CN118252189A

CN118252189A - Uniform layered chocolate milk and preparation method thereof

Info

Publication number: CN118252189A
Application number: CN202410685106.3A
Authority: CN
Inventors: 牛天娇; 马岩峰; 肖然; 杜爽; 姜帆; 祁凌; 赵一凡; 马嘉欣; 高国斌; 刘紫彰
Original assignee: Inner Mongolia Mengniu Dairy Group Co Ltd; Mengniu Hi Tech Dairy Products Beijing Co Ltd
Current assignee: Inner Mongolia Mengniu Dairy Group Co Ltd; Mengniu Hi Tech Dairy Products Beijing Co Ltd
Priority date: 2024-05-30
Filing date: 2024-05-30
Publication date: 2024-06-28

Abstract

The invention relates to the technical field of flavored milk, and provides uniform layered chocolate milk and a preparation method thereof, wherein raw materials comprising raw milk, chocolate and cocoa powder are uniformly mixed to obtain a mixed solution with the viscosity of 3-7mPa.s and the D50 of 1-5 mu m, and the mixed solution is sequentially subjected to preheating, two-stage homogenization, sterilization, cooling, stirring before filling and filling to obtain the chocolate milk; in the stirring process before filling, fluid in the to-be-filled tank forms turbulence when the fluid flows without dead angles. According to the invention, the preparation of the layered chocolate milk with the clean label is realized by optimizing the raw materials to obtain the mixed solution with specific viscosity and particle size and combining a specific stirring process before filling, and the layered chocolate milk is layered uniformly and stably in the shelf life.

Description

Uniform layered chocolate milk and preparation method thereof

Technical Field

The invention relates to the technical field of flavored milk, in particular to uniform layered chocolate milk and a preparation method thereof.

Background

Chocolate milk is a popular flavor milk drink, and is deeply favored by consumers due to the strong chocolate flavor and the fragrant and mellow taste of milk. However, chocolate milk suffers from a major technical problem during production and storage, namely delamination due to incompatibility of the chocolate ingredients with the milk. In the traditional process, cocoa raw materials are difficult to dissolve in milk completely, and over time, particulate matter is prone to sedimentation, forming an obvious sediment layer. To mask this phenomenon, many products on the market use opaque composite packaging films, but this does not fundamentally solve the delamination problem. In addition, in order to increase the ability of the liquid to suspend the particles and to increase the viscosity of the milk, and to prevent the particles from sinking, manufacturers often add stabilizers such as gellan gum, carrageenan, etc. While these additives can improve product stability, they are contrary to consumer pursuits of healthy, natural foods and are increasingly difficult to match consumer demands for "minimally processed foods" and "clean-labeled" chocolate milk products.

In view of the current consumer pursuing health food, in recent years, consumer acceptance of layering phenomenon caused by the characteristics of products is gradually increased, even layering phenomenon is regarded as a sign of real addition of the products, and the action of shaking before drinking is regarded as a way of increasing the interestingness of the products, so that consumers are led to a healthier and natural life style.

Based on the change, how to develop a chocolate milk production process which not only meets the requirements of consumers on clean label products, but also can keep good layering and layering uniformity and stability within the shelf life becomes a technical problem to be solved urgently.

Disclosure of Invention

During the development of chocolate milk for cleaning labels, it was found that there was a lot-to-lot variation in chocolate milk products, even in the same lot of each bottled chocolate milk, the layering height was different, i.e. the layering was not uniform, which resulted in an impaired appearance of the chocolate milk on the shelf.

The invention provides uniform layered chocolate milk and a preparation method thereof, which are used for solving the defects in the prior art.

Specifically, the invention provides a preparation method of uniform layered chocolate milk, which comprises the following steps: mixing raw materials containing raw milk, chocolate and cocoa powder to obtain a mixed solution with the viscosity of 3-7mPa.s and the D50 of 1-5 mu m, and sequentially carrying out preheating, two-stage homogenization, sterilization, cooling, stirring before filling, and filling to obtain the chocolate milk; in the stirring process before filling, fluid in the to-be-filled tank forms turbulence when the fluid flows without dead angles.

The stirring before filling in the invention refers to the stirring process before filling, and filling is performed immediately after the stirring, namely, the material to be filled at the discharge port is directly filled. The to-be-filled tank refers to a container corresponding to stirring before filling and is used for containing the cooled mixed liquid.

Dead-angle free flow in the present invention means that the dead zone of fluid flow is within 0.5%.

The flow dead zone in the present invention refers to a local space that does not participate in the flow of the main fluid and only performs local movement in situ.

In order to realize the cleaning of the labels, raw milk, chocolate and cocoa powder are used as main raw materials, and additive components such as a stabilizer, an emulsifier and the like are not contained, so that the raw material system has the characteristic of easy layering, and the uniformity and the stability of the system are difficult to control.

When the raw material system of the present invention was used, the resultant chocolate milk system was tested and found to be a non-newtonian fluid with a decrease in fluid viscosity with increasing shear force, i.e. with the greatest viscosity at rest and a decrease in viscosity during agitation. In order to control the uniformity and stability of indexes such as quality of chocolate milk in batches or the same batch in actual production, it is important how to control the production flow to realize uniform and stable layering of bottled chocolate milk within shelf life after filling.

