Coffee milk and preparation method thereof

Abstract

The invention provides coffee milk and a preparation method thereof. The coffee milk comprises coffee, raw milk and a penetrating fluid concentrated solution, wherein in terms of the total mass of the coffee milk being 100%, the addition amount of the coffee is 1-9 wt.%; the addition amount of the raw milk is 80-91 wt.%; the addition amount of the penetrating fluid concentrated solution is 1-11 wt.%; the penetrating fluid concentrated solution is prepared by performing ultrafiltration or nanofiltration treatment on raw milk to obtain penetrating fluid, and concentrating the penetrating fluid to obtain the penetrating fluid concentrated solution. The coffee milk provided by the invention is simple in formula, the bitter taste caused by coffee can be effectively reduced without adding additional additives, and the flavor is enriched. Meanwhile, the stability of the coffee milk is good, the shelf life of the product can be prolonged, and the product does not have the phenomena of flocculation, layering, precipitation and the like in the shelf life.

Description

Technical Field

[0001] The invention relates to the technical field of coffee milk, and in particular to coffee milk and a preparation method thereof. Background Art

[0002] Coffee is a beverage made from roasted and ground coffee beans. As one of the three major non-alcoholic beverages in the world, it is a major beverage popular in the world along with cocoa and tea. Coffee concentrate is an industrially produced coffee product, which is generally divided into two processes: hot extraction and cold extraction. Coffee concentrate is acidic, and it tastes slightly sour, followed by a very negative bitter taste. The flavor is also mellow, with a hint of cocoa and caramel.

[0003] Coffee milk is made by adding coffee concentrate to milk. The fragrant and mellow coffee plus the milk with a strong frank aroma form a drink with a double taste enjoyment and can refresh and replenish nutrients. In recent years, there have been endless coffee products. Among them, coffee and milk can be combined into different product categories. Different products are formed according to different ratios of concentrated coffee extract and milk, such as latte, macchiato, cappuccino and flat white. There are many factors that affect the taste and quality of coffee milk. From the perspective of raw materials, the main ones are the type of coffee beans, roasting degree, extraction method and milk quality.

[0004] However, during the shelf life of coffee milk, fat will float up and form a circle of white fat on the packaging. If the physical and chemical indicators of milk are high, this phenomenon is more serious. It is not easy to dissolve after shaking upside down, which affects the terminal image of the product and brings a bad consumption experience to consumers. After tasting the taste of coffee milk products at different periods, the appearance and flavor of the product have changed over time during the shelf life, affecting the sensory perception and product quality of coffee milk products. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a coffee milk and a preparation method thereof. The present invention utilizes raw milk to obtain a permeate after ultrafiltration or nanofiltration treatment, and by adding a concentrated solution of the permeate to the coffee milk, the product flavor of the coffee milk is significantly improved, and the product quality is guaranteed during the shelf life.

[0006] In order to solve the problems existing in the prior art and achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a coffee milk, wherein the coffee milk comprises:

[0008] coffee, raw milk and permeate concentrates;

[0009] Among them, based on the total mass of the coffee milk as 100%, the added amount of the coffee is 1-9wt.%; the added amount of the raw cow's milk is 80-91wt.%; the added amount of the permeate concentrate is 1-11wt.%; the permeate concentrate is: the permeate obtained by ultrafiltration or nanofiltration of raw cow's milk, and the permeate concentrate obtained by concentrating the permeate.

[0010] Furthermore, the raw milk needs to be subjected to impurity removal treatment before ultrafiltration or nanofiltration treatment, and the impurity removal treatment includes filtering and centrifuging the raw milk.

[0011] Furthermore, the impurity removal treatment includes: first passing the raw milk through a bag filter with a mesh size of 80-600, and then centrifuging at a temperature of 2-10° C. and a speed of 4000-6000 rpm.

[0012] Furthermore, the coffee includes at least one of coffee concentrate and coffee powder.

[0013] Furthermore, the pore size of the ultrafiltration membrane of the ultrafiltration treatment is 5000-8000 Daltons, and the filtration temperature of the ultrafiltration membrane is 2-6°C; the pore size of the nanofiltration membrane of the nanofiltration treatment is 200-800MW, and the filtration temperature of the nanofiltration membrane is 4-15°C, and the membrane pressure is 2-6bar.

