Uniformly layered chocolate milk and preparation method therefor

Abstract

The present invention relates to the technical field of flavored milk. Provided are a uniformly layered chocolate milk and a preparation method therefor. The method comprises: uniformly mixing raw materials comprising raw milk, chocolate and cocoa powder to obtain a mixed solution with a viscosity of 3-7 mPa·s and D50 of 1-5 μm, wherein the mixed solution is sequentially subjected to preheating, two-stage homogenization, sterilization, cooling, pre-filling stirring, and filling to obtain the chocolate milk; and during the pre-filling stirring process, a fluid in a container to be filled undergoes dead-angle-free flow while forming a turbulent flow. In the present invention, by means of optimizing the raw materials, the mixed solution with specific viscosity and particle size is obtained, and by means of incorporating a specific pre-filling stirring process, the preparation of layered chocolate milk with a clean label is achieved, and thus the layered chocolate milk maintains uniform and stable layering during its shelf life.

Description

A uniformly layered chocolate milk and a preparation method thereof

[0001] Priority

[0002] The present application claims the priority of the Chinese patent application with the application date of May 30, 2024, the application number of 202410685106.3, and the invention name of "A uniformly layered chocolate milk and a preparation method thereof". TECHNICAL FIELD

[0003] The present application relates to the technical field of flavored milk, in particular to a uniformly layered chocolate milk and a preparation method thereof. BACKGROUND

[0004] As a popular flavored milk drink, chocolate milk is deeply loved by consumers for its rich chocolate flavor and mellow milk taste. However, chocolate milk faces a major technical challenge during production and storage, which is the separation phenomenon caused by the incompatibility of chocolate ingredients and milk. In the traditional process, cocoa raw materials are difficult to completely dissolve in milk, and over time, particulate matter easily settles, forming a distinct sediment layer. In order to mask this phenomenon, many products on the market use opaque composite packaging films, but this cannot fundamentally solve the separation problem. In addition, in order to improve the ability of liquid to suspend particles and enhance the viscosity of milk, preventing particles from sinking, manufacturers often add stabilizers such as gellan gum, carrageenan, etc. These additives, although they can improve product stability, are increasingly difficult to meet consumer demand for "minimal processing food" and "clean label" chocolate milk products, as consumers increasingly pursue healthy and natural food.

[0005] In view of the current consumer pursuit of healthy food, in recent years, consumers have gradually increased their acceptance of the separation phenomenon caused by the nature of the product itself, and even consider the separation phenomenon as a sign of true addition to the product, and shake before drinking as a way to increase product interest, leading consumers to a more healthy and natural lifestyle.

[0006] Based on this change, how to develop a chocolate milk production process that meets consumer demand for clean label products while maintaining good and uniform separation during the shelf life has become a technical problem to be solved. SUMMARY

[0007] During the development of clean label chocolate milk, it was found that there were batch-to-batch differences in chocolate milk products, and even the separation heights of each bottle of chocolate milk in the same batch were different, i.e., the separation was not uniform, which affected the appearance of chocolate milk on the shelf.

[0008] The present application provides a kind of uniform layered chocolate milk and its preparation method to solve the above-mentioned defects existing in the prior art.

[0009] Specifically, the present application provides a kind of preparation method of uniform layered chocolate milk, comprising: mixing raw materials containing raw milk, chocolate and cocoa powder to obtain a mixed solution with a viscosity of 3-7 mPa·s and a D50 of 1-5 μm, the mixed solution is sequentially preheated, two-stage homogenization, sterilization, cooling, pre-filling stirring, filling, and the chocolate milk is obtained; during the pre-filling stirring process, the fluid in the tank flows without dead angle while the fluid forms turbulent flow.

[0010] The pre-filling stirring in the present application refers to the stirring process before filling, and the filling is carried out immediately after the stirring, i.e. the material at the discharge port of the tank is directly filled. Among them, the tank to be filled refers to the container corresponding to the pre-filling stirring, which is used to contain the cooled mixed solution.

[0011] The no-dead-angle flow in the present application refers to that the flow dead zone of the fluid is within 0.5%.

[0012] The flow dead zone in the present application refers to the local space that does not participate in the main fluid flow and only makes local motion in situ.

[0013] In order to realize clean label, the present application uses raw milk, chocolate and cocoa powder as main raw materials, without stabilizer, emulsifier and other additive ingredients, therefore, the raw material system has the characteristics of easy stratification, and it is also difficult to control the uniformity and stability of the system.

[0014] When the raw material system in the present application is used, the formed chocolate milk system is tested, and it is found that the chocolate milk system is a non-Newtonian fluid, the fluid viscosity decreases with the strengthening of shear force, i.e. the viscosity is maximum in the static state, and the viscosity decreases in the stirring process. In order to control the uniformity and stability of the quality indicators of the chocolate milk between batches or in the same batch in actual production, it is very important to control the production process to realize the uniform and stable stratification of the bottled chocolate milk obtained after filling in the shelf life.

[0015] In fact, in the current chocolate milk production process, a long process is included, generally, in the early stage of processing, raw milk and solid material raw materials such as chocolate milk and cocoa powder are preliminarily mixed, and then filtered to remove undissolved / dispersed large particle solid material, and then subjected to two-stage homogenization to break the fat particles in the raw milk and further achieve sufficient dissolution with the solid material raw materials, and then filled. As can be seen, the current process covers multiple mixing steps, and the roles played by different mixing steps are different. The primary mixing stage is mainly for the purpose of solid material crushing and dissolution, and the stirring speed of the stirring device used during mixing is relatively high, generally above 1400r / min. The viscosity of the material system in this stage is the lowest, and further filtration is required. The filtration process also continuously shears the fluid. Then homogenization, however, the sterilization temperature is generally high, which can cause significant changes in the material system and increase the viscosity. The present application found that adding a specific stirring device before filling can fully utilize the properties of the non-Newtonian fluid of the chocolate milk system in the present application to ensure the uniform and stable stratification of the bottled chocolate milk on the shelf after filling based on the non-stratification of chocolate milk at low viscosity.

[0016] The viscosity and D50 of the fluid in the present application are tested in a uniformly mixed state.