In fact, in the current production process of chocolate milk, a longer process flow is included, generally, raw milk and solid materials such as chocolate milk, cocoa powder and the like are required to be primarily mixed in the initial processing stage, then filtration is carried out to remove undissolved/dispersed large-particle solid materials, then two-stage homogenization is carried out to break up fat particles in the raw milk, further full dissolution with the solid materials is realized, and then filling is carried out. Therefore, the current process covers a plurality of mixing steps, different mixing steps play different roles, the primary mixing stage takes the crushing and dissolution of solid matters as the main purpose, the stirring speed of a stirring device adopted in the mixing is higher, generally more than 1400r/min, the viscosity of a material system in the stage is lowest, the material system is required to be further filtered, fluid is continuously sheared in the filtering process, and then homogenized, however, the sterilization temperature is generally higher, the material system is obviously changed, the viscosity is increased, and the invention discovers that the special stirring device is added before filling, so that the non-Newtonian fluid property of the chocolate milk system can be fully utilized, and the uniform and stable layering of bottled chocolate milk in the shelf life after filling can be ensured on the basis that chocolate milk is not layered under low viscosity.

The viscosity and D50 of the fluid in the invention are obtained by testing the fluid in a state of uniform mixing.

According to the preparation method of the uniform layered chocolate milk, the preparation process of the mixed solution comprises the following steps: mixing raw materials comprising raw milk, chocolate and cocoa powder to obtain a premix with the D50 of 6-9 mu m and the thickness of 3-7mPa.s, and filtering to obtain the premix.

As described above, in order to obtain uniform and stable chocolate milk, it is necessary to control the layering problem of the system during the processing, and the viscosity and particle size of the premix are controlled in the premix stage, so that the specific mixture is obtained, thereby laying a foundation for realizing uniform and stable chocolate milk.

When the premix liquid is adopted to prepare the mixed liquid in a filtering mode, the fluid system is more preferably filtered by adopting a circulating filter device, and a filter screen in the circulating filter device is generally 60-80 meshes, and more preferably, the circulating filter time is 15-25 min.

According to the preparation method of the uniform layered chocolate milk, the raw materials comprise, in parts by weight: 850-900 parts of raw milk, 90-135 parts of chocolate and 5-15 parts of cocoa powder.

According to the preparation method of the uniform layered chocolate milk, the raw materials are cow milk, chocolate and cocoa powder; the total cocoa solids content of the chocolate is less than or equal to 40%; the cocoa powder is alkalized cocoa powder.

According to the preparation method of the uniform layered chocolate milk, the to-be-canned comprises the following steps:

A tank body;

The stirring shaft is arranged in the tank body;

the stirring paddle is arranged at the end part of the stirring shaft;

the stirring shaft is obliquely arranged relative to the horizontal plane, and the vertical plane where the stirring shaft is located is eccentrically arranged relative to the central shaft of the tank body.

According to the preparation method of the uniform layered chocolate milk, the normal included angle between the central axis of the stirring shaft and the horizontal plane is 15-45 degrees; a first interval is arranged between the vertical plane where the stirring shaft is located and the central shaft of the tank body, and the first interval is 15% -25% of the diameter of the tank body.

Through the to-be-filled tank with the specific structure, the fluid can be in an optimal fluid motion state during stirring, and the flow dead zone is realized to be within 0.5%, namely no dead angle flow is realized. In addition, the invention makes the rotation center of the object and the mass center not coincide through eccentric and oblique stirring, so that the fluid does irregular motion, and the component speed perpendicular to the axis direction of the flow tube is generated, thereby generating turbulence.

According to the preparation method of the uniform layered chocolate milk, the two-stage homogenization comprises the following steps: first, carrying out primary homogenization under the pressure of 220-240 bar, and then carrying out secondary homogenization under the pressure of 40-50 bar.

The sterilization includes: sterilizing at 122-135 ℃ for 2-6 s.

The stirring process before filling is to perform intermittent stirring at a rotating speed of 100-500 r/min, and the stirring frequency is 2-4 min after every 10-20 min.

Preferably, the total stirring time of stirring before filling is 24-48 min.

The preparation method of the uniform layered chocolate milk comprises the following steps of:

(1) Preheating raw materials containing raw milk, chocolate and cocoa powder at 65-75 ℃, mixing and stirring the preheated materials at the temperature, and cooling to obtain a premix;

preferably, the preheated material is mixed and stirred at this temperature by a stirring device with a bottom center stirring. The bottom center stirring type stirring device is mainly different from the to-be-canned stirring device in that: the length of the stirring shaft enables the stirring paddle to be positioned in a conical area below the tank body, and the stirring shaft is vertically arranged in the tank body and is coaxial with the central shaft of the tank body;

more preferably, the mixing and stirring are carried out for 15-25 min at the temperature of 65-75 ℃ at the rotating speed of 1400-1500 r/min;

(2) Filtering the premix solution through a filter with the mesh number of 60-80 meshes, and cooling to obtain a mixed solution;

(3) Preheating the mixed solution at 65-75 ℃ and then carrying out primary homogenization and secondary homogenization;

(4) Sterilizing the material subjected to secondary homogenization at the temperature of 122-135 ℃;

(5) And cooling the sterilized material, conveying the cooled material to the to-be-filled tank, and stirring and filling the material before filling to obtain the chocolate milk.

The invention also provides the uniform layered chocolate milk prepared by the preparation method of the uniform layered chocolate milk.

According to the uniform layered chocolate milk prepared by the preparation method of the uniform layered chocolate milk, the viscosity of the uniform layered chocolate milk after stable layering is 7-9 mPa.s, and the average particle size D50 is below 0.9 mu m.

