CN115777786A

CN115777786A - Milk powder preparation method capable of improving milk powder dissolution state and milk powder

Info

Publication number: CN115777786A
Application number: CN202211658419.7A
Authority: CN
Inventors: 孙立达; 陈鹏飞; 董春喜; 谢阳; 孙建国; 张永久; 冷友斌
Original assignee: Heilongjiang Feihe Dairy Co Ltd
Current assignee: Heilongjiang Feihe Dairy Co Ltd
Priority date: 2022-12-22
Filing date: 2022-12-22
Publication date: 2023-03-14

Abstract

The invention provides a milk powder preparation method capable of improving the dissolution state of milk powder and milk powder, and relates to the technical field of milk powder. The invention provides a milk powder preparation method capable of improving the dissolution state of milk powder, which comprises the following steps: the preparation method is simple and convenient. For the problem of unqualified dissolution state, the inventor obtains the 3 rd main reason except the 2 main reasons of milk protein denaturation and milk fat free analyzed by the current milk powder industry through system analysis, namely that the dried powder particles contain trace air, are dispersed in water in the brewing and recovering process, do not completely escape from the water during detection and are represented as brewing white points with unqualified dissolution state, so the invention solves the problem of low milk powder dissolution state score by reducing the air content in the milk powder particles.

Description

Milk powder preparation method capable of improving milk powder dissolution state and milk powder

Technical Field

The invention relates to the technical field of milk powder, in particular to a milk powder preparation method capable of improving the dissolution state of the milk powder and the milk powder.

Background

1.1 definition of the dissolution state:

the reconstitution property of the milk powder refers to the capability of the milk powder to be dispersed according to a certain concentration, dissolved in water and reduced into milk, and is an important index for judging the quality of the milk powder. The dissolution state (the brewing white point) is one of the infant formula milk powder brewing performance detection items, and the brewing quality is evaluated through the dissolution effect of particles in water in the milk powder brewing process.

1.2 detection method of dissolution state:

the preparation method comprises the steps of preparing milk powder and water according to the preparation proportion and the water temperature required in a product label, adding the weighed milk powder and water into a container, fixing the sealed container on a mixer holder, starting an instrument, rotating for 15 seconds at a rotating speed of 60r/min, finishing the whole operation within 10 seconds, pouring recovered emulsion into a beaker, standing for 1 minute, immersing 3/4 of a clean microorganism slide into the recovered emulsion, and stirring vigorously for 5 seconds (no circle drawing). The slide was removed vertically, tilted at about 60 ° for 10 seconds, and then the back and bottom of the slide were wiped dry, against a standard plate, on a well-lit black background, with a reading time of no more than 30 seconds.

1.3 dissolution status score criteria as shown in FIG. 1, the score from left to right is 5, 4, 3, 2, 1 and 0.

1.4 for the problem of unqualified dissolution state, the analysis in the milk powder industry at present is the following reasons:

denaturation of milk proteins (1) infection of fresh milk by microorganisms in transportation and storage; (2) lactic acid bacteria propagation results in a decrease in milk pH; (3) adding an alkaline substance into the milk; (4) the heating time of the milk is long, and the heating temperature is high; (5) fat floating; (6) the addition of nutrition enhancers causes the milk pH to drop; (7) whey powder addition results in disruption of the ionic balance of the milk; (8) the low temperature freezing of milk results in casein coagulation.

The processing method of the milk fat dissociation (1) is not proper, such as poor homogenization effect, over high stirring speed and the like; and (2) the raw materials are not used properly.

1.5 Current solutions:

the milk storage temperature is reduced aiming at the milk protein denaturation (1), and the equipment cleaning is enhanced; (2) detecting the collected milk by using a densimeter, and controlling the salt content; (3) perfecting the abnormal milk inspection method; (4) reducing the heat treatment strength; (5) adding sodium salt to improve the heat resistance of the protein; (6) adding an emulsifier; and (7) adding hydrophilic colloid.

For milk fat free: spraying phospholipid on the surface of the powder particles; (2) cooling the concentrated milk; (3) mechanical emulsification treatment; (4) adding an emulsifier; and (5) adding vegetable protein.

