Buffalo milk with long shelf life as well as super-instantaneous sterilization production method and system thereof

Abstract

The invention discloses buffalo milk with a long shelf life and a super-instantaneous sterilization production method and system thereof, and belongs to the technical field of dairy product processing. The method comprises the following steps: carrying out centrifugal sterilization pretreatment on raw buffalo milk; carrying out super-instantaneous sterilization (144 + / -2 DEG C, 0.09 s) by adopting a steam immersion technology; performing flash evaporation cooling; carrying out post-homogenization under the pressure of 23 to 25 MPa; and finally, filling under a sterile condition. The particle size of the fat globules of the buffalo milk product is refined to 0.4-0.8 [mu] m, the shelf life is prolonged to 15 days under the refrigeration condition of 2-6 DEG C, and the fat floating rate is lower than 3.5%. The invention also provides a special production system for realizing the method. According to the scheme, the technical problems of short shelf life and easy floating of fat in buffalo milk processing are effectively solved, and reliable technical support is provided for development of high-quality buffalo milk products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of dairy product processing, and particularly relates to a long-shelf-life water buffalo milk and an ultra-instant sterilization production method and system thereof. BACKGROUND

[0002] As an economic milk source with high nutritional value, water buffalo milk has significantly higher dry matter, fat and protein content than ordinary Holstein milk, thus presenting a richer flavor and taste, and is increasingly favored by the market. However, compared with ordinary cow milk, water buffalo milk has significant differences in composition and physicochemical properties, which also brings unique challenges to its processing. The most prominent problem is its high fat content (usually up to 7%-12%) and larger fat globule size. Studies have shown that the average particle size of water buffalo milk fat globules is about 6.84 μm, which is much larger than that of ordinary cow milk (3-4 μm), and the particle size distribution is wider. This inherent physical property difference makes water buffalo milk products prone to fat floating, delamination and other phenomena during processing and storage, seriously affecting the stability and appearance of the products, and becoming a key technical bottleneck restricting its industrial development.

[0003] At present, most of the water buffalo milk products on the market still use the traditional pasteurization process designed for ordinary cow milk (typical parameters: 72-85℃ / 15-30s, homogenization pressure about 15MPa). This process has inherent defects and poor effect when processing water buffalo milk: first, due to the high fat content (7-12%) and high calcium ion concentration of water buffalo milk, it is more prone to form protein-fat aggregates during pasteurization, hindering heat conduction, resulting in 18-25% lower spore inactivation efficiency than ordinary cow milk. The shelf life of water buffalo milk treated by this process is usually only about 7 days under cold storage conditions of 2-6℃, and the frequent cold chain distribution requirements significantly increase the logistics cost and operational complexity. In addition, we have found that the traditional homogenization pressure is insufficient for water buffalo milk, resulting in obvious fat floating in water buffalo milk products within a short period of time, forming a thick cream layer, which seriously affects the consumer experience.

[0004] To address the above challenges, the industry has tried several technical improvements. For example, a patent (CN106172752A) uses freezing and resuscitation combined with homogenization technology to refine fat globules, but this process route is long and energy-intensive, making it difficult to achieve large-scale production. Another study uses ultra-high pressure jet or ultrasonic homogenization technology, which has some effect, but faces problems such as high equipment investment, low processing efficiency and limited production capacity, which are not ideal solutions for industrial production.

[0005] Therefore, there is an urgent need in the art for an innovative processing technology tailored to the characteristics of water buffalo milk, which is the core technical problem to be solved by the present application. SUMMARY

[0006] In view of the above, it is necessary to provide a long shelf life buffalo milk and its ultra-instant sterilization production method and system, which can simultaneously realize efficient sterilization, significantly prolong shelf life, and completely solve the problem of fat floating, while taking into account the feasibility and economy of production.

[0007] To achieve the above object, the technical scheme adopted by the present application is: A long shelf life buffalo milk, the fat globule size of the buffalo milk is 0.4-0.8 μm, and the fat floating rate is less than 3.5% after 15 days of storage under refrigeration conditions of 2-6℃.

[0008] In the present application, further, the total number of colonies of the buffalo milk is ≤7.5×10 4 CFU / mL, the somatic cell count is ≤2.5×10 4 CFU / mL, and the spore count is ≤10 CFU / mL.

