Fat-containing lactose-removed milk powder and preparation method thereof

Abstract

The invention relates to fat-containing lactose-removed milk powder and a preparation method thereof in the field of modern food and foodstuff processing. The preparation method of the fat-containing lactose-removed milk powder comprises the following steps: diluting raw milk with first alkaline water in an alkaline solution manner, and adjusting the pH value of the raw milk to 6.9-7.1 to prepare diluted milk; heating and homogenizing the diluted milk, and then heating and cooking to prepare cooked milk liquid; a coagulator is added into the cooked milk liquid for marinating, and a jellied bean curd state jellied bean curd-water two-phase body is prepared; crushing the brain-water two-phase body for brain-water separation, removing water and water-soluble substances, and collecting protein mud; dissolving and diluting the protein mud with second alkaline water to prepare diluted milk liquid with the pH value of 6.9-7.1; and carrying out high-temperature sterilization, concentration cooling and spray drying on the diluted milk liquid to prepare the fat-containing lactose-removed milk powder. The technological process is simple and convenient, lactose, estrogen hormone, antibiotic residues, calcium magnesium salt soluble substances and the like can be removed under the fat-containing condition, milk protein, fat and other oil soluble substances are reserved, and the product is higher in nutrition safety.

Description

Technical Field

[0001] This application originates from the National High-Tech Development Program 2006AA10Z328 project "Key technologies for surface modification of soybean protein particles and regulation of physical properties of soybean milk powder", which extends the plant protein food and beverage processing technology to the animal protein beverage and food processing industry. It belongs to the field of modern agriculture, modern food, and bioengineering technology, and specifically relates to a fat-free lactose milk powder and a preparation method thereof. Background Art

[0002] About 70% of adults in the world lack the "lactase" to digest milk lactose. Drinking milk will cause lactose intolerance such as indigestion, bloating, abdominal pain, diarrhea, etc., and lactose also restricts the consumption of people who "avoid sugar". At present, the production processes for lactose-free milk products include membrane separation, enzymatic hydrolysis, defatting-acid precipitation, etc. These production processes are costly and complex, and most of them require that the "water" containing water-soluble substances such as calcium chloride, magnesium salts and vitamins after lactose removal needs to be returned to the protein liquid for re-dissolution. The returned "water" contains animal estrogen, and this type of product has a potential safety hazard. Summary of the invention

[0003] Based on this, one or more embodiments of the present application provide a fat-free lactose milk powder and a preparation method thereof that is easy to produce, can preserve the original ecological functions of milk casein, fatty acids and oil-soluble substances, and has higher safety.

[0004] One or more embodiments of the present application provide a method for preparing fat-free lactose milk powder, comprising the following steps:

[0005] The raw milk is diluted with the first alkaline water, and the pH value of the diluted raw milk is adjusted to 6.9-7.1 to prepare diluted milk;

[0006] The diluted milk is heated and homogenized, and then heated to cook to prepare cooked milk liquid;

[0007] Adding a coagulant to the cooked milk to make a tofu-like brain-water two-phase body;

[0008] The brain-water two-phase body is crushed to separate the brain-water, the water and water-soluble substances are discarded, and the protein mud is collected;

[0009] Using a second alkaline water to dissolve the diluted protein mud to prepare a dilute milk solution with a pH value of 6.9 to 7.1; and,

[0010] Prepare fat-free lactose milk powder from dilute milk liquid.

[0011] In one embodiment, the steps of preparing the alkali-soluble diluted milk meet one or more of the following conditions:

[0012] (A) the first alkaline water and the second alkaline water each independently comprise a phosphate solution having a pH value of 9.0 to 9.5; optionally, the phosphate in the phosphate solution comprises one or a combination of trisodium phosphate and sodium tripolyphosphate; and,

[0013] (B) The dry solid content of the diluted milk is 7wt%~10wt%.

[0014] In one embodiment, the conditions for heating and homogenizing the diluted milk and then heating it to cook include: using steam direct blowing heating method to heat the diluted milk to 50-55°C and homogenize it at a pressure of 2.5Mpa-3.5Mpa, and then heating the homogenized diluted milk to 98°C-100°C and maintaining it for 2min-3min.

[0015] In one embodiment, the steps for preparing the tofu-like brain-water two-phase body meet one or more of the following conditions:

[0016] (1) The temperature of the cooked milk is 72°C to 82°C;

[0017] (2) Adding a coagulant under the condition of the cooked milk flowing;

[0018] (3) The amount of coagulant added is 1.2% to 1.5% of the weight of the cooked milk; and

[0019] (4) The coagulant is selected from one or more of calcium and magnesium brine, calcium lactate, calcium sulfate and glucono-δ-lactone.

[0020] In one embodiment, the preparation method further comprises cooling the cooked milk liquid obtained by heating and then adding a coagulant to perform brine addition under the following conditions:

[0021] A double-layer coil cooler is used, with the center of the interlayer flowing to transport the cooked milk liquid, and the outer layer of cold water cooling in a reverse countercurrent manner, so that the cooked milk liquid is cooled to 72℃~82℃.

[0022] In one embodiment, the steps of preparing the protein mud meet one or more of the following conditions:

[0023] 1) Brain water separation using continuous centrifugation with a separation factor ≥ 3000; and,

[0024] 2) The water content of protein mud is 67%~70%, and the pH value is 5.7~5.8.

[0025] In one embodiment, the steps of preparing the dilute milk satisfy one or more of the following conditions:

[0026] (I) the dilute milk has a dry solid content of 7 wt% to 10 wt% and a pH of 6.9 to 7.1; and

[0027] (II) The mixture of the second alkaline water and the protein mud is treated as follows:

[0028] The first-stage steam jet is heated to 50℃~55℃ and homogenized and refined at 2.5Mpa~3.5Mpa.

[0029] In one embodiment, the step of preparing the dilute milk into the fat-free lactose milk powder comprises:

[0030] The diluted milk is sterilized at high temperature, concentrated and cooled to prepare concentrated milk;

[0031] Spray drying the concentrated milk solution to prepare a fine dry powder; and

[0032] The fine dry powder is sprayed with granulation liquid to carry out agglomeration granulation to prepare fat-free lactose milk powder.

[0033] In one embodiment, the preparation steps of the above-mentioned fat-free lactose milk powder meet one or more of the following conditions:

[0034] I) the steps of high temperature sterilization, concentration and cooling include: using a three-stage steam jet pump to heat in series, so that the dilute milk reaches a sterilization temperature of 121°C to 125°C within 4 to 5 seconds, and directly enters the concentration until the concentrated milk reaches a dry solid content of 15wt% to 20wt%, a temperature of 50 to 52°C, and a pH value of 6.9 to 7.1;

[0035] II) The step of spray drying the concentrated milk solution to prepare a fine dry powder satisfies the following conditions:

[0036] The temperature of the concentrated milk entering the spray drying tower is maintained at 50~52℃, and the dry solid content is maintained at 15wt%~20wt%;

[0037] III) agglomerating and granulating the fine dry powder spray granulation liquid to prepare the step of fat-free lactose milk powder meets one or more of the following conditions:

[0038] (a) Use an agglomeration granulator to spray granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetted powder particles adhere to the dry powder and agglomerate into large particles, and then dry it twice to a moisture content of ≤4.5%;

[0039] (b) The mass ratio of fine dry powder to granulation liquid is: 1:(1.01~1.43);

[0040] (c) The solute content in the granulation liquid is 15wt%~16wt%, and the solute includes maltodextrin, lecithin and soy protein isolate, the mass ratio of maltodextrin, lecithin and soy protein isolate is (13~16):(0.2~0.4):(3~5), and the pH value of the granulation liquid is 6.9~7.1.

