Soluble calcium reinforced thermostable high-protein milk beverage and preparation method thereof

Abstract

The invention relates to the technical field of food processing, and provides a soluble calcium reinforced thermostable high-protein milk beverage and a preparation method thereof.Casein phosphopeptide-calcium chelate is adopted for conducting calcium reinforcement on a raw material system with the protein content being 5% or above, and due to calcium reinforcement, the calcium content of the raw material system is increased to 1.9 g / L or above; the milk beverage prepared by the method has excellent thermal stability on the premise of high calcium, high protein and no addition of exogenous stabilizers. Furthermore, in combination with TG enzyme treatment, the heat stability of the high-protein beverage is further improved. The method disclosed by the invention can comprise a heat treatment process at the temperature of more than or equal to 130 DEG C, a raw material system does not generate flocculation in the processing process, and precipitates are greatly reduced, so that the method is very beneficial to industrial production of the milk beverage.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a soluble calcium-fortified high-protein milk beverage and its preparation method, and more particularly to a soluble calcium-fortified heat-stable high-protein milk beverage and its preparation method. Background Technology

[0002] With increasing health awareness and a booming fitness market, the high-protein dairy beverage market is experiencing rapid growth. These products typically use milk protein concentrate (MPC) as a raw material, with a protein content of 6% or higher, aiming to meet the needs of athletes, fitness enthusiasts, and the elderly for high-quality protein supplementation. At the same time, calcium, a key element for maintaining bone and muscle health, is also increasingly in demand. Therefore, developing dairy beverages with both high protein and high calcium content has significant market potential.

[0003] To achieve calcium fortification, a common approach in existing technologies is to add insoluble calcium salts, such as calcium carbonate. However, this approach has inherent drawbacks. First, insoluble calcium salts like calcium carbonate are suspended in liquids and will settle due to gravity during product storage, forming a white precipitate layer at the bottom of the container, severely affecting the product's appearance and quality uniformity. To solve this problem, stabilizers (such as carrageenan and xanthan gum) must be added to the formulation to create a suspension system. This not only increases production costs but also complicates the product's ingredient list, contradicting current consumer trends that favor clean labels and simplified ingredient lists.

[0004] Another technical approach involved using soluble calcium salts, but experiments revealed that this caused even more severe thermal stability problems in high-protein dairy beverage systems. The colloidal system of high-protein dairy beverages is inherently very sensitive to heat treatment. During ultra-high temperature (UHT) sterilization, essential for commercial aseptic processing, the addition of soluble calcium salts led to a sharp increase in the concentration of free calcium ions in the system. This had two destructive effects: first, it neutralized the negative charge on the surface of casein micelles, disrupting the electrostatic repulsion stabilization mechanism; second, the highly reactive calcium ions acted as "calcium bridges" at high temperatures, forming cross-links between protein molecules. The combined effect of these two factors caused violent and irreversible aggregation, flocculation, and precipitation of proteins during heat treatment, potentially clogging production equipment and preventing the final product from forming a homogeneous and stable liquid state.

[0005] Therefore, developing a high-protein dairy beverage that can effectively fortify calcium, withstand stringent ultra-high temperature sterilization without protein flocculation, and maintain a uniform and stable liquid state throughout its shelf life is of great application value. Summary of the Invention

[0006] This invention provides a soluble calcium-fortified heat-stable high-protein milk beverage and its preparation method, which achieves effective calcium fortification and enables the product to withstand harsh ultra-high temperature sterilization without protein flocculation, maintaining a uniform and stable liquid state throughout its shelf life without the addition of any stabilizers.

[0007] In a first aspect, the present invention provides a dairy beverage in which casein phosphopeptide-calcium chelate is added to a raw material system with a protein content of 5% or more, followed by treatment with TG enzyme and then enzyme inactivation; the casein phosphopeptide-calcium chelate fortifies the raw material system with calcium, thereby increasing the calcium content of the raw material system to 1.9 g / L or more.

