one of Items 1 to 10.

[0098] Item 13. An animal food comprising the protein composition of Item 11.

[0099] Item 14. A method for preparing a protein composition from a starting material comprising egg protein and egg fat, comprising:

[0100] (a) adjusting the pH of the starting material to between pH 5 and 7,

[0101] (b) adding an effective amount of lipase to the starting material to form a mixture,

[0102] (c) incubating the mixture of step (b) at a temperature between 30° C. and 60° C. for a period of at least 10 minutes to obtain a digested mixture,

[0103] (d) subjecting the digested mixture to a separation process to form at least two phases, the at least two phases comprising a protein phase and a lipid phase,

[0104] (e) collecting the protein phase to obtain a protein composition,

[0105] (f) optionally, concentrating the protein phase to provide a concentrated protein composition,

[0106] (g) optionally, drying the high protein composition to provide a dried protein composition,

[0107] (h) optionally, subjecting the dried protein composition to a heat treatment, thereby obtaining a heat-treated dried protein composition.

[0108] Item 15. The method according to Item 14, wherein the starting material comprises egg white and egg yolk, and wherein before the starting material is subjected to the process of step (a), the starting material comprises greater than 0.2 weight percent of egg yolk based on the total solids.

[0109] Item 16. A protein composition obtained according to the method of Item 14 or 15.

[0110] Item 17. A concentrated protein composition obtained according to the method of Item 14 or 15.

[0111] Item 18. A dried protein composition obtained according to the method of Item 14 or 15.

[0112] Item 19. A heat-treated dried protein composition obtained according to the method of Item 14 or 15.

[0113] Item 20. An animal food comprising one or more of the following: the protein composition of item 11 or 16, the concentrated protein composition of item 17, the dry protein composition of item 18, or the heat-treated dry protein composition of item 19.

[0114] It should be noted that, as used in this specification and claims, the singular forms "a", "an", and "the" include plural objects unless the context clearly indicates otherwise. Thus, for example, reference to "a device" may include reference to one device as well as two or more devices unless the context clearly limits it to reference to one device.

[0115] The terms "between" and "at least" used herein are inclusive. For example, the range of "between 5 and 10" refers to any amount that is equal to or greater than 5 and equal to or less than 10.

[0116] As used herein, the term "about" when referring to a measurable value (e.g., an amount, a duration, etc.) is intended to encompass variations of ±10%, more preferably ±5%, and even more preferably ±2% of the specified value. Such variations are suitable for reproducing the disclosed methods and products. In certain embodiments, the term "about" may be omitted so that the indicated value is an exact value.

[0117] Unless otherwise indicated, the percentages of certain ingredients in the compositions are by weight. Various commercially available products may have been described or used in the present disclosure. It should be appreciated that the reference to these products is for illustrative purposes only. Without departing from the spirit of the present disclosure, certain physical and / or chemical properties and compositions of the products may be modified. It will be appreciated by those of ordinary skill in the art that, in some cases, it may be more desirable or more convenient to change the physical and / or chemical properties or compositions of one or more of these products to achieve the same or similar purpose as taught in the present disclosure.

[0118] Example

[0119] The following examples are provided to illustrate the present invention, but are not intended to limit the present invention thereto. Reagents, materials and instruments are presented as representative components, and those skilled in the art can make various substitutions or modifications according to the foregoing disclosure without departing from the principles and spirit of the present invention.