[0009] The present application also proposes an ultra-instant sterilization method for buffalo milk, comprising the following steps: (1) centrifugal sterilization pretreatment of raw buffalo milk; (2) ultra-instant sterilization of the sterilized buffalo milk using steam immersion technology; (3) flash evaporation cooling of the sterilized buffalo milk; (4) high-pressure homogenization of the flash-evaporated and cooled buffalo milk; (5) aseptic filling of the homogenized buffalo milk.

[0010] In the present application, further, the centrifugal sterilization pretreatment conditions are: treatment temperature 55±1℃, drum rotation speed 4700±100 rpm; the sterilization machine automatically discharges residue every 20 minutes of operation, and each discharge lasts for 3 minutes.

[0011] In the present application, further, the ultra-instant sterilization conditions are: sterilization temperature 144±2℃, sterilization time 0.09s.

[0012] In the present application, further, the high-pressure homogenization pressure is 23-25 MPa; the high-pressure homogenization is post-homogenization, i.e. after the sterilization and flash evaporation steps.

[0013] In the present application, further, the aseptic filling comprises: sending the buffalo milk into an aseptic storage tank maintaining a positive pressure sterile air environment for temporary storage, and then filling it into a pre-sterilized container through a filling device and sealing; the filling device is arranged in an environment with a cleanliness of at least ISO 5 level according to ISO 14644-1 standard.

[0014] The present application also proposes a buffalo milk production system, comprising, in sequence along the material flow direction: centrifugal sterilizer; steam infusion ultraflash pasteurization equipment; flash tank; high pressure homogenizer; sterile storage tank, which is configured with a device for maintaining positive pressure sterile air; filling device, which is arranged in an ISO 5 level clean environment.

[0015] In the present application, further, the centrifugal sterilizer is configured to process at a temperature of 55±1℃ and at a rotational speed of 4700±100rpm; the centrifugal sterilizer is further configured with an automatic residue discharge program that operates every 20 minutes and lasts for 3 minutes each time.

[0016] In the present application, further, the steam infusion ultraflash pasteurization equipment is configured to operate at a sterilization temperature of 144±2℃ and a sterilization time of 0.09s; the high pressure homogenizer is configured to operate at a homogenization pressure of 23-25MPa.

[0017] Compared with the prior art, the present application has at least the following beneficial effects: Compared with the prior art, the technical solution provided by the present application achieves significant beneficial effects through the synergistic optimization and innovative combination of each process step, which is embodied in the following aspects: First, the present application significantly prolongs the shelf life of buffalo milk products. By adopting the combination process of "centrifugal sterilization pretreatment" and "ultraflash pasteurization (144±2℃ / 0.09s)", high-efficiency sterilization is achieved. The sterilization pretreatment can effectively remove more than 85% of the microbial load (including heat-resistant spores) in raw milk, creating conditions for ultra-short-time sterilization. The shelf life of the final product under cold storage conditions of 2-6℃ is significantly prolonged from 7 days for traditional buffalo milk pasteurized products to 15 days. This not only greatly reduces the frequency and cost of cold chain logistics, but also provides reliable protection for the market circulation of buffalo milk products.

[0018] Second, while achieving high-efficiency sterilization, the present application has the dual advantages of high thermal efficiency and good nutrient retention. The steam infusion ultraflash pasteurization technology adopted has high heat transfer efficiency and can complete the heating-cooling process in a very short time (0.09s), reducing the loss of heat-sensitive nutrients compared to traditional pasteurization processes, and better preserving the natural flavor of buffalo milk. At the same time, due to the extremely short heating time, the heat energy consumption per unit of product is significantly reduced, reflecting the environmental advantages of energy saving and emission reduction.

[0019] Third, the present application effectively solves the technical problem of buffalo milk fat floating. In view of the characteristics of high fat content (7-12%) and large average fat globule size (6.84-8.7 μm) of buffalo milk, the "high-pressure post-homogenization" process is innovatively adopted, the homogenization pressure is increased to 23-25 MPa, and the homogenization process is arranged after heat treatment. This process arrangement makes the fat globule size stable and refined to 0.4-0.8 μm, and because there is no subsequent heat treatment after homogenization, the newly formed fat globule membrane structure remains intact, thereby maintaining stability during storage. Experimental data show that the fat floating rate of the product at the end of the 15-day shelf life is stable at below 3.5%, significantly improving the stability and sensory quality of the product.

