Preparation method and application of yak milk skin powder

Abstract

The invention discloses a preparation method and application of yak milk skin powder. Through the synergistic effect of the flavor embedding agent (such as beta-cyclodextrin) and the water activity regulating agent (such as isomaltooligosacharide) and in combination with the integrated process of staged low-temperature dehydration and nitrogen-filled packaging, the problems that the flavor of the traditional yak dairy product is easy to dissipate, the grease is easy to oxidize and the shelf life is short are essentially solved. The core of the invention lies in that the characteristic flavor substances of the yak milk are effectively locked through molecular inclusion, and oxidation deterioration and microbial growth are significantly inhibited by regulating and controlling the microenvironment of the system. The prepared yak milk skin powder product is excellent in performance, the characteristic flavor retention rate is higher than 90%, the peroxide value is lower than 5 meq / kg, the rehydration property is good, dissolution is rapid, and the yak milk skin powder product has excellent storage stability and convenience. According to the preparation method, the natural nutrition and flavor of the yak milk are reserved to the maximum extent.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a method for preparing yak milk skin powder and its application. Background Technology

[0002] Yak milk, produced at altitudes above 3,000 meters on the Qinghai-Tibet Plateau, boasts natural advantages such as its pristine environment, lack of pollution, and rich nutritional value. However, due to the harsh climate, inconvenient transportation, and significant seasonal fluctuations in supply in the high-altitude region, the storage and long-distance transportation of fresh yak milk are extremely difficult, severely limiting its commercial development and market promotion. Currently, commercially available yak milk products are mostly in the form of liquid milk or traditional cheese, generally facing bottlenecks such as short shelf life, easy loss of flavor, and high transportation costs, making it difficult to achieve large-scale distribution and high-value-added transformation of plateau-specific dairy products.

[0003] While existing yak milk processing technology has made some progress, it is mostly concentrated in the primary processing stage. This results in limited product variety, insufficient storage stability, and damage to the unique flavor compounds and nutrients of yak milk during processing. Furthermore, traditional drying processes such as high-temperature spray drying easily lead to protein denaturation, oil oxidation, and flavor deterioration, making it difficult to maintain product quality during long-term storage. Therefore, there is an urgent need to develop a new form of yak milk product that can maximize the preservation of the natural flavor and nutrients of yak milk while possessing good storage stability and convenience. This would overcome geographical limitations, promote the commercialization and industrialization of this unique plateau resource, and contribute to rural revitalization and sustainable development in pastoral areas. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a method for preparing yak milk skin powder and its application. This invention solves the problems of difficult storage, difficult transportation, and low commercialization of high-altitude yak milk due to geographical limitations.

[0005] This invention can be achieved through the following technical solutions: A yak milk skin powder comprises the following components in parts by weight: 10-30 parts yak milk, 15-25 parts whole milk powder, 8-12 parts condensed milk, 8-12 parts eggs, 10-20 parts shortening, 2-5 parts whey protein powder, 0.03-0.15 parts natural antioxidant, 0.5-2 parts flavor encapsulating agent, and 4-11 parts water activity regulator.

[0006] Preferably, the natural antioxidant is vitamin E or tea polyphenols.

[0007] Preferably, the flavor encapsulating agent is β-cyclodextrin or gum arabic.

[0008] Preferably, the water activity regulator is isomaltooligosaccharide or food-grade glycerol.

[0009] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, natural antioxidants, flavor encapsulators, and water activity regulators at 40-50℃ and shear emulsify at 8000-12000rpm for 3-5 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 80-100℃ for 15-25 minutes to set it, then continue baking at 60-80℃ for 30-50 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine pulverization to a particle size ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ with cold air until the moisture content is ≤4%, then pack it with nitrogen filling and the packaging material is aluminum-plastic composite film.

[0010] Preferably, the mixing time in step 1 is 10-30 minutes.

[0011] Preferably, the ultrafine pulverization in step 2 is carried out in a turbine-type ultrafine pulverizer equipped with a cooling air system.

[0012] Preferably, the cold air drying in step 3 uses a fluidized bed drying device.

[0013] Preferably, the residual oxygen content inside the packaging after nitrogen filling in step 3 is ≤1%.

[0014] Preferably, the yak milk skin powder is used in the preparation of food.