[0017] According to the preparation method of the uniform stratified chocolate milk of the present application, the preparation process of the mixed liquid includes: mixing raw materials including raw milk, chocolate and cocoa powder to obtain a premix liquid with a viscosity of 3-7mPa·s and a D50 of 6-9μm, and then filtering to obtain the mixed liquid.

[0018] As mentioned earlier, in order to obtain uniform and stable chocolate milk, it is necessary to control the stratification of the system during processing. By controlling the viscosity and particle size of the premix liquid in the premixing stage, it is helpful to obtain the above-mentioned specific mixed liquid, which lays the foundation for achieving uniform and stable chocolate milk.

[0019] When the above-mentioned premix liquid is used to prepare the aforementioned mixed liquid by filtration, the fluid system of the present application is more preferably filtered by a circulating filter device. Generally, the filter screen in the circulating filter device is 60-80 mesh, and further preferably, the circulating filtration time is 15-25 minutes.

[0020] According to the preparation method of the uniform stratified chocolate milk of the present application, the raw materials include: 850-900 parts by weight of raw milk, 90-135 parts by weight of chocolate, and 5-15 parts by weight of cocoa powder.

[0021] The raw materials of the preparation method of the uniform layered chocolate milk are raw cow milk, chocolate and cocoa powder; the total cocoa solid content of the chocolate is less than or equal to 40%; and the cocoa powder is alkaliized cocoa powder.

[0022] The preparation method of the uniform layered chocolate milk according to the present application comprises the following steps:

[0023] A tank body;

[0024] A stirring shaft installed in the tank body;

[0025] A stirring paddle installed at the end of the stirring shaft;

[0026] The stirring shaft is arranged obliquely relative to the horizontal plane, and the vertical plane in which the stirring shaft is arranged is arranged eccentrically relative to the central axis of the tank body.

[0027] The included angle between the central axis of the stirring shaft and the normal of the horizontal plane is 15° to 45°; and the vertical plane in which the stirring shaft is arranged and the central axis of the tank body have a first distance, and the first distance is 15% to 25% of the diameter of the tank body.

[0028] Through the specific structure of the tank to be filled, the fluid in the present application can be in the best fluid motion state during stirring, and the flow dead zone is within 0.5%, that is, there is no dead angle flow. Moreover, the present application makes the center of rotation of the object and the center of mass not coincide through eccentric and oblique stirring, so that the fluid makes irregular motion, generates a component velocity perpendicular to the axis direction of the flow pipe, and thus generates turbulent flow.

[0029] The two-stage homogenization in the preparation method of the uniform layered chocolate milk according to the present application comprises the following steps: first-stage homogenization is carried out at a pressure of 220 bar to 240 bar, and then second-stage homogenization is carried out at a pressure of 40 bar to 50 bar.

[0030] The sterilization comprises the following steps: sterilization is carried out at a temperature of 122°C to 135°C, and the sterilization time is 2 s to 6 s.

[0031] The pre-filling stirring process is intermittent stirring at a rotation speed of 100 r / min to 500 r / min, and the stirring frequency is 2 min to 4 min per interval of 10 min to 20 min.

[0032] Preferably, the total length of the pre-filling stirring is 24 min to 48 min.

[0033] The preparation method of the uniform layered chocolate milk according to the present application comprises the following steps:

[0034] (1) preheat raw materials containing raw milk, chocolate and cocoa powder at a temperature of 65-75°C, and mix and stir the preheated materials at the temperature, and then cool to obtain a premix;

[0035] Preferably, the preheated materials are mixed and stirred at the temperature by using a bottom center stirring device. The bottom center stirring device of the present application is mainly different from the above-mentioned tank to be filled in that the length of the stirring shaft is such that the stirring paddle is located in the conical region below the tank body, and the stirring shaft is vertically arranged in the tank body and coaxial with the central axis of the tank body.

[0036] More preferably, the mixing and stirring is continuously stirred at a rotation speed of 1400-1500 r / min at a temperature of 65-75°C for 15-25 min.

[0037] (2) filter the premix through a filter with a mesh size of 60-80 mesh, and then cool to obtain a mixed liquid;

[0038] (3) preheat the mixed liquid at a temperature of 65-75°C, and then perform primary homogenization, and then perform secondary homogenization;

[0039] (4) sterilize the materials after the secondary homogenization at a temperature of 122-135°C;

[0040] (5) cool the sterilized materials, and then deliver them to the tank to be filled to perform the pre-filling stirring and filling, thereby obtaining the chocolate milk.

[0041] The present application also provides a uniformly layered chocolate milk prepared by the preparation method of the uniformly layered chocolate milk as described above.

[0042] The uniformly layered chocolate milk prepared by the preparation method of the uniformly layered chocolate milk according to the present application has a viscosity of 7-9 mPa·s after stable layering, and an average particle size D50 of less than 0.9 μm.

[0043] The present application provides a uniformly layered chocolate milk and a preparation method thereof. Through in-depth research on a raw material system containing raw milk, chocolate and cocoa powder and not containing additional additives such as stabilizers, the chocolate milk is prepared by using a specific mixed liquid in sequence through preheating, two-stage homogenization, sterilization, cooling, pre-filling stirring and filling. In particular, during the pre-filling stirring, the fluid in the tank to be filled flows without dead angle and forms turbulent flow, thereby realizing the uniform and stable layer height of the chocolate milk on the shelf.

[0044] In addition, the system uniformity also to some extent overcomes the problem of great difference in chocolate content and other components between different chocolate milk samples in the same batch, leading to great difference in product thickness, cocoa flavor and roasting flavor, and improves the terminal presentation effect and product experience of the product. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0046] Fig. 1 is a schematic diagram of the internal structure of the to-be-filled can in a first perspective view according to the present application.

[0047] Fig. 2 is a schematic diagram of the partial structure of the to-be-filled can in a second perspective view according to the present application.

[0048] Fig. 3 is a schematic diagram of the partial structure of the to-be-filled can according to the present application.

[0049] Reference signs: 10, can body; 11, inner can; 12, outer can; 13, first through hole; 14, second through hole; 15, connecting platform; 20, stirring shaft; 30, stirring paddle; 40, connecting cone; 50, reinforcing ring; 60, driving motor. DETAILED DESCRIPTION

[0050] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present application.