[0041] One or more embodiments of the present application provide a fat-free lactose milk powder, which is prepared by the preparation method of the fat-free lactose milk powder of any of the above embodiments.

[0042] This application has at least the following beneficial effects:

[0043] The present application adds alkaline water to raw milk, and while alkali-dissolving and diluting the raw milk, it can also alkali-dissolve the calcium metal ions of casein calcium therein, so that it loses the function of coagulating protein and becomes a water-soluble complex dispersed in water, thereby making casein independent, preserving fatty acids and vitamins and retaining the casein hydrogel and water separation functions. Afterwards, the diluted milk is heated and cooked by the method of "bitter tofu", and the milk can be coagulated into a "tofu brain state" brain-water two-phase body, and then the brain-water two-phase body is broken for brain-water separation, and the separated water and water-soluble substances are discarded, and a "protein mud" with more than 70% lactose removed can be obtained, and most of the animal estrogen, water-soluble calcium-magnesium salt complex, non-protein nitrogen, pesticide and antibiotic residues as water-soluble components are also removed together, improving food safety. The protein mud after delactose is degelled again with alkaline hydrolysis to "de-coagulate" into a solution, which can be further prepared into fat-free lactose milk powder.

[0044] The process of this application is simple, and the method of "alkali dissolution, coagulation, and thawing" is used to remove lactose, estrogen, antibiotic residues, and calcium and magnesium salt-soluble substances under fat-containing conditions, while retaining the oil-soluble substances such as milk casein, whey protein, milk fatty acids, and vitamins involved in the gel, which is conducive to the production of a new fat-defractose milk powder product, and is an original industry "blank" technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0046] Figure 1 is a schematic diagram of an animal protein-encapsulated hydrogel-water body obtained by a rehydration point test of common commercially available milk powder;

[0047] Figure 2 This is a process flow chart of Example 1 of the present application;

[0048] Figure 3 This is a schematic diagram of the state of the fat-free lactose milk powder prepared in Example 1 of the present application after being brewed with boiling water;

[0049] Figure 4This is a comparison chart of the technical differences between the condensation method of Example 1 of the present application and the traditional acid precipitation-alkali dissolution method. DETAILED DESCRIPTION

[0050] The present application will be further described in detail below in conjunction with the accompanying drawings, embodiments and examples. It should be understood that these embodiments and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms, is not limited to the embodiments and examples described herein, and those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent form obtained also falls within the protection scope of the present application. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application, and it should be understood that the present application can be implemented without one or more of these details.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing implementation modes and embodiments and are not intended to limit this application.

[0052] the term

[0053] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0054] The terms "and / or", "or / and", and "and / or" used in this article include any one of two or more related listed items, and also include any and all combinations of related listed items, and the arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions that are all connected by "logical and", and undoubtedly includes technical solutions that are all connected by "logical or". For example, "A and / or B" includes three parallel solutions of A, B and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, the technical solution that is all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, the combination of any two or any three of A, B, C, and D, and also includes the combination of four of A, B, C, and D (that is, the technical solution that is all connected by "logical AND").

[0055] In the present application, "plurality", "multiple", "multiple times", "multiples", etc., unless otherwise specified, refer to a quantity greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0056] As used herein, "combination thereof", "any combination thereof", "any combination thereof" etc. include all suitable combinations of any two or more of the listed items.

[0057] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0058] Herein, “preferred”, “better”, “more preferred” and “suitable” are merely used to describe implementation methods or examples with better effects, and it should be understood that they do not constitute limitations on the scope of protection of this application.

[0059] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0060] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0061] In the present application, the terms "first", "second", "third", "fourth", etc. in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0062] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0063] In the present application, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical distribution is considered continuous within the above numerical interval, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical range, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints. In this article, it is equivalent to directly listing each integer, such as t is an integer selected from 1 to 10, indicating that t is any integer selected from the integer group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges included therein.

[0064] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0065] In the present application, %(w / w) and wt% both represent weight percentage, %(v / v) refers to volume percentage, and %(w / v) refers to mass volume percentage.

[0066] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the application purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail, or it can be adaptively modified according to the description of this application.

[0067] Terminology interpretation: The following is the interpretation of the industry terms cited in this application by the inventor of this technology. ——The interpretation combines practical experience and operating skills in the industry to explain the terminology in this application document.

[0068] Industry knowledge: For the names, functions and technical terms of different additives in this application, please refer to the following document: "Food Additives Handbook (3rd Edition)", Ling Guanting et al., Chemical Industry Press, February 2003.

[0069] Industry Knowledge :For protein processing techniques and terms such as "phosphorylation" in this application, please refer to the following literature: Processing Technology, Jiang Zhiwei et al., Chemical Industry Press, January 2003.

[0070] Alkali dilution: Use specific alkaline water to dilute raw milk. The alkali-soluble casein calcium "calcium magnesium salt" becomes a water-soluble substance with no charged polar complex type that no longer reacts with protein to form a gel, and a dilution solution is prepared.

[0071] Heating homogenization: The diluted milk needs to be heated to 50℃~55℃ and homogenized and refined under a low pressure of 2.5Mpa~3.5Mpa. It is well known in the industry that for every 10℃ increase in the protein liquid, the protein denaturation rate will increase 600 times. As the temperature rises, the protein molecular chains will gradually unfold and extend. At this time, if high-pressure homogenization of more than ten or dozens of MPa is used, the instantaneous pressure increase and pressure relief changes will produce contraction, expansion and tearing shear forces, which will shorten the long protein chains. The water content of the short molecular chain protein when it is gelled and curled is much less than that of the long molecular chain gel, which is equivalent to a reduction in the "activity of the broth". The "soy milk powder" currently on the market is the ironclad evidence that the water-containing gel of the protein is inactivated by high-temperature and high-pressure homogenization.

[0072] Protein micelle particles: microscopic protein bodies formed by the dissociation and fusion activities of soy protein molecules in liquid can form large particle clusters. Different organized forms have different functions. For example, "calcium casein micelle particles" are different from the "microscopic tofu pudding·pre-gel" cluster particles formed by soy protein and the trace calcium magnesium phytate gel it contains. The peripheral protein of the soy protein "cluster particles" has the function of continuing to "dip tofu with brine" and re-gelling. The "micelle protein particles" of milk casein calcium are microscopic "bundle-type" gels formed by casein and divalent calcium salts. There is no protein exposed on the surface of the tree trunk on the "tree trunk-like" protein micelles. Therefore, calcium casein does not have the function of auxiliary agent-encapsulated hydrogel. This is one of the important differences between the functions of soy and milk proteins.