[0020] Fourth, the present application realizes the systematic innovation of buffalo milk processing technology. By organically integrating the technologies of sterilization pretreatment, ultra-instant sterilization, flash evaporation, high-pressure post-homogenization, sterile storage and ultra-clean filling, a complete processing solution for buffalo milk is formed. This solution overcomes the technical bottleneck in buffalo milk processing and provides reliable technical support for the development of high-quality buffalo milk products, which has a positive significance for promoting the development of buffalo milk industry. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Fig. 1 is a structural schematic diagram of the buffalo milk production system of the present application; In the figure, the reference numerals are: 1, centrifugal sterilization machine; 2, steam immersion type ultra-instant sterilization equipment; 3, flash evaporation tank; 4, high-pressure homogenizer; 5, sterile storage tank; 6, filling device.

[0022] Figure 2 Fig. 2 is a flow chart of the ultra-instant sterilization production process of the present application. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, therefore the present application is not limited by the specific implementation disclosed below.

[0024] Example 1: Specific implementation of the process of the present application 1. Raw material selection and acceptance: High-quality fresh buffalo milk produced by healthy buffaloes is selected as the raw material. The raw milk shall meet the following standards: total bacterial count ≤1.0×10 6 CFU / mL, somatic cell count ≤5.0×10 5The raw milk should have the following characteristics: spore count ≤150 CFU / mL, fat content ≥7.5%, and protein content ≥4.5%. After passing inspection, the raw milk should be rapidly cooled to below 4°C and temporarily stored.

[0025] 2. Sterilization pretreatment: Raw buffalo milk is preheated to 55±1℃ and then pumped into a centrifugal sterilizer (such as the GEA SeparaPress or Westfalia Separator MSa series) for pretreatment. The sterilizer's drum speed is controlled at 4700±100 rpm. To maintain high separation efficiency, the system is set to automatically discharge residue every 20 minutes, with each discharge lasting 3 minutes. This step effectively removes most microorganisms, somatic cells, and impurities from the raw milk, significantly reducing the load on subsequent sterilization processes.

[0026] 3. Ultra-instant sterilization: The pre-sterilized milk is pumped via a high-pressure pump into a steam immersion ultra-fast sterilization system (such as SPX FLOW's APV direct-injection sterilizer or Tetra Pak's indirect heating system). The milk is instantly mixed with high-pressure clean steam in the pipeline and precisely and uniformly heated to a core sterilization temperature of 144±2°C, which is maintained for approximately 0.09 seconds. This ultra-high temperature, ultra-short time (UHT) treatment instantly inactivates all pathogens and the vast majority of spoilage microorganisms, including heat-resistant spores.

[0027] 4. Flash evaporation treatment: After sterilization, the high-temperature milk feed is immediately transferred to a vacuum flash tank (such as SPX FLOW's Vac-Vator) via a pressure-reducing valve. This valve smoothly reduces the material pressure from the positive pressure of the sterilization system to the vacuum environment required by the flash tank. Under vacuum, the small amount of additional water injected into the milk evaporates instantly, carrying away a significant amount of latent heat of vaporization, causing the material temperature to rapidly drop from 144°C to 25-30°C. This process not only achieves rapid cooling but also effectively removes any cooked taste that may have been produced during high-temperature heating, restoring the natural aroma and flavor of buffalo milk.

[0028] 5. Homogenization after high pressure: The flash-cooled milk is pumped into a high-pressure homogenizer (e.g. GEA Niro Soavi NS series or APV Gaulin homogenizer) by aseptic pump. It is critical that this homogenization step is set after heat treatment (post-homogenization). In view of the high fat content and large fat globule size of buffalo milk, the present invention adopts a single-stage homogenization mode, with the homogenization pressure set at 23-25 MPa. The reason for using high-intensity single-stage homogenization instead of the commonly used two-stage homogenization for dairy products is to exert a one-time, sufficiently intense mechanical shear force on the large fat globules in buffalo milk, ensuring that they are fully broken up and refined. In this mode, the fat globule size is significantly reduced from 6.84-8.7 pm in the raw material to 0.4-0.8 pm, and the distribution is more uniform. Since homogenization occurs after sterilization, the protein film on the surface of the newly formed tiny fat globules no longer undergoes heat treatment during subsequent storage, and thus remains intact and stable, thereby significantly reducing the risk of fat globule aggregation and floating from the root.