1.6 disadvantages of the prior art: for the problem of unqualified dissolving state, the milk powder industry analyzes 2 main reasons of milk protein denaturation and milk fat dissociation, the existing milk powder enterprises solve the problems by adding sodium salt, an emulsifier and a hydrophilic colloid, reducing the heat treatment strength of materials, reducing the exhaust temperature of a drying tower in the drying process and the like, and have higher risks for the component and character change of the milk powder for infant formula, microbial control and equipment blockage.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The first purpose of the invention is to provide a milk powder preparation method capable of improving the dissolution state of milk powder, so as to solve the problem of low score of the dissolution state of milk powder.

A second object of the present invention is to provide a powdered milk.

In a first aspect, the present invention provides a method for preparing milk powder capable of improving the dissolution state of milk powder, comprising: mixing raw materials for preparing the milk powder, homogenizing, concentrating, spray drying and cooling in sequence to prepare the milk powder;

the mixing comprises the following steps: stirring the preparation raw materials by a stirrer to uniformly mix the preparation raw materials;

the homogenizing comprises: homogenizing the mixed material liquid and the edible vegetable oil by a homogenizer to ensure that the edible vegetable oil is uniformly dispersed;

the concentration mode comprises evaporation concentration, so that the homogenized feed liquid is primarily concentrated;

the spray drying is to spray dry the concentrated feed liquid by a spray gun to prepare granular milk powder;

the cooling means comprises static fluidized bed cooling such that the temperature of the spray dried milk powder is reduced.

As a further technical scheme, in the material mixing process, the material liquid submerges a stirring paddle of a stirrer.

As a further technical scheme, in the concentration process, the density of the feed liquid is concentrated to 1140-1150kg/m ³ 。

As a further technical scheme, spray drying is carried out by adopting a spray gun with the abrasion of a spray gun pore plate within 0.2 mm;

preferably, the spray pressure is from 200 to 250bar.

As a further technical scheme, the thickness of a powder layer of the static fluidized bed is controlled to be more than 10 cm.

As a further technical scheme, the mixing is to mix the preparation raw materials of the milk powder;

the preparation raw materials of the milk powder comprise the following components in parts by weight: 1700-1900 parts of fresh milk, 360-400 parts of desalted whey powder, 140-170 parts of skim milk powder, 60-90 parts of lactose, 15-25 parts of fructose, 10-20 parts of whey protein powder, 2-8 parts of arachidonic acid grease powder, 2-8 parts of docosahexaenoic acid grease powder and 2-8 parts of calcium carbonate, wherein the dry matter content is 12.2%;

preferably, the edible vegetable oil is used in an amount of 110-140 parts by mass.

As a further technical scheme, the fresh milk comprises raw milk or raw goat milk.

As a further technical scheme, the pressure for homogenizing is 125-135bar.

As a further technical scheme, the step of sterilizing fresh milk is also included before the mixing;

the sterilization means includes pasteurization.

In a second aspect, the invention provides a milk powder prepared by the preparation method.

Compared with the prior art, the invention has the following beneficial effects:

for the problem of unqualified dissolution state, the inventor obtains the 3 rd main reason, except for 2 main reasons of milk protein denaturation and milk fat free analyzed in the current milk powder industry, through system analysis, that the dried powder particles contain trace air, the dried powder particles are dispersed in water in the brewing and recovering process, the dried powder particles do not completely escape from the water during detection, and the dried powder particles are expressed as brewing white spots with unqualified dissolution state, therefore, the invention provides a method for improving the dissolution state of milk powder, and the method solves the problem of low milk powder dissolution state score by reducing the air content in the milk powder particles, and has the following significance:

1. improve the quality of the milk powder.

Ensures that the milk powder particles are completely and quickly dispersed and dissolved in water, and improves the sensory effect of the milk powder after being mixed.

2. The method is used for determining a new direction of problem analysis for a producer, and reducing the problem solving time, the economic cost and the risk of unqualified product quality.

When the dissolution state of the milk powder is unqualified, part of enterprise and literature judgment reasons are milk protein denaturation and milk fat dissociation, and the problems are solved by adding sodium salt, an emulsifier and a hydrophilic colloid, reducing the heat treatment strength of materials, reducing the exhaust temperature of a drying tower in the drying process and the like, and the risks of component and property change of the infant milk powder, microorganism control and equipment blockage are high.

3. The milk powder mixing knowledge is supplemented for consumers, and the worry and the market complaint rate are reduced.