[0073] It is well known in the industry that "tofu in brine" is a water-filled hot gel food that has been brine-fried (i.e., with the addition of additives).

[0074] Fat-containing desolventizing: remove lactose and estrogen that does not participate in protein gel, antibiotic residues and calcium and magnesium salt soluble substances under fat-containing conditions. Adding calcium and magnesium salts during terminal fine powder granulation can maintain the calcium-phosphorus balance of the new product.

[0075] Instant dissolution in boiling water: Instant dissolution of powder with boiling water above 95℃ is to revive the protein at high temperature, adapt to the cooling of cold cups and bowls and stirring, so that the prepared liquid can be cooled to the "marinating" temperature zone of 72-82℃.

[0076] Brain-water two-phase body: that is, the food and water organization system in the tofu brain state.

[0077] Protein mud: It is an organized, soft solid high-protein body that can be picked up by hand. It is soluble in alkaline water but insoluble in ordinary water. Therefore, if you want to dissolve the protein mud into a solution, you can only dilute it with alkaline water.

[0078] Fine powder granulation : Fine powder is sprayed with granulation liquid in a boiling agglomeration granulator, which is a well-known technology in the industry.

[0079] Binder: Gelatin and carrageenan are well-known binders. Soy protein isolate rehydration solution has viscosity itself and can replace other binders. However, the amount of soy protein isolate used is much greater than that of well-known binders.

[0080] Isolating agent: When soy protein isolate and milk protein powders are agglomerated into large instant particles, maltodextrin, xylitol and other isolating agents with very high solubility are needed between the particles. The amount of maltodextrin added will affect the protein content of the product. Therefore, isolating agents such as maltodextrin are also important additives when designing the protein content of new products.

[0081] Lecithin: It can adjust the hydrophobic base of oil, exposing the hydrophilic base on the surface of protein to become instant powder.

[0082] Phosphorylation: It can make the surface of proteins and protein particles carry negative charge, disintegrate the "calcium" of casein calcium, make casein "independent", restore the functions of water absorption, additive-encapsulated hydrogel, etc., and make new foods.

[0083] The inventors of this application found that ordinary milk powder itself has a relatively weak "halogenation-water-encapsulation gel-water separation" performance, and thus proposed a new process for preparing fat-free lactose milk powder by "coagulation-decoagulation". This can be specifically explained by the following commercial milk powder rehydration and halogenation test.

[0084] Rehydration point test of common commercial milk powder

[0085] Purchase ordinary commercially available milk powder, which contains about 25wt% protein, 28wt% fat, 38wt% carbohydrates, and about 9wt% sodium and other impurities. Use boiling water above 95℃ to brew 50g milk powder, add 1.5g sodium tripolyphosphate powder (P5 for short), stir to make lump-free milk, cool to 75~82℃, add 1.2g tofu coagulant powder to make broth, stir for several circles and let stand for more than 5 minutes to solidify into a "tofu brain state" water-encapsulated gel, cut the gel to form an animal protein water-encapsulated gel-water separation body, see Figure 1.

[0086] The rehydration and brine test of ordinary commercially available milk powder has proved that ordinary milk powder itself has weak "brine addition-water-encapsulated gel-water separation" performance. Through this study, the inventors of the present application discovered that the performance of protein-encapsulated water gel can be regulated by phosphorylation of auxiliary agents such as P5 and brine coagulant, and then the "brain-water" gel can be separated with the help of a separator, and the water separation and water-soluble substances can be abandoned to complete the fat-free lactose treatment of milk powder, and the feasibility of the new process of "coagulation-thaw" to prepare fat-free lactose milk powder has been proved.

[0087] In a first aspect of the present application, a method for preparing fat-free lactose milk powder is provided, comprising the following steps:

[0088] The raw milk is diluted with the first alkaline water, and the pH value of the diluted raw milk is adjusted to 6.9-7.1 to prepare diluted milk;

[0089] The diluted milk is heated and homogenized, and then heated to cook to prepare cooked milk liquid;

[0090] Adding a coagulant to the cooked milk to make a tofu-like brain-water two-phase body;

[0091] The brain-water two-phase body is crushed to separate the brain-water, the water and water-soluble substances are discarded, and the protein mud is collected;

[0092] Using a second alkaline water to dissolve the diluted protein mud to prepare a dilute milk solution with a pH value of 6.9 to 7.1; and

[0093] Prepare fat-free lactose milk powder from dilute milk liquid.

[0094] In the preparation method of the present application, the pH value of the raw milk is adjusted to, for example, 6.90, 6.91, 6.92, 6.93, 6.94, 6.95, 6.96, 6.97, 6.98, 6.99, 7.0, 7.01, 7.02, 7.03, 7.04, 7.05, 7.06, 7.07, 7.08, 7.09, 7.10; the pH value of the prepared dilute milk is, for example, 6.90, 6.91, 6.92, 6.93, 6.94, 6.95, 6.96, 6.97, 6.98, 6.99, 7.0, 7.01, 7.02, 7.03, 7.04, 7.05, 7.06, 7.07, 7.08, 7.09, 7.10.

[0095] In one example, the dry solid content of the raw milk is 10wt%~13wt%. For example, the dry solid content of the raw milk can be 10wt%, 10.5wt%, 11wt%, 11.5wt%, 12wt%, 12.5wt%, or 13wt%.

[0096] The present application embodiment is a method for preparing a fat-free lactose milk powder provided by the above technical solution, wherein alkaline water is added to raw milk, and the calcium metal ions of casein calcium therein can be alkali-dissolved while diluting the raw milk, so that it loses the function of coagulating protein, becomes a water-soluble complex dispersed in water, and then makes casein independent, can preserve fatty acids and vitamins and retain the function of casein-encapsulated hydrogel and water separation. Afterwards, the diluted milk is heated and cooked by the method of "bitter bean curd", and the milk can be coagulated into a "bean curd brain state" of brain water two-phase body, and then the brain water two-phase body is broken for brain water separation, and the separated water and water-soluble matter are discarded, and the "protein mud" with more than 70% lactose removed can be obtained, and most of the animal estrogen, water-soluble calcium magnesium salt complex, non-protein nitrogen, pesticide and antibiotic residues as water-soluble components are also removed together, which improves edible safety. The protein mud after delactose is again "de-coagulated" into a solution by alkaline hydrolysis to de-gel the gel body, and can be further prepared into fat-free lactose milk powder. The process of this application is simple, and utilizes the method of "alkaline dissolution, coagulation, and thawing" to remove lactose and estrogen that does not participate in protein gel, antibiotic residues, and water-soluble substances such as calcium and magnesium salts under fat-containing conditions, while retaining oil-soluble substances such as milk protein and milk fat, which is conducive to the production of a new fat-defractose milk powder product, and is an original industry "blank" technology.