According to the uniform layered chocolate milk and the preparation method thereof, raw material systems containing raw milk, chocolate and cocoa powder and containing no additional additives such as stabilizing agents are subjected to intensive research, and specific mixed liquid is adopted to sequentially perform preheating, two-stage homogenization, sterilization, cooling, stirring before filling and filling to prepare the chocolate milk; particularly, in the process of controlling stirring before filling, fluid in the to-be-filled tank forms turbulence when the fluid flows without dead angles, so that the uniform and stable layering height of chocolate milk on a shelf is realized.

In addition, the system is uniform, the problems of thick product thickness, cocoa flavor and baking flavor difference caused by large component differences such as chocolate content and the like among different chocolate milk samples in the same batch are solved to a certain extent, and the terminal presentation effect and the product experience of the product are improved.

Drawings

In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic view of the internal structure of a can to be filled provided by the invention under a first view angle.

Fig. 2 is a schematic view of a partial structure of a to-be-canned can according to the present invention at a second viewing angle.

Fig. 3 is a schematic diagram of a partial structure to be canned according to the present invention.

Reference numerals:

10. a tank body; 11. an inner tank; 12. an outer tank; 13. a first through hole; 14. a second through hole; 15. a connection station; 20. a stirring shaft; 30. stirring paddles; 40. a connecting cone; 50. a reinforcing ring; 60. and driving the motor.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

A tank to be filled (which may also be referred to as a stirring tank) suitable for stirring before filling according to the present invention is described below with reference to fig. 1 to 3, and the structure thereof includes a tank body 10, a stirring shaft 20, and a stirring paddle 30. A stirring shaft 20 is installed in the tank 10. The stirring paddle 30 is mounted to an end of the stirring shaft 20.

Wherein, the stirring shaft 20 is inclined relative to the horizontal plane, and the vertical plane where the stirring shaft 20 is located is eccentric relative to the central axis of the tank body 10. The stirring shaft 20 is obliquely arranged in the tank body 10, and the stirring paddle 30 is arranged at the end part of the stirring shaft 20 and can rotate to drive the fluid in the tank body 10 to realize uniform mixing. Wherein, stirring rake 30 rotatable mounting is in the bottom of (mixing) shaft 20, and (mixing) shaft 20's top and jar body 10 fixed connection provide the mounted position for stirring rake 30 through setting up (mixing) shaft 20. Optionally, the rotation axis of the stirring paddle 30 coincides with the central axis of the stirring shaft 20, so as to ensure the balance of the stress of the stirring shaft 20 and improve the installation stability of the stirring paddle 30.

The vertical plane in which the stirring shaft 20 is located refers to a vertical plane in which the central axis of the stirring shaft 20 is located, and the plane is parallel to the central axis of the tank 10.

Specifically, an acute angle is formed between the central axis of the stirring shaft 20 and the horizontal plane, so that the stirring shaft 20 is obliquely arranged in the tank 10.

The stirring shaft 20 extends vertically, and a space is formed between the vertical plane where the stirring shaft 20 is located and the central axis of the tank body 10, so that the stirring shaft 20 is eccentrically arranged.

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

Taking the processing of chocolate milk as an example, the chocolate milk is quasi-plastic fluid in non-Newtonian fluid, if the stirring is uneven in the stirring process, the positions of layering lines formed by precipitation after filling are different, and bad experience is brought to users. After the stirring tank is used, the stirring paddle 30 is used for stirring, the stirring is reduced along with the strengthening of the stirring degree, and the viscosity is maximum when the stirring tank is at rest, so that the stable and lower viscosity of a product in the processing process needs to be ensured to avoid layering, and the viscosity is increased to form uniform and consistent layering after the processing is finished.

Optionally, 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. It will be appreciated that the length of the stirring shaft 20 varies depending on the size of the tank 10 and the amount of fluid filled in the tank 10. For example, if the amount of fluid injected into the tank 10 is less than half the capacity of the tank 10, the stirring shaft 20 may be designed to be relatively long. As another example, if the amount of fluid injected into tank 10 exceeds half the capacity of tank 10, stirring shaft 20 may be shortened appropriately. It should be noted that, the amount of fluid injected into the tank 10 needs to submerge the stirring paddle 30 to ensure that the stirring paddle 30 can operate smoothly.

Optionally, the stirring rake 30 is installed to the tip of (mixing) shaft 20, and wherein, (mixing) shaft 20 is inclined for the horizontal plane to set up for jar center pin eccentric of body 10, thereby make (mixing) shaft 20 be the slope form and set up in jar body 10, can fully stir the fluid in jar body 10 when stirring of stirring rake 30, effectively reduce stirring dead zone, promote stirring effect.

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

The normal to the horizontal plane refers to the vertical direction, i.e., the central axis of the tank 10. The included angle formed between the central axis of the stirring shaft 20 and the normal of the horizontal plane is alpha, and the angle is any angle between 15 degrees, 20 degrees, 45 degrees or 15 degrees to 45 degrees. Compared with the traditional stirring shaft 20 vertically arranged in the tank body 10, the inclined stirring shaft 20 rotates to generate a flowing field which can effectively improve the mixing effect of fluid in the tank body 10.

Optionally, a first distance H is provided between the vertical plane in which the stirring shaft 20 is located and the central axis of the tank 10. The first spacing H is 15% -25% of the diameter R of the tank body 10.

