Protective agent as well as preparation method and application thereof

Abstract

The invention discloses a protective agent as well as a preparation method and application thereof. The protective agent is prepared from inulin, fructo-oligosaccharide and erythritol. According to the protective agent provided by the invention, the inulin, the fructo-oligosaccharide and the erythritol are compounded to form a mixed protective agent, so that the heat resistance of functional protein in the bovine colostrum processing process can be improved, and the protective agent has a good protective effect on immune globulin (Ig-G) and lactoferrin (LF) in the processing process. Moreover, the three components all have probiotic effects, so that the development of high-value bovine coloctrum functional products is facilitated, and the comprehensive benefits of the bovine coloctrum are improved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and relates to a protective agent and a preparation method and application thereof. Background Art

[0002] Bovine colostrum refers to the milk of healthy cows within the first three days after giving birth. It is rich in nutrients and active ingredients, and has multiple health benefits such as immune regulation, growth and development, and intestinal regulation. Bovine colostrum has higher viscosity and density than normal milk. At the same time, bovine colostrum contains more total solids, fat, protein, minerals, and vitamins, and contains more types and quantities of bioactive ingredients, such as immunoglobulins (IgG) and lactoferrin (LF) and other functional proteins. However, the physical and chemical properties of bovine colostrum are poor in high temperature environments, and the loss of functional proteins in high temperature environments is large, and its biological activity cannot be truly exerted. Experiments have found that as the heating temperature of bovine colostrum increases, the viscosity increases and the fluidity deteriorates. This characteristic limits the large-scale development of bovine colostrum products in the food field. At present, the content of bioactive ingredients in the bovine colostrum functional products on the market is low, the form is relatively single, and lacks certain functionality.

[0003] In order to improve the stability of IgG during heating, there are two common solutions: one is to add some protective agents such as sugars, polyols, etc., and the other is microencapsulation. However, microencapsulation is difficult to achieve and expensive, and is currently only in the experimental stage. Studies have shown that sucrose and sugar alcohols can make proteins stable during heat treatment.

[0004] Zhang Jianhui et al. studied the protective effects of glycine, sucrose and mannitol as heat denaturation protective agents for bovine colostrum active immunoglobulin (IgG). The experiments found that the effects were in the order of glycine > mannitol > sucrose, and determined that under heat treatment conditions of 75°C for 5 minutes, the ideal formula of the bovine colostrum immune active IgG composite heat protectant was: 3% glycine addition, 3% sucrose addition, and 4% mannitol addition.

[0005] Yang Hong et al. selected three substances, glycine, maltitol and inulin, and optimized the formula of bovine colostrum IgG composite thermal protectant through response surface methodology, and obtained an optimal IgG composite thermal protectant with the following formula: 0.48% glycine, 14.98% inulin and 12.50% maltitol. The composite thermal protectant with this formula has a certain stabilizing effect on the IgG structure and can reduce the activity loss of IgG in bovine colostrum during heat treatment. After heat treatment at 75°C for 5 minutes, the IgG activity retention rate can reach 36.59%, which is 16.25% higher than that of the IgG sample in the blank control group.

[0006] Li Jianlei and others studied the effect of adding protective agents to the solution on the activity of immunoglobulins, where the protective agents were glycine, sucrose, and sorbitol. The study showed that the protective agent had a significant protective effect on the activity of immunoglobulins, and as the concentration of the protective agent increased, the protective effect became more obvious. However, when the amount of protective agent added was too high (≤30%), the protective effect would decrease.

[0007] Liu et al. found that the activity retention rate of lactoferrin in milk was low under pasteurization conditions. Liu Liping et al. found that the lactoferrin content was lower after treatment at 72°C for 15s compared with untreated colostrum. Chen et al. found that heat treatment at 72.5°C for 15s resulted in a loss of more than 40% of lactoferrin. However, there are few studies on whether protective agents have a protective effect on lactoferrin during processing. Summary of the invention

[0008] In view of the above-mentioned technical problems existing in the prior art, the purpose of the present invention is to propose a protective agent and a preparation method and application thereof. Specifically, a protective agent for maintaining the activity of functional proteins and a preparation method and application thereof are provided, and an application of erythritol as a protective agent is also provided.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a use of erythritol as a protective agent, wherein the erythritol is used as a protective agent to maintain the activity of functional proteins in bovine colostrum.

[0011] Erythritol, as a sugar alcohol substance, is widely used in food. Erythritol has strong hydration effect and can interact with the water in protein molecules to prevent protein from losing water, thereby helping to maintain the structure and function of functional proteins. At the same time, studies have shown that erythritol is a natural oxidant, which can theoretically slow down protein oxidation.

[0012] The present invention has shown through research that using erythritol as a protective agent can effectively maintain the activity of functional proteins in bovine colostrum, and can not only protect the activity of immunoglobulins, but also protect the activity of lactoferrin. Moreover, erythritol has a prebiotic effect, which is conducive to the development of high-value bovine colostrum functional products and improves the comprehensive benefits of bovine colostrum.

[0013] Preferably, the erythritol is used as a protective agent to maintain the activity of functional proteins during the processing of bovine colostrum.

[0014] Preferably, the bovine colostrum processing process comprises:

[0015] (A) defatting bovine colostrum to obtain defatted bovine colostrum;

[0016] (B) sterilizing the defatted bovine colostrum, coagulating the milk, and filtering the milk to obtain a whey liquid from which casein has been removed;

[0017] (C) ultrafiltration and concentration of the whey solution obtained in step (B) to allow immunoglobulin and lactoferrin to enter the retentate, and retain the retentate;

[0018] (D) adding a protective agent to the reflux liquid, and then pasteurizing the reflux liquid to obtain bovine colostrum whey protein;

[0019] Wherein, the protective agent in step (D) is erythritol.

