Buffalo milk double skin milk and preparation method thereof

Abstract

The present invention relates to the field of buffalo double skin milk processing, and in particular to a buffalo milk double skin milk and a preparation method thereof. The present invention utilizes the characteristics of buffalo milk protein and fat content to form a suitable single layer of milk skin to prepare double skin milk, and at the same time, appropriately adds rennet and lipase to replace cow milk and egg white protein for high-heat coagulation, adds calcium ions to increase the speed and hardness of coagulation, introduces an emulsifier stabilizer, and improves the water holding capacity of the product; in addition, lipase and / or concentrated jam are added to the raw milk to enrich the product flavor. The present invention not only ensures the thick and heavy skin of the double skin milk and stable coagulation, fully retains the traditional taste and flavor of the double skin milk, and can give a fuller frankincense, but also can regulate products with different fruity flavors according to the needs of different groups of people, and the entire process does not need to introduce new equipment, and production can be achieved using the existing equipment of the dairy enterprise. In addition, low-temperature treatment is used throughout the process to maximize the retention of cow milk and egg active substances, which is comparable to the nutritional activity of pasteurized milk.

Description

[Technical field]

[0001] The invention relates to the technical field of buffalo double skin milk processing, in particular to buffalo double skin milk and a preparation method thereof. [Background technology]

[0002] Buffalo milk has a strong flavor and a high total milk solids content. It is an excellent raw material for making various high-end dairy products. Relying on the characteristics of buffalo milk, such as thick milk, rich milk flavor, large casein micelle diameter, and conducive to coagulation, its product quality is difficult to replace by other cow milk products. It is paste-like, white in color, delicate and smooth in texture, and sweet and light in taste. It can be eaten hot or cold, moisturizing the lungs and nourishing the skin, suitable for all ages. Its peculiarity is that it contains double layers of milk skin, one layer is sweet and fragrant, and the second layer is fragrant, so it is called double skin milk. It has mature commercial value and a widely popular consumer base in the market. Nowadays, it is loved and paid attention to by more and more domestic and foreign tourists, the demand is increasing, and the market prospects are broad.

[0003] At present, Shuangpi milk is mostly known as a "folk snack" by people. It is sold locally in a mode of being made and sold on the spot. Its production method also simply follows the traditional folk craftsmanship. It is basically handmade, workshop-style or kitchen-style production. It has a short shelf life, small production scale, low degree of standardization, large randomness in operation, and large differences in texture and flavor. It has not yet formed a mature large-scale production and commercial promotion product. How to realize the industrialization and promotion of traditional buffalo dairy products such as Shuangpi milk will play an important role in protecting and carrying forward the traditional food culture, and will also bring new economic growth points to the buffalo dairy industry.

[0004] In Guangdong and Guangxi, some dairy companies have industrialized the production of "double-skin milk" products, mainly in three forms: one is to make it into a powdered product; the second is to use food additives such as pectin and gelatin to form a curd product without egg white; the third is to make the traditional double-skin milk into a single-skin milk, which has the same appearance and state, but is inferior to the traditional double-skin milk in taste and flavor. Some companies are also developing the industrial production technology of double-skin milk, but due to the relatively complex process and equipment, the research and development results are only in a semi-automatic state, requiring certain manual operations, and it is difficult to form a certain production scale. The key process of double-skin milk lies in the formation of milk skin and curd, that is, first use the milk cooling process to form a layer of milk skin containing fat and milk protein; then use egg white protein and milk protein to mix, heat over a low fire, and then cool to form a second layer of milk skin containing fat, milk protein, and egg white protein; at the same time, use egg white protein to heat and denature and coagulate, and form curd after cooling. Stabilizers can be added to enhance the curd stability of double-skin milk. At present, the industrialization of double-skin milk is difficult, mainly because of the difficulty in developing fully automatic equipment to form double-layer milk skin and the difficulty in beating fresh egg white evenly, especially the difficulty in designing and manufacturing the equipment for piercing the skin of double-skin milk and sucking out the milk. Although there are some studies on the production process of double-skin milk in China, these process technologies have no obvious differences and advantages compared with traditional processes, and their application in industrial production is very limited. There is no industrial product with good stability, and the process technology needs to be continuously improved and upgraded to truly realize the industrialization and promotion of the product.

