Thick milk prepared by membrane concentration process and preparation method thereof

Abstract

The invention discloses thick milk prepared by a membrane concentration process and a preparation method thereof, and the method for preparing the thick milk by the membrane concentration process comprises the following steps: obtaining raw milk with a protein index of 3.2-3.6 g / 100g; carrying out 1.5-2.2 times of ultrafiltration treatment and 2.1-3.3 times of reverse osmosis treatment to effectively prepare a concentrated raw material semi-finished product with the protein content of 4.65-4.75 g / 100g; and the concentrated raw materials are subjected to homogenization, pasteurization, milk base compounding and direct sterilization so as to obtain a final product with the protein content of 5.40-5.45 g / 100g and the fat content of 10.6-10.9 g / 100g. According to the preparation method disclosed by the invention, a thick milk product which is free from obvious fat floating, precipitation and bleeding and fine, smooth and mellow in mouth feel can be effectively obtained by matching processes, and small molecular components in the cow milk can be completely utilized in a lossless manner within the shelf life of 6 months.

Description

Technical Field

[0001] The invention relates to the field of cow milk, and in particular to thick milk prepared by a membrane concentration process and a preparation method thereof. Background Art

[0002] Thick milk is a new type of milk, first used to prepare coffee and milk tea. It can enhance the flavor of the beverage, blend a mellower tongue pressure, and increase the value of the whole cup of product. Thick milk is a new type of milk that is made using low-temperature membrane separation technology and then compounded with milk-based raw materials. Specifically, membrane separation technology is used to separate and purify molecules such as milk fat, milk protein, lactose, and milk mineral salts in milk. Because its indicators are higher than ordinary milk, the flavor is richer and the texture is mellower. Because the intuitive feeling is that the product is mellower, it is called thick milk, also named thick cow's milk or thick milk, thick milk.

[0003] Thick milk products disclosed in the prior art, for example: a component reconstituted thick milk and its preparation method disclosed in CN112970851A, which uses direct reverse osmosis treatment of part of the milk to obtain 1# concentrate, and the remaining milk is first subjected to milk fat separation to obtain cream and skim milk respectively, and then the skim milk is ultrafiltered to obtain 2# concentrate and 2# permeate respectively, and the cream is pasteurized and then mixed with 1# concentrate, 2# concentrate, 2# permeate and other ingredients online, and then the finished product is obtained through emulsification shearing, heating and other steps. The preparation of this thick milk product is complicated, and because there is a specific ratio between 2# concentrate, 2# permeate, cream and 1# concentrate, the above-mentioned partial liquids cannot be fully utilized, that is, the full nutritional utilization of dairy products cannot be achieved, which will lead to the loss of some nutrients.

[0004] Conventional attempts to fully utilize all nutrients often result in obvious fat floating, precipitation or water separation problems within the six-month shelf life after compounding. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is that the thick milk with full nutritional utilization disclosed in the prior art generally has the problem of obvious fat floating, precipitation or water separation; thus, a thick milk prepared by a membrane concentration process and a preparation method thereof which solves the above problems and has a simpler preparation process is provided.

[0006] To this end, the present invention provides the following technical solutions:

[0007] A method for preparing thick emulsion by membrane concentration process, comprising:

[0008] Obtain raw milk with a protein index of 3.2-3.6g / 100g;

[0009] Ultrafiltration treatment process: raw milk is used for ultrafiltration, the ultrafiltration temperature is 2-6°C, the ultrafiltration multiple is 1.5-2.2 times, and UF concentrate and UF permeate are obtained after ultrafiltration;

[0010] Reverse osmosis treatment process: Use UF permeate for reverse osmosis filtration, reverse osmosis temperature 2-6℃, reverse osmosis multiple 2.1-3.3 times, and obtain RO concentrate and RO permeate after reverse osmosis;

[0011] Semi-finished product preparation: RO concentrate and UF concentrate are mixed to prepare concentrated raw materials, the protein content of the concentrated raw materials is 4.65-4.75g / 100g;

[0012] Homogenization of concentrated raw materials: homogenization temperature 65-75℃, homogenization first-stage pressure 48-50bar, second-stage pressure 240-250bar;

