Preparation method of liquid camel milk

Abstract

The invention discloses a preparation method of liquid camel milk, and belongs to the technical field of food processing. The preparation method of the liquid camel milk provided by the invention comprises the following steps: (1) homogenizing a mixture containing raw materials camel milk and a calcium chelating agent; and (2) performing ultrahigh-temperature instantaneous sterilization on the homogenized mixture to obtain the liquid camel milk, in the step (1), the calcium chelating agent is selected from at least one of disodium hydrogen phosphate, sodium hexametaphosphate and sodium citrate. The added calcium chelating agent chelates free calcium ions in camel milk, so that the thermal stability of the product is remarkably improved. The obtained ultra-high-temperature sterilized camel milk is in a uniform fluid state and has no precipitation and layering phenomena in the shelf life.

Description

Technical Field

[0001] This application belongs to the field of food processing technology, and in particular relates to a method for preparing liquid camel milk. Background Technology

[0002] Camel milk, as a unique milk source with high nutritional value, has attracted widespread attention from consumers in recent years. Compared with other animal milks, camel milk does not contain the allergen β-lactoglobulin, reducing the risk of allergies; moreover, its β-casein content is significantly higher than that of cow's milk. Since β-casein is more easily broken down by digestive enzymes, camel milk casein has better digestibility. Existing research shows that the calcium content of camel milk is significantly higher than that of cow's milk. The calcium content of cow's milk is approximately 1257 mg / 100g, while that of camel milk is as high as approximately 1579.19 mg / L. In addition, camel milk is rich in lactoferrin, immunoglobulins, lysozyme, polyunsaturated fatty acids, oligosaccharides, and other bioactive substances. Studies have shown that these bioactive substances have potential benefits in regulating blood sugar.

[0003] Ultra-high temperature (UHT) sterilization is a commonly used sterilization process for liquid dairy products, widely used in the dairy industry due to its high sterilization efficiency and the advantage of room temperature storage for several months. However, when applied to camel milk, the high temperature causes protein denaturation. These denatured proteins gradually form irreversible precipitates during storage, leading to quality defects such as product stratification and sedimentation, which seriously affects the shelf life of liquid camel milk products.

[0004] To address the aforementioned issues, adding calcium chelating agents is a low-cost and effective solution. Regarding the selection of calcium chelating agents, while studies have shown that sodium citrate is commonly used to improve the thermal instability of sheep milk, it does not address the unique characteristics of camel milk. Furthermore, other stabilizers used in the market, although they can reduce sedimentation, can easily lead to abnormally high viscosity in camel milk, affecting its taste. These existing technologies do not fully consider the unique protein composition and calcium ion distribution characteristics of camel milk, and therefore cannot fundamentally solve its UHT processing stability problem. Summary of the Invention

[0005] To overcome the aforementioned deficiencies in the existing technology, this application provides a method for preparing liquid camel milk. By adding three calcium chelating agents—disodium hydrogen phosphate, sodium hexametaphosphate, and sodium citrate—the method chelates free calcium ions released upon heating to maintain ionic balance, thereby significantly improving the thermal stability of camel milk. It also provides auxiliary stabilizing effects such as buffering pH and increasing electrostatic repulsion between casein particles. This application uses pH, particle size, zeta potential, turbidity, viscosity, sedimentation amount, and stability coefficient as detection indicators to determine the optimal type and amount of calcium chelating agent for preparing camel milk under optimal stability, providing a theoretical basis for camel milk production and processing. Furthermore, the type and amount of all calcium chelating agents in this application strictly comply with the provisions of GB 2760-2024 "National Food Safety Standard for the Use of Food Additives," ensuring safety.

[0006] To achieve the above-mentioned objectives, this application provides the following technical solution: On the one hand, this application provides a method for preparing liquid camel milk, comprising the following steps: (1) Homogenize the mixture containing raw camel milk and calcium chelating agent; (2) The homogenized mixture is subjected to ultra-high temperature instantaneous sterilization to obtain the liquid camel milk; In step (1), the calcium chelating agent is selected from at least one of disodium hydrogen phosphate, sodium hexametaphosphate, and sodium citrate.

[0007] Optionally, in step (1), the calcium chelating agent is a combination of disodium hydrogen phosphate and sodium citrate.

[0008] Optionally, in the composition, the mass ratio of disodium hydrogen phosphate to sodium citrate is 2 to 4:1.

[0009] Optionally, in the composition, the mass ratio of disodium hydrogen phosphate to sodium citrate is 3:1.

[0010] Optionally, in step (1), the amount of calcium chelating agent added is 0.1 to 0.3% of the mass of the raw camel milk.

[0011] Optionally, in step (1), the pressure of the homogenization process is 15~20MPa; The homogenization process takes 1 to 2 minutes.

