Frozen camel milk with milk skin and preparation method of frozen camel milk

Abstract

The invention relates to the technical field of food processing, in particular to frozen camel milk with milk skin and a preparation method thereof.The preparation method comprises the following steps that firstly, after camels produce milk, the temperature of the raw material camel milk is reduced to 0-2 DEG C from 37 DEG C within 10 minutes, the raw material camel milk is stored in 304 stainless steel, and nitrogen is introduced into a tank for protection during storage; step 2, after the raw milk reaches a factory, the total number of bacterial colonies is less than or equal to 20000 CFU / g, the protein content is more than or equal to 3.8 g / 100g, and the fat content is more than or equal to 4.5 g / 100g; through a series of measures such as rapid cooling, low-temperature storage, nitrogen introduction for protection, production and processing time shortening, low-temperature centrifugal separation, appropriate-temperature mixing and stirring, rapid cooling and the like, microbial reproduction is effectively inhibited, the oxidation speed of fat and protein in camel milk is slowed down, and decomposition and loss of nutritional ingredients are reduced; active nutrient substances in the camel milk are reserved to the maximum extent, and meanwhile, the content of active lactoferrin in the stock solution is increased.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a frozen camel milk with a milk skin and its preparation method. Background Technology

[0002] Camel milk is a niche and unique dairy product. In recent years, with the continuous advancement of breeding and manufacturing technologies, consumers have gradually begun to come into contact with and appreciate this nutritious dairy product. Compared with ordinary dairy cows, camels produce less milk, with a daily yield of about 5-7 catties (2.5-3.5 catties). Despite the low yield, camel milk is rich in nutrients, such as active lactoferrin, vitamin C, unsaturated fatty acids, and various small molecules. These nutrients are significantly higher than in other dairy products, thus attracting more and more consumers. The announcement number CN116746609A discloses a frozen yak milk and its preparation method. This method involves cooling the filtered yak milk, placing it in a freezing tunnel for low-temperature freezing, and then freezing it in an ice storage facility. This process ensures the quality of the yak milk and makes it more stable, allowing for a storage period of over one year. However, these traditional processing methods often struggle to simultaneously address the issues of maximizing the preservation of active nutrients in camel milk during processing and achieving the desired milk skin technology. Summary of the Invention

[0003] The present invention aims to solve the problem of reducing the muttony smell and preserving the milk skin, that is, to remove the muttony smell while retaining the original rich taste and milk skin of camel milk.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing frozen camel milk with a milk skin, characterized by comprising the following steps: Step 1: After the camel produces milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. Nitrogen gas is introduced into the tank for protection during storage. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s and stored at 70-75℃ for no more than 2 hours. Step 4: Dispense the defatted liquid into 5-10L centrifuge bottles, centrifuge at 15000G centrifugation force at 0-4℃ for 20 minutes, take the supernatant, heat the supernatant to 35-40℃ and mix it with light cream, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag, and then quickly place the packaging bag into a freezing tunnel. It is required to freeze within 10-20 minutes, and then place it in a -20℃ cold storage until it is completely frozen.

[0005] Furthermore, in step one, the time from production to processing of the raw milk does not exceed 12 hours, and during storage, the stirring speed of the side agitator is 10-20 revolutions per minute to ensure that nitrogen and camel milk are in full contact.

[0006] Furthermore, in step five, the packaging bag material is a thick, high-barrier PE black and white film, with a total thickness requirement of 80-120 micrometers.

[0007] Furthermore, in step five, the freezing tunnel employs a three-stage gradient cooling system, divided into three independent temperature control zones: a pre-cooling zone, a quick-freezing zone, and a deep-freezing zone. The pre-cooling zone maintains -5°C for 5 minutes, slowly lowering the temperature to ensure a uniform decrease in the center temperature of the camel milk. The quick-freezing zone maintains -25°C for 8 minutes, rapidly passing through the zone of maximum ice crystal formation to create fine ice crystals. The third stage maintains -35°C for 5 minutes, further reducing the temperature to -35°C to ensure that the center temperature of the camel milk is ≤-18°C.