[0051] The to-be-filled can (which can also be called a stirring can) suitable for pre-filling stirring according to the present application will be described below in combination with Figs. 1-3, and its structure includes a can body 10, a stirring shaft 20 and a stirring paddle 30. The stirring shaft 20 is installed in the can body 10. The stirring paddle 30 is installed at the end of the stirring shaft 20.

[0052] The stirring shaft 20 is arranged obliquely relative to the horizontal plane, and the vertical plane in which the stirring shaft 20 is arranged is arranged eccentrically relative to the central axis of the tank body 10. The stirring shaft 20 is arranged obliquely in the tank body 10, and the stirring paddle 30 is arranged rotatably at the end of the stirring shaft 20 to drive the fluid in the tank body 10 to be mixed uniformly. The stirring paddle 30 is arranged rotatably at the bottom end of the stirring shaft 20, and the top of the stirring shaft 20 is fixedly connected with the tank body 10, so that the stirring shaft 20 provides a mounting position for the stirring paddle 30. Optionally, the rotation axis of the stirring paddle 30 coincides with the central axis of the stirring shaft 20, so as to balance the force acting on the stirring shaft 20 and improve the mounting stability of the stirring paddle 30.

[0053] It should be noted that the vertical plane in which the stirring shaft 20 is arranged refers to the vertical plane in which the central axis of the stirring shaft 20 is arranged, and the plane is parallel to the central axis of the tank body 10.

[0054] Specifically, the central axis of the stirring shaft 20 forms an acute angle with the horizontal plane, so that the stirring shaft 20 is arranged obliquely in the tank body 10.

[0055] The stirring shaft 20 extends vertically, and the vertical plane in which the stirring shaft 20 is arranged has a spacing relative to the central axis of the tank body 10, so that the stirring shaft 20 is arranged eccentrically.

[0056] Therefore, when the stirring paddle 30 rotates to stir the fluid in the tank body 10, the flow dead zone in the tank body 10 can be effectively reduced, the flow dead zone is controlled to be less than 0.5%, and the uniformity of fluid stirring is effectively improved.

[0057] Taking the processing of chocolate milk as an example, the chocolate milk is a pseudoplastic fluid in non-Newtonian fluid, and if the stirring is not uniform during the stirring process, the position of the stratification line formed by the precipitation after filling is not uniform, which brings a bad experience to the user. After the stirring tank is used, the stirring paddle 30 stirs, and the stirring degree is reduced, and the viscosity is the largest when it is static, so it is necessary to ensure that the product has stable and low viscosity during the processing process to avoid stratification, and the viscosity increases after the processing is completed to form uniform and consistent stratification.

[0058] Optionally, a driving motor 60 is fixedly arranged outside the tank body 10, and the driving motor 60 is in transmission connection with the stirring shaft 20. It can be understood that the length of the stirring shaft 20 is different according to the specifications of the tank body 10 and the filling amount of the fluid in the tank body 10. For example, if the filling amount of the fluid in the tank body 10 is less than half of the capacity of the tank body 10, the stirring shaft 20 can be designed to be relatively long. For another example, if the filling amount of the fluid in the tank body 10 exceeds half of the capacity of the tank body 10, the stirring shaft 20 can be appropriately shortened. It should be noted that the amount of fluid filled into the tank body 10 needs to submerge the stirring paddle 30, so as to ensure that the stirring paddle 30 can run smoothly.

[0059] Optionally, the end of the stirring shaft 20 is provided with a stirring paddle 30, wherein the stirring shaft 20 is inclined relative to the horizontal plane and is eccentrically arranged relative to the central axis of the tank 10, so that the stirring shaft 20 is arranged in the tank 10 in an inclined manner, and the stirring paddle 30 can fully stir the fluid in the tank 10, effectively reducing the stirring dead zone and improving the stirring effect.

[0060] Optionally, the normal angle between the central axis of the stirring shaft 20 and the horizontal plane is 15°-45°.

[0061] The normal of the horizontal plane refers to the vertical direction, that is, the central axis of the tank 10. The angle between the central axis of the stirring shaft 20 and the normal of the horizontal plane is α, which is 15°, 20°, 45°, or any angle between 15° and 45°. Compared with the conventional vertical stirring shaft 20 arranged in the tank 10, the flow field generated by the rotation of the inclined stirring shaft 20 can effectively improve the mixing effect of the fluid in the tank 10.

[0062] Optionally, the vertical plane in which the stirring shaft 20 is arranged has a first spacing H from the central axis of the tank 10. The first spacing H is 15%-25% of the diameter R of the tank 10.

[0063] The stirring shaft 20 is not arranged on the central symmetry plane of the tank 10, but is arranged on one side of the tank 10. Through fluid stirring simulation test, it is known that the eccentrically arranged stirring shaft 20 in combination with the inclined arrangement can effectively reduce the flow dead zone area in the tank 10, reduce the amount of fluid that is not stirred, and improve the stirring effect. For example, the first spacing is 15% of the diameter of the tank 10, and for example, the first spacing H is 20% or 25% of the diameter R of the tank 10. Of course, the first spacing H can also be the product of any value between the diameter R of the tank 10 and 15%-25%.

[0064] The tank 10 includes a cylindrical section and a frustoconical section arranged at both ends of the cylindrical section, and the diameter of the tank 10 refers to the diameter of the cylindrical section of the tank 10.

[0065] The tank 10 includes an inner tank 11 and an outer tank 12, and the outer tank 12 is located outside the inner tank 11 to form a heat preservation interlayer between the inner tank 11 and the outer tank 12. The inner tank 11 is provided with a first through hole 13, and the outer tank 12 is provided with a second through hole 14. In order to facilitate the installation of the stirring shaft 20, the stirring tank further includes a connecting cone 40. The connecting cone 40 is fixed at the second through hole 14, and the end of the stirring shaft 20 away from the stirring paddle 30 is connected to the connecting cone 40 through the first through hole 13. The driving motor 60 is connected to the stirring shaft 20 through the connecting cone 40.