[0005] Therefore, it is necessary to study and improve the processing technology of buffalo milk double skin milk, and develop a buffalo milk double skin milk processing method that is suitable for large-scale production and easy to operate. [Summary of the invention]

[0006] In view of the above, it is necessary to study and improve the processing technology of buffalo milk double skin milk, and develop a buffalo milk double skin milk processing method that is suitable for large-scale production and easy to operate.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A buffalo double skin milk, the double skin milk is composed of the following components: 100 parts of buffalo milk, 0.5-1.5 parts of egg raw materials, 2-10 parts of flavoring agents, 0.1-0.6 parts of emulsifier stabilizer, 0.001-0.030 parts of calcium chloride, 2.5-8 parts of concentrated jam, 0.0005-0.004 parts of rennet, and 500-1500u / kg of lipase;

[0009] The egg raw material is one or more of egg white powder and whole egg powder;

[0010] The flavoring agent is one or more of sucrose, inulin, and trehalose;

[0011] The emulsion stabilizer is one or more of gelatin, carrageenan and gelatin powder;

[0012] The concentrated jam is one or more of lychee, blueberry, mango and strawberry.

[0013] Furthermore, the chymosin is CHY-MAXTM Power NB;

[0014] The lipase was purchased from Nanning Pangbo Bioengineering Co., Ltd.

[0015] The present invention also includes a method for preparing the buffalo double skin milk, the method comprising the following steps:

[0016] (1) Weighing the raw materials according to the above weight ratio;

[0017] (2) filtering the fresh buffalo milk and standardizing the protein content to 4.2%. The standardization method is as follows: measuring the protein content of the fresh milk, if it is greater than 4.2%, adding drinking water to dilute it to 4.2%, and if it is less than 4.2%, separating and skimming to remove part of the fat and then adjusting the protein content to 4.2%, thereby obtaining raw buffalo milk;

[0018] (3) Preheating the buffalo raw milk to 55-65° C.;

[0019] (4) mixing the buffalo milk preheated in step (3) with the egg raw material, flavoring agent, emulsifier stabilizer, calcium chloride and concentrated jam, homogenizing the mixture and then pasteurizing the mixture to obtain sterilized raw material milk;

[0020] (5) cooling the sterilized raw material milk in step (4) to 25-40° C.;

[0021] (6) After the rennet and / or lipase is dissolved, it is added to the raw material milk after cooling in step (5), and stirred evenly; it is filled into a packaging container that has been pre-cleaned and disinfected, and the milk is coagulated at a constant temperature of 33-42° C. for 30-180 minutes, thereby obtaining the finished product of the double-skin milk.

[0022] Furthermore, the refrigerated temperature of the double skin milk product in step (6) is 2-8°C.

[0023] Furthermore, the homogenization temperature in step (4) is 55-65° C. and the pressure is 15-25 MPa.

[0024] Furthermore, the pasteurization in step (4) is performed at 62-65°C for 30-40 min, or 72°C for 15 s.

[0025] The present invention has the following beneficial effects:

[0026] 1) The present invention introduces a food-grade rennet that contains highly specific cleavage of κ-casein to coagulate milk, and at the same time adds calcium ions that can increase enzyme activity and facilitate milk polymerization. Different from the traditional process of high heat and long-term induction to cause heat denaturation of milk protein and egg white protein to produce gel, the present invention uses enzymatic hydrolysis technology to achieve standardized coagulation, thereby achieving repeatability of product process and controllability of quality.

[0027] 2) The present invention has the significant effect of adding lipase, firstly, accelerating the coagulation, the normal pH of fresh milk is 6.6, chymosin belongs to acidic protease, the optimum pH is 5.2-6.3, the lower the pH of milk, the faster the coagulation reaction speed, lipase hydrolyzes fat to produce a large amount of free fatty acids, reduces the acidity of the reaction solution, and creates a low acid environment; at the same time, after the enzymatic hydrolysis of fat, the surface microstructure and trace element content are changed, more wrinkled surfaces are exposed to promote the attachment of chymosin, and κ-casein is exposed in a hydrophobic environment, and the affinity between chymosin and κ-casein is increased, which is conducive to chymosin to more easily approach the protein substrate. These two factors jointly promote the acceleration of coagulation and shorten the coagulation time. The second is to increase the flavor, by releasing more fat-derived flavoring substances, the whole double skin milk is more intense, soft and fuller than the frankincense flavor of the traditional process.