The stirring shaft 20 is not arranged on the central symmetry plane of the tank body 10, but is arranged at one side of the tank body 10, and according to fluid stirring simulation tests, the stirring shaft 20 which is eccentrically arranged is matched with the inclined arrangement, so that the flow dead area in the tank body 10 can be effectively reduced, the fluid quantity which is not stirred is reduced, and the stirring effect is improved. For example, the first spacing is 15% of the diameter of the can 10, and for another example, the first spacing H is 20% or 25% of the diameter R of the can 10. Of course, the first distance H may be a product of the diameter R of the tank 10 and any value between 15% and 25%.

The tank 10 includes a cylindrical section and frustum sections disposed at two ends of the cylindrical section, and the diameter of the tank 10 refers to the diameter of the cylindrical section in the tank 10.

The tank body 10 comprises an inner tank 11 and an outer tank 12, wherein the outer tank 12 is positioned outside the inner tank 11, and a heat insulation interlayer is formed between the inner tank 11 and the outer tank 12. The inner vessel 11 is provided with a first through hole 13 and the outer vessel 12 is provided with a second through hole 14. To facilitate installation of the stirring shaft 20, the stirring tank further comprises a connecting cone 40. The connecting cone 40 is fixed at the second through hole 14, and one end of the stirring shaft 20 away from the stirring paddle 30 passes through the first through hole 13 to be connected with the connecting cone 40. The drive motor 60 is connected to the stirring shaft 20 via a connecting cone 40.

A connecting cone 40 extends partially through the second throughbore 14 into the outer vessel 12 for providing a location for the mounting of the stirring shaft 20. It will be appreciated that the connecting cone 40 is sealingly connected to the outer can 12 of the can 10. For example, one end of the connection cone 40 is welded and fixed in the second through hole 14.

The outer tank 12 is provided with a connecting table 15 in a protruding manner, and a connecting cone 40 is fixed to the connecting table 15.

The mounting position of the connection cone 40 is determined according to the size of the can 10. In one embodiment, the tank 10 is relatively large in size and the connecting cone 40 is mounted to the cylindrical section of the tank 10. In yet another embodiment, where the tank 10 is smaller in size, the connecting cone 40 may be mounted to a conical section of the tank 10.

On the basis of the above embodiment, the reinforcing ring 50 is mounted at the second through hole 14.

The reinforcing ring 50 is used for locally reinforcing around the second through hole 14 of the can body 10, enhancing the strength of the can body 10 and preventing the structural weakening of the can body 10 due to the opening. Specifically, the reinforcing ring 50 is welded to the outer can 12. The reinforcing ring 50 is made of the same material as the can 10.

The stirring paddle 30 includes a plurality of paddles that are uniformly distributed around the circumference of the stirring shaft 20. Alternatively, the number of paddles is three or four.

Optionally, the tank 10 is provided with a liquid inlet and a liquid outlet, and the liquid level of the liquid inlet is lower than that of the liquid outlet. For example, a liquid inlet is formed at a low liquid level at the bottom of the tank 10, and a liquid outlet is formed at a high liquid level at the bottom of the tank 10, so long as the liquid inlet is located at a lower position than the liquid outlet. Fluid flowing in from the liquid inlet can flow out after being stirred by the stirring paddle 30, so that the fluid is prevented from directly flowing out after entering, and the consistency of the fluid performance of the outflow tank body 10 is ensured.

Since chocolate milk is a pseudoplastic fluid in non-newtonian fluid, the viscosity is maximum at rest due to the reduction of stirring degree during stirring, and therefore, it is necessary to ensure stable and low viscosity of the product during processing to avoid delamination. For this purpose, the stirring tank further comprises a controller electrically connected to the driving motor 60, the controller controlling the stirring paddle 30 to intermittently stir.

The controller controls the stirring shaft 20 to stir for a preset time at preset intervals, which is disposed outside the tank 10, so that a user can conveniently set the preset time and the preset time.

Specifically, when chocolate milk is prepared in the embodiment of the invention, the chocolate milk is prepared by stirring sterilized materials before filling the materials in a to-be-filled tank as shown in fig. 1-3. Specifically, the packaging material comprises several types of packaging materials with the following structures.

First kind to be canned (i.e. the stirring paddle 30 is positioned in the middle of the can body)

A to-be-canned tank is shown in fig. 1, and comprises a tank body 10, a stirring shaft 20 and a stirring paddle 30. The tank 10 comprises a cylindrical section and frustum sections arranged at two ends of the cylindrical section, and the diameter of the tank 10 refers to the diameter of the cylindrical section in the tank 10. A stirring shaft 20 is installed in the tank 10. The stirring paddle 30 is mounted to an end of the stirring shaft 20. Under the view angle shown in fig. 1, the included angle α between the central axis of the stirring shaft 20 and the central axis of the tank 10 is 15 ° to 45 °, that is, the stirring shaft 20 is obliquely disposed in the tank 10. In the view shown in fig. 2, the stirring shaft 20 extends vertically, and a first distance H is provided between a vertical plane on which the stirring shaft 20 is located and a central axis of the tank 10. The first spacing H is 15% -25% of the diameter R of the tank body 10. The stirring paddle 30 includes three paddles that 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, which is referred to as the cylindrical section of the tank 10.

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.

As shown in fig. 3, the tank body 10 includes an inner tank 11 and an outer tank 12, the outer tank 12 being located outside the inner tank 11, and a heat insulating interlayer being formed between the inner tank 11 and the outer tank 12. The inner vessel 11 is provided with a first through hole 13 and the outer vessel 12 is provided with a second through hole 14. To facilitate the installation of the stirring shaft 20, the to-be-canned further comprises a connecting cone 40. The connecting cone 40 is fixed at the second through hole 14, and one end of the stirring shaft 20 away from the stirring paddle 30 passes through the first through hole 13 to be connected with the connecting cone 40. The drive motor 60 is connected to the stirring shaft 20 via a connecting cone 40.