[0097] In some embodiments, the steps of preparing the alkali-soluble diluted milk meet one or more of the following conditions:

[0098] (A) the first alkaline water and the second alkaline water each independently comprise a phosphate solution having a pH value of 9.0 to 9.5; optionally, the phosphate in the phosphate solution comprises one or a combination of trisodium phosphate and sodium tripolyphosphate; and,

[0099] (B) The dry solid content of the diluted milk is 7wt%~10wt%.

[0100] Optionally, the first alkaline water and the second alkaline water independently include phosphate solutions with pH values ​​of, for example, 9.0, 9.1, 9.2, 9.3, 9.4, and 9.5. The dry solid content of the diluted milk is, for example, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, and 10wt%.

[0101] In some embodiments, the conditions for heating and homogenizing the diluted milk and then heating it to cook include: using steam direct heating to heat the diluted milk to 50-55°C and homogenize and refine it under a pressure of 2.5Mpa-3.5Mpa, and then heating the homogenized diluted milk to 98°C-100°C and keeping it for 2min-3min. Optionally, the temperature of the diluted milk after heating can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, and the pressure used for homogenization and refinement using a 25 Mpa universal homogenizer can be 2.5Mpa, 2.6Mpa, 2.7Mpa, 2.8Mpa, 3.0Mpa, 3.3Mpa, 3.5Mpa; the homogenized diluted milk is heated to a temperature of, for example, 98°C, 98.5°C, 99°C, 99.5°C, 100°C; and the holding time is, for example, 2min, 2.2min, 2.4min, 2.6min, 2.8min, 3min.

[0102] In some embodiments, the steps for preparing the tofu-like brain-water two-phase body satisfy one or more of the following conditions:

[0103] (1) The temperature of the cooked milk is 72°C to 82°C, for example, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C;

[0104] (2) Adding a coagulant under the condition of the cooked milk flowing;

[0105] (3) The amount of coagulant added is 1.2% to 1.5% of the weight of the cooked milk, such as 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, 1.5%; and,

[0106] (4) The coagulant is selected from one or more of calcium magnesium brine, calcium lactate, calcium sulfate (to maintain calcium-phosphorus balance) and glucono-δ-lactone (abbreviated as: lactone, whose acidity can adjust the pH value of the product).

[0107] In some embodiments, the preparation method further comprises cooling the cooked milk liquid obtained by heating and then adding a coagulant for brine addition under the following conditions: a double-layer coil cooler is used, the cooked milk liquid is transported by the flow in the center of the interlayer, and the outer layer of cold water is cooled by reverse countercurrent flow, so that the cooked milk liquid is cooled to 72°C to 82°C.

[0108] In some embodiments, the steps of preparing the protein mud satisfy one or more of the following conditions:

[0109] 1) Brain water separation is performed by continuous centrifugal separation with a separation factor ≥ 3000, for example, the continuous centrifugal separation is performed by a sedimentation-type horizontal continuous separator with a separation factor of, for example, 3000, 3500, or 4000; and,

[0110] 2) The water content of the protein mud is 67%~70%, and the pH value is 5.7~5.8. The water content of the protein mud is, for example, 67%, 67.5%, 68%, 68.5%, 69%, 69.5%, and 70%, and the pH value is, for example, 5.7, 5.71, 5.72, 5.73, 5.74, 5.75, 5.76, 5.77, 5.78, 5.79, and 5.8.

[0111] In some embodiments, the steps of preparing the dilute milk satisfy one or more of the following conditions:

[0112] (I) the dilute milk has a dry solid content of 7wt% to 10wt% and a pH of 6.9 to 7.1, for example, the dry solid content of the dilute milk is 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, and the pH is 6.90, 6.91, 6.92, 6.93, 6.94, 6.95, 6.96, 6.97, 6.98, 6.99, 7.0, 7.01, 7.02, 7.03, 7.04, 7.05, 7.06, 7.07, 7.08, 7.09, 7.10; and,

[0113] (II) The mixture of the second alkaline water and the protein mud is treated as follows: a first-stage steam jet is heated to 50°C-55°C, and homogenized and refined at a pressure of 2.5Mpa-3.5Mpa, a first-stage steam jet is heated to, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, and a 25 Mpa universal homogenizer is used for homogenization and refinement. The pressure used is, for example, 2.5Mpa, 2.6Mpa, 2.7Mpa, 2.8Mpa, 2.9Mpa, 3.0Mpa, 3.3Mpa, 3.5Mpa.

[0114] In some embodiments, the step of preparing the dilute milk into fat-free lactose milk powder comprises:

[0115] The diluted milk is sterilized at high temperature, concentrated and cooled to prepare concentrated milk;

[0116] Spray drying the concentrated milk solution to prepare a fine dry powder; and

[0117] The fine dry powder is sprayed with granulation liquid to carry out agglomeration granulation to prepare fat-free lactose milk powder.

[0118] Optionally, after the dilute milk is sterilized at high temperature, concentrated and cooled, the concentrated milk can be packaged into a liquid milk product when the dry solid content reaches 10wt% to 13.5wt%.

[0119] In some embodiments, the steps for preparing the above-mentioned fat-free lactose milk powder meet one or more of the following conditions:

[0120] I) The steps of high temperature sterilization, concentration and cooling include: using a three-stage steam jet pump in series for heating, so that the dilute milk reaches a sterilization temperature of 121°C to 125°C within 4 to 5 seconds, and directly entering concentration until the concentrated milk has a dry solid content of 15wt% to 20wt%, a temperature of 50 to 52°C, and a pH value of 6.9 to 7.1, wherein the sterilization temperature is, for example, 121°C, 122°C, 123°C, 124°C, and 125°C, and the concentration is, for example, until the concentrated milk has a dry solid content of 15wt%, 16wt%, and 18wt%. %, 17wt%, 18wt%, 19wt%, 20wt%, the temperature is, for example, 50°C, 51°C, 52°C, the pH value is, for example, 6.90, 6.91, 6.92, 6.93, 6.94, 6.95, 6.96, 6.97, 6.98, 6.99, 7.0, 7.01, 7.02, 7.03, 7.04, 7.05, 7.06, 7.07, 7.08, 7.09, 7.10, and the concentration method can be, for example, double-effect falling film concentration;

[0121] II) The step of spray drying the concentrated milk solution to prepare a fine dry powder satisfies the following conditions:

[0122] The temperature of the concentrated milk entering the spray drying tower is maintained at 50-52°C, for example, the temperature is maintained at 50°C, 51°C, and 52°C, and the dry solid content is maintained at 15wt%-20wt%, for example, the dry solid content is maintained at 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, and 20wt%;

[0123] III) agglomerating and granulating the fine dry powder spray granulation liquid to prepare the step of fat-free lactose milk powder meets one or more of the following conditions:

[0124] (a) using an agglomeration granulator to spray granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetting powder particles adhere to the dry powder and agglomerate into large particles, and then secondary drying to a moisture content of ≤4.5%, for example, secondary drying to a moisture content of 4.5%, 4.4%, 4.3%, 4.2%, 4.1%, 3.9%, 3.7%, 3.5%;