[0008] Studies have found that casein phosphopeptide-calcium chelates, compared to inorganic calcium supplements, not only have higher bioavailability but also exhibit superior thermal stability compared to common soluble calcium when used fortifying high-protein dairy beverages at the same calcium addition level. This invention utilizes casein phosphopeptide-calcium chelates to fortify high-protein beverages with calcium and reduces the adverse effects of calcium addition on thermal stability through TG enzyme treatment. Excellent stability is achieved without the need for emulsifiers and stabilizers during heat treatment. This not only simplifies the production process but also avoids undesirable flavor and texture problems that may result from the addition of stabilizers and emulsifiers, enabling the preparation of clean-label dairy beverages.

[0009] Generally, in raw material systems with a protein content of 5% or more, the higher the protein content, the more difficult it is to optimize the stability. In this invention, the protein content in the raw material system can be further preferably 6% or more, further preferably 7% or more, further preferably 8% or more, further preferably 9% or more, further preferably 10% or more, further preferably 11% or more, and further preferably 12% or more.

[0010] The amount of TG enzyme has a critical effect on thermal stability. In the dairy beverage provided by the present invention, the amount of TG enzyme is 3~6 U / g protein.

[0011] The amount of TG enzyme used in this invention is 3~6 U / g protein, for example, it can be any value or a range of values ​​among 3 U / g, 4 U / g, 5 U / g, and 6 U / g.

[0012] According to the dairy beverage provided by the present invention, the casein phosphopeptide-calcium chelate is obtained by chelating casein phosphopeptide and calcium ions; The casein phosphopeptide-calcium chelate of this invention is a casein hydrolysate calcium chelate with a calcium content higher than the calcium content of the raw material system where the protein content is more than 5%. Preferably, the calcium content of the casein phosphopeptide-calcium chelate is less than 25%.

[0013] The calcium content of the casein phosphopeptide-calcium chelate described in this invention is less than 25%, and can be any value or a range of values ​​from 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, and 25%.

[0014] More preferably, the amount of casein phosphopeptide-calcium chelate used increases the calcium content of the raw material system by less than 0.6 g / L.

[0015] In this invention, the increase in calcium content of the raw material system is less than 0.6 g / L, which can be any value or a range of values ​​from 0.05 g / L, 0.10 g / L, 0.15 g / L, 0.20 g / L, 0.25 g / L, 0.30 g / L, 0.35 g / L, 0.40 g / L, 0.45 g / L, 0.50 g / L, 0.55 g / L, and 0.60 g / L.

[0016] The casein phosphopeptide-calcium chelate of the present invention can also be understood as a calcium-rich casein phosphopeptide, which can be prepared using conventional methods in the art, such as existing protein enzymatic hydrolysis techniques. Alternatively, it can be prepared using the method described in the reference Preparation, characterization, and osteogenic activity mechanism of casein phosphopeptide-calcium chelate, DOI 10.3389 / fnut.2022.960228.

[0017] According to the dairy beverage provided by the present invention, the calcium content in the raw material system is less than 2.4 g / L.

[0018] The calcium content in the raw material system described in this invention is below 2.4 g / L, for example, it can be any value or a range of values ​​from 1.80 g / L, 1.85 g / L, 1.90 g / L, 1.95 g / L, 2.00 g / L, 2.05 g / L, 2.10 g / L, 2.15 g / L, 2.20 g / L, 2.25 g / L, 2.30 g / L, 2.35 g / L, and 2.40 g / L.

[0019] Preferably, the raw material system with a protein content of 5% or more is prepared using concentrated milk protein as the main raw material; Preferably, the concentrated milk protein has a protein content of more than 50% and a calcium content of 1% to 3%.

[0020] Compared to plant protein, milk protein is easier to digest and absorb. Its amino acid composition is more reasonable and the ratio is closer to the human body's needs. In particular, it has a very high content of branched-chain amino acids (leucine, isoleucine, and valine), which can effectively promote muscle protein synthesis.

[0021] The concentrated milk protein has a protein content of 50% or more, for example, it can be any value or a range of values ​​from 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%.

[0022] The concentrated milk protein contains 1% to 3% protein and 1% to 3% calcium. For example, it can be any value or a range of values ​​from 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, to 3.0%.

[0023] According to the dairy beverage provided by the present invention, the raw materials of the dairy beverage do not contain colloidal stabilizers; Preferably, the raw materials of the dairy beverage are concentrated milk protein, casein phosphopeptide-calcium chelate, and water.