[0012] Optionally, in step (1), the pressure of the homogenization process is independently selected from any value of 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa or any range between two of them.

[0013] Optionally, in step (1), the homogenization time is independently selected from any value of 1 min, 1.5 min, 2 min, or any range between the two.

[0014] Optionally, in step (2), the temperature of the ultra-high temperature instantaneous sterilization is 135~137℃; The ultra-high temperature instantaneous sterilization time is 3~5 seconds.

[0015] Optionally, in step (2), the temperature of the ultra-high temperature instantaneous sterilization is independently selected from any value of 135℃, 136℃, 137℃ or any range between two of them.

[0016] Optionally, in step (2), the time for ultra-high temperature instantaneous sterilization is independently selected from any value of 3s, 4s, 5s or any range between the two.

[0017] Secondly, this application provides liquid camel milk prepared by the above-mentioned preparation method.

[0018] Compared with the prior art, this application has the following advantages: (1) The method for preparing liquid camel milk provided in this application involves adding three calcium chelating agents: disodium hydrogen phosphate, sodium hexametaphosphate, and sodium citrate. These agents chelate the free calcium ions released after heating to maintain ion balance, thereby significantly improving the thermal stability of camel milk. The method also provides auxiliary stabilizing effects such as buffering pH and increasing electrostatic repulsion between casein particles. This application uses pH, particle size, zeta potential, turbidity, viscosity, sedimentation amount, and stability coefficient as detection indicators to determine the types and amounts of calcium chelating agents added to adjust the camel milk under optimal stability, providing a theoretical basis for the production and processing of camel milk.

[0019] (2) The application adopts a homogeneous production process, which can better match the existing UHT milk processing equipment and pipelines in the factory, has practical production convenience, and meets the needs of the factory's assembly line production.

[0020] (3) The UHT liquid camel milk prepared in this application has a good tissue state, is a uniform fluid, and has no obvious stratification. Detailed Implementation

[0021] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0022] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0023] Unless otherwise specified, the analytical methods in the embodiments all adopt conventional instrument or equipment settings and conventional analytical methods.

[0024] The camel milk used in the following examples and comparative studies was collected from Bactrian camels in the Alashan region of Inner Mongolia Autonomous Region. Six female camels of similar age and parity, lactating and in good health were selected for the experiment. Machine milking was used for sampling, and the udders of the female camels were wiped and disinfected beforehand; 500 mL of milk sample was collected from each camel per sampling. The disodium hydrogen phosphate, sodium hexametaphosphate, and sodium citrate used in the experiment were all food-grade additives provided by Dalian Kexin Chemical Co., Ltd.

[0025] Example 1 A method for preparing liquid camel milk, comprising the following steps: (1) Prepare fresh raw camel milk, add 0.1% and 0.3% of disodium hydrogen phosphate by weight of camel milk respectively, and homogenize at 18 MPa; (2) The homogenized mixture was subjected to ultra-high temperature instantaneous sterilization (135℃, 5s) to obtain the liquid camel milk, which was stored at -80℃ for testing.

[0026] Example 2 A method for preparing liquid camel milk, comprising the following steps: (1) Prepare fresh raw camel milk, add sodium hexametaphosphate at 0.1% and 0.3% of the camel milk mass respectively, and homogenize at 18 MPa; (2) The homogenized mixture was subjected to ultra-high temperature instantaneous sterilization (135℃, 5s) to obtain the liquid camel milk, which was stored at -80℃ for testing.

[0027] Example 3 A method for preparing liquid camel milk, comprising the following steps: (1) Prepare fresh raw camel milk, add sodium citrate at 0.1% and 0.3% of the weight of camel milk respectively, and homogenize at 18 MPa; (2) The homogenized mixture was subjected to ultra-high temperature instantaneous sterilization (135℃, 5s) to obtain the liquid camel milk, which was stored at -80℃ for testing.

[0028] Example 4 A method for preparing liquid camel milk, comprising the following steps: (1) Prepare fresh raw camel milk, add 0.1% of disodium hydrogen phosphate and sodium citrate (the mass ratio of disodium hydrogen phosphate and sodium citrate is 3:1) and homogenize at 18 MPa; (2) The homogenized mixture was subjected to ultra-high temperature instantaneous sterilization (135℃, 5s) to obtain the liquid camel milk, which was stored at -80℃ for testing.

[0029] Comparative Example 1 A method for preparing liquid camel milk, comprising the following steps: Fresh raw camel milk was prepared and subjected to ultra-high temperature instantaneous sterilization (135℃, 5s) to obtain liquid camel milk, which was then stored at -80℃ for testing.

[0030] Comparative Example 2 A method for preparing liquid camel milk, comprising the following steps: The only difference from Example 4 is that disodium hydrogen phosphate is replaced with sodium pyrophosphate.