[0120] Example 1 pH for digestion

[0121] The goal of these experiments was to separate fat and protein from liquid whole eggs (a mixture of yolk and egg white, a very stable liquid mixture). The starting material was a mixture of whole eggs, which was approximately 20% egg white, 10% egg yolk and 70% water by volume. The mixture contained about 44% fat (% dry basis) and about 55% protein (% dry basis). All starting materials were from whole eggs that are not edible to humans. Several sets of experiments were conducted using different enzymes, pH and temperature. For four different enzymes: Esterase / lipase (EDC, best recommended pH 7-8, enzyme activity 425 FIP / g), LIPASERO 2 (EDC, best recommended pH 5-6, enzyme activity 225-300 BGE / g), Lipomod 34P (BioCatalyst, best recommended pH 5-8, enzyme activity 225 BGE / g), LIPASE RO concentrate (EDC, optimally recommended pH 7-7.5, enzyme activity 180FIPU / mg) was tested. In short, the pH of a mixture of egg yolk and egg white was measured, and when the pH exceeded the range of 5-6.5, acetic acid (pH adjusting agent) was added to adjust the pH to 5-6.5. The enzyme was then added to the mixture of egg yolk and egg white and incubated at different temperatures and pH values. After digestion was complete, the digested mixture was centrifuged in a desktop centrifuge to separate the phases containing fat and protein. In these experiments, 3 layers were obtained after centrifugation. The top phase mainly contained low-density fat (the first fat phase), the middle phase contained water and protein (protein phase), and the bottom phase contained high-density lipids and egg impurities (the second fat phase, referred to as "pellet").

[0122] To illustrate the determination of the optimal pH for digestion, Table 1 shows several batches of changes in the pH of the starting material and the addition of Results when esterase / lipase.

[0123] Fat extraction was calculated as (fat separated after centrifugation) / (initial feedstock - fat in egg) x 100%. Fat content was measured using a CEM Oracle NMR instrument. The protein (dry basis) in Table 1 is based on the protein content in the mesophase. Protein was analyzed using a LECO combustion furnace nitrogen analyzer. Solids content was analyzed using a CEM Smart 6 microwave moisture analyzer.

[0124] The success of the trial was measured by how much fat and protein was separated.

[0125] Table 1 Comparison of protein / fat separation at different lipase digestion pH

[0126]

[0127] As shown in Table 1, at a lower pH (eg, 6.5 or 6), the amount of fat in the fat phase and the amount of protein in the protein phase were significantly higher than those at pH 7 or 8.

[0128] Based on all the tests, it was determined that the optimal pH for all enzymes was between 5-6.5, which is different from the optimal pH recommended by some suppliers. The optimal temperature was also determined to be 37-50° C., more specifically 37-45° C. Regarding the amount of enzyme used, the optimal usage rate was 0.04 weight percent to 0.3 weight percent of the whole egg aqueous solution.

[0129] Example 2 Temperature during phase separation

[0130] The purpose of this experiment was to evaluate the effect of temperature on the separation process (centrifugation). The raw material was a mixture of whole eggs, which was about 20% egg white, 10% egg yolk and 70% water by volume. The mixture contained about 44% fat (% dry basis) and about 55% protein (% dry basis). All enzyme digestion reactions were performed at the same temperature, pH and the same amount of time. The only difference was the temperature of the separation step (in this case a benchtop centrifuge was used).

[0131] Success is measured by the amount of fat phase: the higher the fat phase content by weight, the better the separation.

[0132] Table 2

[0133]

[0134] As can be seen from Table 2, the lower the temperature, the better the phase separation effect. In this example, the separation at 10°C is 17% more than at 25°C, and 25% more than at 40°C.

[0135] As mentioned above, this temperature reduction goes against most literature and expert advice (and the expectations of Stoke's Law). In fact, it is common sense to increase the temperature to improve the separation of the phases using mechanical separation.

[0136] Statistical analysis of the method using enzymes disclosed in Example 3 compared to the control method not using enzymes

[0137] The purpose of this study was to compare the effectiveness of the method disclosed herein with a baseline method (eggs processed under the same conditions but without the addition of enzymes). The goal was to determine whether the new method was significantly better than the baseline. To achieve this goal, a Z-test was performed.

[0138] For the disclosed method, 8 samples were tested with optimized parameters (pH, reaction temperature, enzyme usage, separation temperature). The bottom phase (precipitate) was measured after separation and recorded as weight percentage. See summary statistics below:

[0139]

[0140]

[0141] The baseline used was eggs with the same processing parameters (pH, reaction temperature, separation temperature) except that the enzyme usage was 0. For this baseline test, the separation was 13.16%. Therefore, the optimal value for separation without enzymes was 15%.