[0008] According to a second aspect of the present invention, the present invention also provides frozen camel milk with a skin, prepared by the above-described preparation method.

[0009] Compared with the prior art, the beneficial effects of the present invention are: the present invention effectively inhibits the reproduction of microorganisms, slows down the oxidation rate of fat and protein in camel milk, reduces the decomposition and loss of nutrients, and retains the active nutrients in camel milk to the greatest extent by means of a series of measures such as rapid cooling, low temperature storage, nitrogen protection, shortening production and processing time, low temperature centrifugation, appropriate temperature mixing and stirring, and rapid cooling. The temperature of the raw camel milk was reduced from 37°C to 0-2°C within 10 minutes. 37°C is the suitable temperature for microbial growth. Rapid cooling can effectively reduce microbial activity, inhibit their growth, and reduce the damage of microorganisms to active lactoferrin in camel milk. The low temperature environment (0-2°C) can also slow down the oxidation rate of fat and protein in camel milk, prevent oxidation reaction from damaging active lactoferrin, and thus maintain its activity. The raw milk is temporarily stored at a temperature of 2-4℃. This low-temperature environment can effectively inhibit the growth and reproduction of most microorganisms, reduce the consumption and destruction of active lactoferrin by microorganisms, extend the shelf life of raw milk, and ensure the stability of active lactoferrin. Nitrogen gas is introduced into the tank during storage to isolate oxygen and prevent the camel milk from oxidizing and deteriorating due to contact with oxygen. Oxygen is an important factor that causes the oxidation of nutrients in camel milk, and active lactoferrin is also easily affected by oxygen and loses its activity. Introducing nitrogen gas can create a relatively stable low-oxygen environment for it, ensuring the stability of active lactoferrin. At the same time, nitrogen gas can remove air from the tank, reduce the living space of microorganisms, and further reduce the risk of microbial damage to active lactoferrin. The time from raw milk production to processing is no more than 12 hours, which reduces the time for microorganisms to multiply in camel milk, reduces the damage of microbial metabolites to active lactoferrin, and ensures that camel milk maintains a high level of freshness and active lactoferrin content before processing. The raw milk is separated into two parts, cream and skim milk, using a disc centrifugation process, with the separation temperature controlled at 0-4℃. The low temperature environment can reduce the activity of microorganisms, prevent the camel milk from spoiling during centrifugation, and at the same time help to maintain the nutritional components and flavor of the camel milk, avoiding the destruction of active lactoferrin by high temperature. Heating the supernatant to 35-40℃ will not destroy the nutrients and flavor compounds in camel milk due to excessive heat. This temperature is far below the critical temperature for protein denaturation; operating within this range will not cause protein denaturation, thus preserving the nutritional components and bioactivity of the proteins in camel milk to the greatest extent. The relatively low temperature of 35-40℃ effectively inhibits the rate of fat oxidation, reduces the formation of fat oxidation products, and maintains the nutritional quality of the fat in camel milk. Operating at 35-40℃ can prevent the decomposition of vitamins due to high temperatures, thereby maintaining the stability and nutritional value of vitamins in camel milk. The relatively low temperature of 35-40℃ also reduces the loss of volatile flavor compounds, preserving the rich aroma of camel milk. Within this suitable temperature range, the decomposition rate of flavor compounds is slow, better preserving the original flavor characteristics of camel milk, ensuring that the thawed and cooked camel milk still has a rich and mellow taste. After packaging, quickly place the packaging bag into the freezing tunnel, where it will freeze within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen. Rapid cooling can shorten the time that camel milk is at high or normal temperature, reducing the decomposition and loss of nutrients, including active lactoferrin. Detailed Implementation