A connecting cone 40 extends partially through the second throughbore 14 into the outer vessel 12 for providing a location for the mounting of the stirring shaft 20. The connecting cone 40 is sealingly connected to the outer can 12 of the can body 10. For example, one end of the connection cone 40 is welded and fixed in the second through hole 14. The mounting position of the connection cone 40 is determined according to the size of the can 10. When the size of the can 10 is large, as shown in fig. 1, the connection cone 40 is installed at the cylindrical section of the can 10. When the size of the can 10 is small, as shown in fig. 3, the connection cone 40 may be installed at a cone section of the can 10.

A reinforcing ring 50 is mounted at the second through hole 14. The reinforcing ring 50 is used for locally reinforcing around the second through hole 14 of the can body 10, enhancing the strength of the can body 10 and preventing the structural weakening of the can body 10 due to the opening. Specifically, the reinforcing ring 50 is welded to the outer can 12. The reinforcing ring 50 is made of the same material as the can 10.

A liquid inlet is arranged at the low liquid level at the bottom of the tank body 10, and a liquid outlet is arranged at the high liquid level at the bottom of the tank body 10. Fluid flowing in from the liquid inlet can flow out after being stirred by the stirring paddle 30, so that the fluid is prevented from directly flowing out after entering, and the consistency of the fluid performance of the outflow tank body 10 is ensured.

Second kind to be canned (i.e. the stirring paddle 30 is positioned at the bottom of the pot body)

Substantially the same as the first type of can to be filled, the only difference is that: the length of the stirring shaft 20 is such that the stirring paddle 30 is located at the bottom of the tank, which is referred to as the conical region below the tank.

The specific techniques or conditions are not identified in the examples and are described in the literature in this field or are carried out in accordance with the product specifications. The reagents or equipment used were conventional products available for purchase by regular vendors without the manufacturer's attention.

The raw milk of the invention is derived from the stock company of the inner Mongolian milk industry (group).

The chocolate is prepared from milk powder, white sugar and cocoa butter, and the total content of cocoa solids is less than or equal to 40%.

The cocoa powder is prepared by grinding cocoa beans, and is alkalized cocoa powder.

The cocoa powder and chocolate of the present invention do not contain stabilizers.

The following describes the practice of the invention in connection with preferred embodiments thereof.

Example 1

A preparation method of chocolate milk comprises the following steps:

(1) Raw material preparation: the weight portions are as follows: 900 parts by weight of raw milk, 90 parts by weight of chocolate and 10 parts by weight of cocoa powder.

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at the temperature of 75 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 3 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 15min at 75 ℃ with a rotating speed of 1400 r/min.

The viscosity of the feed liquid A is 3.23+/-0.07 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 6.18+/-0.01 mu m measured by a Mastersizer particle size analyzer.

(3) And (3) circularly filtering the feed liquid A by a filter with 60 meshes for 15min, and cooling to 3 ℃ to obtain feed liquid B.

Wherein the viscosity of the feed liquid B is 3.11+/-0.10 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid B was 3.81.+ -. 0.13. Mu.m, measured by a Mastersizer particle sizer.

(4) Preheating: the feed liquid B is preheated at 65 ℃.

(5) Homogenizing: the preheated material was first homogenized at a pressure of 230bar and then second homogenized at a pressure of 45 bar.

(6) Sterilizing: sterilizing the homogenized material at 125 deg.c for 3s.

(7) Stirring: cooling the sterilized material to 3 ℃, then entering the first type of material to be canned, stirring to obtain material liquid C, and then filling the material liquid C to obtain the bottled chocolate milk. Wherein, the included angle alpha between the central axis of the first-class stirring shaft to be canned and the central axis of the tank body is 30 degrees, and the first interval H is 15% of the diameter R of the tank body; the stirring is carried out intermittently at a rotating speed of 300r/min, the stirring frequency is that stirring is carried out for 2min at intervals of 15min, and the total stirring time is 24min; the flow dead area of the feed liquid C in the stirring process is 0.1%.

Example 2

A preparation method of chocolate milk comprises the following steps:

(1) Raw material preparation: the weight portions are as follows: 850 parts by weight of raw milk, 135 parts by weight of chocolate and 15 parts by weight of cocoa powder.

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at 70 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 4 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 20min at 70 ℃ by adopting the rotating speed of 1450 r/min.

The viscosity of the feed liquid A is 4.15+/-0.53 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 6.27+/-0.13 mu m measured by a Mastersizer particle size analyzer.

(3) Circularly filtering the feed liquid A by a filter with 70 meshes for 20min, and cooling to 2 ℃ to obtain feed liquid B; wherein the viscosity of the feed liquid B is 3.51+ -0.31 mPa.s as measured by an Anton Paar viscometer.

The average particle diameter D50 of the feed liquid B was 3.72.+ -. 0.23. Mu.m, as measured by a Mastersizer particle sizer.

(4) Preheating: the feed liquid B is preheated at 70 ℃.

(5) Homogenizing: the preheated mass was first homogenized at a pressure of 235bar and then second homogenized at a pressure of 48 bar.

(6) Sterilizing: sterilizing the homogenized material at 130 ℃ for 4s.