[0125] (b) the mass ratio of the fine dry powder to the granulation liquid is: 1:(1.01-1.43), for example, 1:1.01, 1:1.03, 1:1.05, 1:1.10, 1:1.12, 1:1.16, 1:1.20, 1:1.22, 1:1.28, 1:30, 1:1.43;

[0126] (c) the solute content in the granulation liquid is 15wt%-16wt%, the solute includes maltodextrin, lecithin and soy protein isolate, the mass ratio of maltodextrin, lecithin and soy protein isolate is (13-16):(0.2-0.4):(3-5), the pH value of the granulation liquid is 6.9-7.1, the solute content in the granulation liquid is, for example, 15wt%, 15.2wt%, 15.4wt%, 15.6wt%, 15.8wt%, 16wt%, the mass ratio of maltodextrin, lecithin and soy protein isolate is, for example, 13:0.2:3, 13:0.2:4, 13:0.2:5, 13:0.3:3, 13:0.3:4, 13:0.3:5 :5, 14:0.2:3, 14:0.2:4, 14:0.2:5, 14:0.3:4, 15:0.2:3, 15:0.2:4, 15:0.2:5, 15:0.3:4, 16:0.2:3, 16:0.2:4, 16:0.2:5, 16:0.3:4, 16:0.4:5, and the pH value of the granulation liquid is, for example, 6.90, 6.91, 6.92, 6.93, 6.94, 6.95, 6.96, 6.97, 6.98, 6.99, 7.0, 7.01, 7.02, 7.03, 7.04, 7.05, 7.06, 7.07, 7.08, 7.09, 7.10.

[0127] Among them, soy protein isolate is mainly used as a binder to agglomerate milk protein powder into large particles, maltodextrin is used as an isolating agent to isolate the large particles of soy protein isolate and milk protein powder into large instant particles to prevent them from further agglomeration, and lecithin can adjust the hydrophobic base of the oil to expose the hydrophilic base on the protein surface to become instant powder.

[0128] Of course, calcium and magnesium salts can also be added during fine powder granulation to maintain the calcium-phosphorus balance of the new product. Therefore, food-grade calcium and magnesium salts known in the industry can also be added to the granulation liquid. The amount of addition can be selected according to known technology and will not be elaborated here.

[0129] The embodiment of the present application provides a method for preparing fat-free lactose milk powder provided by the above technical scheme, wherein the fine dry powder obtained by spray drying is further sprayed with granulation liquid, so that the fine dry powder can be agglomerated from fine powder with a particle size of 80-120 mesh into large-particle powder with a particle size of 30-50 mesh. Since the single powder particles are heavier, sink faster, the binding force between powder particles is low, and it is not easy to agglomerate, the dispersibility and solubility are better, and instant solubility is achieved, which can further solve the problems of poor dispersibility, lumps, and non-instant solubility of the currently produced sugar-free milk powder when mixed with boiling water or cold water.

[0130] In some embodiments, after the step of preparing the fat-free lactose milk powder, a packaging step may be further included. Optionally, the packaging step adopts a nitrogen-filled packaging method, for example, a food-grade moisture-proof, breathable oxidation-proof plastic film is used to fill nitrogen and package into a small package of powder for cup hot water beverage, and the packaging specifications may be, for example, 10g, 20g, 30g, 50g of small packages of milk powder. The shelf life of the packaged milk powder is ≥12 months.

[0131] In a second aspect of the present application, a fat-free lactose milk powder is provided, which is prepared by the method for preparing fat-free lactose milk powder according to any of the above-mentioned embodiments.

[0132] The embodiments of the present application will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0133] In the following specific embodiments, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0134] Example 1

[0135] according to Figure 2 The flowchart shown in the figure is used to prepare the fat-free lactose milk powder, and the specific steps are as follows:

[0136] (1) Add alkaline water to milk

[0137] Test, collect and store raw milk according to GB19301-2010 national standard for raw milk;

[0138] Raw milk with a dry solid content of 13 wt % and a pH value of 6.6 is diluted with alkaline water with a pH value of 9.5 to prepare diluted milk, so that the dry solid content of the obtained diluted milk is 10 wt % and the pH value is 7.0. The alkaline water is a trisodium phosphate solution.

[0139] (2) Heat to homogenize, then heat until cooked

[0140] The diluted milk was heated to 50°C by direct steam blowing and homogenized at a pressure of 2.5 MPa. The homogenized diluted milk was then heated to 100°C and maintained for 2 minutes to prepare cooked milk liquid.

[0141] (3) Cooling point brine

[0142] A double-layer coil cooler is used, with the center of the interlayer flowing to transport the cooked milk, and the outer layer of cold water cooling the cooked milk in a reverse countercurrent manner to reduce the temperature of the cooked milk to 82°C; a coagulant is added while the cooked milk is flowing, and the amount of coagulant added is 1.2% of the weight of the cooked milk. The coagulant uses powdered calcium magnesium brine.

[0143] (4) Solidification into brain

[0144] The cooked milk liquid after the marinade is stirred to slowly solidify into a tofu-like brain-water two-phase body; alternatively, a rotor pump can be used to slowly transport it into a heating coil for 5 minutes, and it can be solidified into a tofu-like brain-water two-phase body during flow.

[0145] (5) Brain water separation

[0146] The brain-water two-phase body was stirred and crushed, and then continuously centrifuged by a sedimentation-type horizontal continuous separator with a separation factor of 3000. The separated water and water-soluble substances were discarded, and the protein mud was collected. The water content of the protein mud was 67% and the pH value was 5.8.

[0147] (6) Dilute the protein paste and homogenize at low temperature

[0148] The protein mud is dissolved and diluted with alkaline water with a pH value of 9.5 to prepare a dilute milk solution with a pH value of 7.0 and a dry solid content of 10wt%. The dilute milk solution is heated to 50°C by a primary steam jet and then homogenized and refined under a pressure of 2.5Mpa. The alkaline water is a sodium tripolyphosphate solution.

[0149] (7) High temperature sterilization

[0150] A three-stage steam jet pump is used in series to heat the homogenized dilute milk so that the dilute milk reaches the sterilization temperature of 121°C within 4 seconds.

[0151] (8) Concentration and cooling

[0152] The double-effect falling film concentration method is adopted to directly concentrate the dilute milk liquid with a temperature of 121°C. The temperature of the concentrated milk liquid produced is 50°C and the dry solid content is 15wt%.

[0153] (9) Spray powder making

[0154] The concentrated milk liquid was kept at a temperature of 50°C and a dry solid content of 15wt%, and the concentrated milk liquid was transported to a spray drying tower by a plunger high-pressure pump for spraying at the drying tower nozzle to produce fine dry powder with a particle size of 80 mesh.

[0155] (10) Fine powder granulation

[0156] The agglomeration granulator is used to spray the granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetted powder particles are bonded and agglomerated with the dry powder into large particles of 30 mesh, and then dried twice to a moisture content of 4.5% to prepare fat-free lactose milk powder. The mass ratio of fine dry powder to granulation liquid is 1:1.43, the solute content in the granulation liquid is 15wt%, and the solute includes maltodextrin, lecithin and soy protein isolate, and the mass ratio of maltodextrin, lecithin and soy protein isolate is 13:0.2:3.