[0024] According to the dairy beverage provided by the present invention, after the TG enzyme treatment is completed, a heat treatment at a temperature of 130°C or higher is performed.

[0025] The heat treatment at a temperature greater than or equal to 130°C described in this invention can be any value or a range of values ​​from 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C, and 160°C.

[0026] In the actual production of dairy beverages, heat treatment is an unavoidable processing technique. For the raw material system used to prepare these beverages, higher thermal stability during heat treatment results in higher quality and more stable product quality, which is particularly important for industrial production. Research has found that by using the specific raw material system described above, along with TG enzyme treatment, the raw material system can maintain excellent stability under heat treatment conditions at temperatures greater than or equal to 130°C.

[0027] According to the dairy beverage provided by the present invention, after the TG enzyme treatment is completed, a UHT ultra-high temperature sterilization process is performed.

[0028] More preferably, the temperature of the UHT ultra-high temperature sterilization process is 135~150℃ and the time is 2~8s.

[0029] The temperature described in this invention is 135~150℃, for example, it can be any value or a numerical range composed of any values ​​among 135℃, 140℃, 145℃, and 150℃.

[0030] The time mentioned in this invention is 2 to 8 seconds, for example, it can be any value or a numerical range composed of any values ​​among 2s, 3s, 4s, 5s, 6s, 7s, and 8s.

[0031] According to the dairy beverage provided by the present invention, the average particle size of the dairy beverage is less than 350 nm.

[0032] The average particle size described in this invention is below 350nm, and can be any value or a range of values ​​among 350nm, 330nm, 310nm, 290nm, 270nm, 250nm, 230nm, 210nm, 190nm, 170nm, 150nm, 130nm, 110nm, 90nm, 70nm, and 50nm.

[0033] The average particle size of a milk beverage reflects both the stability of the system and its microstructure. In this invention, controlling the average particle size of the milk beverage within the aforementioned range is beneficial for obtaining a high-calcium, high-protein milk beverage with better thermal stability.

[0034] Secondly, the present invention also provides a method for preparing the milk beverage, comprising: adding casein phosphopeptide-calcium chelate to a raw material system with a protein content of 5% or more, then treating it with TG enzyme, and then inactivating the enzyme; wherein the casein phosphopeptide-calcium chelate fortifies the raw material system with calcium, and the calcium fortification increases the calcium content of the raw material system to 1.9 g / L or more.

[0035] The method for preparing the dairy beverage according to the present invention includes: The casein phosphopeptide-calcium chelate was mixed with the other raw materials except TG enzyme in water to obtain the first mixture; The first mixture is homogenized to obtain a second mixture; preferably, the homogenization pressure is 10~50MPa, the number of homogenizations is 1~3, and the temperature is 25~55℃; the purpose of homogenization is to fully dissolve the milk raw material (such as concentrated milk protein) in the first mixture. The TG enzyme is mixed with the second mixture and treated at a temperature at which the TG enzyme is active to obtain a third mixture; preferably, the temperature at which the TG enzyme is active is 45~55°C, and the treatment time is more than 4 hours, more preferably 4~6 hours; The third mixture is subjected to enzyme inactivation treatment to obtain a fourth mixture; preferably, the enzyme inactivation temperature is above 75°C and the enzyme inactivation time is above 5 minutes.

[0036] The fourth mixture is then sterilized by heat treatment at a temperature of 130°C or higher to obtain the milk beverage.

[0037] The homogenizing pressure described in this invention is 10~50 MPa, for example, it can be any value or a range of values ​​among 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, and 50 MPa.

[0038] The temperature described in this invention is 25~55℃, for example, it can be any value or a numerical range composed of any values ​​among 25℃, 30℃, 35℃, 45℃, and 55℃.

[0039] The TG enzyme described in this invention has an activity temperature of 45~55℃, for example, it can be any value or a numerical range composed of any values ​​among 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, and 55℃.

[0040] The processing time described in this invention is 4 hours or more, for example, it can be any value or a numerical range composed of any values ​​from 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, and 10h.