[0013] Pasteurization: The concentrated raw materials are homogenized and then pasteurized and cooled to 2-6°C;

[0014] Milk-based compounding: the concentrated raw material after pasteurization is heated to 65-70°C, and protein powder, stabilizer, emulsifier, buffer salt and anhydrous butter are added, and after mixing, a compound material with a protein content of 5.40-5.45g / 100g and a fat content of 10.6-10.9g / 100g is obtained; wherein the emulsifier is monoglyceride and phospholipid in a mass ratio of (2.3-2.7):2; the buffer salt is sodium hexametaphosphate and disodium hydrogen phosphate in a mass ratio of (0.6-0.8):0.8;

[0015] Direct sterilization: sterilization temperature 145-147℃, time 2-4s;

[0016] Final product: After cooling, aseptic filling is performed; the protein content of the final product is 5.40-5.45g / 100g, and the fat content is 10.6-10.9g / 100g;

[0017] A sterilization homogenization step is also included before or after the direct sterilization step. The homogenization temperature of the sterilization homogenization step is 65-75° C., the first-level homogenization pressure is 70-80 bar, and the second-level pressure is 350-400 bar.

[0018] A post-mixing homogenization step is added between the compounding and the direct sterilization.

[0019] The homogenization temperature of the homogenization step after batching is 65-70°C, the first-level homogenization pressure is 48-50 bar, and the second-level homogenization pressure is 240-250 bar.

[0020] In the compound ingredients, the added amount of protein powder is 3-4%, the added amount of stabilizer is 0.1-0.3%, the added amount of emulsifier is 0.2-0.5%, the added amount of anhydrous butter is 5-6%, and the added amount of buffer salt is 0.05-0.16%.

[0021] The stabilizer is carrageenan;

[0022] and / or, the mass ratio of monoglyceride to phospholipid in the emulsifier is 2.5:2;

[0023] And / or, the mass ratio of sodium hexametaphosphate to disodium hydrogen phosphate in the buffer salt is 0.7:0.8.

[0024] The compound ingredients also include 1.0-1.5% of sweetener.

[0025] The sweetener is white sugar.

[0026] The pasteurization conditions are 72-85° C., 15 s.

[0027] A thick emulsion prepared by a membrane concentration process is prepared by the above method.

[0028] The technical solution of the present invention has the following advantages:

[0029] 1. In the method for preparing thick milk by a membrane concentration process provided by the present invention, a low-temperature combined membrane (ultrafiltration membrane + reverse osmosis membrane) filtration technology is used to regulate the milk components. Under a specific concentration multiple, only the RO permeate is excluded to obtain a concentrated raw material with a protein content of 4.65-4.75g / 100g with no loss of basic nutrition. The concentrated raw material is homogenized and pasteurized to obtain a concentrated milk-based compound, and combined with a direct sterilization process and an aseptic homogenization process, a thick milk category with a protein content of 5.40-5.45g / 100g and a fat content of 10.6-10.9g / 100g can be obtained. The method of the present invention only removes the water content of the milk, ensuring that the small molecule components in the milk are fully utilized without loss; and the present invention solves the problem of obvious fat floating, precipitation and water separation in the existing thick milk products during the shelf life of 6 months through a rational design of the process formula, and the taste is optimal while ensuring the balance of the system. Therefore, the invention has the advantages of simple process, complete nutrition without loss, no obvious fat floating, no precipitation and water separation during the shelf life, and delicate, smooth and mellow taste.

[0030] 2. The present invention can effectively refine the particle size by adopting a sterile homogenization process after direct sterilization under specific parameter conditions, further avoiding the problem of fat floating, and ensuring that there is no fat floating within a shelf life of 5 months, and only slight fat floating after 6 months, with significant effects. Furthermore, the present application adopts a three-stage homogenization design, that is, through the coordination of concentrated raw material homogenization, compound ingredient homogenization, and sterile homogenization after direct sterilization, the particle size can be further refined, and the taste can be further improved while meeting the stability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a process flow chart of Example 1 in the present invention. DETAILED DESCRIPTION

[0033] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0034] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0035] Embodiment 1:

[0036] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1 below:

[0037] Table 1

[0038]

[0039]