At present, consumers pay more and more attention to the dissolution state of milk powder after mixing, if white spots appear on the inner wall of the milk bottle after mixing, partial milk powder is possibly judged to be not dissolved, nutrition cannot be completely taken by babies, or the milk powder is judged to deteriorate, so that quality problems exist, and the like, and market complaints are carried out. From the above studies, consumers can pass the quiescence test, and if the white point is a bubble, there is no further concern.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a graph comparing dissolution scores;

FIG. 2 is a photograph showing the examination of the dissolved state;

FIG. 3 is a photograph magnified 10 times in a dissolved state;

FIG. 4 is a photograph of milk powder particles;

FIG. 5 is a 10-fold magnified photograph of milk powder particles;

FIG. 6 is a photograph of the milk powder particles magnified 100 times before adjustment;

FIG. 7 is a classification of causes with a dissolution state of less than 3 points and Biberla chart;

FIG. 8 shows the white spots on the inner wall of the bottle after shaking for different resting times after brewing;

FIG. 9 is a production process flow diagram (wet process);

FIG. 10 shows the fraction of the dissolved state of the materials corresponding to different production processes;

FIG. 11 is a photograph showing the stirring state of the holding tank;

FIG. 12 is a block diagram of a DELAVAN spray gun for atomizing a drying tower;

FIG. 13 is a comparison of atomization of a standard orifice plate and an orifice plate worn beyond 0.2 mm;

FIG. 14 is a photograph showing the results of the detection of the dissolution state of the adjusted powdered milk;

FIG. 15 is a photograph of the adjusted powdered milk particles at 100 times magnification;

FIG. 16 shows bubble data contained in the feed liquid before and after adjustment of the stirrer start level parameters;

FIG. 17 shows data of bubbles contained in the feed liquid before and after adjustment of the discharge density of the evaporator;

FIG. 18 is powder dissolution status data before and after adjustment of spray gun orifice plate wear replacement criteria;

FIG. 19 is the powder dissolution state data before and after adjustment of the opening standard of the baffle of the static bed.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to embodiments and examples, but those skilled in the art will understand that the following embodiments and examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Those who do not specify the conditions are performed according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.

For the problem of unqualified dissolution state, the inventor researches to find that the 3 rd main reason is that the dried powder particles contain trace air, are dispersed in water in the brewing and recovering process, do not completely escape from the water during detection, and are represented as unqualified dissolution state, namely brewing white points.

the homogenizing comprises: homogenizing the mixed material liquid and the edible vegetable oil by a homogenizer to ensure that the edible vegetable oil is uniformly dispersed, wherein the homogenizing pressure is preferably 125-135bar.

In some preferred embodiments, the feed solution is submerged in the paddles of the mixer during mixing.

The inventor researches and finds that the air in the material liquid can increase the air content in the powder particles, and the opening liquid level parameter of the stirrer is set to be too low according to the investigation data, and the liquid level does not exceed the stirring paddle of the stirrer, so that the air is dissolved in the material liquid due to mechanical force in the stirring process. And in the material mixing process, the material liquid is kept to submerge the stirring paddle of the stirrer, so that the air in the material liquid can be reduced.

In some preferred embodiments, the concentration process concentrates the feed solution to a density of 1140-1150kg/m ³ 。

The feeding concentration plays a very important role, the low air content can be caused by the high concentration, but the concentration of the feed liquid cannot be too high, the viscosity of the feed liquid is increased along with the increase of the density of the feed liquid, and the uneven distribution of the feed liquid film of the tube nest of the evaporator and the coke blockage can be caused. When the discharge density of the feed liquid is 1140-1150kg/m ³ Is most preferred.

In some preferred embodiments, spray drying is performed with a spray gun having a spray gun orifice wear within 0.2 mm;

the gun orifice size change can result in air entering the thick milk droplets. The wear of the aperture of the spray gun orifice plate exceeds 0.2mm, and the spray gun is not uniform in atomization, so that air is mixed in the granulation process. The spraying pressure in the present invention is preferably 200 to 250bar.

In some preferred embodiments, the thickness of the powder layer of the static fluidized bed is controlled to be above 10 cm.

The cooling process of the static fluidized bed is that powder is placed on a pore plate, and gas is conveyed from the lower part of the pore plate to cause material particles to move on a gas distribution plate and to be in a suspension state in gas flow, so that a mixed bottom layer of the material particles and the gas is generated just like liquid boiling. The inventor researches and finds that the thinner the thickness of the powdered milk layer on the static fluidized bed is, the easier the air is introduced into the powdered milk particles, and when the thickness of the powdered milk layer on the static fluidized bed is more than 10cm, the air content in the powdered milk particles can be obviously reduced.