[0020] In the method of the present invention, pasteurization is selected in step (D), which can achieve the purpose of sterilization on the one hand, and verify the heat resistance effect of the protective agent on the other hand. The present invention does not specifically limit the pasteurization conditions, which can be carried out according to national standards, for example, heating at 72°C for 15s.

[0021] The present invention avoids the loss of nutrition and limitation of physical and chemical properties of bovine colostrum during heating by adding erythritol as a protective agent during the processing of bovine colostrum. The method uses pasteurization to verify heat resistance. The results show that the bovine colostrum with the addition of erythritol protective agent significantly increases the content of immunoglobulin and lactoferrin functional proteins after pasteurization compared with the bovine colostrum without the addition of protective agent, providing a method for the development of bovine colostrum products.

[0022] Preferably, the defatting method in step (A) comprises: preheating the frozen bovine colostrum to 40° C.-45° C. for thawing, and removing fat by centrifugation.

[0023] Preferably, the centrifugal rotation speed is 6000r / min-8000r / min, for example, it can be 6000r / min, 6200r / min, 6300r / min, 6400r / min, 6500r / min, 6600r / min, 6800r / min, 7000r / min, 7200r / min, 7400r / min, 7500r / min, 7600r / min, 7700r / min, 7800r / min or 8000r / min, etc.

[0024] Preferably, the centrifugation time is 25 min-30 min, for example, it can be 25 min, 26 min, 27 min, 28 min, 29 min or 30 min.

[0025] Preferably, the centrifugation temperature is 40°C-45°C, for example, it can be 40°C, 41°C, 42°C, 43°C, 44°C or 45°C.

[0026] Preferably, the sterilization method of step (B) is ultra-high pressure sterilization, and the pressure of ultra-high pressure sterilization is 400MPa-500MPa, for example, it can be 400MPa, 415MPa, 425MPa, 430MPa, 440MPa, 450MPa, 460MPa, 470MPa, 480MPa, 490MPa or 500MPa, etc.; the temperature is 30°C-40°C, for example, it can be 30°C, 32°C, 34°C, 35°C, 37°C, 38°C or 40°C, etc.; the time is 10min-15min, for example, it can be 10min, 11min, 12min, 13min, 14min or 15min, etc. In the present invention, step (B) adopts ultra-high pressure sterilization, which can reduce the loss of immunoglobulin and lactoferrin compared with pasteurization.

[0027] Preferably, the method for curdling milk in step (B) comprises the following steps: adjusting the pH of the sterilized bovine colostrum to within the range of 6.2-6.6, adding rennet solution, stirring, keeping warm and curdling milk. Exemplarily, the pH may be 6.2, 6.3, 6.4, 6.5 or 6.6, etc.

[0028] Preferably, the amount of chymosin added is 0.02g / L-0.03g / L. The amount of chymosin added refers to the amount of chymosin in 1L of bovine colostrum system with chymosin solution added, in which the content of chymosin is 0.02g-0.03g.

[0029] Preferably, the stirring time is 2 min-3 min, for example, it can be 2 min, 2.2 min, 2.3 min, 2.4 min, 2.5 min, 2.6 min, 2.8 min or 3 min.

[0030] Preferably, the temperature of the heat-insulating and curdling milk is 30°C-40°C, for example, 30°C, 32°C, 33°C, 35°C, 36°C, 38°C or 40°C.

[0031] Preferably, the time for heat preservation and coagulation is 30 min-60 min, for example, 30 min, 33 min, 36 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0032] Preferably, the filter cloth used for filtering in step (B) is 60-80 mesh, and after filtering, the macromolecular casein and the whey liquid are separated.

[0033] Preferably, in step (C), ultrafiltration concentration is performed using a membrane with a molecular weight cutoff of 50 kDa.

[0034] Preferably, in step (D), the erythritol protective agent is untreated erythritol or pre-treated erythritol, and the pre-treated erythritol is prepared by the following method: water and erythritol are mixed and then subjected to ultra-high pressure treatment to obtain pre-treated erythritol. After ultra-high pressure treatment, the requirements of sterilization and homogenization can be met, which is more conducive to its full dissolution and fusion in bovine colostrum. In one embodiment, the water used in this step is distilled sterile water.

[0035] Preferably, in the process of preparing pre-treated erythritol, the pressure of the ultra-high pressure treatment is 400 MPa-500 MPa, for example, it can be 400 MPa, 415 MPa, 425 MPa, 430 MPa, 440 MPa, 450 MPa, 460 MPa, 470 MPa, 480 MPa, 490 MPa or 500 MPa.

[0036] Preferably, in the process of preparing the pre-treated erythritol, the temperature of the ultra-high pressure treatment is 30°C-40°C, for example, 30°C, 32°C, 34°C, 35°C, 37°C, 38°C or 40°C.

[0037] Preferably, in the process of preparing the pre-treated erythritol, the ultra-high pressure treatment time is 10 min-15 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min.

[0038] Preferably, the solid content of the pre-treated erythritol is 40%-60%, for example, it can be 40%, 42.5%, 45%, 47%, 50%, 52%, 55%, 57% or 60%.

[0039] Preferably, in step (D), if the protective agent is pre-treated erythritol, the mass content of the protective agent added to the reflux liquid is 10%-25%;

[0040] Preferably, in step (D), if the protective agent is untreated erythritol, the mass content of the protective agent added to the reflux liquid is 4%-13%;

[0041] Preferably, step (D) further comprises: vacuum freeze-drying the bovine colostrum whey protein to obtain bovine colostrum whey protein powder;

[0042] Preferably, the vacuum freeze-drying temperature is -60°C to -80°C;

[0043] Preferably, the vacuum freeze-drying time is 40h-48h;

[0044] Preferably, during the vacuum freeze-drying process, the material thickness is 4 mm-8 mm.

[0045] In a second aspect, the present invention provides a protective agent for maintaining the activity of a functional protein, wherein the protective agent for maintaining the activity of a functional protein comprises inulin, oligofructose and erythritol.