[0041] This invention provides a soluble calcium-fortified heat-stable high-protein dairy beverage and its preparation method. The method involves adding casein phosphopeptide-calcium chelate to a raw material system with a protein content of 5% or higher, followed by TG enzyme treatment and enzyme inactivation. The casein phosphopeptide-calcium chelate fortifies the raw material system with calcium, increasing the calcium content to over 1.9 g / L. The resulting dairy beverage exhibits excellent heat stability while possessing high calcium and protein content and requiring no exogenous stabilizers.

[0042] Furthermore, by incorporating TG enzyme treatment, the method of the present invention can include heat treatment at a temperature of 130°C or higher, during which the raw material system does not produce flocculation and precipitation is greatly reduced, making it highly suitable for industrial production of dairy beverages. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is the average particle size distribution diagram of test example 1 provided by the present invention, corresponding to proportions 1 to 4.

[0045] Figure 2 This is the average particle size distribution diagram of test example 1 provided by the present invention, corresponding to ratios 5 to 6.

[0046] Figure 3 This is the average particle size distribution diagram of corresponding ratios 9 to 10 in Test Example 1 provided by the present invention.

[0047] Figure 4 The average particle size distribution diagrams of Test Example 1 provided by this invention correspond to Examples 1 to 4.

[0048] Figure 5 The average particle size distribution diagram of test example 1 provided by the present invention corresponds to proportions 13 to 16.

[0049] Figure 6 The average particle size distribution diagram of test example 1 provided by the present invention corresponds to proportions 17 to 20. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] The following is combined Figures 1-6 This invention describes a soluble calcium-fortified high-protein milk beverage and its preparation method.

[0052] The casein phosphopeptide-calcium chelate used in the following embodiments of the present invention has a calcium content of 5% and was purchased from Guangzhou Green Extract Biotechnology Co., Ltd.

[0053] The Tg enzyme used in this invention was purchased from Taixing Dongsheng Biotechnology Co., Ltd.

[0054] The concentrated milk protein in this invention has a protein content of 80% (by mass) and a calcium content of 1.8%.

[0055] Preparation Example 1: Lysine Calcium Chelate Solution Calcium chloride and L-lysine were dissolved in water at a molar ratio of 1:2, heated to 75°C and stirred at 300 rpm for 1 hour. The pH was adjusted to 6.5 with gluconic acid to obtain a lysine-calcium chelate solution.

[0056] Examples 1-4 This embodiment provides a dairy beverage whose raw materials are concentrated milk protein, casein phosphopeptide-calcium chelate and water.

[0057] This embodiment also provides a method for preparing the above-mentioned dairy beverage, the steps of which are as follows: (1) Mix concentrated milk protein and casein phosphopeptide-calcium chelate in water and stir at 50°C and 300 rpm for 1 hour to obtain the first mixture. The mass ratio of casein phosphopeptide-calcium chelate to concentrated milk protein and the mass ratio of concentrated milk protein to water are shown in the table below.

[0058] (2) The first mixture was homogenized at 25℃ and 30MPa for 3 times to obtain the second mixture.

[0059] (3) Mix the TG enzyme with the second mixture and treat it at 50°C for 5 hours to obtain the third mixture; (4) The third mixture was subjected to enzyme inactivation treatment to obtain the fourth mixture; the enzyme inactivation temperature was 75℃ and the enzyme inactivation time was 5min.

[0060] (5) The fourth mixture is then subjected to UHT ultra-high temperature sterilization to obtain the milk beverage. The temperature of the UHT ultra-high temperature sterilization process is 140℃ and the time is 6s.

[0061] The protein and calcium content of the resulting milk beverage is shown in the table below.

[0062] Table 1

[0063] Comparative Examples 1-4 This comparative example provides a dairy beverage whose raw materials are concentrated milk protein, casein phosphopeptide-calcium chelate, and water.

[0064] This comparative example also provides a method for preparing the above-mentioned dairy beverage, the steps of which are as follows: (1) Mix concentrated milk protein and casein phosphopeptide-calcium chelate in water and stir at 50°C and 300 rpm for 1 hour to obtain the first mixture. The protein mass ratio of casein phosphopeptide-calcium chelate to concentrated milk protein and the mass ratio of protein to water in concentrated milk protein are shown in the table below.

[0065] (2) The first mixture was homogenized at 25℃ and 30MPa for 3 times to obtain the second mixture.