[0010] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0011] The present invention provides a technical solution: a method for preparing frozen camel milk with a milk skin, comprising the following steps: Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Camel milk is at a suitable temperature for microbial growth at 37℃. Rapidly cooling it to 0-2℃ can effectively reduce the activity of microorganisms, inhibit their growth, and reduce the damage of microorganisms to the active lactoferrin in camel milk, thereby extending the shelf life of camel milk. The low temperature environment can slow down the oxidation rate of fat and protein in camel milk, maintaining its nutritional value and taste. Introducing nitrogen can isolate oxygen, preventing camel milk from oxidizing and spoiling due to contact with oxygen; at the same time, nitrogen can also remove air from the tank, reducing the living space for microorganisms. Stirring allows nitrogen to be better dispersed in camel milk, improving its protective effect; stirring also prevents the camel milk from separating during storage, maintaining its uniformity. Shortening the time from raw milk production to processing can reduce the time for microorganisms to multiply in camel milk, thereby reducing the risk of camel milk spoilage; rapid processing can ensure the freshness and nutritional value of camel milk and improve the quality of the final product. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. The raw milk is filtered through a 200-mesh filter, which can intercept most impurities, such as feed particles, hair and some somatic cells. The temperature range for temporary storage of raw milk in the insulated tank is 2-4℃. 2-4℃ is a low temperature environment, which can effectively inhibit the growth and reproduction of most microorganisms. The metabolic activity of microorganisms slows down at low temperatures, and their reproduction rate is significantly reduced, thereby reducing the risk of contamination to the raw milk and extending the shelf life of the raw milk. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s and stored at 70-75℃ for no more than 2 hours. Among them, a horizontal spiral sedimentation disc centrifuge was selected, and the separation temperature was controlled at 0-4℃ through a refrigerant circulation system to ensure the physical stability of fat globules; A tubular sterilizer is used for high-temperature short-time sterilization at 72℃ / 15s to maximize flavor retention; after sterilization, the product is stored at 70-75℃ to inhibit microbial growth. Step 4: Dispense the defatted liquid into 5-10L centrifuge bottles, centrifuge at 15000G centrifugation force at 0-4℃ for 20 minutes, take the supernatant, heat the supernatant to 35-40℃ and mix it with light cream, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Among them, the high centrifugal force of 5000G can provide strong separation power, so that impurities and residual fat in the defatted liquid can be effectively separated from the supernatant; the low temperature environment of 0-4℃ can reduce the activity of microorganisms, prevent the camel milk from deteriorating during centrifugation, and also help to maintain the nutritional components and flavor of the camel milk. Heating the supernatant to 35-40℃ is beneficial for better integration of the cream and the supernatant. At this temperature, the cream becomes more fluid and can be more evenly dispersed in the supernatant, while the nutrients and flavor compounds in the camel milk will not be destroyed due to excessive temperature. At 35-40℃, the fat molecules in cream gain energy, weakening the intermolecular forces and reducing the viscosity, thus significantly increasing its fluidity. This improved fluidity allows the cream to flow and disperse more smoothly when mixed with the supernatant, much like water spreads more easily in a river, resulting in a more even distribution in the supernatant. Once the cream is evenly dispersed in the supernatant, stirring at this temperature allows it to better blend with the various components in the supernatant due to its improved fluidity. During stirring, the cream can penetrate the supernatant more quickly, ensuring thorough mixing and preventing incomplete mixing in certain areas, thus guaranteeing a uniform texture in the final camel milk mixture. After mixing, maintain the temperature at 55-60℃ and stir for 5 minutes. The temperature of 55-60℃ can further promote the thorough mixing of the light cream and the supernatant, making the components of both more evenly distributed; stirring for 5 minutes can ensure the uniformity of the mixture and avoid any areas of insufficient mixing. After mixing, the mixture is rapidly cooled to 0-4℃. Rapid cooling can inhibit the growth and reproduction of microorganisms and prevent camel milk from spoiling before canning. At the same time, the low temperature environment can maintain the physical stability of camel milk and reduce the occurrence of phenomena such as fat floating and protein precipitation. Step 5: Pack the mixed camel milk into a packaging bag made of thick, high-barrier PE black and white film with a total thickness of 80-120 microns. After packaging, quickly place the packaging bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen. Among them, thick high-barrier PE black and white film is used as the packaging bag material, with a total thickness of 80-120 microns. This type of packaging bag has good barrier properties, which can effectively block oxygen, moisture and light, prevent camel milk from contacting the external environment and causing oxidation, deterioration and flavor changes, and extend the shelf life of camel milk. The freezing tunnel employs a three-stage gradient cooling system, divided into three independent temperature-controlled zones: a pre-cooling zone, a quick-freezing zone, and a deep-freezing zone. The pre-cooling zone maintains -5°C for 5 minutes, slowly lowering the temperature to ensure a uniform decrease in the core temperature of the camel milk, preventing excessive surface freezing and internal pressure buildup. The quick-freezing zone maintains -25°C for 8 minutes, rapidly passing through the maximum ice crystal formation zone (-1°C to -5°C) to form fine ice crystals, minimizing damage to cell structure. These fine ice crystals also better preserve the physical state of the camel milk, resulting in a taste and texture closer to fresh camel milk after thawing. The third stage maintains -35°C for 5 minutes, further lowering the temperature to -35°C to ensure the core temperature of the camel milk is ≤-18°C, meeting long-term storage requirements. By using gradient cooling, the diameter of ice crystals is controlled to ≤50μm (microscopic detection) to avoid large ice crystals piercing cell membranes and causing water separation after thawing. Rapid freezing can also shorten the time that camel milk is at high or normal temperature, reducing the decomposition and loss of nutrients. Freezing camel milk within 10-20 minutes rapidly lowers its temperature, significantly inhibiting the growth and reproduction of microorganisms. The slowed metabolism and significantly reduced growth rate of microorganisms in the low-temperature environment effectively extends the shelf life of camel milk and reduces the risk of spoilage due to microbial contamination.