[0142] Then a Z test was performed at a significance level of 0.001. When Z = 15.63, we rejected the null hypothesis and concluded that the population mean was significantly greater than the specified value of 15% at a significance level of 0.1%. This means that if no enzyme was used, the separation of the phases would be less than 15%. In contrast, when the disclosed method was used, the phase separation was above 15% with a confidence level of more than 99.9%.

Claims

1. A method for separating protein and fat in a starting material comprising egg protein and egg fat, comprising: (a) adjusting the pH of the starting material to between pH 5 and 7, (b) adding an effective amount of lipase to the starting material to form a mixture, (c) incubating the mixture of step (b) at a temperature between 30° C. and 60° C. for a period of at least 10 minutes to obtain a digested mixture, (d) subjecting the digested mixture to a separation process to form at least two phases, the at least two phases comprising a protein phase and a lipid phase, and (e) collecting the protein phase and the lipid phase separately to obtain a protein composition and a lipid composition.

2. The method of claim 1, wherein the starting material comprises egg white and egg yolk, and wherein the egg yolk in the starting material constitutes more than 0.2 weight percent of the total solids in the starting material.

3. A method according to claim 1 or 2, wherein the starting material is prepared from eggs that have been graded as unfit for direct human consumption.

4. The method according to claim 1, wherein the starting material is prepared from eggs that have been subjected to an incubation process but not hatched or from liquid eggs from an egg-breaking factory.

5. The method of claim 1, wherein the starting material prior to step (a) comprises greater than 1 weight percent of total solids in egg yolk.

6. The method of claim 1, wherein the pH is adjusted using a food grade reagent in step (a).

7. The method according to claim 1, wherein the amount of lipase used in step (b) is 0.01 to 0.3 weight percent of the total starting materials.

8. The method of claim 1, wherein the starting material is not subjected to a fermentation process before or after adding the lipase.

9. The method of claim 1, wherein the protein phase obtained in step (e) comprises less than 20 weight percent fat based on total solids.

10. The method of claim 1, wherein the pH is adjusted to between 5 and 6.5 in step (a).

11. A protein composition obtained according to the method of claim 1.

12. The lipid composition obtained according to the method of claim 1.

13. An animal food comprising the protein composition according to claim 11.

14. A method for preparing a protein composition from a starting material comprising egg protein and egg fat, comprising: (a) adjusting the pH of the starting material to between pH 5 and 7, (b) adding an effective amount of lipase to the starting material to form a mixture, (c) incubating the mixture of step (b) at a temperature between 30° C. and 60° C. for a period of at least 10 minutes to obtain a digested mixture, (d) subjecting the digested mixture to a separation process to form at least two phases, the at least two phases comprising a protein phase and a lipid phase, (e) collecting the protein phase to obtain a protein composition, (f) optionally, concentrating the protein phase to provide a concentrated protein composition, (g) optionally, drying the high protein composition to provide a dried protein composition, (h) optionally, subjecting the dried protein composition to a heat treatment, thereby obtaining a heat-treated dried protein composition.

15. The method of claim 14, wherein the starting material comprises egg white and egg yolk, and wherein the starting material comprises greater than 0.2 weight percent of egg yolk based on total solids before the starting material is subjected to the process of step (a).

16. A protein composition obtained according to the method of claim 14 or 15.

17. A concentrated protein composition obtained according to the method of claim 14 or 15.

18. A dried protein composition obtainable according to the process of claim 14 or 15.

19. A heat-treated dried protein composition obtained according to the method of claim 14 or 15.

20. An animal food comprising the protein composition of claim 11.

21. An animal food comprising the protein composition of claim 16.

22. An animal food comprising the concentrated protein composition of claim 17.

23. An animal food comprising the dry protein composition of claim 18.

24. An animal food comprising the heat-treated dry protein composition of claim 19.

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