[0028] 3) The heat treatment used in the present invention is all low temperature, including preheating and homogenization (55-65°C), low temperature pasteurization (no more than 72°C), and coagulation (33-42°C), which does not exceed the thermal denaturation temperature of buffalo milk protein and egg white protein (both above 75°C), greatly reducing the denaturation damage of protein, while greatly retaining the active functions of heat-sensitive substances in milk and eggs, such as lactoferrin, immunoglobulin, peroxidase, lysozyme, bioactive peptides, etc. At the same time, low temperature coagulation ensures the soft, delicate, smooth texture and taste of the product.

[0029] 4) The present invention realizes precise control of the coagulation time by controlling the process, including cooling temperature, coagulation temperature, enzyme addition amount, type of emulsifier stabilizer, etc., which can meet the needs of small batch coagulation of 30 minutes in milk bars and dessert shops, and can also meet the needs of industrial large batch coagulation of 180 minutes, and is suitable for different processing requirements.

[0030] 5) The invention enriches the flavor of the double skin milk by adding sweet concentrated jam, so that the finished product has a strong milky aroma, prominent fruity aroma, fine texture, smooth taste, and meets the tastes of more different consumers. The double skin milk product is nutritious and delicious and has great market promotion value.

[0031] 6) The present invention mainly utilizes rennet to achieve milk coagulation, and the egg raw material can be powdered whole egg powder and egg powder, which are mature industrial products, and are convenient for direct addition during production. There is no need for the technical operation of extracting clear liquid from fresh eggs, thereby reducing equipment investment.

[0032] In summary: The preparation process of the present invention solves the problem that traditional processes are difficult to achieve batch production of double-skin milk, and at the same time obtains a product with a richer, softer, more delicate and smoother taste than traditional processes. The main obstacles to the industrial production of traditional double-skin milk are the formation of milk skin, the extraction of fresh egg white liquid and the loss of nutrients in high-temperature steaming and curdling, and because the texture is not firm enough, it is difficult to transport and sell over long distances. The present invention determines the industrial production process of high-quality double-skin milk, which mainly utilizes the high content of buffalo milk protein and fat to form a suitable single-layer milk skin, and at the same time, a suitable amount of rennet is added to replace cow milk and egg white protein for high-temperature coagulation, lipase and calcium ions are added to increase the speed of coagulation, and emulsifier stabilizers are introduced to improve the water holding capacity of the product; lipase and / or concentrated jam are added to the raw milk to enrich the flavor of the product. The invention not only ensures the thick texture and stable curd of Shuangpi milk, but also does not require special equipment for extracting fresh egg white. At the same time, it fully retains the traditional taste and flavor of Shuangpi milk, and can give a fuller frankincense. It can also adjust products with different fruity flavors according to the needs of different groups of people. The entire process does not require the introduction of new equipment, and can be produced using the existing equipment of dairy companies. In addition, the full name adopts low-temperature treatment to maximize the retention of active substances in milk and eggs, comparable to the nutritional activity of pasteurized milk. [Specific implementation method]

[0033] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0034] Any feature disclosed in this specification (including any appended claims and abstract), unless otherwise stated, is merely an example of a series of equivalent or similar features.

[0035] Embodiment 1:

[0036] The preparation method of this embodiment is as follows: fresh buffalo milk is filtered, and the milk components are determined. The protein content is 5.0%. 16 parts of drinking water standardized protein are added to 84 parts of fresh buffalo milk to 4.2% to obtain raw buffalo milk; the raw buffalo milk is preheated to 65°C, and each raw material is weighed according to the following weight parts: 100 parts of raw buffalo milk, 1.35 parts of egg white powder, 8 parts of sucrose, 0.1 parts of carrageenan, 0.03 parts of calcium chloride, and 2.5 parts of litchi jam are directly poured into the preheated raw buffalo milk and stirred in a batching tank until completely dissolved to obtain raw and auxiliary milk; the raw and auxiliary milk is placed at a temperature of 65°C and a pressure of 15MPa for homogenization; the homogenized raw and auxiliary milk is sterilized at a sterilization condition of 62°C for 40min; the sterilized raw and auxiliary milk is cooled to 40°C; 0.003 parts of rennet and 1500u / kg of lipase (wherein, rennet is CHY~MAXTM PowerNB, manufactured by Chr. Hansen, Denmark; lipase purchased from Nanning Pangbo Bioengineering Co., Ltd.), was dissolved in a small amount of sterile water and added to the cooled raw material milk, and stirred evenly. After aseptic filling, the milk was coagulated at a constant temperature of 40°C for 30 minutes to obtain the double skin milk product. The finished product was stored at 4°C for 14 days, and no whey was precipitated on the surface.