[0066] (3) The second mixture is then subjected to UHT ultra-high temperature sterilization to obtain a milk beverage. The temperature of the UHT ultra-high temperature sterilization process is 140℃ and the time is 6s.

[0067] The protein and calcium content of the resulting milk beverage is shown in the table below.

[0068] Table 2

[0069] Comparative Examples 5-12 The results were basically the same as those in Comparative Example 1, except that the casein phosphopeptide-calcium chelate was replaced with other calcium-containing substances (as shown in the table below), resulting in a milk beverage with the calcium content shown in the table below.

[0070] Table 3

[0071] Comparative Examples 13-21 The process is basically the same as in Example 1, except that the casein phosphopeptide-calcium chelate is replaced with other calcium-containing substances (as shown in the table below), resulting in a milk beverage with the calcium content shown in the table below.

[0072] Table 4

[0073] To verify the stability of the above-mentioned dairy beverage of the present invention, the formulations of the dairy beverages in the above-mentioned embodiments and comparative examples of the present invention were tested as follows.

[0074] Test case Sample preparation: The mixture obtained before the UHT ultra-high temperature sterilization process in the examples and comparative examples was used as the sample to be tested. That is, the fourth mixture was used as the sample to be tested in Examples 1-4 and Comparative Examples 13-21. The fourth mixture was placed in an environment of 4°C for refrigeration and was kept for later use. The second mixture obtained in step (2) was used as the sample to be tested in Comparative Examples 1-4 and Comparative Examples 5-12. The second mixture was placed in an environment of 4°C for refrigeration and was kept for later use.

[0075] Test metrics and test methods: Thermal flocculation time: Take 2 mL of the sample to be tested and put it into an ampoule. After heat sealing the ampoule, place it in an oil bath at 140℃ and shake it at a constant speed of 8 times per minute. Record the time when flocculation first appears as the thermal flocculation time.

[0076] Centrifugal sedimentation rate: Take 2 mL of the sample to be tested and put it into an ampoule. After heat sealing the ampoule, heat-treat it at 140℃ for 30 s, and then immediately cool it to room temperature under running cold water. Centrifuge at 3000g for 30 min, and dry the precipitate at 105℃ to constant weight. The mass is m. Alternatively, dry 2 mL of the sample directly to constant weight and weigh it. The mass is M. Centrifugal sedimentation rate = m / M × 100%.

[0077] Ethanol stability: Take 2 mL of the sample to be tested in a dry and clean petri dish, and mix it with an equal volume of ethanol of different concentrations. Record the ethanol concentration at which visible flocculation first appears. This concentration is the ethanol stability (%) of the sample. If no flocculation occurs when an equal volume of anhydrous ethanol is mixed with the sample, increase the volume of anhydrous ethanol. At this point, the ethanol stability is the ratio of the volume of anhydrous ethanol to the volume of the sample when visible flocculation occurs (for example, when 2 mL of sample is mixed with 3 mL of anhydrous ethanol, visible flocculation begins to appear. At this point, the ethanol stability is 150%).

[0078] Average particle size: 2 mL of the sample to be tested was placed into an ampoule. After the ampoule was heat-sealed, it was heat-treated at 140℃ for 30 s and then immediately cooled to room temperature under running cool water. The particle size distribution of casein micelles was measured using a nanoparticle size analyzer, with a dilution factor of 1:150 (v / v).

[0079] The test results are as follows: Table 5

[0080] The above data is analyzed as follows: (1) Thermal flocculation time As shown in the table above, the high-protein beverages fortified with casein phosphopeptide-calcium chelate had significantly longer thermal flocculation times than those fortified with calcium chloride and calcium gluconate under different calcium addition conditions.

[0081] Taking a calcium content of 2.2 g / L as an example, the thermal flocculation time of milk beverages fortified with casein phosphopeptide-calcium chelate is 1.85 minutes, while the thermal flocculation times of milk beverages fortified with calcium chloride and calcium gluconate are only 0.18 minutes and 0.34 minutes, respectively. This fully demonstrates that milk beverages fortified with casein phosphopeptide-calcium chelate have better stability under high temperature conditions, can maintain a uniform and stable state for a longer time, and effectively reduce the occurrence of flocculation.