[0157] (11) Packaging

[0158] The fat-free lactose-free milk powder prepared in step (10) is packaged into 10 g small packets of powder in cups using a nitrogen-filled packaging system.

[0159] Example 2

[0160] (1) Add alkaline water to milk

[0161] Test, collect and store raw milk according to GB19301-2010 national standard for raw milk;

[0162] Raw milk with a dry solid content of 13 wt % and a pH value of 6.6 is diluted with alkaline water with a pH value of 9.0 to prepare diluted milk, so that the dry solid content of the obtained diluted milk is 8 wt % and the pH value is 7.0. The alkaline water is a sodium tripolyphosphate solution.

[0163] (2) Heat to homogenize, then heat until cooked

[0164] The diluted milk was heated to 55°C by direct steam heating and homogenized at a pressure of 3.5 MPa. The homogenized diluted milk was then heated to 99°C and maintained for 3 minutes to prepare cooked milk liquid.

[0165] (3) Cooling point brine

[0166] A double-layer coil cooler is used, with the center of the interlayer flowing to transport the cooked milk, and the outer layer of cold water cooling the cooked milk in a reverse countercurrent manner to reduce the temperature of the cooked milk to 72°C; a coagulant is added while the cooked milk is flowing, and the amount of coagulant added is 1.5% of the weight of the cooked milk. The coagulant uses powdered calcium magnesium brine.

[0167] (4) Solidification into brain

[0168] Stir the cooked milk liquid after braising to make it slowly solidify into a tofu-like brain-water two-phase body.

[0169] (5) Brain water separation

[0170] The brain-water two-phase body was stirred and crushed, and then continuously centrifuged by a sedimentation-type horizontal continuous separator with a separation factor of 3500. The separated water and water-soluble substances were discarded, and the protein mud was collected. The water content of the protein mud was 68% and the pH value was 5.7.

[0171] (6) Dilute the protein paste and homogenize at low temperature

[0172] The protein mud is dissolved and diluted with alkaline water with a pH value of 9.0 to prepare a dilute milk solution with a pH value of 7.0 and a dry solid content of 7wt%. The dilute milk solution is heated to 55°C by a primary steam jet and then homogenized and refined under a pressure of 3.0Mpa. The alkaline water is a trisodium phosphate solution.

[0173] (7) High temperature sterilization

[0174] A three-stage steam jet pump is used in series to heat the homogenized dilute milk so that the dilute milk reaches the sterilization temperature of 125°C within 5 seconds.

[0175] (8) Concentration and cooling

[0176] The double-effect falling film concentration method is adopted to directly concentrate the dilute milk liquid with a temperature of 125°C. The temperature of the concentrated milk liquid produced is 52°C and the dry solid content is 20wt%.

[0177] (9) Spray powder making

[0178] The concentrated milk liquid was kept at a temperature of 52° C. and a dry solid content of 20 wt %. The concentrated milk liquid was transported to a spray drying tower by a plunger high-pressure pump and sprayed through a nozzle of the drying tower to produce a fine dry powder having a particle size of 120 mesh.

[0179] (10) Fine powder granulation

[0180] The agglomeration type granulator is used to spray the granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetted powder particles are bonded and agglomerated with the dry powder into large particles of 50 mesh, and then secondary drying is performed to a moisture content of 4.3% to prepare fat-free lactose milk powder. The mass ratio of fine dry powder to granulation liquid is 1:1.01, the solute content in the granulation liquid is 16wt%, and the solute includes maltodextrin, lecithin and soy protein isolate, and the mass ratio of maltodextrin, lecithin and soy protein isolate is 16:0.4:5.

[0181] (11) Packaging

[0182] The fat-free lactose-free milk powder prepared in step (10) is packaged into 10 g small packets of powder in cups using a nitrogen-filled packaging system.

[0183] Example 3

[0184] (1) Add alkaline water to milk

[0185] Test, collect and store raw milk according to GB19301-2010 national standard for raw milk;

[0186] Raw milk with a dry solid content of 13 wt % and a pH value of 6.6 is diluted with alkaline water with a pH value of 9.3 to prepare diluted milk, so that the dry solid content of the obtained diluted milk is 7 wt % and the pH value is 7.1. The alkaline water is a composite solution of trisodium phosphate and sodium tripolyphosphate.

[0187] (2) Heat to homogenize, then heat until cooked

[0188] The diluted milk was heated to 52°C by direct steam blowing and homogenized at a pressure of 3.0 MPa. The homogenized diluted milk was then heated to 98°C and maintained for 3 minutes to prepare cooked milk liquid.

[0189] (3) Cooling point brine

[0190] A double-layer coil cooler is used, with the center of the interlayer flowing to transport the cooked milk, and the outer layer of cold water cooling the cooked milk in a reverse countercurrent manner to cool the cooked milk to 77°C; a coagulant is added under the condition of the cooked milk flowing, and the amount of the coagulant added is 1.3% of the weight of the cooked milk. The coagulant uses powdered calcium lactate and calcium sulfate, and the mass ratio of calcium lactate to calcium sulfate is 1:1.

[0191] (4) Solidification into brain

[0192] Stir the cooked milk liquid after braising to make it slowly solidify into a tofu-like brain-water two-phase body.

[0193] (5) Brain water separation

[0194] The brain-water two-phase body was stirred and crushed, and then continuously centrifuged by a sedimentation-type horizontal continuous separator with a separation factor of 4000. The separated water and water-soluble substances were discarded, and the protein mud was collected. The water content of the protein mud was 70%, and the pH value was 5.8.

[0195] (6) Dilute the protein paste and homogenize at low temperature

[0196] The protein mud is dissolved and diluted with alkaline water with a pH value of 9.3 to prepare a dilute milk liquid with a pH value of 6.9 and a dry solid content of 9wt%. The dilute milk liquid is heated to 53°C by a first-stage steam jet and then homogenized and refined under a pressure of 2.8Mpa. The alkaline water is a composite solution of trisodium phosphate and sodium tripolyphosphate.

[0197] (7) High temperature sterilization

[0198] A three-stage steam jet pump is used in series to heat the homogenized dilute milk so that the dilute milk reaches the sterilization temperature of 123°C within 4 seconds.

[0199] (8) Concentration and cooling

[0200] The double-effect falling film concentration method is adopted to directly concentrate the dilute milk liquid with a temperature of 123°C. The temperature of the concentrated milk liquid produced is 51°C and the dry solid content is 18wt%.

[0201] (9) Spray powder making

[0202] The concentrated milk liquid was kept at a temperature of 51°C and a dry solid content of 18wt%, and the concentrated milk liquid was transported to a spray drying tower by a plunger high-pressure pump for spraying by the drying tower nozzle to prepare a fine dry powder with a particle size of 100 mesh.