[0015] The beneficial effects of this invention are: This invention combines basic components such as yak milk, whole milk powder, condensed milk, eggs, shortening, and whey protein powder, and further introduces flavor encapsulating agents (such as β-cyclodextrin or gum arabic), water activity regulators (such as isomaltooligosaccharide or food-grade glycerin), and natural antioxidants (such as vitamin E or tea polyphenols). Under mild conditions, the mixture is sheared and emulsified to form a stable emulsion. This emulsion then undergoes staged baking and shaping, low-temperature dehydration, and ultra-fine pulverization to micron-level particle size. Finally, it is cold-air dried at low temperature and packaged with nitrogen, forming a complete integrated process of "emulsification-shaping-low-temperature dehydration-micronization-oxygen-controlled packaging." The core of this invention lies in the fact that the flavor encapsulating agent effectively locks in the characteristic flavor substances of yak milk through molecular inclusion, preventing their loss during processing and storage; the water activity regulator significantly reduces the water activity of the product system, inhibiting microbial growth and adverse chemical reactions; and low-temperature dehydration and nitrogen-filled packaging synergistically inhibit oil oxidation and protein denaturation, maximizing the preservation of nutrients and natural flavor. The flavor compounds in this yak milk skin powder can be retained at a rate of over 90%, with a peroxide value of less than 5 meq / kg, a turbidity of less than 50 NTU, a sedimentation rate of less than 6%, and a dissolution time of no more than 100 seconds. It also exhibits good storage stability, resolubility, and consistent taste. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0017] Figure 1 The retention rate of characteristic flavor substances and complete dissolution time of yak milk skin powder; Figure 2 The peroxide value, turbidity, and sedimentation rate of yak milk skin powder were measured. Detailed Implementation

[0018] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0019] Example 1 A yak milk skin powder comprises the following components in parts by weight: 10 parts yak milk, 15 parts whole milk powder, 8 parts condensed milk, 8 parts eggs, 10 parts shortening, 2 parts whey protein powder, 0.03 parts vitamin E, 0.5 parts β-cyclodextrin, and 4 parts isomaltooligosaccharide.

[0020] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, vitamin E, β-cyclodextrin, and isomaltooligosaccharide at 40°C for 30 minutes, and then shear emulsify at 8000 rpm for 5 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 80℃ for 25 minutes to set it, then continue baking at 60℃ for 50 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine grinding in a turbine ultra-fine pulverizer equipped with a cold air system until the particle size is ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ using a fluidized bed dryer until the moisture content is ≤4%. Then, pack it with nitrogen filling, ensuring the residual oxygen content inside the packaging is ≤1%. The packaging material is an aluminum-plastic composite film.

[0021] Example 2 A yak milk skin powder comprises the following components in parts by weight: 20 parts yak milk, 20 parts whole milk powder, 10 parts condensed milk, 10 parts eggs, 15 parts shortening, 3.5 parts whey protein powder, 0.09 parts tea polyphenols, 1.25 parts gum arabic, and 7.5 parts food-grade glycerin.

[0022] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, tea polyphenols, gum arabic, and food-grade glycerin at 50°C for 10 minutes, and then shear emulsify at 12,000 rpm for 3 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 90℃ for 20 minutes to set it, then continue baking at 70℃ for 40 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine grinding in a turbine ultra-fine pulverizer equipped with a cold air system until the particle size is ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ using a fluidized bed dryer until the moisture content is ≤4%. Then, pack it with nitrogen filling, ensuring the residual oxygen content inside the packaging is ≤1%. The packaging material is an aluminum-plastic composite film.

[0023] Example 3 A yak milk skin powder comprises the following components in parts by weight: 30 parts yak milk, 25 parts whole milk powder, 12 parts condensed milk, 12 parts eggs, 20 parts shortening, 5 parts whey protein powder, 0.15 parts vitamin E, 2 parts gum arabic, and 11 parts food-grade glycerin.

[0024] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, vitamin E, gum arabic, and food-grade glycerin at 45°C for 20 minutes, and then shear emulsify at 10,000 rpm for 4 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 100℃ for 15 minutes to set it, then continue baking at 80℃ for 30 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine grinding in a turbine ultra-fine pulverizer equipped with a cold air system until the particle size is ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ using a fluidized bed dryer until the moisture content is ≤4%. Then, pack it with nitrogen filling, ensuring the residual oxygen content inside the packaging is ≤1%. The packaging material is an aluminum-plastic composite film.

[0025] Example 4 A yak milk skin powder comprises the following components in parts by weight: 30 parts yak milk, 15 parts whole milk powder, 12 parts condensed milk, 8 parts eggs, 20 parts shortening, 2 parts whey protein powder, 0.15 parts vitamin E, 0.5 parts β-cyclodextrin, and 4 parts food-grade glycerin.