[0066] The connecting cone 40 partially extends into the outer tank 12 through the second through hole 14 to provide a position for the installation of the stirring shaft 20. It can be understood that the connecting cone 40 is sealingly connected with the outer tank 12 of the tank body 10. For example, one end of the connecting cone 40 is welded and fixed in the second through hole 14.

[0067] The outer tank 12 is provided with a connecting table 15, and the connecting cone 40 is fixed to the connecting table 15.

[0068] The installation position of the connecting cone 40 is determined according to the size of the tank body 10. In an embodiment, the tank body 10 is large in size, and the connecting cone 40 is installed on the cylindrical section of the tank body 10. In another embodiment, the tank body 10 is small in size, and the connecting cone 40 can be installed on the frustum section of the tank body 10.

[0069] On the basis of the above embodiment, a reinforcing ring 50 is installed at the second through hole 14.

[0070] The reinforcing ring 50 is used for local reinforcement around the second through hole 14 of the tank body 10, to enhance the strength of the tank body 10 and prevent structural weakening of the tank body 10 due to the opening. Specifically, the reinforcing ring 50 is welded and fixed to the outer tank 12. The material of the reinforcing ring 50 is the same as that of the tank body 10.

[0071] The stirring paddle 30 includes a plurality of paddles which are uniformly distributed around the circumference of the stirring shaft 20. Optionally, the number of paddles is three or four.

[0072] Optionally, the tank body 10 is provided with an inlet and an outlet, and the liquid level of the inlet is lower than that of the outlet. For example, the inlet is arranged at a low liquid level at the bottom of the tank body 10, and the outlet is arranged at a high liquid level at the bottom of the tank body 10, as long as the inlet is located lower than the outlet. The fluid flowing in from the inlet can flow out after being stirred by the stirring paddle 30, avoiding the fluid flowing out directly after entering, to ensure the consistency of the fluid performance flowing out of the tank body 10.

[0073] Since the chocolate milk is a pseudoplastic fluid in non-Newtonian fluid, it will decrease with the strengthening of the stirring degree during the stirring process, and the viscosity is the largest when it is static. Therefore, it is necessary to ensure the stable and low viscosity of the product during the processing process to avoid stratification. For this purpose, the stirring tank further includes a controller which is electrically connected with the driving motor 60, and the controller controls the intermittent stirring of the stirring paddle 30.

[0074] The controller controls the stirring shaft 20 to stir for a preset time interval, and the controller is arranged outside the tank body 10 to facilitate the user to set the preset time interval and the preset time.

[0075] Specifically, in the preparation of chocolate milk in the embodiment of the present application, the sterilized material is prepared by pre-stirring before filling into the tank as shown in FIGS. 1-3. Specifically, several types of tanks to be filled are included in the following structures.

[0076] The first type of to-be-filled tank (i.e., the stirring paddle 30 is located in the middle of the tank body)

[0077] A to-be-filled tank, as shown in FIG. 1, includes a tank body 10, a stirring shaft 20, and a stirring paddle 30. The tank body 10 includes a cylindrical section and conical sections arranged at both ends of the cylindrical section, and the diameter of the tank body 10 refers to the diameter of the cylindrical section of the tank body 10. The stirring shaft 20 is installed in the tank body 10. The stirring paddle 30 is installed at the end of the stirring shaft 20. As shown in the perspective view of FIG. 1, the angle α between the central axis of the stirring shaft 20 and the central axis of the tank body 10 is 15°-45°, that is, the stirring shaft 20 is arranged obliquely in the tank body 10. As shown in the perspective view of FIG. 2, the stirring shaft 20 extends vertically, and the vertical plane in which the stirring shaft 20 is located has a first spacing H with the central axis of the tank body 10. The first spacing H is 15%-25% of the diameter R of the tank body 10. The stirring paddle 30 includes three blades, which are uniformly distributed around the circumference of the stirring shaft 20. The length of the stirring shaft 20 is such that the stirring paddle 30 is located in the middle of the tank body, which refers to the cylindrical section of the tank body 10.

[0078] A driving motor 60 is fixedly installed outside the tank body 10, and the driving motor 60 is in transmission connection with the stirring shaft 20.

[0079] As shown in FIG. 3, the tank body 10 includes an inner tank 11 and an outer tank 12, and the outer tank 12 is located outside the inner tank 11 to form a thermal insulation interlayer between the inner tank 11 and the outer tank 12. The inner tank 11 is provided with a first through hole 13, and the outer tank 12 is provided with a second through hole 14. In order to facilitate the installation of the stirring shaft 20, the to-be-filled tank further includes a connecting cone 40. The connecting cone 40 is fixed at the second through hole 14, and the end of the stirring shaft 20 away from the stirring paddle 30 is connected to the connecting cone 40 through the first through hole 13. The driving motor 60 is connected to the stirring shaft 20 through the connecting cone 40.

[0080] The connecting cone 40 partially extends into the outer tank 12 through the second through hole 14 to provide a position for the installation of the stirring shaft 20. The connecting cone 40 is sealingly connected to the outer tank 12 of the tank body 10. For example, one end of the connecting cone 40 is welded and fixed in the second through hole 14. The installation position of the connecting cone 40 is determined according to the size of the tank body 10. When the size of the tank body 10 is large, as shown in FIG. 1, the connecting cone 40 is installed in the cylindrical section of the tank body 10. When the size of the tank body 10 is small, as shown in FIG. 3, the connecting cone 40 can be installed in the conical section of the tank body 10.

[0081] A reinforcing ring 50 is installed at the second through hole 14. The reinforcing ring 50 is used for local reinforcement around the second through hole 14 of the tank body 10 to enhance the strength of the tank body 10 and prevent the structural weakening of the tank body 10 due to the opening. Specifically, the reinforcing ring 50 is welded and fixed to the outer tank 12. The material of the reinforcing ring 50 is the same as that of the tank body 10.

[0082] The liquid inlet is arranged at the bottom low liquid level of the tank body 10, and the liquid outlet is arranged at the bottom high liquid level of the tank body 10. The fluid flowing in from the liquid inlet can flow out after being stirred by the stirring paddle 30, so that the fluid entering the tank body 10 can be prevented from directly flowing out, and the performance of the fluid flowing out of the tank body 10 is ensured to be consistent.