[0031] Comparative Example 3 A method for preparing liquid camel milk, comprising the following steps: The only difference from Example 4 is that the ultra-high temperature instantaneous sterilization process is changed to 140°C for 2 seconds.

[0032] Test Example 1 The experimental parameters included pH, particle size, zeta potential, stability coefficient, viscosity, turbidity, and sedimentation amount of the modified camel milk. The effects of different amounts and types of calcium chelating agents on the system stability were analyzed to determine the optimal dosage.

[0033] pH was determined according to the method in GB 5009.237-2016.

[0034] To determine the particle size and zeta potential, the emulsion sample and distilled water were mixed at a ratio of 1:50 (V / V), and then the particle size and zeta potential of camel milk with different added stabilizing salts were measured using a nanoparticle size analyzer.

[0035] To determine the stability coefficient, a 500 μl camel milk sample was diluted 100 times and centrifuged at 3000 rpm for 10 min. The supernatant was retained, and the absorbance was measured at 550 nm.

[0036] Stability coefficient = B2 / B1 B1: Absorbance of the sample before centrifugation; B2: Absorbance of the sample after centrifugation.

[0037] Viscosity was measured under constant temperature conditions of 20℃ and rotation speed of 30r / min. The apparent viscosity of the sample was measured every 6s within 120s for a total of 3 measurements, and the average value was taken as the viscosity of the sample.

[0038] To determine turbidity, the skim emulsion sample was diluted with distilled water to a mass concentration of 2 mg / mL. After vortexing, the absorbance of camel milk with different calcium chelating agents was measured at 633 nm using an ELISA reader. The absorbance was used to represent the turbidity.

[0039] To determine the amount of precipitate, accurately weigh 10g of sample m1, centrifuge at 2760g for 30min, and dry the precipitate at 105℃ to constant weight and measure its dry weight m2.

[0040] Sediment amount = m2 / m1.

[0041] The above are the physicochemical indicators and operating procedures measured in this application.

[0042] The test results are shown in Table 1.

[0043] Table 1 shows the effects of different chelating agents on the stability of camel milk. Note: Different uppercase letters indicate significant differences within groups (p<0.05), and different lowercase letters indicate significant differences between groups (p<0.05).

[0044] Table 1 shows that, comparing the data from each example, the best result was achieved with a compound salt containing 1% disodium hydrogen phosphate and sodium citrate in a 3:1 ratio (Example 4), which significantly improved precipitation, stability coefficient, viscosity, turbidity, average particle size, and zeta potential. Overall, the optimal choice is to add 0.1% (disodium hydrogen phosphate:sodium citrate = 3:1) of the compound salt. The results from the examples further reveal that a higher amount of chelating agent is not always better; there is no simple linear positive correlation between the amount added and the final effect. As shown in Example 2, further increasing the amount of chelating agent not only failed to continuously improve the effect but may even lead to a decrease in stability coefficient, larger particle size, increased precipitation, and increased turbidity. Furthermore, observation of the camel milk in Comparative Example 3 revealed that the UHT camel milk prepared under this process had poor stability, exhibiting stratification after two days of storage at room temperature. This indicates that changing the ultra-high temperature instantaneous sterilization process also has a significant impact on the stability of camel milk.

[0045] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing liquid camel milk, characterized in that, The steps include: (1) Homogenize the mixture containing raw camel milk and calcium chelating agent; (2) The homogenized mixture is subjected to ultra-high temperature instantaneous sterilization to obtain the liquid camel milk; In step (1), the calcium chelating agent is selected from at least one of disodium hydrogen phosphate, sodium hexametaphosphate, and sodium citrate.

2. The method for preparing liquid camel milk according to claim 1, characterized in that, In step (1), the calcium chelating agent is a combination of disodium hydrogen phosphate and sodium citrate.

3. The method for preparing liquid camel milk according to claim 2, characterized in that, In the composition, the mass ratio of disodium hydrogen phosphate to sodium citrate is 2-4:1; Preferably, in the composition, the mass ratio of disodium hydrogen phosphate to sodium citrate is 3:

1.

4. The method for preparing liquid camel milk according to claim 1, characterized in that, In step (1), the amount of calcium chelating agent added is 0.1 to 0.3% of the mass of the raw camel milk.

5. The method for preparing liquid camel milk according to claim 1, characterized in that, In step (1), the pressure of the homogenization process is 15~20MPa; The homogenization process takes 1 to 2 minutes.

6. The method for preparing liquid camel milk according to claim 1, characterized in that, In step (2), the temperature of the ultra-high temperature instantaneous sterilization is 135~137℃; The ultra-high temperature instantaneous sterilization time is 3~5 seconds.

7. Liquid camel milk prepared by the preparation method according to any one of claims 1 to 6.

Images