In some preferred embodiments, the mixing is mixing raw materials for preparing the milk powder;

the preparation raw materials of the milk powder comprise the following components in parts by weight: 1700-1900 parts of fresh milk, 360-400 parts of desalted whey powder, 140-170 parts of skimmed milk powder, 60-90 parts of lactose, 15-25 parts of fructose, 10-20 parts of whey protein powder, 2-8 parts of arachidonic acid grease powder, 2-8 parts of docosahexaenoic acid grease powder and 2-8 parts of calcium carbonate, wherein the dry matter content is 12.2%;

preferably, the formula of the milk powder comprises the following components in parts by weight: raw milk: 1820 parts (based on the solid content of 12.2%), desalted whey powder D70:225 parts, desalted whey powder D90:160 parts, skim milk powder: 155 parts, lactose: 75 parts of fructo-oligosaccharide: 20 parts, concentrated whey protein powder: 5 parts, whey protein powder: 10 parts of walnut oil: 5 parts, arachidonic acid grease powder (10%): 5 parts of docosahexaenoic acid grease powder (7%), 5 parts of calcium carbonate: 5 parts, phospholipid: 2 parts of anhydrous cream: 1 part of compound vitamin (comprising vitamin C, taurine, vitamin E, vitamin A, nicotinic acid, vitamin D, pantothenic acid, biotin, vitamin B12, vitamin K, folic acid, vitamin B1, vitamin B6 and lactose): 3 parts of compound minerals (including ferric pyrophosphate, zinc sulfate, magnesium sulfate, potassium iodate, copper sulfate and lactose): 1 part of compound nutrients (including inositol, L-carnitine, lutein, choline and lactose): 1 part, compound nucleotide: 0.58 portion.

Preferably, the edible vegetable oil (including 1, 3-dioleic acid 2-palmitic acid triglyceride content 49%, sunflower seed oil content 31%, rapeseed oil content 15% and coconut oil content 5%) is used in 110-140 parts by weight, preferably 120 parts by weight.

In some preferred embodiments, the fresh milk comprises raw cow's or goat's milk, or other milk materials known to those skilled in the art.

In some preferred embodiments, the mixing process further comprises a step of sterilizing the fresh milk before, and the sterilization mode is not particularly limited in the present invention, and for example, high temperature sterilization, pasteurization and the like can be adopted.

The air content of the milk powder particles in the milk powder provided by the invention is low, and the score of the dissolution state is high.

The invention is further illustrated by the following specific examples and comparative examples, but it should be understood that these examples are for purposes of illustration only and are not to be construed as limiting the invention in any way.

Example 1

1. Analysis of causes of low fraction in dissolved state

1.1. The method for detecting the dissolution state comprises the following steps:

taking milk powder which is produced by the company and shows a brewing white point as a sample, carrying out brewing according to the brewing proportion and the water temperature required in a product label, adding the weighed milk powder and water into a container, fixing the sealed container on a mixer holder, starting an instrument, rotating for 15 seconds at the rotating speed of 60r/min, finishing the whole operation within 10 seconds, pouring the recovered emulsion into a beaker, standing for 1 minute, immersing 3/4 of a clean microorganism glass slide into the recovered emulsion, and stirring vigorously for 5 seconds (not capable of rounding). The slide was removed vertically, tilted at about 60 ° for 10 seconds, and then the back and bottom of the slide were wiped dry against a standard plate on a well-lit black background for no more than 30 seconds. The results are shown in FIG. 2.

1.2. Analysis of causes of low fraction in dissolved state

The detected brewing white point is observed by a microscope, as shown in fig. 3, the shape is mostly circular, the edge is neat, the center can penetrate light, and the crack disappears in the observation process.

1.3. The results of microscopic and electron microscopic observation of the milk powder particles are shown in fig. 4, 5 and 6, and it can be seen from the pictures that a trace amount of air exists in the milk powder particles.

1.4. The results of microscopic observation of 374 experimental samples of infant formula with dissolution state fraction lower than 3 points from 10/15/2022/1/20/2021 are shown in table 1, wherein 366 bubbles, 97.86% of the content, 5 impurities, 1.34% of the content, 3 insoluble substances, 0.80% of the content are plotted, and the bera plot analysis is shown in fig. 7.