[0046] Inulin is a high molecular weight polysaccharide, usually a fructose polymer composed of 2-60 fructose units connected by β-sugar 2,1 glycosidic bonds. Its main characteristics are that the chain connecting the fructose molecules is longer and the structure is more complex.

[0047] Fructo-oligosaccharides are short-chain sugars formed by 2-10 fructose molecules connected by β-2,1 glycosidic bonds. They have fewer fructose molecules and a simpler structure.

[0048] In the present invention, the chain length of inulin is greater than that of oligofructose.

[0049] The present invention forms a mixed protective agent by compounding inulin, oligofructose and erythritol, which can increase the hydrophobic effect inside the functional protein molecule, make its tertiary structure more stable, help maintain the stability of the functional protein, not only can protect the activity of immunoglobulin, but also can protect the activity of lactoferrin. At the same time, inulin and oligofructose are prebiotics, and erythritol has a prebiotic effect, that is, these three ingredients all have a prebiotic effect, which is conducive to the development of high-value bovine colostrum functional products and improve the comprehensive benefits of bovine colostrum. In addition, erythritol, as a sugar substitute, can be mixed with inulin and oligofructose to reduce sugar content, so as to be better applied to products.

[0050] It can improve the heat resistance of functional proteins in the process of bovine colostrum processing and has a good protective effect on immunoglobulin and lactoferrin during processing. Moreover, these three ingredients have prebiotic effects, which is conducive to the development of high-value bovine colostrum functional products and improve the comprehensive benefits of bovine colostrum.

[0051] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0052] Preferably, based on the total mass of the protective agent as 100%, the content of the inulin is 35%-45%, for example, it can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%; the content of the oligofructose is 35%-45%, for example, it can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%; the content of the erythritol is 10%-30%, for example, it can be 10%, 11%, 12%, 14%, 15%, 16%, 17%, 18%, 20%, 21%, 22%, 23%, 25%, 26%, 27%, 28, 29% or 30%, etc.

[0053] Preferably, based on 100% of the total mass of the protective agent, the content of inulin is 38%-42%, the content of oligofructose is 38%-42%, and the content of erythritol is 16%-24%.

[0054] In a third aspect, the present invention provides a method for preparing a protective agent for maintaining the activity of a functional protein as described in the first aspect, the preparation method comprising the following steps:

[0055] Inulin, oligofructose and erythritol are mixed to obtain the protective agent.

[0056] Preferably, water is added during the mixing process, and ultra-high pressure treatment is performed after the mixing to obtain a pre-treated protective agent. After ultra-high pressure treatment, the requirements of sterilization and homogenization can be achieved, which is more conducive to its full dissolution and fusion in bovine colostrum.

[0057] Preferably, the solid content of the pre-treated protective agent is 40%-60%, for example, it can be 40%, 42.5%, 45%, 47%, 50%, 52%, 55%, 57% or 60%.

[0058] Preferably, the pressure of the ultrahigh pressure treatment is 400 MPa-500 MPa, for example, it can be 400 MPa, 415 MPa, 425 MPa, 430 MPa, 440 MPa, 450 MPa, 460 MPa, 470 MPa, 480 MPa, 490 MPa or 500 MPa.

[0059] Preferably, the temperature of the ultrahigh pressure treatment is 30°C-40°C, for example, it can be 30°C, 32°C, 34°C, 35°C, 37°C, 38°C or 40°C.

[0060] Preferably, the ultrahigh pressure treatment time is 10 min-15 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min.

[0061] In a fourth aspect, the present invention provides a method for processing bovine colostrum, the bovine colostrum processing method comprising the following steps:

[0062] (1) defatting the bovine colostrum to obtain defatted bovine colostrum;

[0063] (2) sterilizing the defatted bovine colostrum, coagulating the milk, and filtering the milk to obtain a whey liquid from which casein has been removed;

[0064] (3) ultrafiltration and concentration of the whey liquid obtained in step (2) to allow immunoglobulin and lactoferrin to enter the retentate protein, and retain the retentate;

[0065] (4) adding the protective agent described in the second aspect to the reflux liquid, and then pasteurizing the reflux liquid to obtain bovine colostrum whey protein powder;

[0066] Wherein, the protective agent is an untreated protective agent or a pre-treated protective agent.

[0067] In the method of the present invention, pasteurization is selected in step (4), which can achieve the purpose of sterilization on the one hand, and verify the heat resistance effect of the protective agent on the other hand. The present invention does not specifically limit the pasteurization conditions, which can be carried out according to national standards, for example, heating at 72°C for 15s.

[0068] The present invention avoids the loss of nutrition and limitation of physical and chemical properties of bovine colostrum during heating by adding a protective agent during the processing of bovine colostrum, and the method uses pasteurization to verify heat resistance. The results show that the bovine colostrum to which the protective agent of the first aspect is added significantly increases the content of immunoglobulin and lactoferrin functional proteins after pasteurization compared with the bovine colostrum to which the protective agent is not added, providing a method for the development of bovine colostrum products.

[0069] Preferably, the defatting method in step (1) comprises: preheating the frozen colostrum to 40°C-45°C for thawing, and removing fat by centrifugation. Exemplarily, the preheating temperature may be 40°C, 41°C, 42°C, 43°C, 44°C or 45°C, etc. By optimizing the preheating temperature, on the one hand, the colostrum can be thawed in a short time, on the other hand, the functional protein in the colostrum is slightly affected at this temperature, and on the other hand, the defatting effect at this temperature is good.

[0070] Preferably, the centrifugal rotation speed is 6000r / min-8000r / min, for example, it can be 6000r / min, 6200r / min, 6300r / min, 6400r / min, 6500r / min, 6600r / min, 6800r / min, 7000r / min, 7200r / min, 7400r / min, 7500r / min, 7600r / min, 7700r / min, 7800r / min or 8000r / min, etc.

[0071] Preferably, the centrifugation time is 25 min-30 min, for example, it can be 25 min, 26 min, 27 min, 28 min, 29 min or 30 min.