[0037] Embodiment 2:

[0038] The preparation method of this embodiment is as follows: fresh buffalo milk is filtered and the milk components are measured. The protein content is 4.8%. 12.5 parts of drinking water standardized protein are added to 87.5 parts of fresh buffalo milk to 4.2% to obtain raw buffalo milk; the raw buffalo milk is preheated to 55°C, and each raw material is weighed according to the following weight parts: 100 parts of raw buffalo milk, 1 part of egg white powder, 7 parts of inulin, 0.3 parts of gelatin powder, 0.002 parts of calcium chloride, and 6 parts of blueberry jam are directly poured into the preheated raw buffalo milk and stirred in a mixing tank until completely dissolved to obtain raw and auxiliary milk; the raw and auxiliary milk is placed at a temperature of 55°C and a pressure of 25MPa for homogenization; the homogenized raw and auxiliary milk is sterilized at 72°C for 15s; the sterilized raw and auxiliary milk is cooled to 37°C; 0.004 parts of rennet and 1000u / kg of lipase (wherein, rennet is CHY~MAXTM PowerNB, manufactured by Chr. Hansen, Denmark; lipase purchased from Nanning Pangbo Bioengineering Co., Ltd.), was dissolved in a small amount of sterile water and added to the cooled raw material milk, and stirred evenly. After aseptic filling, the milk was coagulated at a constant temperature of 42°C for 40 minutes, which was the finished product of Shuangpi milk. The finished product was stored at 6°C for 14 days, and no whey was precipitated on the surface.

[0039] Embodiment 3:

[0040] The preparation method of this embodiment is as follows: fresh buffalo milk is filtered and the milk components are measured. The protein content is 4.0%. 105 parts of fresh buffalo milk are skimmed and 5 parts of fat and other substances are removed to standardize the protein to 4.2% to obtain raw buffalo milk; the raw buffalo milk is preheated to 60° C. and the raw materials are weighed according to the following weight parts: 100 parts of raw buffalo milk, 0.5 parts of whole egg powder, 3 parts of trehalose, 0.5 parts of emulsifier stabilizer (wherein the emulsifier stabilizer is prepared by mixing gelatin: carrageenan: gelatin powder in a ratio of 1:1:1), and 0.02 parts of calcium chloride , 8 portions of concentrated jam (wherein the concentrated jam is composed of mango jam and strawberry jam in a mass ratio of 1:1) are directly poured into the preheated raw buffalo milk and stirred evenly in the batching tank until completely dissolved to obtain raw material milk; the raw material milk is placed at a temperature of 60°C and a pressure of 20MPa for homogenization; the homogenized raw material milk is sterilized at 65°C for 30min; the sterilized raw material milk is cooled to 25°C; 0.0005 portions of rennet and 500u / kg of lipase (wherein the rennet is CHY~MAXTM Power NB, manufactured by: Chr. Hansen, Denmark; lipase is purchased from Nanning Pangbo Bioengineering Co., Ltd.) are weighed by the weight of the raw materials, dissolved with a small amount of sterile water, and added to the cooled raw material milk, and stirred evenly. After aseptic filling, the milk is coagulated at a constant temperature of 33°C for 180min, i.e. the finished product of double skin milk, which is stored at 8°C for 14 days without whey precipitation on the surface.