[0026] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, vitamin E, β-cyclodextrin, and food-grade glycerin at 50°C for 30 minutes, and then shear emulsify at 12000 rpm for 3 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 100℃ for 15 minutes to set it, then continue to bake at 80℃ for 50 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine grinding in a turbine ultra-fine pulverizer equipped with a cold air system until the particle size is ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ using a fluidized bed dryer until the moisture content is ≤4%. Then, pack it with nitrogen filling, ensuring the residual oxygen content inside the packaging is ≤1%. The packaging material is an aluminum-plastic composite film.

[0027] Comparative Example 1: The difference between this comparative example and Example 1 is that β-cyclodextrin is not added.

[0028] A yak milk skin powder comprises the following components in parts by weight: 10 parts yak milk, 15 parts whole milk powder, 8 parts condensed milk, 8 parts eggs, 10 parts shortening, 2 parts whey protein powder, 0.03 parts vitamin E, and 4 parts isomaltooligosaccharide.

[0029] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, vitamin E, and isomaltooligosaccharide at 40°C for 30 minutes, and then shear emulsify at 8000 rpm for 5 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 80℃ for 25 minutes to set it, then continue baking at 60℃ for 50 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine grinding in a turbine ultra-fine pulverizer equipped with a cold air system until the particle size is ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ using a fluidized bed dryer until the moisture content is ≤4%. Then, pack it with nitrogen filling, ensuring the residual oxygen content inside the packaging is ≤1%. The packaging material is an aluminum-plastic composite film.

[0030] Comparative Example 2: The difference between this comparative example and Example 1 is that isomaltooligosaccharide is not added.

[0031] A yak milk skin powder comprises the following components in parts by weight: 10 parts yak milk, 15 parts whole milk powder, 8 parts condensed milk, 8 parts eggs, 10 parts shortening, 2 parts whey protein powder, 0.03 parts isomaltooligosaccharide, and 0.5 parts β-cyclodextrin.

[0032] A method for preparing yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, vitamin E, and β-cyclodextrin at 40°C for 30 minutes, and then shear emulsify at 8000 rpm for 5 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 80℃ for 25 minutes to set it, then continue baking at 60℃ for 50 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine grinding in a turbine ultra-fine pulverizer equipped with a cold air system until the particle size is ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ using a fluidized bed dryer until the moisture content is ≤4%. Then, pack it with nitrogen filling, ensuring the residual oxygen content inside the packaging is ≤1%. The packaging material is an aluminum-plastic composite film.

[0033] Performance testing 1. Flavor retention test Weigh 2.0 g of yak milk hide powder sample and place it in a 20 mL headspace vial. Add 5 mL of saturated sodium chloride solution, seal the vial, and equilibrate in a 60 °C water bath for 30 min. Use a 50 / 30 μm DVB / CAR / PDMS extraction head, insert it into the top of the headspace vial, and adsorb at 60 °C for 40 min. Then, desorb at a 250 °C injection port for 5 min and inject into a gas chromatography-mass spectrometry (GC-MS) system. Chromatographic separation was performed using a DB-WAX capillary column (60 m × 0.25 mm × 0.25 μm). The temperature program was set to initially be 40 °C and hold for 3 min, then increase to 230 °C at a rate of 5 °C / min and hold for 10 min. Mass spectrometry detection was performed using an electron impact ion source (70 eV) at 230 °C, with a scan mass range of m / z 35-450. The obtained mass spectrometry data were qualitatively analyzed using the NIST spectral library, and quantitative analysis was performed on characteristic flavor compounds such as hexanal, nonanal, and 2-heptanone using 2-nonanone as an internal standard. Finally, the retention rates of key flavor compounds before and after storage were calculated to objectively evaluate the flavor stability of the sample. The retention rates (%) of characteristic flavor compounds before and after storage were calculated.

[0034] 2. Oxidation stability test Yak milk hide powder samples were aliquoted into transparent PE bags and placed in a 60℃ constant temperature oven for accelerated oxidation. Peroxide values ​​were measured on days 0, 7, 14, 21, and 28. For the peroxide value test, 2.0 g of yak milk hide powder sample was weighed and added to 30 mL of a chloroform-glacial acetic acid (2:3, v / v) mixture. The mixture was shaken for 30 min, filtered, and 20 mL of the filtrate was collected. 1 mL of saturated potassium iodide solution was added, and the mixture was placed in the dark for 5 min. 100 mL of distilled water was added, and the solution was titrated with 0.01 mol / L sodium thiosulfate standard solution until a pale yellow color was obtained. 1 mL of starch indicator was added, and titration continued until the blue color disappeared. A blank test was performed simultaneously. Peroxide value... POV (meq / kg) = ( V - V 0 )* C *1000 / m ,in, V The volume (mL) of sodium thiosulfate consumed for the sample. V 0 The volume (mL) of sodium thiosulfate consumed is for blank control. C This represents the concentration of sodium thiosulfate (mol / L). m For sample quality. POV ≤10 meq / kg is considered acceptable, and ≤5 meq / kg is considered excellent.