(7) Stirring: cooling the sterilized material to 4 ℃, then entering the first type of material to be canned, stirring to obtain material liquid C, and then filling the material liquid C to obtain the bottled chocolate milk. Wherein, the included angle alpha between the central axis of the first-class stirring shaft to be canned and the central axis of the tank body is 45 degrees, and the first interval H is 25% of the diameter R of the tank body; the stirring is carried out intermittently at a rotating speed of 250r/min, the stirring frequency is that stirring is carried out for 3min at intervals of 15min, and the total stirring time is 36min; the chocolate milk C had a flow dead zone of 0.2% during stirring.

Example 3

A preparation method of chocolate milk comprises the following steps:

(1) Raw material preparation: the weight portions are as follows: 880 parts by weight of raw milk, 115 parts by weight of chocolate and 5 parts by weight of cocoa powder.

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at 65 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 5 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 25min at 65 ℃ with a rotating speed of 1500 r/min.

The viscosity of the feed liquid A is 4.27+/-0.41 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 6.75+/-0.01 mu m measured by a Mastersizer particle size analyzer.

(3) And (3) circularly filtering the feed liquid A by a filter with 80 meshes for 25min, and cooling to 3 ℃ to obtain feed liquid B.

The viscosity of the feed liquid B is 3.72+/-0.14 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid B measured by a Mastersizer particle sizer was 3.57.+ -. 0.03. Mu.m.

(4) Preheating: the feed liquid B is preheated at 65 ℃.

(5) Homogenizing: the preheated material was first homogenized at a pressure of 220bar and then second homogenized at a pressure of 40 bar.

(6) Sterilizing: sterilizing the homogenized material at 135 deg.c for 5s.

(7) Stirring: cooling the sterilized material to 5 ℃, then entering the second type of to-be-canned tank, stirring to obtain feed liquid C, and then filling the feed liquid C to obtain the bottled chocolate milk. Wherein, the included angle alpha between the central axis of the stirring shaft to be canned in the second type and the central axis of the tank body is 30 degrees, and the first interval H is 15% of the diameter R of the tank body; the stirring is carried out intermittently at a rotating speed of 200r/min, the stirring frequency is that stirring is carried out for 4min at intervals of 15min, and the total stirring time is 48min; the chocolate milk C had a flow dead zone of 0.13% during stirring.

Example 4

A preparation method of chocolate milk comprises the following steps:

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at 65 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 1 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 20min at 65 ℃ with a rotating speed of 1400 r/min.

The viscosity of the feed liquid A is 3.86+/-0.11 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 7.56+/-0.30 mu m measured by a Mastersizer particle size analyzer;

(3) And (3) circularly filtering the feed liquid A by a filter with 60 meshes for 20min, and cooling to 4 ℃ to obtain feed liquid B.

The viscosity of the feed liquid B is 3.81+/-0.14 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid B was 4.51.+ -. 0.13. Mu.m, measured by a Mastersizer particle sizer.

(4) Preheating: the feed liquid B is preheated at 75 ℃.

(5) Homogenizing: the preheated mass was first homogenized at a pressure of 235bar and then second homogenized at a pressure of 50 bar.

(6) Sterilizing: sterilizing the homogenized material at 135 deg.c for 3s.

(7) Stirring: cooling the sterilized material to 6 ℃, then entering the second type of to-be-canned tank, stirring to obtain feed liquid C, and then filling the feed liquid C to obtain the bottled chocolate milk. Wherein, the included angle alpha between the central axis of the stirring shaft to be canned in the second type and the central axis of the tank body is 45 degrees, and the first interval H is 25% of the diameter R of the tank body; the stirring is carried out intermittently at a rotating speed of 150r/min, the stirring frequency is that stirring is carried out for 4min at intervals of 10min, and the total stirring time is 48min; the chocolate milk C had a flow dead zone of 0.21% during stirring.

Comparative example 1

A process for the preparation of chocolate milk, which differs substantially in the same way as in example 1, with the only difference that: the structure to be canned in the step (7) is as follows: the included angle alpha between the central axis of the stirring shaft and the central axis of the tank body is 0 degree, and the first interval H is 15 percent of the diameter R of the tank body.

Comparative example 2

A process for the preparation of chocolate milk, which differs substantially in the same way as in example 1, with the only difference that: the structure to be canned in the step (7) is as follows: the included angle alpha of the central axis of the first stirring shaft to be canned and the central axis of the tank body is 30 degrees, and the first interval H is 10% of the diameter R of the tank body.

Comparative example 3

A method of preparing a layered chocolate milk, the steps of which are substantially the same as in example 1, except that: the quality of cocoa powder is replaced by chocolate.

Comparative example 4

A preparation method of chocolate milk comprises the following steps:

(1) Raw material preparation: the weight portions are as follows: 900 parts by weight of raw milk, 75 parts by weight of chocolate and 15 parts by weight of cocoa powder.

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at 65 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 2 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 15min at 65 ℃ with a rotating speed of 1400 r/min.

The viscosity of the feed liquid A is 2.92+/-0.05 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 4.12+/-0.37 mu m measured by a Mastersizer particle size analyzer.

(3) And (3) circularly filtering the feed liquid A by a filter with the mesh number of 50 meshes for 20min, and cooling to 4 ℃ to obtain feed liquid B.

The viscosity of the feed liquid B is 2.31+/-0.16 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid B was 4.01.+ -. 0.31. Mu.m, as measured by a Mastersizer particle sizer.

(4) Preheating: the feed liquid B is preheated at 65 ℃.