[0041] Comparative Example - Traditional Process

[0042] The traditional method of preparing Shuangpi milk is as follows: freshly brought back water buffalo milk is filtered, milk components are determined, and the protein is standardized to 4.2% to obtain raw water buffalo milk. The raw water buffalo milk is preheated to 60°C, 12.5 parts of fresh egg white and 6 parts of sucrose are weighed and poured into the preheated raw water buffalo milk, and stirred evenly in a mixing tank until completely dissolved to obtain raw and auxiliary milk; the raw and auxiliary milk is packaged and sealed, and then placed in boiling water for steaming until solidified, and the finished product is stored at 4°C.

[0043] Test Case

[0044] The buffalo milk double skin milk prepared in Examples 1, 2, 3 and the comparative example was tested for texture, water holding capacity, sensory evaluation and other aspects, wherein the determination method is:

[0045] (1) Texture characteristics

[0046] After the samples were taken out of the refrigerator and thawed to room temperature, texture analysis was performed using an FTC professional research-grade food physical property analyzer to measure the hardness, stickiness, elasticity and chewiness of the samples. The measurement parameters included: a cylindrical probe with a diameter of 25.60 mm and a height of 35.07 mm, a detection speed of 60 mm / min, a deformation percentage of 20%, a starting force of 0.05 N, and a force sensing unit of 50 N.

[0047] (2) Water holding capacity

[0048] Take a 50ml centrifuge tube, record the mass as A1 (g), add 20g of the stirred double skin milk into the centrifuge tube, record the mass after adding the double skin milk as A2 (g), put the double skin milk into a centrifuge, centrifuge at 8000r / min for 20min, discard the supernatant, and accurately weigh the mass of the precipitate A3 (g). The formula is as follows:

[0049] W(%)=(A3-A1) / (A2-A1)×100

[0050] (3) Sensory evaluation

[0051] The scoring group is composed of 10 professional technicians with relevant dairy product tasting knowledge, who score the products according to the four evaluation criteria in Table 1.

[0052] Table 1 Sensory evaluation standard of Shuangpi milk

[0053]

[0054] The index results are detailed in Table 2.

[0055] Table 2 Quality evaluation results of buffalo milk double skin milk of the present invention

[0056]

[0057] The above data show that in terms of texture characteristics, the hardness, viscosity, elasticity and chewiness of Examples 1, 2 and 3 are significantly better than those of the control example (P < 0.05). This is due to the following measures: First, rennet is mainly used for coagulation, and rennet acts on milk κ-casein. In the coagulation process, κ-casein is the only protein that is hydrolyzed, that is, rennet breaks the peptide chain between phenylalanine (Phe105) and methionine (Met106) in the κ-casein sequence. The N-terminal part of the protein molecule, κ-CNF1-105, is called para-κ-casein, which is attached to the protein colloid; the decomposed C-terminal part is called glycopeptide, which is soluble in water. The sudden removal of the hydrophilic glycopeptide leads to an imbalance of intermolecular forces to form para-κ-casein. Para-κ-casein itself is more hydrophobic than κ-casein, and is affected by Ca. 2+ The molecules collide and combine with each other to form a three-dimensional network structure. 2+The unstable αs-casein and β-casein lose the protection of κ-casein, thus coagulating and forming clots. The whole process is carried out at low temperature, which can achieve fine product tissue and uniform texture. The traditional process is mainly the gel of milk protein and egg white protein. Milk protein is composed of casein with high thermal stability and whey protein with poor thermal stability. It is easy to cause protein denaturation after heating. When the temperature exceeds 65°C, the polypeptide chain of whey protein folds and denatures, and the disulfide bonds and thiol groups in the molecules are exposed, reacting with casein, converging with each other, forming protein polymers, reducing the solubility and stability of the milk protein colloid system, and causing milk protein coagulation. Due to heat treatment, the tertiary and quaternary structures of egg white protein undergo irreversible denaturation, first changing from a natural state to a denatured state, forming high molecular weight soluble aggregates through the folding of β-protein, and after the action of disulfide bonds, the pre-gel aggregates gradually thicken to form a gel. Studies have shown that the ideal gel effect can only be achieved when the heat treatment temperature is above 80°C, but when it exceeds 95°C, the protein is severely denatured and no longer has the ability to form a gel, and the gel structure that has been formed is destroyed. The traditional process prepares double skin milk by high-temperature steaming, and the coagulation strength is severe and difficult to control. Second, the embodiment introduces lipase, which enzymatically hydrolyzes fat in double skin milk, generates a large amount of free fatty acids, reduces the pH in milk, and changes the surface microstructure and trace element content, increases the contact surface between rennet and κ-casein, and promotes faster coagulation. Third, the embodiment introduces calcium ions, which promote the rennet coagulation process and improve the coagulation strength. Fourth, the embodiment introduces an emulsifier stabilizer, whose role in double skin milk is to bind water and enhance the texture of double skin milk. Fifth, when calcium ions and emulsifier stabilizers are present in the solution at the same time, calcium ions can promote the gel strength of the emulsifier at low temperatures. Therefore, the texture characteristics of the double skin milk in the embodiment are better than those of the comparative example.