[0083] The second type of tank to be filled (i.e., the stirring paddle 30 is located at the bottom of the tank body)

[0084] The first type of tank to be filled is basically the same, except that the length of the stirring shaft 20 is such that the stirring paddle 30 is located at the bottom of the tank body, which refers to the conical region below the tank body.

[0085] Unless otherwise specified in the examples, the techniques or conditions are carried out according to the techniques or conditions described in the literature in the field, or according to the product instructions. Unless otherwise specified, the reagents or instruments used are conventional products that can be purchased through regular channels.

[0086] In the present application, raw cow milk is derived from Inner Mongolia Mengniu Dairy (Group) Co., Ltd.

[0087] In the present application, chocolate is made from milk powder, white sugar and cocoa butter, and the total cocoa solid content is ≤40%.

[0088] In the present application, cocoa powder is made from cocoa beans, which is alkalized cocoa powder.

[0089] In the present application, neither the cocoa powder nor the chocolate contains a stabilizer.

[0090] The specific implementation process of the present application will be described below in conjunction with the preferred examples of the present application.

[0091] Example 1

[0092] A preparation method of chocolate milk, the steps of which are as follows:

[0093] (1) Raw material preparation: by weight, 900 parts by weight of raw cow milk, 90 parts by weight of chocolate and 10 parts by weight of cocoa powder.

[0094] (2) First preheating: the raw cow milk, chocolate and cocoa powder are preheated at a temperature of 75℃, and a bottom center stirring type stirring device is used to mix and stir the preheated materials at the temperature, and then cooled to 3℃ to obtain a material liquid A; wherein the mixing and stirring is continuously stirred at a speed of 1400r / min at a temperature of 75℃ for 15min.

[0095] The viscosity of the material liquid A is 3.23±0.07mPa·s measured by Anton Paar viscometer; the average particle size D50 of the material liquid A is 6.18±0.01μm measured by Mastersizer particle size instrument.

[0096] (3) The material liquid A is filtered through a filter with a mesh number of 60 for 15 min, and then cooled to 3°C to obtain a material liquid B.

[0097] The viscosity of the material liquid B is 3.11±0.10 mPa·s measured by an Anton Paar viscometer; and the average particle size D50 of the material liquid B is 3.81±0.13 μm measured by a Mastersizer particle size instrument.

[0098] (4) Preheating: The material liquid B is preheated at a temperature of 65°C.

[0099] (5) Homogenization: The preheated material is subjected to primary homogenization at a pressure of 230 bar, and then subjected to secondary homogenization at a pressure of 45 bar.

[0100] (6) Sterilization: The homogenized material is sterilized at a temperature of 125°C for 3 s.

[0101] (7) Stirring: The sterilized material is cooled to 3°C, and then enters the first type of tank to be filled to be stirred to obtain a material liquid C, and the material liquid C is then filled to obtain a bottled chocolate milk. The angle α between the central axis of the stirring shaft of the first type of tank to be filled and the central axis of the tank body is 30°, and the first spacing H is 15% of the diameter R of the tank body; the stirring is intermittent stirring at a speed of 300 r / min, the stirring frequency is 2 min of stirring every 15 min interval, and the total stirring time is 24 min; the flow dead zone of the material liquid C during stirring is 0.1%.

[0102] Example 2

[0103] A preparation method of a chocolate milk, comprising the following steps:

[0104] (1) Raw material preparation: 850 parts by weight of raw milk, 135 parts by weight of chocolate, and 15 parts by weight of cocoa powder.

[0105] (2) First preheating: The raw milk, chocolate, and cocoa powder are preheated at a temperature of 70°C, and a bottom center stirring type stirring device is used to mix and stir the preheated material at the temperature, and then cooled to 4°C to obtain a material liquid A; wherein the mixing and stirring is continuous stirring at a speed of 1450 r / min at a temperature of 70°C for 20 min.

[0106] The viscosity of the material liquid A is 4.15±0.53 mPa·s measured by an Anton Paar viscometer; and the average particle size D50 of the material liquid A is 6.27±0.13 μm measured by a Mastersizer particle size instrument.

[0107] (3) The material liquid A was filtered through a filter with a mesh number of 70 for 20 min, and then cooled to 2°C to obtain a material liquid B; wherein the viscosity of the material liquid B was 3.51±0.31 mPa·s measured by an Anton Paar viscometer.

[0108] The average particle size D50 of the material liquid B was 3.72±0.23 μm measured by a Mastersizer particle size analyzer.

[0109] (4) Preheating: the material liquid B was preheated at a temperature of 70°C.

[0110] (5) Homogenization: the preheated material was subjected to primary homogenization at a pressure of 235 bar, and then subjected to secondary homogenization at a pressure of 48 bar.

[0111] (6) Sterilization: the homogenized material was sterilized at a temperature of 130°C for 4 s.

[0112] (7) Stirring: the sterilized material was cooled to 4°C, and then was put into the first type of tank to be filled to obtain a material liquid C, and then the material liquid C was filled to obtain a bottled chocolate milk. The angle α between the central axis of the stirring shaft of the first type of tank to be filled and the central axis of the tank body was 45°, and the first distance H was 25% of the diameter R of the tank body; the stirring was intermittent stirring at a rotating speed of 250 r / min, the stirring frequency was 3 min of stirring every 15 min interval, and the total stirring time was 36 min; the flow dead zone of the chocolate milk C during stirring was 0.2%.

[0113] Example 3

[0114] A preparation method of a chocolate milk, the steps of which were as follows:

[0115] (1) Preparation of raw materials: by weight, 880 parts of raw cow milk, 115 parts of chocolate, and 5 parts of cocoa powder.

[0116] (2) First preheating: the raw cow milk, chocolate, and cocoa powder were preheated at a temperature of 65°C, and a bottom center stirring type stirring device was used to mix and stir the preheated material at the temperature, and then cooled to 5°C to obtain a material liquid A; wherein the mixing and stirring was continuous stirring at a rotating speed of 1500 r / min at a temperature of 65°C for 25 min.

[0117] The viscosity of the material liquid A was 4.27±0.41 mPa·s measured by an Anton Paar viscometer; the average particle size D50 of the material liquid A was 6.75±0.01 μm measured by a Mastersizer particle size analyzer.