[0072] Preferably, the centrifugation temperature is 40°C-45°C, for example, it can be 40°C, 41°C, 42°C, 43°C, 44°C or 45°C.

[0073] Preferably, the sterilization method of step (2) is ultra-high pressure sterilization, and the pressure of ultra-high pressure sterilization is 400MPa-500MPa, for example, it can be 400MPa, 415MPa, 425MPa, 430MPa, 440MPa, 450MPa, 460MPa, 470MPa, 480MPa, 490MPa or 500MPa, etc.; the temperature is 30°C-40°C, for example, it can be 30°C, 32°C, 34°C, 35°C, 37°C, 38°C or 40°C, etc.; the time is 10min-15min, for example, it can be 10min, 11min, 12min, 13min, 14min or 15min, etc. In the present invention, step (2) adopts ultra-high pressure sterilization, which can reduce the loss of immunoglobulin and lactoferrin compared with pasteurization.

[0074] Preferably, the method for curdling milk in step (2) comprises the following steps: adjusting the pH of the sterilized bovine colostrum to within the range of 6.2-6.6, adding rennet solution, stirring, keeping warm and curdling milk. Exemplarily, the pH may be 6.2, 6.3, 6.4, 6.5 or 6.6, etc.

[0075] Preferably, the amount of chymosin added is 0.02g / L-0.03g / L. The amount of chymosin added refers to the amount of chymosin in 1L of bovine colostrum system with chymosin solution added, in which the content of chymosin is 0.02g-0.03g.

[0076] Preferably, the stirring time is 2 min-3 min, for example, it can be 2 min, 2.2 min, 2.3 min, 2.4 min, 2.5 min, 2.6 min, 2.8 min or 3 min.

[0077] Preferably, the temperature of the heat-insulating and curdling milk is 30°C-40°C, for example, 30°C, 32°C, 33°C, 35°C, 36°C, 38°C or 40°C.

[0078] Preferably, the time for heat preservation and coagulation is 30 min-60 min, for example, 30 min, 33 min, 36 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0079] Preferably, the filter cloth used in the filtration in step (2) is 60-80 mesh. After filtration, the macromolecular casein and the whey liquid are separated.

[0080] Preferably, in step (3), ultrafiltration concentration is performed using a membrane with a molecular weight cutoff of 50 kDa. Preferably, in step (4), if the protective agent is a pre-treatment protective agent, the mass content of the protective agent added to the reflux liquid is 10%-25%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%, etc., preferably 16%-21%.

[0081] Preferably, in step (4), if the protective agent is an untreated protective agent, the mass content of the protective agent added to the reflux liquid is 4%-13%, for example, it can be 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12% or 13%, etc.

[0082] Within a certain range, as the mass content of the protective agent increases, the protective effect increases. However, when the mass content of the protective agent is too large, the protective effect tends to decrease. At the same time, a liquid with a mass content of the protective agent that is too large is not suitable for the product.

[0083] Preferably, step (4) further comprises: vacuum freeze-drying the bovine colostrum whey protein to obtain bovine colostrum whey protein powder.

[0084] Preferably, the vacuum freeze-drying temperature is -60°C to -80°C, for example, -60°C, -65°C, -70°C, -75°C or -80°C.

[0085] Preferably, the vacuum freeze-drying time is 40 h-48 h, for example, it can be 40 h, 41 h, 42 h, 43 h, 44 h, 45 h, 46 h, 47 h or 48 h.

[0086] Preferably, during the vacuum freeze-drying process, the material thickness is 4 mm-8 mm, for example, 4 mm, 5 mm, 6 mm, 7 mm or 8 mm.

[0087] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0088] Compared with the prior art, the present invention has the following beneficial effects:

[0089] (1) The present invention provides a new application of erythritol as a protective agent. Erythritol as a protective agent can effectively maintain the activity of functional proteins in bovine colostrum during processing, improve the heat resistance of functional proteins, and have a good protective effect on immunoglobulins and lactoferrin during processing. Moreover, erythritol has a prebiotic effect, which is conducive to the development of high-value bovine colostrum functional products and improves the comprehensive benefits of bovine colostrum.

[0090] (2) The present invention provides a protective agent, which is formed by compounding inulin, oligofructose and erythritol to form a mixed protective agent, which can improve the heat resistance of functional proteins in the process of bovine colostrum processing and has a good protective effect on immunoglobulin and lactoferrin during the processing. Moreover, these three components all have prebiotic effects, which is conducive to the development of high-value bovine colostrum functional products and improve the comprehensive benefits of bovine colostrum. DETAILED DESCRIPTION

[0091] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0092] In this embodiment, the rennet liquid is prepared by the following method: 1 part by weight of rennet (model: Chr. Hansen 142514) is diluted in 10-50 parts by weight of pure water to obtain the rennet liquid.

[0093] Selection of bovine colostrum

[0094] Frozen bovine colostrum is selected from the mixed colostrum of Holstein cows from Hohhot and Linghe pasture in Inner Mongolia within three days. The mixed colostrum can better represent the average level of bovine colostrum.

[0095] In the examples of the present invention, inulin, oligofructose and erythritol were all purchased from Ubaojia Food Co., Ltd.

[0096] Example 1

[0097] This embodiment provides a protective agent, which, based on the total mass of the protective agent being 100%, includes 35% inulin, 35% oligofructose, and 30% erythritol.

[0098] This embodiment also provides a method for preparing a protective agent, inulin, oligofructose and erythritol are dissolved in pure water (solid content is 50%) in proportion, put into a water bath, evenly mixed and shaken, and then subjected to ultra-high pressure treatment. The parameters of the ultra-high pressure treatment are: pressure of 500 MPa, temperature of 40°C, and time of 15 min to obtain a pre-treated protective agent.