[0058] In terms of water holding capacity, Examples 1, 2, and 3 are significantly higher than the comparative example (P < 0.05), mainly because calcium chloride can enhance the electrostatic effect of double skin milk, aggravate the aggregation between protein molecules, enhance the gel property of whey protein, and improve the water locking capacity of double skin milk; on the other hand, the surface anions of the emulsifier stabilizer interact with the cations on the surface of the protein to form a network structure, so that water cannot flow freely, thereby increasing the water holding capacity. The greater the water holding capacity, the less whey precipitation, and the better the stability of double skin milk.

[0059] In terms of sensory quality, all three embodiments received very high scores, with a smooth and rich taste.

[0060] Embodiment 4:

[0061] This example mainly studies the effects of different components on double skin milk curd:

[0062] Taking Example 1 as a reference, the raw materials of double skin milk are adjusted as follows:

[0063] Experimental group 1: Example 1;

[0064] Experimental group 2: The raw materials contained only rennet and no lipase, as follows:

[0065] Weigh the raw materials according to the following weight: 100 parts of raw buffalo milk, 1.35 parts of egg white powder, 8 parts of sucrose, 0.1 parts of carrageenan, 0.03 parts of calcium chloride, and 2.5 parts of litchi jam are directly poured into the preheated raw buffalo milk and stirred evenly in the mixing tank until completely dissolved to obtain raw and auxiliary milk; the raw and auxiliary milk is placed at a temperature of 65°C and a pressure of 15MPa for homogenization; the homogenized raw and auxiliary milk is sterilized at 62°C for 40min; the sterilized raw and auxiliary milk is cooled to 40°C; 0.003 parts of rennet (wherein, rennet is CHY~MAXTM PowerNB, the manufacturer is: Chr. Hansen, Denmark) is weighed according to the weight of the raw milk, dissolved with a small amount of sterile water, and added to the cooled raw and auxiliary milk, and stirred evenly. After aseptic filling, the milk is coagulated at a constant temperature of 40°C for 50min to obtain the double skin milk product.

[0066] Experimental group 3: The raw materials do not contain calcium ions, as follows:

[0067] Weigh the raw materials according to the following weight: 100 parts of raw buffalo milk, 1.35 parts of egg white powder, 8 parts of sucrose, 0.1 parts of carrageenan, and 2.5 parts of litchi jam are directly poured into the preheated raw buffalo milk and stirred evenly in the mixing tank until completely dissolved to obtain raw and auxiliary milk; the raw and auxiliary milk is placed at a temperature of 65°C and a pressure of 15MPa for homogenization; the homogenized raw and auxiliary milk is sterilized at 62°C for 40min; the sterilized raw and auxiliary milk is cooled to 40°C; 0.003 parts of rennet and 1500u / kg of lipase (wherein, rennet is CHY~MAXTM PowerNB, the manufacturer is: Chr. Hansen of Denmark; lipase is purchased from Nanning Pangbo Bioengineering Co., Ltd.) are weighed based on the weight of the raw milk, dissolved with a small amount of sterile water, and added to the cooled raw and auxiliary milk, and stirred evenly. After aseptic filling, the milk is coagulated at a constant temperature of 36°C for 40min to obtain the double skin milk product.