[0035] 3. Rehydration and solubility test Weigh 1.0 g of yak milk skin powder into a 100 mL beaker, add 50 mL of distilled water (25℃), and stir with a magnetic stirrer at 500 rpm for 5 min. Take the supernatant and measure the turbidity (NTU value) using a turbidimeter. The lower the turbidity, the fewer suspended particles and the better the solubility. Pour the stirred suspension into a graduated centrifuge tube, let it stand for 30 min, record the volume of the bottom sediment (mL), and calculate the sedimentation rate: sedimentation rate (%) = sedimentation volume / total volume × 100%. The lower the sedimentation rate, the better the suspension stability. Take 10 g of the sample and add it to 200 mL of room temperature water, stir at 200 rpm, and record the time (s) until it is completely dissolved and no visible particles are visible.

[0036] Table 1 Performance Test Data

[0037] Table 1 shows that all examples exhibited excellent overall performance, with characteristic flavor substance retention rates exceeding 90%, peroxide values ​​below 5 meq / kg, turbidity below 50 NTU, sedimentation rates below 6.0%, and complete dissolution times shorter than 100 s. This is mainly attributed to the following: the flavor encapsulating agent (β-cyclodextrin) effectively locked in volatile flavor substances in yak milk through molecular inclusion, preventing their escape during processing and storage; the water activity regulator (isomaltooligosaccharide) reduced the system's water activity, inhibiting microbial growth and chemical reactions, while also helping to maintain product texture. In contrast, Comparative Example 1, without the addition of a flavor encapsulating agent, resulted in a significant decrease in characteristic flavor substance retention to 68.4%. Furthermore, due to the lack of encapsulation protection, some oils were more easily exposed to oxidation, leading to a peroxide value increase to 12.6 meq / kg, and the solubility also deteriorated due to component interactions. Comparative Example 2, which did not contain a water activity regulator, had a relatively high water activity, which was not conducive to the long-term stability of flavor (85.3% retention rate). It also accelerated the oxidation reaction (peroxide value 11.2 meq / kg) and reduced the suspension stability after rehydration.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A yak milk skin powder, characterized in that, It includes the following components by weight: 10-30 parts yak milk, 15-25 parts whole milk powder, 8-12 parts condensed milk, 8-12 parts eggs, 10-20 parts shortening, 2-5 parts whey protein powder, 0.03-0.15 parts natural antioxidant, 0.5-2 parts flavor encapsulator, and 4-11 parts water activity regulator.

2. The yak milk skin powder according to claim 1, characterized in that, The natural antioxidants mentioned are vitamin E or tea polyphenols.

3. The yak milk skin powder according to claim 1, characterized in that, The flavor encapsulating agent is β-cyclodextrin or gum arabic.

4. The yak milk skin powder according to claim 1, characterized in that, The water activity regulator is isomaltooligosaccharide or food-grade glycerol.

5. The yak milk skin powder according to claim 1, characterized in that, The preparation method of the yak milk skin powder includes the following steps: Step 1: Mix yak milk, whole milk powder, condensed milk, eggs, shortening, whey protein powder, natural antioxidants, flavor encapsulators, and water activity regulators at 40-50℃ and shear emulsify at 8000-12000rpm for 3-5 minutes to form a homogeneous and stable emulsion. Step 2: First, bake the emulsion at 80-100℃ for 15-25 minutes to set it, then continue baking at 60-80℃ for 30-50 minutes for low-temperature dehydration. After cooling to room temperature, perform ultra-fine pulverization to a particle size ≤80μm to obtain crude yak milk skin powder. Step 3: Dry the crude yak milk skin powder at ≤40℃ with cold air until the moisture content is ≤4%, then pack it with nitrogen filling and the packaging material is aluminum-plastic composite film.

6. The method for preparing yak milk skin powder according to claim 5, characterized in that, The mixing time in step 1 is 10-30 minutes.

7. The method for preparing yak milk skin powder according to claim 5, characterized in that, In step 2, the ultrafine pulverization is carried out in a turbine-type ultrafine pulverizer equipped with a cooling air system.

8. The method for preparing yak milk skin powder according to claim 5, characterized in that, In step 3, the cold air drying uses a fluidized bed drying device.

9. The method for preparing yak milk skin powder according to claim 5, characterized in that, In step 3, the residual oxygen content inside the packaging after nitrogen filling is ≤1%.

10. The yak milk skin powder according to any one of claims 1-4, characterized in that, The application of the yak milk skin powder in food preparation.

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