[0099] This embodiment also provides a method for processing bovine colostrum, comprising the following steps:

[0100] (1) placing frozen bovine colostrum in a water bath, preheating and thawing at 45° C., and then centrifuging in a centrifuge (speed of 8000 r / min, time of 30 min, temperature of 45° C.), thereby defatting to obtain defatted bovine colostrum;

[0101] (2) sterilizing the defatted bovine colostrum by ultra-high pressure treatment (pressure of 500 MPa, temperature of 40° C., time of 15 min), adding rennet solution, stirring for 2 min, and keeping warm at 30° C. for 45 min to achieve coagulation, wherein the rennet content in the bovine colostrum system after adding the rennet solution is 0.03 g / L, filtering with a 60-mesh filter cloth after coagulation to obtain a whey solution from which casein is removed, and performing the first test to test the content of immunoglobulin and lactoferrin;

[0102] (3) selecting a membrane with a molecular weight cut-off of 50 kDa, and performing ultrafiltration and concentration on the whey liquid obtained in step (2), so that the immunoglobulin and lactoferrin enter the retentate, and retaining the retentate;

[0103] (4) adding the above-mentioned pre-treatment protective agent to the reflux liquid, the mass of the protective agent accounting for 13% of the mass of the reflux liquid, and then pasteurizing (temperature of 72° C., time of 15 s) to obtain bovine colostrum whey protein, and performing a second test to test the content of immunoglobulin and lactoferrin;

[0104] (5) The bovine colostrum whey protein obtained in step (4) is subjected to vacuum freeze drying, and the parameters of the vacuum freeze drying are: temperature of -80°C, time of 48 hours, and material thickness of 5 mm, to obtain bovine colostrum whey protein powder, and a third test is performed to test the content of immunoglobulin and lactoferrin.

[0105] Example 2

[0106] The difference between this embodiment and embodiment 1 is that in the method for processing bovine colostrum, the mass of the protective agent in step (4) accounts for 18% of the mass of the reflux liquid.

[0107] Example 3

[0108] The difference between this embodiment and embodiment 1 is that in the method for processing bovine colostrum, the mass of the protective agent in step (4) accounts for 21% of the mass of the reflux liquid.

[0109] Example 4

[0110] The difference between this embodiment and embodiment 3 is that the formula of the protective agent is: based on the total mass of the protective agent being 100%, it includes 40% inulin, 40% oligofructose, and 20% erythritol.

[0111] Example 5

[0112] The difference between this embodiment and embodiment 3 is that the formula of the protective agent is: based on the total mass of the protective agent being 100%, it includes 45% inulin, 45% oligofructose, and 10% erythritol.

[0113] Example 6

[0114] The difference between this embodiment and embodiment 1 is that in the method for processing bovine colostrum, the mass of the protective agent in step (4) accounts for 10% of the mass of the reflux liquid.

[0115] Example 7

[0116] This embodiment provides a protective agent, which, based on the total mass of the protective agent being 100%, includes 35% inulin, 35% oligofructose, and 30% erythritol.

[0117] This embodiment also provides a method for preparing a protective agent, wherein inulin, oligofructose and erythritol are dissolved in pure water (solid content is 60%) in proportion, put into a water bath, mixed and shaken evenly, and then subjected to ultra-high pressure treatment. The parameters of the ultra-high pressure treatment are: pressure of 400 MPa, temperature of 35° C., and time of 15 min to obtain a pre-treated protective agent.

[0118] This embodiment also provides a method for processing bovine colostrum, comprising the following steps:

[0119] (1) placing frozen bovine colostrum in a water bath, preheating and thawing at 45° C., and then centrifuging in a centrifuge (speed of 6000 r / min, time of 25 min, temperature of 50° C.), thereby defatting to obtain defatted bovine colostrum;

[0120] (2) sterilizing the defatted bovine colostrum by ultrahigh pressure treatment (pressure of 400 MPa, temperature of 35° C., time of 15 min), adding rennet solution, stirring for 2 min, and keeping warm at 30° C. for 45 min to achieve coagulation, wherein the rennet content in the bovine colostrum system after adding the rennet solution is 0.02 g / L, filtering with a 60-mesh filter cloth after coagulation to obtain a whey solution from which casein is removed, and performing the first test to test the content of immunoglobulin and lactoferrin;

[0121] (3) selecting a membrane with a molecular weight cut-off of 50 kDa, and performing ultrafiltration and concentration on the whey liquid obtained in step (2), so that the immunoglobulin and lactoferrin enter the retentate, and retaining the retentate;

[0122] (4) adding the above-mentioned pre-treated protective agent to the reflux liquid, the mass of the protective agent accounting for 25% of the mass of the reflux liquid, and then pasteurizing (temperature of 72° C., time of 15 s) to obtain bovine colostrum whey protein, and performing a second test to test the content of immunoglobulin and lactoferrin;

[0123] (5) The bovine colostrum whey protein obtained in step (4) is subjected to vacuum freeze drying, and the parameters of the vacuum freeze drying are: temperature of -70°C, time of 48 hours, and material thickness of 8 mm, to obtain bovine colostrum whey protein powder, and a third test is performed to test the content of immunoglobulin and lactoferrin.

[0124] Example 8

[0125] This embodiment provides a protective agent, which, based on the total mass of the protective agent being 100%, includes 35% inulin, 35% oligofructose, and 30% erythritol.

[0126] This embodiment also provides a method for preparing a protective agent, wherein inulin, oligofructose and erythritol are dissolved in pure water (solid content is 40%) in proportion, put into a water bath, mixed and shaken evenly, and then subjected to ultra-high pressure treatment. The parameters of the ultra-high pressure treatment are: pressure of 450 MPa, temperature of 35° C., and time of 15 min to obtain a pre-treated protective agent.