[0012] Methods for evaluating the effects of frozen camel milk after thawing and boiling: Before consuming frozen milk, thaw it at room temperature or under refrigeration until it is about half liquid. Then, pour the liquid into a pot and simmer over low heat, stirring gently as needed, until milk foam appears. Stop heating and cool to 40-60℃. This yields the cooked camel milk feed. The camel milk feed is then evaluated in various ways, using the following methods: (1) Fat detection: After removing the top 2-8mm of liquid (removing the surface milk skin), take the remaining liquid for fat detection. The results are shown in the effect example for the liquid fat value. The lower the fat content in the liquid, the more fat floats on the surface. The more fat floats on the surface, the easier it is to form a thicker or more milk skin. The fat detection method is in accordance with GB5413.3.

[0013] (2) The raw milk used in the experiment was tested for lactoferrin, and the value was used as a control. The lactoferrin test method was in accordance with GB 5009.299-2024.

[0014] (3) Judgment of the state of the liquid after thawing: If the milk separates into water and milk after thawing, it is considered that the quality has declined; Example 2

[0015] A method for preparing frozen camel milk with a skin includes the following steps: Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: Sterilize the cream at 72℃ for 15 seconds, then cool and bottle it. Step 4: Dispense the defatted liquid into 5-10L centrifuge bottles, centrifuge at 15000G centrifugation force at 0-4℃ for 20 minutes, take the supernatant, heat the supernatant to 35-40℃ and mix it with light cream, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag made of thick, high-barrier PE black and white film with a total thickness of 80-120 microns. After packaging, quickly place the packaging bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen.

[0016] Compared with Example 1, Example 2 differs in that the raw camel milk is not separated into fats, but is directly sterilized at 72°C for 15 seconds, cooled, and then canned; the active lactoferrin content of the frozen milk is tested. Example 3

[0017] Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s and stored at 70-75℃ for no more than 2 hours. Step 4: Heat the defatted liquid to 35-40℃ and mix it with the light cream. After mixing, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag made of thick, high-barrier PE black and white film with a total thickness of 80-120 microns. After packaging, quickly place the packaging bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen.