[0040] The specific preparation process of the thick milk is as follows: Figure 1 As shown, the details are as follows:

[0041] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.4g / 100g, and the amount of raw milk used is 1225kg;

[0042] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.1 times, 583 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0043] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 2.1 times, and 306 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0044] (4) Semi-finished product: 306 kg of RO concentrate was backfilled into 583 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.68 g / 100 g;

[0045] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize after homogenization at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0046] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0047] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 250 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0048] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0049] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0050] Embodiment 2:

[0051] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 2 below:

[0052] Table 2

[0053]

[0054] The specific preparation process of the thick milk is as follows:

[0055] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.2g / 100g, and the amount of raw milk used is 1304kg;

[0056] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.2 times, 593 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0057] (3) Reverse osmosis (RO) treatment process: UF permeate is used for reverse osmosis filtration, the reverse osmosis temperature is 6°C, the reverse osmosis multiple is 2.4 times, and 296 kg of RO concentrate and the remaining amount of RO permeate are obtained after reverse osmosis;

[0058] (4) Semi-finished product: 296 kg of RO concentrate was backfilled into 593 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.69 g / 100 g.

[0059] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize after homogenization at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0060] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0061] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 250 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0062] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0063] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0064] Embodiment 3:

[0065] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 3 below:

[0066] Table 3

[0067]

[0068] The specific preparation process of the thick milk is as follows:

[0069] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.6g / 100g, and the amount of raw milk used is 1158kg;

[0070] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 1.5 times, after UF, 772 kg of UF concentrate and the remaining amount of UF permeate were obtained;

[0071] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 3.3 times, and 117 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0072] (4) Semi-finished product: 117 kg of RO concentrate was backfilled into 772 kg of UF concentrate to achieve lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.69 g / 100 g;

[0073] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize after homogenization at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0074] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0075] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 250 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0076] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0077] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0078] Embodiment 4:

[0079] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1. The specific preparation process of the thick milk in this embodiment is as follows:

[0080] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.4g / 100g, and the amount of raw milk used is 1225kg;

[0081] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.1 times, 583 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0082] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 2.1 times, and 306 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0083] (4) Semi-finished product: 306 kg of RO concentrate was backfilled into 583 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.68 g / 100 g;

[0084] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize after homogenization at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0085] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0086] (7) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. Homogenization is performed before direct sterilization at a temperature of 72°C and a pressure of 400 bar / 80 bar.

[0087] (8) Final product: Cool to 15-25℃ and aseptically fill.

[0088] Embodiment 5:

[0089] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1. The specific preparation process of the thick milk in this embodiment is as follows:

[0090] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.4g / 100g, and the amount of raw milk used is 1225kg;

[0091] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.1 times, 583 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0092] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 2.1 times, and 306 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0093] (4) Semi-finished product: 306 kg of RO concentrate was backfilled into 583 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.68 g / 100 g;

[0094] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize after homogenization at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0095] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0096] (7) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a pressure of 350 bar / 70 bar.

[0097] (8) Final product: Cool to 15-25℃ and aseptically fill.

[0098] Embodiment 6:

[0099] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1. The specific preparation process of the thick milk in this embodiment is as follows:

[0100] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.4g / 100g, and the amount of raw milk used is 1225kg;

[0101] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.1 times, 583 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0102] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 2.1 times, and 306 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0103] (4) Semi-finished product: 306 kg of RO concentrate was backfilled into 583 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.68 g / 100 g;

[0104] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize after homogenization at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0105] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0106] (7) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0107] (8) Final product: Cool to 15-25℃ and aseptically fill.

[0108] Embodiment 7:

[0109] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1. The specific preparation process of the thick milk in this embodiment is as follows:

[0110] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.4g / 100g, and the amount of raw milk used is 1225kg;

[0111] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.1 times, 583 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0112] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 2.1 times, and 306 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0113] (4) Semi-finished product: 306 kg of RO concentrate was backfilled into 583 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.68 g / 100 g;

[0114] (5) Pasteurization system: preheat to a homogenization temperature of 75°C, homogenize after batching, homogenization pressure is 240 bar / 48 bar, pasteurize after homogenization, pasteurization conditions are 72°C / 15s, and cool to 5°C;

[0115] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials were transferred into the batching tank, heated to 65° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar were added in sequence under high shearing, and the cycle shearing was continued for 18 minutes. The remaining pasteurized concentrated raw materials were heated online, added online to the base material and mixed to obtain the compound ingredients;

[0116] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 240 bar / 48 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0117] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 145°C for 4 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 65°C and a pressure of 400 bar / 80 bar.