[0068] Experimental group 4: The raw materials do not contain emulsifiers, as follows:

[0069] Weigh the raw materials according to the following weight: 100 parts of raw buffalo milk, 1.35 parts of egg white powder, 8 parts of sucrose, 0.03 parts of calcium chloride, and 2.5 parts of litchi jam are directly poured into the preheated raw buffalo milk and stirred evenly in the mixing tank until completely dissolved to obtain raw and auxiliary milk; the raw and auxiliary milk is placed at a temperature of 65°C and a pressure of 15MPa for homogenization; the homogenized raw and auxiliary milk is sterilized at 62°C for 40min; the sterilized raw and auxiliary milk is cooled to 40°C; 0.003 parts of rennet and 1500u / kg of lipase (wherein, rennet is CHY~MAXTM PowerNB, the manufacturer is: Chr. Hansen of Denmark; lipase is purchased from Nanning Pangbo Bioengineering Co., Ltd.) are weighed according to the weight of the raw milk, dissolved with a small amount of sterile water, and added to the cooled raw and auxiliary milk, and stirred evenly. After aseptic filling, the milk is coagulated at a constant temperature of 36°C for 30min to obtain the double skin milk product.

[0070] Experimental Group 5: The raw milk was Holstein milk, and other preparation methods were consistent with Example 1.

[0071] The coagulation of experimental groups 1 to 5 was observed, and the results are shown in Table 3:

[0072] Table 3 Effect of different embodiments on curd

[0073]

[0074] As shown in Table 3, the double skin milk of experimental group 1 had the best shape, no whey precipitation on the surface, and could still maintain a good shape on the 14th day, while the double skin milk of experimental groups 2-5 all had significantly affected the coagulation effect to varying degrees.

[0075] Embodiment 5:

[0076] This example studies the effects of different coagulation temperatures on the coagulation of double-skin milk, as follows:

[0077] A gradient experiment was conducted on the coagulation temperature, i.e. 30-45°C, with each 1°C as an experimental group, and the coagulation effect was observed as follows:

[0078] Table 4 Effect of different temperatures on curdling

[0079]

[0080]

[0081] From Table 4, it can be seen that the coagulation effect of double skin milk is good when the temperature is between 33-42°C.

[0082] The above results show that the present invention introduces food-grade rennet containing highly specific cleavage of κ-casein to coagulate milk, and at the same time adds calcium ions that can increase enzyme activity and facilitate milk polymerization. Different from the high-heat and long-term induction in the traditional process to make milk protein and egg white protein thermally denatured to produce gel, the enzymatic hydrolysis technology is used to achieve standardized coagulation, and the repeatability and quality controllability of the product process are achieved. The heat treatment used in the present invention is all low temperature, including preheating and homogenization (55-65°C), low-temperature pasteurization (not exceeding 72°C), and coagulation (33-42°C), which does not exceed the thermal denaturation temperature of buffalo milk protein and egg white protein (both above 75°C), greatly reducing the denaturation damage of the protein, while greatly retaining the active functions of heat-sensitive substances in milk and eggs, such as lactoferrin, immunoglobulin, peroxidase, lysozyme, bioactive peptides, etc. At the same time, low-temperature coagulation ensures the soft, delicate, smooth texture and taste of the product. The present invention realizes precise control of the coagulation time by controlling the process, including cooling temperature, coagulation temperature, enzyme addition amount, emulsifier stabilizer type, etc., which can meet the needs of small batches of milk bars and dessert shops for short-term 30min coagulation, and can also meet the needs of industrial large-scale long-term 180min coagulation, and is suitable for different processing requirements. The present invention not only promotes coagulation by adding lipase, enzymolyzing buffalo milk fat, but also releases more fat-derived flavoring substances, so that the whole double skin milk is more intense, soft and full than the frankincense flavor of the traditional process. The present invention enriches the flavor of the double skin milk by adding sweet and fragrant concentrated jam, so that the finished product has a strong milk fragrance, outstanding fruit fragrance, fine texture, smooth mouthfeel, and meets the tastes of more different consumers. It is a nutritious and delicious dairy product with considerable market promotion value. The present invention mainly utilizes rennet to realize coagulation, and the egg raw material can be powdered whole egg powder and egg powder, and there are mature industrial products, which are convenient for direct feeding during production, without the technical operation of extracting clear liquid from fresh eggs, and reducing equipment investment.