[0018] Compared with Example 1, Example 3 differs in that the centrifugal separation process of the camel milk feed liquid is omitted, and the content of active lactoferrin in frozen camel milk is evaluated. Example 4

[0019] Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s and stored at 70-75℃ for no more than 2 hours. Step 4: Dispense the defatted liquid into 5-10L centrifuge bottles, centrifuge at 0-4℃ for 20 minutes with a centrifugal force of 15000G, take the supernatant and mix it with the 70-75℃ light cream liquid. After mixing, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag made of thick, high-barrier PE black and white film with a total thickness of 80-120 microns. After packaging, quickly place the packaging bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen.

[0020] Compared with Example 1, Example 4 differs in that the supernatant is heated to 35-40℃, and the heating process is eliminated. Instead, the supernatant at 0-4℃ is directly mixed with the light cream liquid at 70-75℃, and the mixing effect is judged. Example 5

[0021] Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s and stored at 70-75℃ for no more than 2 hours. Step 4: Dispense the defatted liquid into 5-10L centrifuge bottles, centrifuge at 15000G centrifugation force at 0-4℃ for 20 minutes, take the supernatant, heat the supernatant to 35-40℃ and mix it with light cream, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag made of thin, low-barrier PE black and white film with a total thickness of 20-60 micrometers. After packaging, quickly place the packaging bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen.

[0022] Compared with Example 1, Example 5 differs in that the packaging material is a thin, low-barrier PE black and white film, which was used to determine the effect of frozen camel milk on shelf life. Example 6

[0023] Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s. After sterilization, the light cream is homogenized at a pressure of 180-220 bar and stored at 70-75℃ for no more than 2 hours. Step 4: Dispense the defatted liquid into 5L-10L centrifuge bottles, centrifuge at 15000G centrifugation force at 0-4℃ for 20 minutes, take the supernatant, heat the supernatant to 35-40℃ and mix it with light cream, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag made of thick, high-barrier PE black and white film with a total thickness of 80-120 microns. After packaging, quickly place the packaging bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -20°C cold storage until it is completely frozen.

[0024] Compared with Example 1, Example 6 differs in that the cream undergoes a homogenization process after sterilization, with a homogenization pressure of 180-220 bar. The effect of the frozen camel milk on the milk skin after thawing is judged, and the amount of milk skin is indicated by the fat value of the thawed liquid. The raw milk is directly boiled as a control sample. Example 7

[0025] Step 1: After the camels produce milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in 304 stainless steel. During storage, nitrogen gas is introduced into the tank for protection. During storage, the side agitator is stirred at a speed of 10-20 revolutions per minute to ensure that the nitrogen gas is in full contact with the camel milk and to prevent oxygen from contacting the milk. The time from raw milk production to processing does not exceed 12 hours. Step 2: After the raw milk arrives at the factory, the total bacterial count must be ≤20000 CFU / g, the protein content must be ≥3.8g / 100g, and the fat content must be ≥4.5g / 100g. After passing through a 200-mesh filter, the raw milk is directly placed into the raw milk tank for temporary storage. Step 3: The raw milk is separated into two parts, light cream and skim milk, using a disc centrifuge process. The separation temperature is 0-4℃. After separation, the fat content of the skim milk is less than 1.0g / 100g. The light cream is sterilized at 72℃ for 15s and stored at 70-75℃ for no more than 2 hours. Step 4: Dispense the defatted liquid into 5-10L centrifuge bottles, centrifuge at 15000G centrifugation force at 0-4℃ for 20 minutes, take the supernatant, heat the supernatant to 35-40℃ and mix it with light cream, keep the temperature at 55-60℃ and stir for 5 minutes, then quickly cool it down to 0-4℃. Step 5: Pack the mixed camel milk into a packaging bag made of thick, high-barrier PE black and white film with a total thickness of 80-120 microns. After packaging, quickly place the bag into a freezing tunnel and freeze it within 10-20 minutes. Then place it in a -18°C cold storage until it is completely frozen.

[0026] Compared with Example 1, Example 7 differs in that the camel milk freezing process is carried out at -18°C to determine the effect of frozen camel milk after thawing within its shelf life.