[0127] This embodiment also provides a method for processing bovine colostrum, comprising the following steps:

[0128] (1) placing frozen bovine colostrum in a water bath, preheating and thawing at 45° C., and then centrifuging in a centrifuge (speed of 6500 r / min, time of 30 min, temperature of 45° C.), thereby defatting to obtain defatted bovine colostrum;

[0129] (2) sterilizing the defatted bovine colostrum by ultrahigh pressure treatment (pressure of 450 MPa, temperature of 35° C., time of 15 min), adding rennet solution, stirring for 2 min, and keeping warm at 30° C. for 45 min to achieve coagulation, wherein the rennet content in the bovine colostrum system after adding the rennet solution is 0.02 g / L, filtering with a 60-mesh filter cloth after coagulation to obtain a whey solution from which casein is removed, and performing the first test to test the content of immunoglobulin and lactoferrin;

[0130] (3) selecting a membrane with a molecular weight cut-off of 50 kDa, and performing ultrafiltration and concentration on the whey liquid obtained in step (2), so that the immunoglobulin and lactoferrin enter the retentate, and retaining the retentate;

[0131] (4) adding the above-mentioned pre-treatment protective agent to the reflux liquid, the mass of the protective agent accounting for 18% of the mass of the reflux liquid, and then pasteurizing (temperature of 72° C., time of 15 s) to obtain bovine colostrum whey protein, and performing a second test to test the content of immunoglobulin and lactoferrin;

[0132] (5) The bovine colostrum whey protein obtained in step (4) is subjected to vacuum freeze drying, and the parameters of the vacuum freeze drying are: temperature of -80°C, time of 48 hours, and material thickness of 4 mm, to obtain bovine colostrum whey protein powder, and a third test is performed to test the content of immunoglobulin and lactoferrin.

[0133] Example 9

[0134] This embodiment also provides a method for processing bovine colostrum, comprising the following steps:

[0135] (1) Pre-treating erythritol by mixing erythritol with water and then subjecting the mixture to ultra-high pressure treatment (pressure of 500 MPa, temperature of 40° C., and time of 15 min) to obtain pre-treated erythritol, wherein the solid content of the pre-treated erythritol is 50%, and the pre-treated erythritol is set aside.

[0136] (2) placing the frozen colostrum in a water bath, preheating and thawing at 45° C., and then centrifuging in a centrifuge (speed of 8000 r / min, time of 30 min, temperature of 45° C.) to defat and obtain defatted colostrum;

[0137] (2) sterilizing the defatted bovine colostrum by ultra-high pressure treatment (pressure of 500 MPa, temperature of 40° C., time of 15 min), adding rennet solution, stirring for 2 min, and keeping warm at 30° C. for 45 min to achieve coagulation, wherein the rennet content in the bovine colostrum system after adding the rennet solution is 0.03 g / L, filtering with a 60-mesh filter cloth after coagulation to obtain a whey solution from which casein is removed, and performing the first test to test the content of immunoglobulin and lactoferrin;

[0138] (3) selecting a membrane with a molecular weight cut-off of 50 kDa, and performing ultrafiltration and concentration on the whey liquid obtained in step (2), so that the immunoglobulin and lactoferrin enter the retentate, and retaining the retentate;

[0139] (4) adding the above-mentioned pre-treated erythritol to the reflux liquid, with the mass of the protective agent accounting for 21% of the mass of the reflux liquid, and then pasteurizing (temperature of 72° C., time of 15 s) to obtain bovine colostrum whey protein, and performing a second test to test the content of immunoglobulin and lactoferrin;

[0140] (5) The bovine colostrum whey protein obtained in step (4) is subjected to vacuum freeze drying, and the parameters of the vacuum freeze drying are: temperature of -75°C, time of 42 hours, and material thickness of 4 mm, to obtain bovine colostrum whey protein powder, and a third test is performed to test the content of immunoglobulin and lactoferrin.

[0141] Example 10

[0142] This embodiment also provides a method for processing bovine colostrum, comprising the following steps:

[0143] (1) Pre-treating erythritol by mixing erythritol with water and then subjecting the mixture to ultra-high pressure treatment (pressure of 475 MPa, temperature of 35° C., and time of 12 min) to obtain pre-treated erythritol, wherein the solid content of the pre-treated erythritol is 50%, and the pre-treated erythritol is set aside.

[0144] (2) placing the frozen colostrum in a water bath, preheating and thawing at 42° C., and then centrifuging in a centrifuge (speed of 7500 r / min, time of 25 min, temperature of 42° C.) to defat and obtain defatted colostrum;

[0145] (2) sterilizing the defatted bovine colostrum by ultra-high pressure treatment (pressure of 450 MPa, temperature of 40° C., time of 10 min), adding rennet solution, stirring for 3 min, and keeping warm at 35° C. for 30 min to achieve coagulation, wherein the rennet content in the bovine colostrum system after adding the rennet solution is 0.025 g / L, filtering with a filter cloth of 80 mesh after coagulation to obtain a whey solution from which casein is removed, and performing the first test to test the content of immunoglobulin and lactoferrin;

[0146] (3) selecting a membrane with a molecular weight cut-off of 50 kDa, and performing ultrafiltration and concentration on the whey liquid obtained in step (2), so that the immunoglobulin and lactoferrin enter the retentate, and retaining the retentate;

[0147] (4) adding the above-mentioned pre-treated erythritol to the reflux liquid, with the mass of the protective agent accounting for 15% of the mass of the reflux liquid, and then pasteurizing (temperature of 72° C., time of 15 s) to obtain bovine colostrum whey protein, and performing a second test to test the content of immunoglobulin and lactoferrin;

[0148] (5) The bovine colostrum whey protein obtained in step (4) is subjected to vacuum freeze drying, and the parameters of the vacuum freeze drying are: temperature of -75°C, time of 42 hours, and material thickness of 4 mm, to obtain bovine colostrum whey protein powder, and a third test is performed to test the content of immunoglobulin and lactoferrin.

[0149] Embodiment 11

[0150] This embodiment also provides a method for processing bovine colostrum, comprising the following steps:

[0151] (1) Pre-treating erythritol by mixing erythritol with water and then subjecting the mixture to ultra-high pressure treatment (pressure of 425 MPa, temperature of 38° C., and time of 10 min) to obtain pre-treated erythritol, wherein the solid content of the pre-treated erythritol is 55%, and the pre-treated erythritol is set aside.