(6) Sterilizing: sterilizing the homogenized material at 125 deg.c for 4s.

(7) Stirring: cooling the sterilized material to 4 ℃, then entering the first type of material to be canned, stirring to obtain material liquid C, and then filling the material liquid C to obtain the bottled chocolate milk. Wherein, the included angle alpha between the central axis of the first-class stirring shaft to be canned and the central axis of the tank body is 0 degree (vertical stirring), and the first interval H is 15% of the diameter R of the tank body; the stirring is carried out intermittently at a rotating speed of 300r/min, the stirring frequency is that stirring is carried out for 3min at intervals of 15min, and the total stirring time is 36min; the chocolate milk C had a flow dead zone of 5.61% during stirring.

Comparative example 5

A preparation method of chocolate milk comprises the following steps:

(1) Raw material preparation: the weight portions are as follows: 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.

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at 70 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 3 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 20min at 70 ℃ with a rotating speed of 1500 r/min.

The viscosity of the feed liquid A is 8.55+/-0.40 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 10.12+/-0.23 mu m measured by a Mastersizer particle size analyzer.

The viscosity of the feed liquid B is 7.25+/-0.32 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid B measured by a Mastersizer particle sizer was 8.24.+ -. 0.32. Mu.m.

(4) Preheating: the feed liquid B is preheated at 70 ℃.

(5) Homogenizing: the preheated mass was first homogenized at a pressure of 225bar and then second homogenized at a pressure of 50 bar.

(6) Sterilizing: sterilizing the homogenized material at 130 ℃ for 3s.

(7) Stirring: cooling the sterilized material to 3 ℃, then entering the first type of material to be canned, stirring to obtain material liquid C, and then filling the material liquid C to obtain the bottled chocolate milk. Wherein, the included angle alpha between the central axis of the first-class stirring shaft to be canned and the central axis of the tank body is 60 degrees, and the first interval H is 25% of the diameter R of the tank body; the stirring is carried out intermittently at a rotating speed of 350r/min, the stirring frequency is that stirring is carried out for 4min at intervals of 10min, and the total stirring time is 36min; the chocolate milk C had a flow dead zone of 7.21% during stirring.

Comparative example 6

A preparation method of chocolate milk comprises the following steps:

(2) Preheating for the first time: preheating raw milk, chocolate and cocoa powder at the temperature of 75 ℃, mixing and stirring the preheated materials at the temperature by adopting a stirring device with a central stirring bottom, and cooling to 4 ℃ to obtain a feed liquid A; wherein, the mixing and stirring are carried out for 25min at 75 ℃ with a rotating speed of 1500 r/min.

The viscosity of the feed liquid A is 4.51+/-0.23 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid A is 6.38+/-0.24 mu m measured by a Mastersizer particle size analyzer.

(3) And (3) circularly filtering the feed liquid A by a filter with 60 meshes for 15min, and cooling to 5 ℃ to obtain feed liquid B.

The viscosity of the feed liquid B is 7.66+/-0.02 mPa.s measured by an Anton Paar viscometer; the average particle diameter D50 of the feed liquid B measured by a Mastersizer particle sizer was 8.56.+ -. 0.11. Mu.m.

(4) Preheating: the feed liquid B is preheated at 75 ℃.

(5) Homogenizing: the preheated mass was first homogenized at a pressure of 235bar and then second homogenized at a pressure of 40 bar.

(6) Sterilizing: sterilizing the homogenized material at 130 ℃ for 5s.

(7) Stirring: cooling the sterilized material to 6 ℃, then entering the second type of to-be-canned tank, stirring to obtain feed liquid C, and then filling the feed liquid C to obtain the bottled chocolate milk. The first spacing H of the second type to-be-canned is 30% of the diameter R of the can body, and the first spacing H is 20% of the diameter R of the can body; the stirring is carried out intermittently at a rotating speed of 200r/min, the stirring frequency is that stirring is carried out for 2min at intervals of 15min, and the total stirring time is 32min; the chocolate milk C had a flow dead zone of 5.54% during stirring.

The bottled chocolate milk prepared in each example and comparative example was allowed to stand at a certain temperature for a certain period of time, the layering conditions were observed, and the layered chocolate milk was subjected to viscosity, average particle size D50, chromaticity and mouthfeel tests, wherein the viscosity, average particle size D50, chromaticity and mouthfeel tests were all performed by sampling after layering, and the layered chocolate was subjected to shaking to make it uniform before the test.

The test method and the test result related by the invention are as follows:

(1) Specific results of the tests of viscosity (measured with an Anton Paar viscometer), average particle diameter D50 (measured with a Mastersizer particle sizer), zero order kinetic model fitting coefficient R2 are shown in the following table:

from the table above, it can be seen that: the amounts of cocoa powder and chocolate and the processing technique produced affect the viscosity and particle size of the sample, the viscosity of the products of examples 1 to 4 is 7 to 9 mpa-s and the average particle size D50 is below 0.9 μm.

When the cocoa powder was not added (comparative example 3), the viscosity of the sample increased and the average particle diameter D50 increased, so that the ratio of chocolate and cocoa powder was selected in an appropriate range.

(2) Layering consistency test: the heights of the layers in the bottled chocolate milk obtained in examples and comparative examples were observed at temperatures of 4 c at times 2h, 4h, 8h, 24h, 72h, 168h and 360h, respectively, and 100 bottles of each example and comparative example were taken for observation, and the average value and standard value thereof were recorded (data in the following table are average value ± standard deviation).