[0118] (3) The material liquid A was filtered through a filter with a mesh number of 80 for 25 min, and then cooled to 3°C to obtain a material liquid B.

[0119] The viscosity of the material liquid B was 3.72±0.14 mPa·s measured by an Anton Paar viscometer; and the average particle size D50 of the material liquid B was 3.57±0.03 μm measured by a Mastersizer particle size analyzer.

[0120] (4) Preheating: The material liquid B was preheated at a temperature of 65°C.

[0121] (5) Homogenization: The preheated material was subjected to primary homogenization at a pressure of 220 bar, and then subjected to secondary homogenization at a pressure of 40 bar.

[0122] (6) Sterilization: The homogenized material was sterilized at a temperature of 135°C for 5 s.

[0123] (7) Stirring: The sterilized material was cooled to 5°C, and then was put into the second type of tank to be filled to be stirred to obtain a material liquid C, and then the material liquid C was filled to obtain a bottled chocolate milk. The angle a between the central axis of the stirring shaft of the second type of tank to be filled and the central axis of the tank body was 30°, and the first distance H was 15% of the diameter R of the tank body; the stirring was intermittent stirring at a rotation speed of 200 r / min, the stirring frequency was 4 min of stirring every 15 min of interval, and the total stirring time was 48 min; the flow dead zone of the chocolate milk C during stirring was 0.13%.

[0124] Example 4

[0125] A preparation method of a chocolate milk, the steps of which were as follows:

[0126] (1) Preparation of raw materials: 900 parts by weight of raw milk, 90 parts by weight of chocolate, and 10 parts by weight of cocoa powder.

[0127] (2) First preheating: The raw milk, chocolate, and cocoa powder were preheated at a temperature of 65°C, and a bottom center stirring type stirring device was used to mix and stir the preheated material at the temperature, and then cooled to 1°C to obtain a material liquid A; wherein the mixing and stirring was continuous stirring at a rotation speed of 1400 r / min at a temperature of 65°C for 20 min.

[0128] The viscosity of the material liquid A was 3.86±0.11 mPa·s measured by an Anton Paar viscometer; and the average particle size D50 of the material liquid A was 7.56±0.30 μm measured by a Mastersizer particle size analyzer.

[0129] (3) The material liquid A was filtered through a filter with a mesh number of 60 for 20 min, and then cooled to 4℃ to obtain a material liquid B.

[0130] The viscosity of the material liquid B was 3.81±0.14 mPa·s measured by an Anton Paar viscometer; and the average particle size D50 of the material liquid B was 4.51±0.13 μm measured by a Mastersizer particle size analyzer.

[0131] (4) Preheating: The material liquid B was preheated at a temperature of 75℃.

[0132] (5) Homogenization: The preheated material was subjected to primary homogenization at a pressure of 235 bar, and then subjected to secondary homogenization at a pressure of 50 bar.

[0133] (6) Sterilization: The homogenized material was subjected to sterilization at a temperature of 135℃ for 3 s.

[0134] (7) Stirring: The sterilized material was cooled to 6℃, and then was put into the second type of tank to be filled for stirring to obtain a material liquid C, which was then filled into bottles to obtain the bottled chocolate milk. In the second type of tank to be filled, the included angle α between the central axis of the stirring shaft and the central axis of the tank body was 45°, and the first spacing H was 25% of the diameter R of the tank body. The stirring was intermittent stirring at a rotation speed of 150 r / min, and the stirring frequency was 4 min of stirring every 10 min of interval, and the total stirring time was 48 min. The flow dead zone of the chocolate milk C during stirring was 0.21%.

[0135] Comparative Example 1

[0136] A preparation method of chocolate milk, the steps of which were basically the same as those of Example 1, except that the structure of the tank to be filled in step (7) was that the included angle α between the central axis of the stirring shaft and the central axis of the tank body was 0°, and the first spacing H was 15% of the diameter R of the tank body.

[0137] Comparative Example 2

[0138] A preparation method of chocolate milk, the steps of which were basically the same as those of Example 1, except that the structure of the tank to be filled in step (7) was that the included angle α between the central axis of the stirring shaft and the central axis of the tank body was 30° in the first type of tank to be filled, and the first spacing H was 10% of the diameter R of the tank body.

[0139] Comparative Example 3

[0140] A preparation method of layered chocolate milk, the steps of which were basically the same as those of Example 1, except that the cocoa powder was replaced by chocolate with the same mass.

[0141] Comparative Example 4

[0142] A method for preparing chocolate milk, comprising the following steps:

[0143] (1) Raw material preparation: by weight, it is: 900 parts raw milk, 75 parts chocolate and 15 parts cocoa powder.

[0144] (2) First preheating: The raw milk, chocolate and cocoa powder are preheated at 65°C and the preheated materials are mixed and stirred at this temperature using a bottom center stirring device. Then, the mixture is cooled to 2°C to obtain liquid A. The mixing and stirring is carried out continuously at 65°C for 15 minutes at a speed of 1400r / min.

[0145] The viscosity of the feed solution A was measured to be 2.92 ± 0.05 mPa·s using an Anton Paar viscometer; the average particle size D50 of the feed solution A was measured to be 4.12 ± 0.37 μm using a Mastersizer particle size analyzer.

[0146] (3) After circulating and filtering liquid A through a 50-mesh filter for 20 minutes, it is cooled to 4°C to obtain liquid B.

[0147] The viscosity of the feed solution B was measured to be 2.31 ± 0.16 mPa·s using an Anton Paar viscometer; the average particle size D50 of the feed solution B was measured to be 4.01 ± 0.31 μm using a Mastersizer particle size analyzer.

[0148] (4) Preheating: Preheat liquid B to 65°C.

[0149] (5) Homogenization: The preheated material is homogenized at a pressure of 230 bar, and then homogenized at a pressure of 45 bar.

[0150] (6) Sterilization: The homogenized material is sterilized at 125°C for 4 seconds.