[0027] Example 1 Evaluation Project Example 1 Example 2 Example 3 Raw milk control sample Active lactoferrin content (g / L) 192 97 170 177 The active lactoferrin values ​​of Example 2 and the control sample illustrate that the temperature of traditional pasteurization will destroy the content of active lactoferrin; the comparison between Example 3 and Example 1 shows that centrifugation can increase the lactoferrin content. Example 2 The results of Example 4 show that fat precipitation occurred during the mixing of the two liquids, and the liquids could not be completely mixed; only by using appropriate parameters can the mixing uniformity be guaranteed, while the content of active lactoferrin can be increased at the same time.

[0028] Example 3 A comparison of Example 5 and Example 1 shows that after 3 months of storage, the camel milk in Example 5 exhibits a more pronounced yellowing of sensory color, indicating a decline in quality.

[0029] Example 4 Evaluation Project Example 1 Example 6 Control sample after boiling raw milk Fat index of raw milk Fat content of the liquid after removing the milk skin (g / 100g) 0.9 1.8 1.1 4.6 Example 6 shows that after homogenization, the fat content of the liquid material increased significantly, indicating that the amount of fat that can form milk skin was reduced; at the same time, the camel milk treated in Example 1 formed more milk skin compared with the control sample.

[0030] Example 5 The results of Example 7 showed that after the camel milk was frozen for 2 months, water-milk separation occurred during the thawing process, which disrupted the stable system of the camel milk. The fat content of the boiled liquid reached more than 2.0%, indicating that the fat that formed the milk skin was reduced.

[0031] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method of preparing frozen camel milk with a milk skin, characterized in that, Comprising the following steps: Step one, after the camel produces milk, the raw camel milk is cooled from 37°C to 0-2°C within 10 minutes and stored in a 304 stainless steel tank. Nitrogen is introduced into the tank during storage for protection; Step two, after the raw milk reaches the factory, the total number of colonies is required to be ≤20000 CFU / g, the protein content is ≥3.8g / 100g, and the fat content is ≥4.5g / 100g. The raw milk is directly stored in the raw milk tank after passing through a 200-mesh filter; Step three, the raw milk is separated into cream and skim milk by disc centrifugal separation process at a temperature of 0-4°C. The fat content of the skim milk is less than 1.0g / 100g. The cream is sterilized at 72°C / 15s and stored at 70-75°C for no more than 2 hours; Step four, the skim milk is divided into 5-10L centrifuge bottles and centrifuged at 0-4°C for 20 minutes under the action of 15000G centrifugal force. The supernatant is taken and warmed to 35-40°C, then mixed with the cream. After mixing, the temperature is maintained at 55-60°C for 5 minutes, and then rapidly cooled to 0-4°C; Step five, the mixed camel milk is packaged in a packaging bag, and the packaging bag is quickly placed in a freezing tunnel after packaging. It is required to form a frozen state within 10-20 minutes, and then placed in a-20°C freezer until completely frozen.

2. A method of preparing frozen camel milk with cream as claimed in claim 1, characterized in that, The raw milk in step one is stored for no more than 12 hours from production to processing. The side stirring paddle is stirred at a speed of 10-20 revolutions per minute during storage to allow nitrogen to fully contact the camel milk.

3. A method of preparing frozen camel milk with cream as claimed in claim 1, characterized in that, The packaging bag material in step five is thick high-barrier PE black and white film with a total thickness of 80-120 microns.

4. A process for preparing frozen camel milk with cream as claimed in claim 1, wherein, The freezing tunnel in step five uses three-stage gradient cooling, divided into three independent temperature control zones: pre-cooling zone, quick-freezing zone, and deep-freezing zone. The pre-cooling zone is maintained at-5°C for 5 minutes, slowly cooling the camel milk to evenly reduce the center temperature; the quick-freezing zone is maintained at-25°C for 8 minutes, quickly passing through the maximum ice crystal generation zone to form fine ice crystals; the third segment is maintained at-35°C for 5 minutes, further reducing the temperature to-35°C, ensuring that the center temperature of the camel milk is ≤-18°C.

5. The frozen camel milk with milk skin obtained by the preparation method of any one of claims 1-4.