[0118] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0119] Embodiment 8:

[0120] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1. The specific preparation process of the thick milk in this embodiment is as follows:

[0121] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.4g / 100g, and the amount of raw milk used is 1225kg;

[0122] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.1 times, 583 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0123] (3) Reverse osmosis (RO) treatment process: UF permeate was used for reverse osmosis filtration, the reverse osmosis temperature was 6°C, the reverse osmosis multiple was 2.1 times, and 306 kg of RO concentrate and the remaining amount of RO permeate were obtained after reverse osmosis;

[0124] (4) Semi-finished product: 306 kg of RO concentrate was backfilled into 583 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.68 g / 100 g;

[0125] (5) Pasteurization system: preheat to a homogenization temperature of 65°C, homogenize after batching, the homogenization pressure is 250 bar / 48 bar, pasteurize after homogenization, the pasteurization condition is 85°C / 15s, and cool to 5°C;

[0126] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials were transferred into the batching tank, heated to 70° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar were added in sequence under high shearing, and the cycle shearing was continued for 18 minutes. The remaining pasteurized concentrated raw materials were heated online, added online to the base material and mixed to obtain the compound ingredients;

[0127] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 240 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0128] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 146°C for 3 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 75°C and a pressure of 400 bar / 80 bar.

[0129] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0130] Embodiment 9:

[0131] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 4 below.

[0132] Table 4

[0133]

[0134] The specific preparation process of the thick milk in this embodiment is shown in Example 1.

[0135] Embodiment 10:

[0136] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 5 below.

[0137] Table 5

[0138]

[0139] The specific preparation process of the thick milk in this embodiment is shown in Example 1.

[0140] Comparative Example 1

[0141] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 6 below:

[0142] Table 6

[0143]

[0144]

[0145] The specific preparation process of the thick milk is as follows:

[0146] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 3.0g / 100g, and the amount of raw milk used is 1390kg;

[0147] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.2 times, 632 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0148] (3) Reverse osmosis (RO) treatment process: UF permeate is used for reverse osmosis filtration, the reverse osmosis temperature is 6°C, the reverse osmosis multiple is 2.95 times, and 257 kg of RO concentrate and the remaining amount of RO permeate are obtained after reverse osmosis;

[0149] (4) Semi-finished product: 257 kg of RO concentrate was backfilled into 632 kg of UF concentrate to achieve lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.69 g / 100 g.

[0150] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize after batching, homogenization pressure is 250 bar / 50 bar, pasteurize after homogenization, pasteurization conditions are 85°C / 15s, and cool to 5°C;

[0151] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0152] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 250 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0153] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0154] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0155] Comparative Example 2

[0156] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 7 below:

[0157] Table 7

[0158]

[0159] The specific preparation process of the thick milk is as follows:

[0160] (1) Raw milk storage temperature is 5°C, raw milk protein is 3.0 g / 100 g, and the amount of raw milk used is 1435 kg;

[0161] (2) Ultrafiltration (UF) treatment process: UF temperature 5.5°C, UF multiple 2.2 times, 652 kg of UF concentrate and the remaining amount of UF permeate were obtained after UF;

[0162] (3) Reverse osmosis (RO) treatment process: UF permeate is used for reverse osmosis filtration, the reverse osmosis temperature is 6°C, the reverse osmosis multiple is 3.3 times, and 237 kg of RO concentrate and the remaining amount of RO permeate are obtained after reverse osmosis;

[0163] (4) Semi-finished product: 237 kg of RO concentrate was backfilled into 652 kg of UF concentrate to achieve a lossless design. The amount of semi-finished product (concentrated raw material) was 889 kg, and the protein index was 4.84 g / 100 g;