Samples with standard deviations of layering heights within 0.10 in different bottled chocolate milk treated identically and tested at the same time are regarded as good layering consistency.

The specific results are shown in the following table:

From the table above, it can be seen that: the layering heights of examples 1-4 are smaller than the standard deviation of the layering heights of comparative examples 1-5, the layering heights of different chocolate milk are measured within 0.10cm at the same time, and the layering heights of the examples are better in consistency, so that the product with consistent layering heights in shelf life can be obtained by adopting the raw material formula range and the stirring mode.

In addition, it can be seen from the above table that examples 1, 3 to 4 and comparative example 3 have a faster sedimentation rate, and reach the highest sedimentation point around 4 hours, which is positively correlated with their low viscosity, and the sedimentation height does not change by more than 15% within 15 days after 24 hours of shelf life.

Example 2 and comparative example 4 reached the highest point of precipitation around 8 hours, and the precipitation height did not change by more than 30% after 24 hours of shelf life.

(3) Sensory evaluation: the chocolate milk prepared in the examples and the comparative examples were subjected to sensory evaluation, wherein the number of people participating in the sensory evaluation was 33, and the sensory evaluation indexes including overall preference, color, chocolate taste, milk flavor, sweetness and smoothness were respectively tasted. Wherein, specific sensory evaluation criteria are shown in the following table:

the test results of the examples and comparative examples of the present invention are shown in the following table:

From the table above, it can be seen that: the overall preference of the chocolate milk prepared in examples 1-4 was higher than that of comparative examples 1-6 and was substantially at a suitable level in terms of color, chocolate flavor, milk flavor, sweetness and smoothness, and was acceptable.

As can be seen from example 1 and comparative example 3, the samples with too little cocoa powder added had lower color and chocolate taste intensity than example 1.

(3) Chromaticity: the chocolate milk prepared in the examples and the comparative examples is tested by a spectrocolorimeter, and the test method is as follows: after correcting the instrument by a white board and a blackboard, shaking the sample to be measured uniformly, taking 15mL, placing the sample into a glass cuvette, and measuring in a small hole reflection modeValues. Wherein,Is a brightness index, with a larger value indicating a whiter shade; Indicating a degree of redness, a larger value indicates a redder tint, Indicating a degree of green, a larger value indicating a greener shade; indicating a degree of yellow, a larger value indicates a more yellow shade, Indicating the degree of blue, a larger value indicates a bluish shade.

It can be seen from the above table in combination with sensory consumer preferences: when chocolate milkValues at 54 to 62 of the total number of the components,The value is between 6 and 8.5,And when the value is 10-13, the method is more in line with the cognition and preference of consumers on the color of the chocolate milk.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing uniform layered chocolate milk, comprising the steps of: mixing raw materials comprising raw milk, chocolate and cocoa powder to obtain a mixed solution with the viscosity of 3-7mPa.s and the D50 of 1-5 mu m, and sequentially carrying out preheating, two-stage homogenization, sterilization, cooling, stirring before filling, and filling to obtain the chocolate milk;

in the stirring process before filling, fluid in the to-be-filled tank forms turbulence when the fluid flows without dead angles.

2. A method of preparing a homogeneous layered chocolate milk according to claim 1 wherein said process of preparing said blend comprises: mixing raw materials comprising raw milk, chocolate and cocoa powder to obtain a premix with the D50 of 6-9 mu m and the thickness of 3-7mPa.s, and filtering to obtain the premix.

3. A method of preparing a homogeneous layered chocolate milk according to claim 2 wherein said ingredients comprise, in parts by weight: 850-900 parts of raw milk, 90-135 parts of chocolate and 5-15 parts of cocoa powder.

4. A method of preparing a homogeneous layered chocolate milk according to claim 3 wherein said materials are cow's milk, chocolate and cocoa powder; the total cocoa solids content of the chocolate is less than or equal to 40%; the cocoa powder is alkalized cocoa powder.

5. A method of preparing a homogeneous layered chocolate milk according to claim 1, wherein said to-be-canned comprises:

A tank body;

The stirring shaft is arranged in the tank body;

the stirring paddle is arranged at the end part of the stirring shaft;

6. The method for preparing the uniform layered chocolate milk according to claim 5, wherein the normal included angle between the central axis of the stirring shaft and the horizontal plane is 15-45 degrees; a first interval is arranged between the vertical plane where the stirring shaft is located and the central shaft of the tank body, and the first interval is 15% -25% of the diameter of the tank body.

7. A method of preparing a homogeneous layered chocolate milk according to claim 1, wherein,

The two-stage homogenization comprises: firstly, carrying out primary homogenization under the pressure of 220-240 bar, and then carrying out secondary homogenization under the pressure of 40-50 bar;

the sterilization includes: sterilizing at 122-135 ℃ for 2-6 s;

8. A method of preparing a homogeneous layered chocolate milk according to any one of claims 1 to 7, wherein said method comprises the steps of:

(1) Preheating raw materials comprising raw milk, chocolate and cocoa powder at 65-75 ℃, mixing and stirring the preheated materials at the temperature, and cooling to obtain a premix;

9. A homogeneous layered chocolate milk produced by the process of any one of claims 1 to 8.

10. The homogeneous layered chocolate milk manufactured by the method for manufacturing the homogeneous layered chocolate milk according to claim 9, wherein the viscosity of the homogeneous layered chocolate milk after stable layering is 7-9 mpa-s, and the average particle size D50 is below 0.9 μm.