TABLE 1 reason classification and ratio of dissolution state less than 3 points

Form(s) of	Number of	Cumulative percentage (%)
			Air bubble	336	97.86
Impurities	5	99.20
			Insoluble substance	3	100.00

From the above results, it is presumed that the brew white point may be caused by bubbles.

2. Influence of test rest time on bubble dissipation condition after brewing

After brewing according to the dissolution state detection method, the container was kept still for 5min, 10min and 15min, and then shaken, and it was found that the brewing white spots on the inner wall of the container gradually disappeared, as shown in fig. 8.

3. Conclusion analysis

The dried powder particles contain a trace amount of air, are dispersed in water during reconstitution, do not completely escape from the water during detection, and appear as reconstituted white spots.

4. Reason investigation

4.1 staged detection and analysis of production Process

The production process flow is shown in fig. 9, the material dissolution state detection is carried out on the processes of vacuum mixing, homogenizing, wet mixing, storage, evaporation concentration and static bed cooling in the infant formula powder production in a segmented manner, and the result is shown in fig. 10, and the abnormal conditions of the dissolution state are all bubbles.

4.2 investigation of production Process flow

And (3) identifying the positions of air possibly introduced into each process by combining a production process flow chart, and analyzing and checking 8 production processes.

4.3 analysis of major influencing factors

4.3.1 air in the feed solution leads to an increase in the air content of the flour particles

According to the data to be investigated, the opening liquid level parameter of the stirrer is set to be too low (the stirring paddle of the stirrer is exposed on the surface of the material liquid, as shown in fig. 11), air is dissolved in the material liquid due to mechanical force in the stirring process, the material liquid after mixing is detected in a mode that the material liquid is submerged in the stirring paddle, and bubbles in the material liquid are obviously reduced. Data of the bubbles contained in the feed liquid before and after adjustment of the agitator start level parameters are shown in fig. 16.

4.3.2 the feed concentration plays a very important role, a high concentration leading to a low air content

In the preparation process of the raw milk powder, the discharge density of an evaporator is 1130 +/-5 kg/m ³ Low density, resulting in high air content, when the evaporator discharge density is adjusted to 1145 + -5 kg/m ³ Then, the bubbles in the feed liquid are obviously reduced. Data of the bubbles contained in the feed liquid before and after adjustment of the discharge density of the evaporator are shown in FIG. 17。

4.3.3 spray gun orifice size variations can result in air ingress into the thick milk droplets

The structure diagram of a DELAVAN spray gun is shown in FIG. 12, the atomization pair before and after the wear of a spray gun orifice plate is shown in FIG. 13, the aperture wear of the spray gun orifice plate is found to exceed 0.2mm, the atomization of the spray gun is not uniform, so that air is mixed in the granulation process, the actual value and the standard size of the spray gun orifice plate size of a drying tower are subjected to data collection and are measured 56 times, wherein the difference between the 40 times of actual value and the standard size is more than or equal to 0.2mm. The powder dissolution status data before and after the adjustment of the spray gun orifice plate wear replacement criteria are shown in fig. 18.

4.3.4 the height of the powder layer of the static fluidized bed of the drying tower is controlled to be lower than 10cm, which causes the introduction of air into the milk powder particles, the granulation effect is poor, and when the height of the powder layer of the static fluidized bed of the drying tower is controlled to be higher than 10cm, the air content in the milk powder particles is obviously reduced. The data of the powder dissolution state before and after the adjustment of the opening standard of the baffle of the static bed is shown in FIG. 19.

Example 2

A method for preparing milk powder comprises:

1. receiving fresh milk: sampling and detecting raw milk after the raw milk reaches a factory, cooling the raw milk to 0-4 ℃ through a plate heat exchanger after the raw milk is qualified, and pumping the raw milk into a storage tank for temporary storage;

2. and (3) pasteurization: heating raw milk in a plate heat exchanger for sterilization at 80.0 +/-2 deg.c for 16-20s, low temperature short time sterilizing to kill harmful microbes and ensure the nutrients in raw milk not to be destroyed, cooling to 0-6.0 deg.c and storing in pasteurized milk storing tank;