[0203] (10) Fine powder granulation

[0204] The agglomeration granulator is used to spray the granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetted powder particles are bonded and agglomerated with the dry powder into large particles of 40 mesh, and then secondary drying is performed to a moisture content of 4.5% to prepare fat-free lactose milk powder. The mass ratio of the fine dry powder to the granulation liquid is 1:1.30, the solute content in the granulation liquid is 16wt%, and the solute includes maltodextrin, lecithin and soy protein isolate, and the mass ratio of maltodextrin, lecithin and soy protein isolate is 14:0.3:4.

[0205] (11) Packaging

[0206] The fat-free lactose-free milk powder prepared in step (10) is packaged into 10 g small packets of powder in cups using a nitrogen-filled packaging system.

[0207] Example 4

[0208] (1) Add alkaline water to milk

[0209] Test, collect and store raw milk according to GB19301-2010 national standard for raw milk;

[0210] Raw milk with a dry solid content of 13 wt % and a pH value of 6.6 is diluted with alkaline water with a pH value of 9.0 to prepare diluted milk, so that the dry solid content of the obtained diluted milk is 8 wt % and the pH value is 6.9. The alkaline water is a composite solution of trisodium phosphate and sodium tripolyphosphate.

[0211] (2) Heat to homogenize, then heat until cooked

[0212] The diluted milk was heated to 50°C by direct steam blowing and homogenized at a pressure of 2.8 MPa. The homogenized diluted milk was then heated to 100°C and maintained for 2 minutes to prepare cooked milk liquid.

[0213] (3) Cooling point brine

[0214] A double-layer coil cooler is used, with the center of the interlayer flowing to transport the cooked milk liquid, and the outer layer of cold water cooling the cooked milk liquid in a reverse countercurrent manner to reduce the temperature of the cooked milk liquid to 80°C; a coagulant is added under the condition of the cooked milk liquid flowing, and the amount of the coagulant added is 1.5% of the weight of the cooked milk liquid. The coagulant is powdered glucono-δ-lactone.

[0215] (4) Solidification into brain

[0216] Stir the cooked milk liquid after braising to make it slowly solidify into a tofu-like brain-water two-phase body.

[0217] (5) Brain water separation

[0218] The brain-water two-phase body was stirred and broken, and then continuously centrifuged by a sedimentation-type horizontal continuous separator with a separation factor of 3000. The separated water and water-soluble substances were discarded, and the protein mud was collected. The water content of the protein mud was 68% and the pH value was 5.8.

[0219] (6) Dilute the protein paste and homogenize at low temperature

[0220] The protein mud is dissolved and diluted with alkaline water with a pH value of 9.5 to prepare a dilute milk liquid with a pH value of 7.0 and a dry solid content of 8wt%. The dilute milk liquid is heated to 50°C by a first-stage steam jet and then homogenized and refined under a pressure of 2.8Mpa. The alkaline water is a trisodium phosphate solution.

[0221] (7) High temperature sterilization

[0222] A three-stage steam jet pump is used in series to heat the homogenized dilute milk so that the dilute milk reaches the sterilization temperature of 121°C within 4 seconds.

[0223] (8) Concentration and cooling

[0224] The double-effect falling film concentration method is adopted to directly concentrate the dilute milk liquid with a temperature of 121°C. The temperature of the concentrated milk liquid produced is 50°C and the dry solid content is 15wt%.

[0225] (9) Spray powder making

[0226] The concentrated milk liquid was kept at a temperature of 50°C and a dry solid content of 15wt%, and the concentrated milk liquid was transported to a spray drying tower by a plunger high-pressure pump for spraying at the drying tower nozzle to produce fine dry powder with a particle size of 90 mesh.

[0227] (10) Fine powder granulation

[0228] The agglomeration granulator is used to spray the granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetted powder particles are bonded and agglomerated with the dry powder to form large particles of 30 mesh, and then secondary drying is performed to a moisture content of 4.4% to prepare fat-free lactose milk powder. The mass ratio of fine dry powder to granulation liquid is 1:1.16, the solute content in the granulation liquid is 16wt%, and the solute includes maltodextrin, lecithin and soy protein isolate, and the mass ratio of maltodextrin, lecithin and soy protein isolate is 15:0.2:5.

[0229] (11) Packaging

[0230] The fat-free lactose-free milk powder prepared in step (10) is packaged into 10 g small packets of powder in cups using a nitrogen-filled packaging system.

[0231] Example 5

[0232] Compared with Example 1, only the composition of the granulation liquid during the fine powder granulation in step (10) is changed. The solute content of the granulation liquid is 15 wt %. The solute only includes maltodextrin and lecithin, and does not contain soy protein isolate. The mass ratio of maltodextrin to lecithin is 13:3.2.

[0233] Ingredient testing:

[0234] The fat-free lactose milk powder prepared in the above examples was tested for protein, fat, carbohydrate, impurity and moisture content with reference to GB 5009.5, GB 5413.3, GB 5413.5, GB 5413.30 and GB 5009.3, respectively. The test results are shown in the following table:

[0235] Table 1 Component test results of fat-free lactose milk powder in different examples

[0236]

[0237] Boiling water test:

[0238] Take 10g of each of the fat-free lactose milk powders of Examples 1-5, and brew them with 200ml of boiling water above 95°C, and observe the dissolution state of the milk powder in the boiling water. The results are shown in the following table: Figure 3 The state of the fat-free lactose milk powder prepared in Example 1 after being brewed with boiling water is also shown.

[0239] Table 2 The boiling water brewing state of fat-free lactose milk powder in different embodiments

[0240]

[0241] As shown in Table 2, the fat-free lactose milk powder prepared by Examples 1-4 of the present application has good instant solubility, is not easy to form lumps after being brewed with boiled water, can quickly settle in boiled water and be evenly dispersed, and has a fast dissolution rate. After dissolution, the bubbles disappear by themselves, there is no foam, and the solution is a translucent emulsion. This shows that the granulation liquid solutes maltodextrin, lecithin and soy protein isolate used in the examples of the present application are a better combination, and the fat-free lactose milk powder with good instant solubility can be obtained.

[0242] Flour milling technology comparison:

[0243] The current traditional acid precipitation-alkali dissolution production process for making "lactose-free milk powder" is: collect milk → mechanical degreasing → lower the pH with edible hydrochloric acid → condense the protein to the isoelectric point of the protein with lactic acid → ultrafilter the supernatant to remove lactose → alkali-dissolve the precipitated protein → reconstitute the mixed desugared liquid → homogenize → sterilize at high temperature → make lactose-free liquid milk → concentrate and cool → spray dry to make lactose-free solid milk powder.

[0244] In addition, liquid milk can also be mixed with ordinary milk to produce low-lactose liquid milk; or the solid milk powder can be mixed with ordinary milk powder using the above-mentioned dry method to produce low-lactose milk powder.