[0014] Furthermore, the permeate is concentrated by passing the permeate through a reverse osmosis membrane for concentration.

[0015] Furthermore, the reverse osmosis membrane is an organic reverse osmosis membrane, the concentration ratio of the reverse osmosis membrane is 1.1-1.3; the filtration temperature of the reverse osmosis membrane is 2-6°C.

[0016] In a second aspect, the present invention provides a method for preparing the coffee milk as described above, the preparation method comprising: subjecting raw milk to ultrafiltration or nanofiltration treatment to obtain a permeate, concentrating the permeate to obtain a permeate concentrate; and mixing, homogenizing and sterilizing the permeate concentrate, raw milk and coffee to obtain the coffee milk.

[0017] Furthermore, the method for preparing the coffee milk comprises the following steps:

[0018] (1) removing impurities from raw milk: first passing the raw milk through a bag filter with a mesh size of 80-600, and then centrifuging at a temperature of 2-10° C. and a speed of 4000-6000 rpm;

[0019] (2) ultrafiltration or nanofiltration is performed on the raw milk after the impurity removal treatment in step (1) to obtain a permeate; the pore size of the ultrafiltration membrane of the ultrafiltration treatment is 5000-8000 Daltons, and the filtration temperature of the ultrafiltration membrane is 2-6° C.; the pore size of the nanofiltration membrane of the nanofiltration treatment is 200-800 MW, and the filtration temperature of the nanofiltration membrane is 4-15° C., and the membrane pressure is 2-6 bar;

[0020] (3) Concentrating the permeate in step (2) to obtain a permeate concentrate, wherein the concentration method is: concentrating the permeate through a reverse osmosis membrane, wherein the reverse osmosis membrane is an organic reverse osmosis membrane, the concentration ratio of the reverse osmosis membrane is 1.1-1.3, and the filtration temperature of the reverse osmosis membrane is 2-6° C.;

[0021] (4) The permeate concentrate, raw milk and coffee in step (3) are mixed, homogenized and sterilized to obtain the coffee milk; based on the total mass of the coffee milk as 100%, the amount of coffee added is 1-9wt.%, the amount of raw milk added is 80-91wt.%, and the amount of permeate concentrate added is 1-11wt.%.

[0022] Furthermore, the homogenization treatment in step (4) is a two-stage homogenization, wherein the pressure of the first-stage homogenization is 30-40 bar, the pressure of the second-stage homogenization is 170 bar-230 bar, and the homogenization temperature is 50-65°C.

[0023] The beneficial effects of the above technical solution of the present invention are as follows:

[0024] The present invention provides a coffee milk and a preparation method thereof, wherein the coffee milk comprises: coffee, raw milk and a permeate concentrate; wherein, based on the total mass of the coffee milk being 100%, the amount of coffee added is 1-9wt.%; the amount of raw milk added is 80-91wt.%; the amount of permeate concentrate added is 1-11wt.%; the permeate concentrate is: the permeate is obtained by ultrafiltration or nanofiltration of raw milk, and the permeate is concentrated to obtain a permeate concentrate. The present invention can provide a coffee milk with a simple formula and a preparation method thereof, and the coffee milk of the present invention can effectively reduce the bitter taste brought by coffee without the need for additional additives, and enrich the flavor, and at the same time, the coffee milk has good stability, can extend the shelf life of the product, and the product will not have flocculation, stratification, precipitation and the like during the shelf life, thereby ensuring the product quality during the shelf life. DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with specific implementation modes. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the present invention.

[0026] In a first aspect, the present invention provides a coffee milk, wherein the coffee milk comprises:

[0027] Coffee, raw milk and permeate concentrate; wherein, based on the total mass of the coffee milk as 100%, the added amount of coffee is 1-9wt.%; the added amount of raw milk is 80-91wt.%; the added amount of permeate concentrate is 1-11wt.%; the permeate concentrate is: the permeate obtained by ultrafiltration or nanofiltration of raw milk, and the permeate concentrate obtained by concentrating the permeate.