[0082] When treated with TG enzyme, taking a calcium content of 2.2 g / L as an example, TG enzyme treatment significantly extended the thermal flocculation time of the casein phosphopeptide-calcium chelate-fortified milk beverage from 1.85 minutes to 5.43 minutes. In contrast, the increase in thermal flocculation time of the mixture of calcium chloride and calcium gluconate after TG enzyme treatment was smaller, far lower than that of the casein phosphopeptide-calcium chelate-fortified milk beverage. This indicates that TG enzyme treatment can effectively enhance the thermal stability of the casein phosphopeptide-calcium chelate-fortified milk beverage, improve the calcium tolerance of the system, and enable it to resist flocculation more effectively under high temperature conditions, maintaining better physical stability. Although the thermal flocculation time of the mixture of calcium chloride and calcium gluconate in the TG enzyme-treated milk beverage changed compared to the untreated sample, the increase was limited, and its thermal stability was still inferior to that of the casein phosphopeptide-calcium chelate-fortified sample.

[0083] (2) Centrifugal sedimentation rate Under all calcium addition conditions, the centrifugal sedimentation rate of milk beverages fortified with casein phosphopeptide-calcium chelate was significantly lower than that of milk beverages fortified with calcium chloride and calcium gluconate. This means that milk beverages fortified with casein phosphopeptide-calcium chelate are less prone to sedimentation after heat treatment, thus ensuring greater product stability.

[0084] After treatment with TG enzyme, the centrifugation sedimentation rate of all TG enzyme-treated samples was lower than that of untreated samples. Among them, when the calcium content was 2.4 g / L, the centrifugation sedimentation rate of the casein phosphopeptide-calcium chelate-fortified milk beverage after TG enzyme treatment was 6.48%, which was significantly lower than the 8.54% of the untreated samples.

[0085] (3) Ethanol stability The data in the table above show that, at various calcium addition levels, the casein phosphopeptide-calcium chelate-fortified milk beverages exhibit higher ethanol stability, and the ethanol concentration at which flocculation begins is significantly higher than that of milk beverages fortified with calcium chloride and calcium gluconate.

[0086] Taking a calcium content of 2.0 g / L as an example, the ethanol stability of milk beverages fortified with casein phosphopeptide-calcium chelate is 66.66%, while that of milk beverages fortified with calcium chloride and calcium gluconate is 37.33% and 40.66%, respectively. This further highlights the stability advantage of high-protein beverages fortified with casein phosphopeptide-calcium chelate.

[0087] When treated with TG enzyme, taking a calcium content of 2.0 g / L as an example, ethanol stability was further improved after TG enzyme treatment. At the same calcium addition level, the heat stability of milk beverages fortified with TG enzyme combined with casein phosphopeptide-calcium chelate was superior to the other two calcium fortifiers. Specifically, when treated with TG enzyme, taking a calcium content of 2.4 g / L as an example, enzyme treatment increased the ethanol stability of milk beverages fortified with casein phosphopeptide-calcium chelate from 43.66% to 86.66%, more than doubling, while the improvement was smaller for milk beverages fortified with calcium chloride and calcium gluconate. This highlights the technical advantage of TG enzyme treatment combined with casein phosphopeptide-calcium chelate fortification in improving product stability.

[0088] (4) Average particle size The particle size distribution diagrams of Examples 1-4 and Comparative Examples 1-20 are as follows: Figures 1-6 As shown, it can be seen that: When the calcium content was below 2.4 g / L, the average particle size of the casein phosphopeptide-calcium chelate-fortified milk beverage showed little change; however, when the calcium content reached 2.4 g / L, the average particle size significantly increased to 313.4 nm. Further analysis of the particle size distribution revealed that when the calcium content was below 2.4 g / L, the casein particle size distribution of the casein phosphopeptide-calcium chelate-fortified milk beverage was relatively uniform, with little change in particle size before and after heat treatment; however, when the calcium content was below 2.4 g / L, the peak value of the particle size distribution curve shifted to the right, indicating that small casein micelles aggregated and formed larger micelles.

[0089] In contrast, after heat treatment, the casein particle size distribution of samples fortified with calcium chloride and calcium gluconate showed a rightward shift or a bimodal phenomenon only when the calcium content was 2.0 g / L. This indicates that under these two calcium fortification methods, casein micelles are more likely to aggregate or flocculate during heat treatment.