[0151] (7) Stirring: After sterilization, the material is cooled to 4°C and then entered into the first type of filling tank for stirring to obtain liquid C. Liquid C is then filled to obtain bottled chocolate milk. Among them, the angle α between the central axis of the stirring shaft of the first type of filling tank and the central axis of the tank body is 0° (vertical stirring), and the first spacing H is 15% of the tank diameter R; the stirring is carried out intermittently at a speed of 300 r / min, the stirring frequency is 3 min every 15 min, and the total stirring time is 36 min; the dead zone of the chocolate milk C during the stirring process is 5.61%.

[0152] Comparative Example 5

[0153] A chocolate milk preparation method, the steps are as follows:

[0154] (1) Raw material preparation: by weight parts, for: 850 parts by weight of raw milk, 135 parts by weight of chocolate (fat 40%, fineness 15 μm) and 15 parts by weight of natural cocoa powder.

[0155] (2) First preheating: raw milk, chocolate and cocoa powder are preheated at a temperature of 70℃, and the preheated material is mixed and stirred at the temperature by using a bottom center stirring device, and then cooled to 3℃, to obtain a material liquid A; wherein the mixing and stirring is continuously stirred at a speed of 1500 r / min at a temperature of 70℃ for 20 min.

[0156] The viscosity of the material liquid A is 8.55±0.40 mPa·s measured by Anton Paar viscometer; the average particle size D50 of the material liquid A is 10.12±0.23 μm measured by Mastersizer particle size instrument.

[0157] (3) The material liquid A is cooled to 3℃ after being circulated and filtered through a filter with a mesh size of 80 for 25 min to obtain a material liquid B.

[0158] The viscosity of the material liquid B is 7.25±0.32 mPa·s measured by Anton Paar viscometer; the average particle size D50 of the material liquid B is 8.24±0.32 μm measured by Mastersizer particle size instrument.

[0159] (4) Preheating: the material liquid B is preheated at a temperature of 70℃.

[0160] (5) Homogenization: the preheated material is subjected to primary homogenization at a pressure of 225 bar, and then subjected to secondary homogenization at a pressure of 50 bar.

[0161] (6) Sterilization: the homogenized material is sterilized at a temperature of 130℃ for 3 s.

[0162] (7) Stirring: the sterilized material is cooled to 3℃ and then enters the above-mentioned first type of tank for stirring to obtain a material liquid C, and the material liquid C is then filled, to obtain a bottled chocolate milk. The angle α between the central axis of the stirring shaft of the first type of tank and the central axis of the tank body is 60°, and the first distance H is 25% of the tank body diameter R; the stirring is intermittent stirring at a speed of 350 r / min, the stirring frequency is 4 min of stirring every 10 min interval, and the total stirring time is 36 min; the flow dead zone of the chocolate milk C during stirring is 7.21%.

[0163] Comparative Example 6

[0164] A chocolate milk preparation method, the steps are as follows:

[0165] (1) Raw material preparation: 850 parts by weight of raw milk, 135 parts by weight of chocolate and 15 parts by weight of cocoa powder.

[0166] (2) First preheating: raw milk, chocolate and cocoa powder are preheated at a temperature of 75°C, and the preheated material is mixed and stirred at the temperature by using a bottom center stirring device, and then cooled to 4°C to obtain a material liquid A; wherein the mixing and stirring is continuously stirred at a speed of 1500r / min at a temperature of 75°C for 25min.

[0167] The viscosity of the material liquid A is 4.51±0.23mPa·s measured by Anton Paar viscometer; the average particle size D50 of the material liquid A is 6.38±0.24μm measured by Mastersizer particle size instrument.

[0168] (3) The material liquid A is cooled to 5°C after being circulated and filtered through a filter with a mesh size of 60 for 15min to obtain a material liquid B.

[0169] The viscosity of the material liquid B is 7.66±0.02mPa·s measured by Anton Paar viscometer; the average particle size D50 of the material liquid B is 8.56±0.11μm measured by Mastersizer particle size instrument.

[0170] (4) Preheating: the material liquid B is preheated at a temperature of 75°C.

[0171] (5) Homogenization: the preheated material is homogenized at a pressure of 235bar, and then homogenized at a pressure of 40bar.

[0172] (6) Sterilization: the homogenized material is sterilized at a temperature of 130°C for 5s.

[0173] (7) Stirring: the sterilized material is cooled to 6°C and then stirred in the above-mentioned second type of tank to obtain a material liquid C, and the material liquid C is then filled to obtain a bottled chocolate milk. The first distance H of the second type of tank is 30% of the tank diameter R, and the first distance H is 20% of the tank diameter R; the stirring is intermittent stirring at a speed of 200r / min, the stirring frequency is 2min stirring every 15min interval, and the total stirring time is 32min; the flow dead zone of the chocolate milk C during stirring is 5.54%.

[0174] The bottled chocolate milk prepared in each embodiment and comparative example was observed for stratification under certain temperature and for a certain time, and the viscosity, average particle size D50, color and taste of the stratified chocolate milk were tested, wherein the viscosity, average particle size D50, color and taste were tested by sampling after stratification, and before testing, the stratified chocolate was shaken to make it uniform.

[0175] The test method and results related to the present application are as follows:

[0176] (1) The specific results of the viscosity (measured by Anton Paar viscometer), average particle size D50 (measured by Mastersizer particle size instrument), and zero-order kinetics model fitting coefficient R2 are shown in the following table:

[0177] As can be seen from the above table, the content of cocoa powder and chocolate and the production process affect the viscosity and particle size of the sample. The viscosity of the products of embodiments 1-4 is 7-9 mPa·s, and the average particle size D50 is below 0.9 μm.

[0178] When no cocoa powder is added (comparative example 3), the viscosity of the sample increases, and the average particle size D50 increases, so the ratio of chocolate and cocoa powder should be selected within an appropriate range.

[0179] (2) Stratification consistency test: at a temperature of 4℃, the stratification height of the bottled chocolate milk obtained from the embodiments and comparative examples was observed at 2h, 4h, 8h, 24h, 72h, 168h and 360h, and 100 bottles were taken for observation for each embodiment and comparative example, and the average value and standard value (the data in the table below are average value ± standard deviation) were recorded.

[0180] The sample with a standard deviation of stratification height in the same treatment of different bottled chocolate milk detected at the same time within 0.10 was considered to have good stratification consistency.