[0245] Compared with the traditional acid precipitation-alkali dissolution method, the preparation process of Example 1 of the present application (hereinafter referred to as the condensation method) has significant differences in adjusting pH value, process procedures, food safety, etc. Figure 4 It can be seen that the pH value of the brain water obtained by the coagulation method of the present application is 5.8, and the pH value of the brain water obtained by the acid precipitation-alkali dissolution method is 4.5, and the difference between the two is 1.3. The former needs to increase the pH by 1.2 to adjust to the neutral pH 7.0, and the latter needs to increase the pH by 2.5 to adjust to pH 7.0. The former brain water is only 1.2 away from pH 7.0, while the latter is 2.5 away. Therefore, the former is easier to adjust to the neutral pH 7.0, and can guarantee the safety of food to a great extent. Moreover, according to the industry's common knowledge, excessive heating, excessive mechanical processing, and extreme pH will damage protein and fat. For example, extreme alkalinity will saponify fat, and extreme acidity such as pH 4.5 will oxidize fat and rancidify oil. Therefore, the traditional technology must remove fat before removing lactose, but the present application does not need to remove fat, and can retain the nutrition and efficacy of milk fat at the same time. In addition, the traditional acid precipitation-alkaline dissolution method requires the use of edible hydrochloric acid to lower the pH, and sodium hydroxide is required in the alkaline dissolution protein precipitation step. Strong acid and strong base neutralization process is prone to produce odor, which is not conducive to environmental protection. The coagulation method of the present application does not use strong acid and strong base, greatly reduces the odor of acid-base neutralization, and is more environmentally friendly.

[0246] The technical features of the above-mentioned implementation modes and examples can be combined in any appropriate manner. To make the description concise, not all possible combinations of the technical features in the above-mentioned implementation modes and examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0247] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as a limitation on the scope of protection of the patent application. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several deformations and improvements can be made, which all belong to the protection scope of the present application. In addition, it should be understood that after reading the above-mentioned teaching content of the present application, the technicians in this field can make various changes or modifications to the present application, and the equivalent forms obtained also fall within the protection scope of the present application. It should also be understood that the technical solutions obtained by the technicians in this field through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the protection scope of the claims attached to the present application. Therefore, the protection scope of the patent of the present application shall be based on the content of the attached claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A method for preparing fat-free lactose milk powder, It is characterized in that The steps include: The raw milk is diluted with the first alkaline water, and the pH value of the diluted raw milk is adjusted to 6.9-7.1 to prepare diluted milk; The diluted milk is heated and homogenized, and then heated to cook to prepare cooked milk liquid; Adding a coagulant to the cooked milk to produce brine to prepare a tofu-like brain-water two-phase body; The brain-water two-phase body is crushed to separate the brain-water, the water and water-soluble substances are discarded, and the protein mud is collected; Diluting the protein mud with a second alkaline water to prepare a dilute milk solution with a pH value of 6.9 to 7.1; and, The dilute milk solution is prepared into fat-free lactose milk powder.

2. The preparation method according to claim 1, It is characterized in that The step of preparing the diluted milk satisfies one or more of the following conditions: (A) the first alkaline water and the second alkaline water each independently comprise a phosphate solution with a pH value of 9.0 to 9.5; optionally, the phosphate in the phosphate solution comprises one or a combination of trisodium phosphate and sodium tripolyphosphate; and, (B) The dry solid content of the diluted milk is 7wt%~10wt%.

3. The preparation method according to claim 1, It is characterized in that The conditions for heating and homogenizing the diluted milk and then heating it to cook include: using steam direct blowing heating method to heat the diluted milk to 50-55° C. and homogenize and refine it under a pressure of 2.5Mpa-3.5Mpa, and then heating the homogenized diluted milk to 98° C.-100° C. and keeping it for 2min-3min.

4. The preparation method according to claim 1, It is characterized in that The steps for preparing the tofu-like brain-water two-phase body meet one or more of the following conditions: (1) The temperature of the cooked milk liquid is 72°C to 82°C; (2) adding the coagulant under the flow condition of the cooked milk; (3) The amount of the coagulant added is 1.2% to 1.5% of the weight of the cooked milk; and (4) The coagulant is selected from one or more of calcium and magnesium brine, calcium lactate, calcium sulfate and glucono-δ-lactone.

5. The preparation method according to claim 4, It is characterized in that The preparation method further comprises cooling the cooked milk liquid obtained by heating and then adding the coagulant to perform brine quenching under the following conditions: A double-layer coil cooler is used, the center flow of the interlayer transports the cooked milk liquid, and the outer layer of cold water cools the cooked milk liquid in a reverse countercurrent manner, so that the cooked milk liquid is cooled to 72°C to 82°C.

6. The preparation method according to claim 1, It is characterized in that The steps of preparing the protein mud meet one or more of the following conditions: 1) Brain water separation using continuous centrifugation with a separation factor ≥ 3000; and, 2) The water content of the protein mud is 67% to 70%, and the pH value is 5.7 to 5.

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7. The preparation method according to claim 1, It is characterized in that The steps of preparing the dilute milk liquid meet one or more of the following conditions: (I) the dilute milk has a dry solid content of 7wt% to 10wt% and a pH value of 6.9 to 7.1; and (II) The mixture of the second alkaline water and the protein mud is treated as follows: The first-stage steam jet is heated to 50℃~55℃ and homogenized and refined at 2.5Mpa~3.5Mpa.

8. The preparation method according to any one of claims 1 to 7, It is characterized in that The step of preparing the dilute milk liquid into fat-free lactose milk powder comprises: sterilizing the dilute milk at high temperature, concentrating and cooling the dilute milk to prepare concentrated milk; spray drying the concentrated milk solution to prepare fine dry powder; and The fine dry powder is sprayed with granulation liquid to carry out agglomeration granulation to prepare fat-free lactose milk powder.

9. The preparation method according to claim 8, It is characterized in that The preparation steps of the fat-free lactose milk powder meet one or more of the following conditions: I) the steps of high temperature sterilization and concentration cooling include: using a three-stage steam jet pump to heat in series, so that the dilute milk reaches a sterilization temperature of 121° C. to 125° C. within 4 to 5 seconds, and directly entering concentration until the concentrated milk reaches a dry solid content of 15wt% to 20wt%, a temperature of 50 to 52° C., and a pH value of 6.9 to 7.1; II) The step of spray drying the concentrated milk solution to prepare a fine dry powder satisfies the following conditions: The temperature of the concentrated milk entering the spray drying tower is maintained at 50-52° C., and the dry solid content is maintained at 15wt%-20wt%; and III) The step of agglomerating and granulating the fine dry powder by spraying the granulation liquid to prepare the fat-free lactose milk powder satisfies one or more of the following conditions: (a) Use an agglomeration granulator to spray granulation liquid into the negative pressure hot air boiling fine dry powder in the machine, so that the surface rewetted powder particles adhere to the dry powder and agglomerate into large particles, and then dry it twice to a moisture content of ≤4.5%; (b) the mass ratio of the fine dry powder to the granulation liquid is: 1:(1.01-1.43); and, (c) The solute content in the granulation liquid is 15wt%~16wt%, and the solute includes maltodextrin, lecithin and soy protein isolate, the mass ratio of maltodextrin, lecithin and soy protein isolate is (13~16): (0.2~0.4): (3~5), and the pH value of the granulation liquid is 6.9~7.

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10. A fat-free lactose instant milk powder, It is characterized in that The method is prepared by any one of claims 1 to 9.

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