[0029] 6. Aseptic storage and filling: The homogenized finished milk enters a pre-CIP (clean-in-place) and SIP (sterilization-in-place) treated aseptic storage tank for temporary storage. The aseptic tank is always connected to sterile air filtered through a 0.22 pm filter, and maintains a certain positive pressure (e.g. 5-10 kPa) to prevent the entry of external bacteria-laden air. Finally, the milk is transported to the filling device through aseptic pipelines. The filling device is set in a clean room certified by ISO 14644-1, with a cleanliness level of ISO 5, or under a laminar flow hood equipped with a high-efficiency air filter (HEPA), to ensure the aseptic state of the filling environment. The product is filled into packaging containers that have been sterilized by hydrogen peroxide spraying or ultraviolet light, and immediately sealed to obtain the final product.

[0030] 7. Finished product storage: The sealed product is transported and stored under refrigeration at 2-6°C. The shelf life of buffalo milk produced by this process can be extended to more than 15 days, and there is no fat floating phenomenon during the entire shelf life, with stable sensory quality.

[0031] Example 2: Specific implementation of the system of the present invention This example combines Figure 1 A dedicated production system for implementing the above method is described in detail.

[0032] Reference Figure 1 (see the schematic diagram showing the connection of various components), the buffalo milk production system of the present invention includes the following equipment connected by aseptic pipelines and aseptic pumps in the order of material flow: Centrifugal sterilizer 1: Its feed inlet is used to receive raw buffalo milk. This equipment is equipped with a temperature control system and a speed control system, which can accurately execute the process parameters (55±1℃, 4700±100 rpm) described in step 2 of Example 1.

[0033] Steam immersion ultra-instantaneous sterilization equipment 2: Its inlet is connected to the outlet of the centrifugal sterilizer 1 via a first delivery pump. This equipment integrates a steam injection device, a high-temperature holding tube, and a precision temperature sensor to achieve sterilization conditions of 144±2℃ / 0.09s.

[0034] Pressure reducing valve and flash tank 3: The inlet of the flash tank 3 is connected to the outlet of the sterilization equipment 2 via a pressure reducing valve. This pressure reducing valve is a key component to ensure the safe and stable entry of high-temperature materials from the sterilization system into the vacuum flash tank. The tank is connected to a vacuum generation system and a condensation system for rapid cooling and deodorization.

[0035] High-pressure homogenizer 4: Its inlet is connected to the outlet of the flash tank 3 via a second delivery pump. This homogenizer is configured for single-stage homogenization and can stably provide a homogenization pressure of 23-25 ​​MPa to meet the special requirements for refining buffalo milk fat globules.

[0036] Aseptic storage tank 5: Its inlet is connected to the outlet of the high-pressure homogenizer 4. This tank is equipped with a CIP / SIP cleaning and sterilization system, an aseptic air filtration system, and a positive pressure maintenance device, and is used to temporarily store the homogenized aseptic semi-finished product.

[0037] Filling device 6: It is connected to the outlet of the aseptic storage tank 5 via a sterile pipe. The filling device is installed in a cleanroom certified by ISO 14644-1 and with a cleanliness level of ISO 5, and is used to aseptically fill the product into pre-sterilized containers and seal them.

[0038] The system's modular integration of units, coordinated by a central control unit (PLC), forms a continuous, closed, and highly efficient buffalo milk processing line.

[0039] Example 3: Verification of the effectiveness of the invention To fully verify the effectiveness of the process of this invention, the same batch of raw buffalo milk raw materials was used. First, the efficiency of sterilization pretreatment was verified. Then, different homogenization pressures (15MPa, 20MPa, 23-25MPa) were used for processing, and the key indicators of the finished products were tested. The results are shown in the table below.

[0040]

[0041] The results show that the centrifugal sterilization pretreatment process can effectively remove ≥85% of microorganisms (including spores that are difficult to kill) and somatic cells from raw buffalo milk, significantly reducing the microbial load of the subsequent ultra-short-time sterilization process. This is the prerequisite and guarantee for achieving ultra-short-time and efficient sterilization.

[0042] Subsequently, the sterilized buffalo milk was processed. 15 MPa represents the traditional pre-homogenization process (Comparative Example 1), 20 MPa represents the process that did not meet the requirements of this invention (Comparative Example 2), and 23-25 ​​MPa high-pressure homogenization represents the process of this invention (Example). The results are shown in the table below:

[0043] Based on the results in Table 2, the following conclusions can be drawn: (1) Fat globule refinement effect: As shown in the table, increasing the homogenization pressure from 15 MPa to 20 MPa has a certain refining effect on fat globules (from 1-5 μm to 1-3 μm), but the effect is limited and fails to break through the critical point of 1 μm. However, the homogenization process after 25 MPa used in this invention successfully and stably refines the fat globule size to the submicron level of 0.4-0.8 μm, which is significantly better than the former two.