[0083] In summary, the preparation process of the present invention solves the problem that traditional processes are difficult to achieve batch production of double-skin milk, and at the same time obtains a product with a richer, softer, more delicate and smoother taste than traditional processes. The main obstacles to the industrial production of traditional double-skin milk are the formation of milk skin, the extraction of fresh egg white liquid and the loss of nutrients in high-temperature steaming and curdling, and because the texture is not firm enough, it is difficult to achieve long-distance transportation and sales. The present invention determines the industrial production process of high-quality double-skin milk, which mainly utilizes the high content of buffalo milk protein and fat to form a suitable single-layer milk skin, and at the same time, a suitable amount of rennet is added to replace cow milk and egg white protein for high-temperature curdling, calcium ions are added to increase the hardness of the curd, and an emulsifier stabilizer is introduced to improve the water holding capacity of the product; lipase and / or concentrated jam are added to the raw milk to enrich the flavor of the product. The invention not only ensures the thick texture and stable curd of Shuangpi milk, but also does not require special equipment for extracting fresh egg white. At the same time, it fully retains the traditional taste and flavor of Shuangpi milk, and can give it a fuller frankincense. It can also adjust products with different fruity flavors according to the needs of different groups of people. The entire process does not require the introduction of new equipment, and production can be achieved using the existing equipment of dairy companies. In addition, low-temperature treatment is used throughout the process to maximize the retention of active substances in milk and eggs, comparable to the nutritional activity of pasteurized milk.

[0084] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A buffalo double skin milk, characterized in that: The double skin milk is composed of the following components: 100 parts of buffalo milk, 0.5-1.5 parts of egg raw materials, 2-10 parts of flavoring agents, 0.1-0.6 parts of emulsifier stabilizer, 0.001-0.030 parts of calcium chloride, 2.5-8 parts of concentrated jam, 0.0005-0.004 parts of rennet, and 500-1500u / kg of lipase; The egg raw material is one or more of egg white powder and whole egg powder; The flavoring agent is one or more of sucrose, inulin, and trehalose; The emulsion stabilizer is one or more of gelatin and carrageenan; The concentrated jam is one or more of lychee, blueberry, mango and strawberry; The preparation method of buffalo double skin milk comprises the following steps: (1) Weigh the raw materials according to the above weight ratio; (2) filtering fresh buffalo milk and standardizing the protein content to 4.2% to obtain buffalo raw milk; (3) Preheat the buffalo raw milk to 55-65°C; (4) mixing the buffalo milk preheated in step (3) with the egg raw material, flavoring agent, emulsifier stabilizer, calcium chloride and concentrated jam, homogenizing the mixture and then pasteurizing the mixture to obtain sterilized raw material milk; (5) Cooling the sterilized raw material milk in step (4) to 25-40° C.; (6) After the rennet and lipase are dissolved, they are added to the raw and auxiliary milk cooled in step (5) and stirred evenly; the mixture is filled into a packaging container that has been pre-cleaned and sterilized, and the milk is coagulated at a constant temperature of 33-42° C. for 30-180 minutes to obtain the finished product of double-skin milk; The homogenization temperature in step (4) is 55-65° C. and the pressure is 15-25 MPa.

2. A method for preparing the buffalo double skin milk as claimed in claim 1, characterized in that: The method comprises the following steps: (1) Weigh the raw materials according to the weight ratio; (2) filtering fresh buffalo milk and standardizing the protein content to 4.2% to obtain buffalo raw milk; (3) Preheat the buffalo raw milk to 55-65°C; (4) mixing the buffalo milk preheated in step (3) with the egg raw material, flavoring agent, emulsifier stabilizer, calcium chloride and concentrated jam, homogenizing the mixture and then pasteurizing the mixture to obtain sterilized raw material milk; (5) Cooling the sterilized raw material milk in step (4) to 25-40° C.; (6) After the rennet and lipase are dissolved, they are added to the raw and auxiliary milk cooled in step (5) and stirred evenly; the mixture is filled into a packaging container that has been pre-cleaned and sterilized, and the milk is coagulated at a constant temperature of 33-42° C. for 30-180 minutes to obtain the finished product of double-skin milk; The homogenization temperature in step (4) is 55-65° C. and the pressure is 15-25 MPa.

3. The method according to claim 2, characterized in that The refrigerated temperature of the double skin milk product in step (6) is 2-8°C.

4. The method according to claim 2, characterized in that: The pasteurization conditions in step (4) are 62-65° C. for 30-40 min, or 72° C. for 15 s.

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