[0090] Overall, casein phosphopeptide-calcium chelates have a relatively small impact on the structural stability of casein micelles during heat treatment, and can mitigate aggregation or flocculation caused by heat to some extent. However, excessive calcium addition can still lead to decreased thermal stability, thus adversely affecting the product.

[0091] The samples treated with TG enzyme showed smaller average particle sizes after heat treatment compared to the untreated samples. Taking a casein phosphopeptide-calcium chelate-fortified milk beverage as an example, at a calcium content of 2.4 g / L, the average particle size of the untreated sample after heat treatment was 313.4 nm, while after TG enzyme treatment, the average particle size significantly decreased to 172.1 nm, with a smaller change in the particle size distribution curve. Although the average particle size increased slightly in the other two calcium fortification methods, the particle size distribution curves at calcium contents of 2.2 g / L and 2.4 g / L showed a rightward shift of the peak and a double-peak phenomenon. This clearly demonstrates that TG enzyme treatment can effectively reduce the adverse effects of calcium addition on the product's thermal stability, thereby improving the product's thermal stability. Furthermore, the combination of TG enzyme treatment and casein phosphopeptide-calcium chelate fortification has significant advantages in improving product thermal stability.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dairy beverage, characterized in that, The preparation process of the dairy beverage includes: adding casein phosphopeptide-calcium chelate to a raw material system with a protein content of more than 5%, then treating it with TG enzyme, and then inactivating the enzyme; the casein phosphopeptide-calcium chelate fortifies the raw material system with calcium, and the calcium fortification increases the calcium content of the raw material system to more than 1.9 g / L.

2. The dairy beverage according to claim 1, characterized in that, The dosage of the TG enzyme is 3-6 U / g protein.

3. The dairy beverage according to claim 1 or 2, characterized in that, The casein phosphopeptide-calcium chelate is obtained by chelating casein phosphopeptide and calcium ions. Preferably, the calcium content of the casein phosphopeptide-calcium chelate is less than 25%. More preferably, the amount of casein phosphopeptide-calcium chelate used increases the calcium content of the raw material system by less than 0.6 g / L.

4. The dairy beverage according to any one of claims 1 to 3, characterized in that, In raw material systems with a protein content of 5% or higher, the calcium content is below 2.4 g / L; Preferably, the raw material system with a protein content of 5% or more is prepared from concentrated milk protein as the main raw material; Preferably, the concentrated milk protein has a protein content of more than 50% and a calcium content of 1% to 3%.

5. The dairy beverage according to any one of claims 1 to 4, characterized in that, The raw materials of the dairy beverage do not contain colloidal stabilizers; Preferably, the raw materials of the dairy beverage are concentrated milk protein, casein phosphopeptide-calcium chelate, and water.

6. The dairy beverage according to any one of claims 1 to 5, characterized in that, After the TG enzyme treatment is completed, a heat treatment at a temperature of 130°C or higher is performed.

7. The dairy beverage according to any one of claims 1 to 6, characterized in that, After the TG enzyme treatment is completed, an ultra-high temperature sterilization process (UHT) is performed.

8. The dairy beverage according to any one of claims 1 to 7, characterized in that, The average particle size of the dairy beverage is below 350 nm.

9. A method for preparing the dairy beverage according to any one of claims 1 to 8, characterized in that, include: After adding casein phosphopeptide-calcium chelate to a raw material system with a protein content of 5% or more, the raw material system is treated with TG enzyme and then the enzyme is inactivated; the casein phosphopeptide-calcium chelate fortifies the raw material system with calcium, and the calcium fortification increases the calcium content of the raw material system to more than 1.9 g / L.

10. The method for preparing the dairy beverage according to claim 9, characterized in that, include: The casein phosphopeptide-calcium chelate was mixed with the other raw materials except TG enzyme in water to obtain the first mixture; The first mixture is homogenized to obtain a second mixture; The TG enzyme is mixed with the second mixture and treated at a temperature at which the TG enzyme is active to obtain a third mixture; The third mixture is subjected to enzyme inactivation treatment to obtain the fourth mixture; The fourth mixture is then sterilized by heat treatment at a temperature of 130°C or higher to obtain the milk beverage.

Images