[0028] Since the coffee concentrate is acidic, it will make the coffee milk system sour and cause protein denaturation, which will make the coffee milk unstable. During the shelf life, it is easy to have quality deterioration problems such as fat floating, oxidation, cheese ring formation, protein denaturation and coffee particle precipitation, which seriously affect the product appearance quality and flavor taste. In view of the above problems, the inventors found that after reverse osmosis concentration of ultrafiltration or nanofiltration permeate, by adding permeate concentrate to coffee milk, the taste of coffee milk can be effectively improved, making it rich in better flavor and better product quality. Based on this, the present invention provides a new formula of coffee milk, specifically, the coffee milk in the present invention includes: coffee, raw milk and permeate concentrate; wherein the permeate concentrate refers to: raw milk is treated with ultrafiltration or nanofiltration to obtain permeate, and the permeate is concentrated to obtain permeate concentrate.

[0029] At present, when ultrafiltration or nanofiltration membranes are used to prepare concentrated milk, the permeate after passing through the membrane is usually discarded as a by-product. The present invention uses the permeate of ultrafiltration or nanofiltration as a raw material, concentrates the permeate to obtain a permeate concentrate with a richer milk flavor, and creatively uses the permeate concentrate as a raw material to mix with coffee and milk to obtain a coffee milk. The permeate concentrate is added in the present invention to improve the sour taste of coffee milk products, fat floating, flocculation, stratification, precipitation and other problems caused by system instability. The coffee milk in the present invention can effectively reduce the bitter taste brought by coffee and enrich the flavor without the need for additional additives. At the same time, the product has good stability, and it has been verified through experiments that it can extend the shelf life of the product and improve the product quality.

[0030] In the present invention, the amount of the permeate concentrate added is 1-11wt.%, based on the total mass of the coffee milk being 100%. If the amount of the permeate concentrate added is too high, the taste of the product will be salty and the taste will be poor. If the amount of the permeate concentrate added is too low, the effect of improving the flavor and quality of the coffee milk cannot be achieved. Furthermore, through experimental verification, it is found that based on the total mass of the coffee milk being 100%, the permeate concentrate is preferably added at 5%-6wt%, which can achieve the best effect. Furthermore, the amount of the permeate concentrate added is preferably 5.5-9.5wt.%; the amount of the coffee added is preferably 6.0-9.0wt.%; and the amount of the raw milk added is preferably 81.5-88.5wt.%. In the preferred amount of addition, the coffee milk system can be guaranteed to be stable and the flavor is better.

[0031] According to some embodiments of the present invention, the raw milk needs to be subjected to impurity removal treatment before ultrafiltration or nanofiltration treatment, and the impurity removal treatment includes filtering and centrifuging the raw milk.

[0032] According to some embodiments of the present invention, the impurity removal treatment includes: first passing the raw milk through a bag filter with a mesh size of 80-600, and then centrifuging at a temperature of 2-10° C. and a speed of 4000-6000 rpm.

[0033] According to some embodiments of the present invention, the pore size of the ultrafiltration membrane of the ultrafiltration treatment is 5000-8000 Daltons, and the filtration temperature of the ultrafiltration membrane is 2-6°C; the pore size of the nanofiltration membrane of the nanofiltration treatment is 200-800MW, and the filtration temperature of the nanofiltration membrane is 4-15°C, and the membrane pressure is 2-6bar.

[0034] According to some embodiments of the present invention, the method for concentrating the permeate is: concentrating the permeate through a reverse osmosis membrane. Further, the reverse osmosis membrane is an organic reverse osmosis membrane, the concentration ratio of the reverse osmosis membrane is 1.1-1.3, and the filtration temperature of the reverse osmosis membrane is 2-6°C.

[0035] The present invention also provides a specific processing method for the permeate concentrate, comprising first removing impurities from the raw milk: first passing the raw milk through a bag filter with a mesh size of 80-600, and then centrifuging at a temperature of 2-10°C and a speed of 4000-6000rpm; then subjecting the raw milk after the impurity removal to ultrafiltration or nanofiltration to obtain a permeate; wherein the pore size of the ultrafiltration membrane of the ultrafiltration treatment is 5000-8000 Daltons, and the filtration temperature of the ultrafiltration membrane is 2-6°C; the pore size of the nanofiltration membrane of the nanofiltration treatment is 200-800MW, the filtration temperature of the nanofiltration membrane is 4-15°C, and the membrane pressure is 2-6bar; finally, the permeate is concentrated to obtain a permeate concentrate, and the concentration method is: the permeate is concentrated through a reverse osmosis membrane, the reverse osmosis membrane is an organic reverse osmosis roll membrane, the concentration ratio of the reverse osmosis membrane is 1.1-1.3, and the filtration temperature of the reverse osmosis membrane is 2-6°C.