[0152] (2) placing the frozen colostrum in a water bath, preheating and thawing at 48° C., and then centrifuging in a centrifuge (speed of 6500 r / min, time of 28 min, temperature of 48° C.) to defat and obtain defatted colostrum;

[0153] (2) After the skimmed bovine colostrum is sterilized by ultrahigh pressure treatment (pressure of 465 MPa, temperature of 40° C., time of 15 min), rennet solution is added, stirred for 2.5 min, and then kept at 35° C. for 60 min to achieve coagulation, the rennet content in the bovine colostrum system after the addition of the rennet solution is 0.03 g / L, and after coagulation, the milk is filtered using an 80-mesh filter cloth to obtain a whey liquid from which casein is removed, and the first test is performed to test the content of immunoglobulin and lactoferrin;

[0154] (3) selecting a membrane with a molecular weight cut-off of 50 kDa, and performing ultrafiltration and concentration on the whey liquid obtained in step (2), so that the immunoglobulin and lactoferrin enter the retentate, and retaining the retentate;

[0155] (4) adding the above-mentioned pre-treated erythritol to the reflux liquid, with the mass of the protective agent accounting for 19% of the mass of the reflux liquid, and then pasteurizing (temperature of 72° C., time of 15 s) to obtain bovine colostrum whey protein, and performing a second test to test the content of immunoglobulin and lactoferrin;

[0156] (5) The bovine colostrum whey protein obtained in step (4) is subjected to vacuum freeze drying, and the parameters of the vacuum freeze drying are: temperature of -70°C, time of 46 hours, and material thickness of 4.5 mm, to obtain bovine colostrum whey protein powder, and a third test is performed to test the content of immunoglobulin and lactoferrin.

[0157] Comparative Example 1

[0158] The difference between this comparative example and Example 3 is that the protective agent is inulin.

[0159] Comparative Example 2

[0160] The difference between this comparative example and Example 3 is that the protective agent is oligofructose.

[0161] Comparative Example 3

[0162] The difference between this comparative example and Example 3 is that no protective agent is added in the processing method of bovine colostrum.

[0163] Tests for immunoglobulins and lactoferrin: Tests were performed using a liquid chromatograph (Thermo Fisher Vanquish). For the test method for lactoferrin, see GB5009.299-2024 National Food Safety Standard, Determination of lactoferrin in food. For the test method for immunoglobulins, see T / SSFS0002-2021, Determination of immunoglobulin IgG in milk and dairy products.

[0164] See Table 1 for the results.

[0165] Table 1

[0166]

[0167] It can be known from Examples 1-8 that a mixed protective agent is formed by compounding inulin, oligofructose and erythritol, which can improve the heat resistance of functional proteins in the process of bovine colostrum processing, and has a good protective effect on immunoglobulin and lactoferrin during processing. Moreover, these three ingredients all have prebiotic effects, which are conducive to the development of high-value bovine colostrum functional products and improve the comprehensive benefits of bovine colostrum. Comparative Example 3 does not add a protective agent, and Comparative Example 1 uses a single type of inulin as a protective agent. Comparative Example 2 uses a single type of oligofructose as a protective agent, and the test results show that after pasteurization and vacuum freeze drying, the contents of immunoglobulin and lactoferrin are greatly reduced. This shows that the compounding of inulin, oligofructose and erythritol has a synergistic effect.

[0168] Furthermore, by comparing Examples 1-3 and Example 6, it can be seen that within a certain range, as the amount of the protective agent increases, the activity of immunoglobulin and lactoferrin in the bovine colostrum processing is more preferably increased in an amount of 16%-21%.

[0169] By comparing Example 1 with Examples 4-5, it can be seen that there is a preferred range for the dosage ratio of inulin, oligofructose and erythritol in the protective agent. The preferred ratio is that based on the total mass of the protective agent as 100%, the content of inulin is 38%-42%, the content of oligofructose is 38%-42%, and the content of erythritol is 16%-24%.

[0170] It can be seen from Examples 9-11 that a single type of erythritol has a good effect on maintaining the activity of immunoglobulins and lactoferrin during the processing of bovine colostrum.

[0171] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A use of erythritol as a protective agent, characterized in that: The erythritol is used as a protective agent to maintain the activity of functional proteins in bovine colostrum.

2. The use of erythritol as a protective agent according to claim 1, characterized in that The erythritol is used as a protective agent to maintain the activity of functional proteins in the process of bovine colostrum processing.

3. The use of erythritol as a protective agent according to claim 1 or 2, characterized in that: The bovine colostrum processing process comprises: (A) defatting bovine colostrum to obtain defatted bovine colostrum; (B) sterilizing the defatted bovine colostrum, coagulating the milk, and filtering the milk to obtain a whey liquid from which casein has been removed; (C) ultrafiltration and concentration of the whey solution obtained in step (B) to allow immunoglobulin and lactoferrin to enter the retentate, and retain the retentate; (D) adding a protective agent to the reflux liquid, and then pasteurizing the reflux liquid to obtain bovine colostrum whey protein; Wherein, the protective agent in step (D) is erythritol.