[0164] (5) Pasteurization system: preheat to a homogenization temperature of 68°C, homogenize after batching, homogenization pressure is 250 bar / 50 bar, pasteurize after homogenization, pasteurization conditions are 85°C / 15s, and cool to 5°C;

[0165] (6) Milk-based compounding: 195 kg of pasteurized concentrated raw materials (the amount of concentrated raw materials is 30 times the amount of stabilizer + emulsifier) ​​are transferred into the batching tank, the temperature is raised to 68° C., and protein powder, anhydrous butter, stabilizer, emulsifier, buffer salt and white sugar are added in sequence under high shearing, and the cycle shearing is repeated for 18 minutes. The remaining pasteurized concentrated raw materials are then heated online, added online to the base material and mixed to obtain the compound ingredients;

[0166] (7) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 250 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0167] (8) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0168] (9) Final product: Cool to 15-25℃ and aseptically fill.

[0169] Comparative Example 3

[0170] A membrane concentration process is used to prepare thick milk, which differs from Example 1 in that no membrane concentration is performed and protein powder is directly added to achieve a protein index substantially the same as that of Example 1; the specific preparation process of the thick milk is as follows:

[0171] (1) The storage temperature of raw milk is 5°C, the raw milk protein is 2.9g / 100g, and the amount of raw milk used is 812kg;

[0172] (2) Semi-finished product: 77 kg of protein powder is added to raw milk to form 889 kg of semi-finished product, and the protein index of the semi-finished product is 4.68 g / 100 g;

[0173] (3) Pasteurization system: preheat the semi-finished product to a homogenization temperature of 68°C, homogenize at a homogenization pressure of 250 bar / 50 bar, pasteurize at a pasteurization condition of 85°C / 15s, and cool to 5°C;

[0174] (4) Milk-based compounding: 195 kg of the pasteurized semi-finished product was transferred into the batching tank, and the temperature was raised to 68° C. The same amount and composition of protein powder 36 kg, anhydrous butter 55 kg, stabilizer 2 kg, emulsifier 4.5 kg, buffer salt 1.5 kg and white sugar 12 kg were added in sequence under high shearing, and the cycle shearing was continued for 18 minutes. The remaining pasteurized concentrated raw material was then heated online, added online to the base material and mixed to obtain the compound ingredient;

[0175] (5) After compounding, the compounded ingredients are homogenized at a temperature of ±2°C from the compounding temperature and a pressure of 250 bar / 50 bar. After homogenization, the compounded ingredients are cooled to ≤5°C for storage;

[0176] (6) Direct sterilization system: The compound ingredients are directly sterilized at a temperature of 147°C for 2 seconds. After direct sterilization, aseptic homogenization is performed at a temperature of 72°C and a homogenization pressure of 400 bar / 80 bar.

[0177] (7) Final product: Cool to 15-25℃ and aseptically fill.

[0178] Comparative Example 4

[0179] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 1. The difference between this comparative example and Example 1 is that during the preparation process, the direct sterilization and aseptic homogenization steps are replaced by tubular sterilization and pre-sterilization homogenization steps, the homogenization conditions are: 400bar / 80bar, and the sterilization conditions are: 147°C, 2s.

[0180] Comparative Example 5

[0181] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 8 below:

[0182] Table 8

[0183]

[0184] The specific preparation process of the thick milk is the same as that of Example 1.

[0185] Comparative Example 6

[0186] A membrane concentration process is used to prepare thick milk, and its raw material composition is shown in Table 9 below:

[0187] Table 9

[0188]

[0189]

[0190] The specific preparation process of the thick milk is the same as that of Example 1.

[0191] Experimental Example 1:

[0192] The protein and fat contents of the final products prepared in the examples and comparative examples were tested using laboratory FT120. The test results are shown in Table 10 below.

[0193] Table 10

[0194]

[0195]

[0196] The protein and fat contents of the final products of Examples 1-10 and Comparative Examples 4-6 are comparable, but the fat content of Comparative Examples 1-3 is increased.

[0197] Experimental Example 2:

[0198] The samples obtained in Examples 1 to 10 and Comparative Examples 1 to 6 were stored at room temperature (25° C.) for 180 days, and the floating, stratification and precipitation of fat were observed at regular intervals. The observation results are shown in Table 11.