[0181] The specific results are shown in the following table:

[0182] As can be seen from the above table, the stratification height of embodiments 1-4 has a smaller standard deviation of stratification height compared to comparative examples 1-5, which is within 0.10 cm. The stratification height of the embodiments is more consistent when measuring the stratification height of different chocolate milk at the same time, indicating that the raw material formula range and stirring method in the present application can obtain a product with consistent stratification height during the shelf life.

[0183] In addition, it can also be seen from the above table that the settling speed of Example 1, Examples 3-4 and Comparative Example 3 is relatively fast, and reaches the highest point of precipitation in about 4 hours, which is positively correlated with their low viscosity, and the change in the height of precipitation within the shelf life of 24 hours and 15 days is not more than 15%.

[0184] Example 2 and Comparative Example 4 reach the highest point of precipitation in about 8 hours, and the change in the height of precipitation within the shelf life of 24 hours is not more than 30%.

[0185] (3) Sensory evaluation: The chocolate milk prepared in the examples and comparative examples is subjected to sensory evaluation, the number of people participating in the sensory evaluation is 33, tasting is carried out respectively, and the sensory evaluation indexes include overall preference, color, chocolate flavor, milk flavor, sweetness and smoothness. Among them, the specific sensory evaluation standard is shown in the following table:

[0186] The test results of the examples and comparative examples of the present application are shown in the following table:

[0187] It can be seen from the above table that the overall preference of the chocolate milk prepared in Examples 1-4 is higher than that of Comparative Examples 1-6, and the color, chocolate flavor, milk flavor, sweetness and smoothness are basically at a suitable level and can be recognized.

[0188] It can be seen from Example 1 and Comparative Example 3 that the color and chocolate flavor intensity of the sample with too little cocoa powder are lower than those of Example 1.

[0189] (3) Color: The chocolate milk prepared in the examples and comparative examples is tested by a spectrophotometer, and the test method is as follows: after the instrument is calibrated with a white board and a black board, the sample to be tested is shaken, 15 mL is taken and placed in a glass cuvette, and the L*, a* and b* values are measured in a small hole reflection mode. Among them, L* is the brightness index, the larger the value, the whiter the color; a*>0 indicates the degree of redness, the larger the value, the redder the color, a*<0 indicates the degree of greenness, the larger the value, the greener the color; b*>0 indicates the degree of yellowness, the larger the value, the yellower the color, b*<0 indicates the degree of blueness, the larger the value, the bluer the color.

[0190] It can be seen from the above table and the sensory consumer preference that when the L* value of the chocolate milk is 54-62, the a* value is 6-8.5, and the b* value is 10-13, it is more in line with the cognition and preference of consumers for the color of chocolate milk.

[0191] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing uniformly layered chocolate milk, characterized in that, include: Raw materials including raw milk, chocolate and cocoa powder are mixed to obtain a mixture with a viscosity of 3 to 7 mPa·s and a D50 of 1 to 5 μm. The mixture is then subjected to preheating, two-stage homogenization, sterilization, cooling, stirring before filling, and filling to obtain the chocolate milk. During the pre-filling stirring process, the fluid in the container to be filled flows without dead zones while simultaneously forming turbulence.

2. The method for preparing uniformly layered chocolate milk according to claim 1, characterized in that, The preparation process of the mixture includes: mixing raw materials including raw milk, chocolate and cocoa powder to obtain a premix with a pressure of 3-7 mPa·s and a D50 of 6-9 μm, and then filtering to obtain the mixture.

3. The method for preparing uniformly layered chocolate milk according to claim 1 or 2, characterized in that, The ingredients, by weight, include: 850-900 parts raw milk, 90-135 parts chocolate, and 5-15 parts cocoa powder.

4. The method for preparing uniformly layered chocolate milk according to any one of claims 1-3, characterized in that, The raw materials are raw milk, chocolate, and cocoa powder; the total cocoa solids content of the chocolate is ≤40%; and the cocoa powder is alkalized cocoa powder.

5. The method for preparing uniformly layered chocolate milk according to any one of claims 1-4, characterized in that, The cans to be filled include: Tank body; A stirring shaft is installed inside the tank. A stirring paddle is installed at the end of the stirring shaft; The stirring shaft is inclined relative to the horizontal plane, and the vertical plane in which the stirring shaft is located is eccentrically positioned relative to the central axis of the tank.

6. The method for preparing uniformly layered chocolate milk according to claim 5, characterized in that, The angle between the central axis of the stirring shaft and the normal of the horizontal plane is 15° to 45°; there is a first distance between the vertical plane where the stirring shaft is located and the central axis of the tank, the first distance being 15% to 25% of the diameter of the tank.

7. The method for preparing uniformly layered chocolate milk according to any one of claims 1-6, characterized in that, The two-stage homogenization includes: first-stage homogenization at a pressure of 220 bar to 240 bar, and then second-stage homogenization at a pressure of 40 bar to 50 bar. The sterilization includes sterilization at a temperature of 122℃ to 135℃ for a time of 2s to 6s. The pre-filling stirring process is carried out intermittently at a speed of 100r / min to 500r / min, with a stirring frequency of 2 to 4 minutes every 10 to 20 minutes.

8. The method for preparing uniformly layered chocolate milk according to any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: (1) The raw materials including raw milk, chocolate and cocoa powder are preheated at a temperature of 65°C to 75°C, and the preheated materials are mixed and stirred at this temperature, and then cooled to obtain a premixed liquid. (2) The premixed liquid is filtered through a filter with a mesh size of 60 to 80 mesh and then cooled to obtain a mixed liquid; (3) The mixture is preheated to 65℃~75℃ and then homogenized in the first stage, followed by the second stage of homogenization; (4) The material after secondary homogenization is sterilized at a temperature of 122℃~135℃; (5) After the sterilized material is cooled, it is transported to the container to be filled for pre-filling stirring and filling to obtain the chocolate milk.

9. The uniformly layered chocolate milk prepared by the method of any one of claims 1 to 8.

10. The uniformly layered chocolate milk prepared by the method for preparing uniformly layered chocolate milk according to claim 9, characterized in that, The viscosity of the uniformly layered chocolate milk after stable layering is 7-9 mPa·s, and the average particle size D50 is below 0.9 μm.

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