4. The use of erythritol as a protective agent according to claim 3, characterized in that: The degreasing method in step (A) comprises: preheating the frozen bovine colostrum to 40° C.-45° C. to thaw, and removing fat by centrifugation; Preferably, the centrifugal speed is 6000r / min-8000r / min; Preferably, the centrifugation time is 25min-30min; Preferably, the centrifugation temperature is 40°C-45°C; Preferably, the sterilization method in step (B) is ultra-high pressure sterilization, the pressure of the ultra-high pressure sterilization is 400MPa-500MPa, the temperature is 30°C-40°C, and the time is 10min-15min; Preferably, the method for coagulating milk in step (B) comprises the following steps: adjusting the pH of the sterilized bovine colostrum to be within the range of 6.2-6.6, adding rennet solution, stirring, keeping warm and coagulating milk; Preferably, the amount of chymosin added is 0.02 g / L-0.03 g / L; Preferably, the stirring time is 2 min-3 min; Preferably, the temperature of the heat preservation and curdling is 30°C-40°C; Preferably, the time of heat preservation and curdling is 30min-60min; Preferably, the filter cloth used in the filtration in step (B) is 60-80 mesh; Preferably, in step (C), ultrafiltration concentration is performed using a membrane with a molecular weight cutoff of 50 kDa; Preferably, in step (D), the erythritol protective agent is untreated erythritol or pre-treated erythritol, and the pre-treated erythritol is prepared by the following method: mixing water and erythritol, and then subjecting the mixture to ultra-high pressure treatment to obtain pre-treated erythritol; Preferably, in the process of preparing the pre-treated erythritol, the pressure of the ultra-high pressure treatment is 400MPa-500MPa; Preferably, in the process of preparing the pre-treated erythritol, the temperature of the ultra-high pressure treatment is 30°C-40°C; Preferably, in the process of preparing the pre-treated erythritol, the ultra-high pressure treatment time is 10 min-15 min; Preferably, the solid content of the pre-treated erythritol is 40%-60%; Preferably, in step (4), if the protective agent is pre-treated erythritol, the mass content of the protective agent added to the reflux liquid is 10%-25%; Preferably, in step (D), if the protective agent is untreated erythritol, the mass content of the protective agent added to the reflux liquid is 4%-13%; Preferably, step (D) further comprises: vacuum freeze-drying the bovine colostrum whey protein to obtain bovine colostrum whey protein powder; Preferably, the vacuum freeze-drying temperature is -60°C to -80°C; Preferably, the vacuum freeze-drying time is 40h-48h; Preferably, during the vacuum freeze-drying process, the material thickness is 4 mm-8 mm.

5. A protective agent for maintaining the activity of a functional protein, characterized in that: The protective agent for maintaining the activity of functional proteins includes inulin, oligofructose and erythritol.

6. The protective agent for maintaining the activity of functional proteins according to claim 5, characterized in that: Based on the total mass of the protective agent as 100%, the content of the inulin is 35%-45%, the content of the oligofructose is 35%-45%, and the content of the erythritol is 10%-30%; Preferably, based on 100% of the total mass of the protective agent, the content of inulin is 38%-42%, the content of oligofructose is 38%-42%, and the content of erythritol is 16%-24%.

7. A method for preparing a protective agent for maintaining the activity of a functional protein as claimed in claim 5 or 6, characterized in that: The preparation method comprises the following steps: Inulin, oligofructose and erythritol are mixed to obtain the protective agent.

8. The preparation method according to claim 7, characterized in that: Water is also added during the mixing process, and ultra-high pressure treatment is performed after the mixing to obtain a pre-treated protective agent; Preferably, the solid content of the pre-treated protective agent is 40%-60%; Preferably, the pressure of the ultrahigh pressure treatment is 400MPa-500MPa; Preferably, the temperature of the ultra-high pressure treatment is 30°C-40°C; Preferably, the ultrahigh pressure treatment time is 10 min-15 min.

9. A method for processing bovine colostrum, characterized in that: The bovine colostrum processing method comprises the following steps: (1) defatting the bovine colostrum to obtain defatted bovine colostrum; (2) sterilizing the defatted bovine colostrum, coagulating the milk, and filtering the milk to obtain a whey liquid from which casein has been removed; (3) ultrafiltration and concentration of the whey liquid obtained in step (2) to allow immunoglobulin and lactoferrin to enter the reflux liquid, and retain the reflux liquid; (4) adding the protective agent according to claim 5 or 6 to the reflux liquid, and then pasteurizing the reflux liquid to obtain bovine colostrum whey protein; Wherein, the protective agent is an untreated protective agent or a pre-treated protective agent.

10. The bovine colostrum processing method according to claim 9, characterized in that: The degreasing method in step (1) comprises: preheating the frozen bovine colostrum to 40° C.-45° C. to thaw, and removing fat by centrifugation; Preferably, the centrifugal speed is 6000r / min-8000r / min; Preferably, the centrifugation time is 25min-30min; Preferably, the centrifugation temperature is 40°C-45°C; Preferably, the sterilization method in step (2) is ultra-high pressure sterilization, the pressure of the ultra-high pressure sterilization is 400MPa-500MPa, the temperature is 30°C-40°C, and the time is 10min-15min; Preferably, the method for coagulating milk in step (2) comprises the following steps: adjusting the pH of the sterilized bovine colostrum to be within the range of 6.2-6.6, adding rennet solution, stirring, keeping warm and coagulating milk; Preferably, the amount of chymosin added is 0.02 g / L-0.03 g / L; Preferably, the stirring time is 2 min-3 min; Preferably, the temperature of the heat preservation and curdling is 30°C-40°C; Preferably, the time of heat preservation and curdling is 30min-60min; Preferably, the filter cloth used in the filtration in step (2) is 60-80 mesh; Preferably, in step (3), ultrafiltration concentration is performed using a membrane with a molecular weight cutoff of 50 kDa; Preferably, in step (4), if the protective agent is a pre-treatment protective agent, the mass content of the protective agent added to the reflux liquid is 10%-25%, preferably 16%-21%; Preferably, in step (4), if the protective agent is an untreated protective agent, the mass content of the protective agent added to the reflux liquid is 4%-13%; Preferably, step (4) further comprises: vacuum freeze-drying the bovine colostrum whey protein to obtain bovine colostrum powder; Preferably, the vacuum freeze-drying temperature is -60°C to -80°C; Preferably, the vacuum freeze-drying time is 40h-48h; Preferably, during the vacuum freeze-drying process, the material thickness is 4 mm-8 mm.

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