[0199] Table 11

[0200]

[0201]

[0202]

[0203] From the above table, we can see that:

[0204] Compared with Example 1, in Comparative Example 1-3, more milk and protein powder were added, and a small amount of fat floated after 120 days of storage, and the system was relatively unstable;

[0205] Comparative Example 4 Compared with Example 1, when the tubular indirect sterilization process was adopted, the homogenization process before sterilization could not refine the accumulated fat, and some fat floated after 120 days;

[0206] Compared with Example 1, in Comparative Example 5, due to the change in the added content of the buffer salt component, water precipitation occurred at the bottom after 120 days of storage, and the system was relatively unstable;

[0207] Compared with Example 1, in Comparative Example 6, more phospholipids were added, which increased the floating of fat and resulted in a stronger beany taste.

[0208] Examples 1 to 10 showed good stability; in particular, the fat floating was significantly improved, and there was no obvious floating of stored fat during the storage period.

[0209] It can be seen from the above that the present invention can effectively achieve the effect of significantly improving the fat floating during the shelf life and better improve the product stability by limiting the range of process steps and process parameter conditions, combined with the control of raw material concentration multiples and raw material protein content and fat content.

[0210] Experimental Example 3:

[0211] The viscosity, particle size and clarity index of the final products prepared in the examples and comparative examples were analyzed. The specific analysis method is as follows:

[0212] Viscosity Analyzer: The viscosity data is analyzed by using the American Brookfield Viscometer. The data is valid when the torque is 15-85%. The data of each process sample is taken 3 times as the average value.

[0213] Particle size analyzer: LA-960 laser particle size analyzer was used for particle size analysis, with the transmittance set to 70%-90%, distilled water as the dispersant, and the number of measurements was 5000. The D90 value was taken as the product particle size index, and each sample was repeated 3 times to take the average value.

[0214] Clarification index: The stability analysis was performed using a LUMiSizer stability analyzer, with a sample volume of 1.0 ml and an ion speed of 4000 rpm. The clarification index was taken as the product stability index, and each sample was repeated 3 times to take the average value. The analysis results are shown in Table 12 below.

[0215] Table 12

[0216]

[0217] From the results in Table 12 above, we can see that:

[0218] In Comparative Examples 1-4, compared with the examples, the viscosity is large and the particle size is large; in Comparative Example 3, a large amount of protein powder is added, and the viscosity is high while the fat content is also high; in Comparative Example 4, the fat floating content is high and the particle size is large. Comparative Example 5 has a large viscosity and a smaller fat particle size than the comparative examples, but due to the increase in the sodium phosphate content, the clarification index is significantly improved. Combined with the results in Table 10, it can be seen that the stability during the shelf life has decreased; in Comparative Example 6, the viscosity and particle size data are better than the comparative examples, but its clarification index is also significantly improved. Combined with the results in Table 10, it can be seen that its stability is not ideal.

[0219] In the embodiments, by comparing embodiments 1-8 with the comparative example, it can be seen that by controlling the emulsifier to be monoglyceride and phospholipid in a mass ratio of (2.3-2.7):2; the buffer salt to be sodium hexametaphosphate and disodium hydrogen phosphate in a mass ratio of (0.6-0.8):0.8, and optimizing the process parameters, steps and conditions, the product can have no obvious fat floating, no precipitation and no water precipitation within the six-month shelf life, thereby significantly improving the product stability.

[0220] Experimental Example 4:

[0221] 30 people were randomly selected to evaluate their preference based on five aspects, namely, milk flavor, aftertaste, smoothness, thickness, and sensory perception. The preference evaluation rules are shown in Table 13 below.

[0222] Table 13

[0223]

[0224] The scoring results based on the preference evaluation are shown in Table 14 below:

[0225] Table 14

[0226]

[0227]

[0228] As can be seen from the above table, Examples 1-10 are better in the sensory test, and Example 1 has the highest score.