[0044] (2) Inhibition of fat buoyancy: As shown in the table, the fat buoyancy rate is absolutely negatively correlated with the homogenization effect. The fat buoyancy rate of the product processed by the traditional 15MPa process is as high as 12.8% or more after 15 days. Although the 20MPa process has improved this somewhat (7.5-7.8%), it is still higher than the acceptable range of 5% and cannot solve the substantial problem. Only the process of this invention can stably control the fat buoyancy rate below 3.5%, completely solving the problem of fat stability in buffalo milk products.

[0045] (3) Non-obviousness of the process of the present invention: The above data proves that simply increasing the homogenization pressure (e.g., from 15 MPa to 20 MPa) cannot achieve the technical effect of the present invention. The pressure must be significantly increased to 23-25 ​​MPa and combined with the subsequent homogenization process to produce a qualitative leap and achieve unexpected synergistic effects. This fully demonstrates the inventiveness and non-obviousness of the present invention.

[0046]

[0047] In summary, the sterilization pretreatment laid the foundation for ultra-short-time sterilization; ultra-instantaneous sterilization combined with high-pressure homogenization solved the problems of sterilization and fat stabilization; and the final product achieved the two core objectives of extending shelf life and inhibiting fat precipitation.

[0048] The above embodiments are merely examples of several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention.

Claims

1. A long-shelf-life buffalo milk, characterized in that, The fat globules in the buffalo milk have a diameter of 0.4-0.8 μm, and after being stored at 2-6℃ for 15 days, the fat floating rate is less than 3.5%.

2. The buffalo milk according to claim 1, characterized in that, The total bacterial count of the buffalo milk was ≤7.5×10⁻⁶. 4 CFU / mL, somatic cell count ≤2.5×10 4 Cells / mL, spore count ≤10 CFU / mL.

3. A method for ultra-short-term sterilization of buffalo milk, characterized in that, Includes the following steps: (1) Centrifuge sterilization pretreatment of raw buffalo milk; (2) The sterilized buffalo milk is sterilized by steam immersion technology for ultra-instantaneous sterilization; (3) Flash-cool the sterilized buffalo milk; (4) High-pressure homogenization of the buffalo milk after flash evaporation and cooling; (5) The homogenized buffalo milk is filled under aseptic conditions.

4. The method according to claim 3, characterized in that, The conditions for the centrifugal sterilization pretreatment are: treatment temperature 55±1℃, drum speed 4700±100rpm; the sterilizer automatically discharges slag once every 20 minutes of operation, and each slag discharge lasts for 3 minutes.

5. The method according to claim 3, characterized in that, The conditions for ultra-instantaneous sterilization are: sterilization temperature 144±2℃, sterilization time 0.09s.

6. The method according to claim 3, characterized in that, The pressure of the high-pressure homogenization is 23-25 ​​MPa; the high-pressure homogenization is a post-homogenization, that is, it is located after the sterilization and flash evaporation steps.

7. The method according to claim 3, characterized in that, The aseptic filling process includes: temporarily storing buffalo milk in an aseptic storage tank that maintains a positive pressure aseptic air environment, and then filling it into a pre-sterilized container and sealing it using a filling device.

8. A buffalo milk production system, characterized in that, Including those connected sequentially along the material flow direction: Centrifugal sterilizer (1); steam immersion ultra-instantaneous sterilization equipment (2); flash tank (3); high pressure homogenizer (4); aseptic storage tank (5); filling device (6).

9. The system according to claim 8, characterized in that, The centrifugal sterilizer (1) is configured with a processing temperature of 55±1℃ and a drum speed of 4700±100rpm; the centrifugal sterilizer (1) is also configured with an automatic slag discharge program that runs once every 20 minutes and lasts for 3 minutes each time.

10. The system according to claim 8, characterized in that, The steam immersion ultra-instantaneous sterilization equipment (2) is configured with a sterilization temperature of 144±2℃ and a sterilization time of 0.09s; the high-pressure homogenizer (4) is configured with a homogenization pressure of 23-25MPa.

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