3. vacuum material mixing: according to the production formula, pasteurized milk and RO water are pumped into a circulating mixing system consisting of a wet mixing tank and a vacuum mixer, when the mixing temperature reaches 40 ℃, the vacuum mixer automatically extracts other raw materials (lactose, desalted whey powder, whey protein powder, concentrated whey protein powder and the like) -mineral matter tanks (compound mineral matters, sodium citrate, potassium chloride and the like) -calcium carbonate tanks (calcium carbonate, calcium hydrogen phosphate and the like) -vitamin tanks (compound vitamins, compound nutrients and the like) -after the addition, the system circulates and mixes for 600s to ensure that the raw materials are uniformly mixed, water pushing operation is carried out after the mixing is finished, and materials of the wet mixing circulation system are pumped into the wet mixing tank;

the formula of the milk powder comprises the following components in parts by weight: raw milk: 1820 parts (based on the solid content of 12.2%), desalted whey powder D70:225 parts, desalted whey powder D90:160 parts, skim milk powder: 155 parts of edible vegetable blend oil (comprising 49% of 1, 3-dioleate 2-palmitic acid triglyceride, 31% of sunflower seed oil, 15% of rapeseed oil and 5% of coconut oil): 120 parts, lactose: 75 parts of fructo-oligosaccharide: 20 parts, concentrated whey protein powder: 5 parts, whey protein powder: 10 parts of walnut oil: 5 parts of arachidonic acid grease powder (10%): 5 parts of docosahexaenoic acid grease powder (7%), 5 parts of calcium carbonate: 5 parts, phospholipid: 2 parts of anhydrous cream: 1 part of compound vitamin (comprising vitamin C, taurine, vitamin E, vitamin A, nicotinic acid, vitamin D, pantothenic acid, biotin, vitamin B12, vitamin K, folic acid, vitamin B1, vitamin B6 and lactose): 3 parts of compound minerals (including ferric pyrophosphate, zinc sulfate, magnesium sulfate, potassium iodate, copper sulfate and lactose): 1 part of compound nutrients (including inositol, L-carnitine, lutein, choline and lactose): 1 part, compound nucleotide: 0.58 portion.

4. Homogenizing and wet mixing storage: the edible plant blend oil and the wet mixed feed liquid synchronously enter a homogenizer for homogenization, the homogenization pressure is 125-135bar, fat balls become small after homogenization, the fat is guaranteed to be uniformly distributed in the feed liquid, free fat is prevented from being produced when products are mixed, and therefore fat floating is effectively prevented, and the edible plant blend oil is easier to digest and absorb. Cooling the feed liquid to 3-10 ℃ after homogenizing, and temporarily storing the feed liquid in a wet mixing storage tank;

5. and (3) evaporation and concentration: the material is pumped into the evaporator balance cylinder by the mixing storage tank, enters the flash evaporation type preheater for heating (the temperature of feed liquid at the outlet of the preheater is 40.0-55.0 ℃) and then enters the flash evaporation tank, and is pumped into the sterilizer and the heat preservation pipe by the flash evaporation discharge pump for sterilization, wherein the sterilization temperature is 95.0 +/-2 ℃, and the heat preservation time is as follows: 6-8s, the sterilized materials enter an effect body for concentration, the effect body is subjected to steam heating through a hot pressure pump, the materials are subjected to evaporation concentration through a first effect body (the effect body temperature is 65.0-80.0 ℃), a second effect body (the effect body temperature is 60.0-70.0 ℃) and a third effect body (the effect body temperature is 55.0-65.0 ℃) in sequence, and the materials reach the required material concentration (the dry matter content is 40-55 percent) and then enter a thick milk tank;

6. preheating concentrated milk: heating the concentrated milk to 70-80 ℃ by a tubular heat exchanger (improving the flowability of the concentrated milk), and then feeding the concentrated milk into an atomization system;

7. atomizing and agglomerating: the spraying pressure is 200-250bar, the thick milk is atomized into small droplets through a spray gun, and the droplets and the powder particles are bonded together to achieve the agglomeration effect, so that larger powder particles are formed;

8. cooling in a stationary bed: the concentrated milk liquid drops fall into a static bed at the bottom of the drying tower after being dried instantly by hot air, the opening degree of a static bed current plate is less than or equal to 10 percent, and the milk powder is obtained after the temperature of the milk powder is reduced to 30-35 ℃ by passing through a fluidized bed after the temperature of 60-65 ℃ is reduced by air;

wherein, the preparation method satisfies the following conditions:

a. the starting liquid level parameter of a stirring motor of the material liquid storage tank is set to be 24 percent, so that the material liquid passes through a stirring paddle of the stirrer in the material mixing process;

b. the discharge density of evaporation concentration is set to be 1140-1150kg/m ³ ；

c. Selecting a spray drying atomizer with the abrasion of a spray gun orifice plate within 0.2 mm;

d. opening degree standard of a stationary bed baffle: less than or equal to 10 percent, so that the thickness of the powder layer of the fluidized bed is more than 10 cm.