[0229] Compared with Example 1, Example 2-3 has moderate taste, low aftertaste, and no obvious difference;

[0230] Compared with Example 1, Examples 4-6 have uneven tastes, with the top layer of fat floating and thick taste and slightly yellow color; the bottom layer is relatively refreshing and thin in taste;

[0231] Compared with Example 1, there is no obvious difference between Example 9 and Example 1;

[0232] Compared with Example 1, there is no obvious difference between Example 10 and Example 1;

[0233] Compared with Example 1, Comparative Example 1-2 has a higher milk addition, a higher fat content, and a thicker taste. From a cost perspective, the milk loss is higher.

[0234] Comparative Example 3 Compared with Example 1, the milk does not undergo a membrane concentration process, the exogenous protein content is high, the denaturation rate is high, the smoothness of the mouthfeel is poor, and the astringency is strong;

[0235] Compared with Example 1, the sensory color of Comparative Example 4 is yellowish;

[0236] Compared with Example 1, the protein in Comparative Example 5 was slightly grainy;

[0237] Compared with Example 1, in Comparative Example 6, the lecithin derived from soybeans has a stronger beany smell.

[0238] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing thick emulsion by membrane concentration process, characterized in that: include: Obtain raw milk with a protein index of 3.2-3.6g / 100g; Ultrafiltration treatment process: raw milk is used for ultrafiltration, the ultrafiltration temperature is 2-6°C, the ultrafiltration multiple is 1.5-2.2 times, and UF concentrate and UF permeate are obtained after ultrafiltration; Reverse osmosis treatment process: Use UF permeate for reverse osmosis filtration, reverse osmosis temperature 2-6℃, reverse osmosis multiple 2.1-3.3 times, and obtain RO concentrate and RO permeate after reverse osmosis; Semi-finished product preparation: RO concentrate and UF concentrate are mixed to prepare concentrated raw materials, the protein content of the concentrated raw materials is 4.65-4.75g / 100g; Homogenization of concentrated raw materials: homogenization temperature 65-75℃, homogenization first-stage pressure 48-50bar, second-stage pressure 240-250bar; Pasteurization: The concentrated raw materials are homogenized and then pasteurized and cooled to 2-6°C; Milk-based compounding: the concentrated raw material after pasteurization is heated to 65-70°C, protein powder, stabilizer, emulsifier, buffer salt and anhydrous butter are added, and mixed to obtain the compound material; wherein the emulsifier is monoglyceride and phospholipid in a mass ratio of (2.3-2.7):2; the buffer salt is sodium hexametaphosphate and disodium hydrogen phosphate in a mass ratio of (0.6-0.8):0.8; Direct sterilization: sterilization temperature 145-147℃, time 2-4s; Final product: After cooling, aseptic filling is performed; the protein content of the final product is 5.40-5.45g / 100g, and the fat content is 10.6-10.9g / 100g; A sterilization homogenization step is also included before or after the direct sterilization step. The homogenization temperature of the sterilization homogenization step is 65-75° C., the first-level homogenization pressure is 70-80 bar, and the second-level pressure is 350-400 bar.

2. The method according to claim 1, characterized in that A post-mixing homogenization step is added between the compounding and the direct sterilization.

3. The method according to claim 2, characterized in that The homogenization temperature of the homogenization step after batching is 65-70°C, the first-level homogenization pressure is 48-50 bar, and the second-level homogenization pressure is 240-250 bar.

4. The method according to any one of claims 1 to 3, characterized in that: In the compound ingredients, the added amount of protein powder is 3-4%, the added amount of stabilizer is 0.1-0.3%, the added amount of emulsifier is 0.2-0.5%, the added amount of anhydrous butter is 5-6%, and the added amount of buffer salt is 0.05-0.16%.

5. The method according to any one of claims 1 to 4, characterized in that: The stabilizer is carrageenan; and / or, the mass ratio of monoglyceride to phospholipid in the emulsifier is 2.5:2; And / or, the mass ratio of sodium hexametaphosphate to disodium hydrogen phosphate in the buffer salt is 0.7:0.

8.

6. The method according to any one of claims 1 to 5, characterized in that: The compound ingredients also include 1.0-1.5% of sweetener.

7. The method according to claim 6, characterized in that The sweetener is white sugar.

8. The method according to any one of claims 1 to 7, characterized in that: The pasteurization conditions are 72-85° C., 15 s.

9. A thick milk prepared by membrane concentration process, characterized in that: The method is prepared by any one of claims 1 to 8.

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