The dissolution state score of the prepared milk powder is detected, the result is shown in figure 14, no brewing white point is observed, and the score is 5; the prepared powdered milk is observed by an electron microscope, and the result is shown in figure 15, and the air content in the powdered milk particles can be obviously reduced.

Comparative example 1

The difference from example 2 is that:

a. the starting liquid level parameter of a stirring motor of the material liquid storage tank is set to be 19%, and a stirring paddle of a stirrer is exposed on the surface of the material liquid in the material mixing process;

b. the discharge density of evaporation concentration is set to be 1125-1135kg/m ³ ；

c. A spray dryer with a spray gun orifice plate worn by more than 0.2 mm;

d. opening degree standard of a baffle of a static bed: >10% such that the thickness of the powder layer of the fluidized bed is within 10 cm.

Detecting the dissolution state score of the prepared milk powder, wherein the result is shown in figure 2, and the score is less than 3; the prepared milk powder was observed by electron microscopy, and as a result, as shown in fig. 5 and 6, it was seen that a trace amount of air was present in the milk powder particles.

Comparative example 2

The difference from comparative example 1 is that:

a. the starting liquid level parameter of the stirring motor of the material liquid storage tank is set to be 24 percent, so that in the material mixing process, the material liquid submerges the stirring paddle of the stirrer.

b. The discharge density of evaporation concentration is set to be 1140-1150kg/m ³ 。

c. A spray drying atomizer was selected in which the wear of the spray gun orifice plate was within 0.2mm.

Comparative example 3

The difference from comparative example 1 is that:

Comparative example 4

The difference from comparative example 1 is that:

c. A spray dryer with a wear of the orifice plate of the spray gun within 0.2mm is selected.

Comparative example 5

The difference from comparative example 1 is that:

b. discharge density setting for evaporative concentrationIs 1140-1150kg/m ³ 。

c. A spray dryer with a lance orifice plate wear within 0.2mm was selected.

d. The opening degree standard of the baffle of the static fluidized bed is as follows: less than or equal to 10 percent, so that the thickness of the powder layer is more than 10 cm.

The results of the tests performed on the above 4 comparative examples are shown in table 2, and it is concluded that if 3 of the adjustments and 1 of the adjustments are not adjusted, the dissolution state of the product is not qualified, and if all the adjustments are adjusted, the dissolution state is qualified: the 4 aspects all affect the detection result of the dissolution state of the product.

TABLE 2

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing milk powder capable of improving the dissolution state of the milk powder is characterized by comprising the following steps: mixing raw materials for preparing the milk powder, homogenizing, concentrating, spray drying and cooling in sequence to prepare the milk powder;

2. A method for preparing milk powder according to claim 1, characterized in that during mixing, the feed liquid is passed through the paddles of the mixer.

3. The method for preparing milk powder according to claim 1, wherein in the concentration process, the density of the feed liquid is concentrated to 1140-1150kg/m ³ 。

4. The method for preparing powdered milk according to claim 1, wherein spray drying is performed using a spray gun having a wear of 0.2mm or less of a spray gun orifice;

preferably, the spraying pressure is from 200 to 250bar.

5. The method for preparing powdered milk according to claim 1, wherein the thickness of the powder layer of the static fluidized bed is controlled to be 10cm or more.

6. The method for preparing milk powder according to claim 1, wherein the mixing is mixing raw materials for preparing milk powder;

preferably, the edible vegetable oil is used in an amount of 110-140 parts by weight.

7. The method of claim 6, wherein the fresh milk comprises raw milk or raw goat milk.

8. A method of preparing a milk powder according to claim 1, wherein the homogenising pressure is 125-135bar.

9. The milk powder preparation method according to claim 1, further comprising a step of sterilizing fresh milk before mixing;

the sterilization means includes pasteurization.

10. A powdered milk produced by the production method according to any one of claims 1 to 9.