[0036] According to some embodiments of the present invention, the coffee comprises at least one of coffee concentrate and coffee powder. According to some embodiments of the present invention, the raw milk comprises at least one of whole milk and skim milk that have been or have not been concentrated by UF / NF. The protein content in the raw milk is preferably 2.9-3.8 g / 100 g. In addition, when whole milk is used, the fat content in the whole milk is preferably 4.0-4.8 g / 100 g.

[0037] In a second aspect, the present invention provides a method for preparing the coffee milk as described above, the preparation method comprising: subjecting raw milk to ultrafiltration or nanofiltration treatment to obtain a permeate, concentrating the permeate to obtain a permeate concentrate; and mixing, homogenizing and sterilizing the permeate concentrate, raw milk and coffee to obtain the coffee milk.

[0038] According to some other embodiments of the present invention, the method for preparing coffee milk comprises the following steps:

[0039] (1) removing impurities from raw milk: first passing the raw milk through a bag filter with a mesh size of 80-600, and then centrifuging at a temperature of 2-10° C. and a speed of 4000-6000 rpm;

[0040] (2) ultrafiltration or nanofiltration is performed on the raw milk after the impurity removal treatment in step (1) to obtain a permeate; the pore size of the ultrafiltration membrane of the ultrafiltration treatment is 5000-8000 Daltons, and the filtration temperature of the ultrafiltration membrane is 2-6° C.; the pore size of the nanofiltration membrane of the nanofiltration treatment is 200-800 MW, and the filtration temperature of the nanofiltration membrane is 4-15° C., and the membrane pressure is 2-6 bar;

[0041] (3) Concentrating the permeate in step (2) to obtain a permeate concentrate, wherein the concentration method is: concentrating the permeate through a reverse osmosis membrane, wherein the reverse osmosis membrane is an organic reverse osmosis membrane, the concentration ratio of the reverse osmosis membrane is 1.1-1.3, and the filtration temperature of the reverse osmosis membrane is 2-6° C.;

[0042] (4) The permeate concentrate, raw milk and coffee in step (3) are mixed, homogenized and sterilized to obtain the coffee milk; based on the total mass of the coffee milk as 100%, the amount of coffee added is 1-9wt.%, the amount of raw milk added is 80-91wt.%, and the amount of permeate concentrate added is 1-11wt.%.

[0043] According to some other embodiments of the present invention, the homogenization process in step (4) is a two-stage homogenization, wherein the pressure of the first-stage homogenization is 30-40 bar, the pressure of the second-stage homogenization is 170 bar-230 bar, and the homogenization temperature is 50-65°C.

[0044] According to some other embodiments of the present invention, the sterilization in step (4) is pasteurization, ultra-pasteurization and ultra-high temperature instantaneous sterilization, the temperature is 72-138°C, and the time is 4-300s; the cooling temperature is cooled to 15-25°C; and the filling is aseptic filling.

[0045] The present invention provides a coffee milk and a preparation method thereof. Compared with the prior art, the present invention combines raw cow milk, coffee concentrate and ultrafiltration or nanofiltration milk permeate concentrate, and uses the permeate concentrate to improve the taste of coffee milk, so that a coffee milk product with rich flavor and smooth taste can be obtained, and the shelf life and product quality of the product can be improved. At the same time, the formula of the coffee milk in the present invention is simple, and the coffee milk prepared by the present invention uses the original material in raw cow milk, and no additional additives are required. Compared with products with additives such as colloid, dextrin, sugar esters and other sugar derivatives, sodium bicarbonate, dipotassium hydrogen phosphate, starch, stearate, stabilizers, etc., the coffee milk in the present invention has healthier product attributes. Finally, the preparation method provided in the present invention has a simple process, is easy to operate, and is suitable for industrial production and market promotion and application.

[0046] The present invention will be further described below through some specific embodiments.

[0047] It should be noted that:

[0048] (1) The coffee concentrate used in the following examples and comparative examples has a Brix of 15±1%, a pH of 5.2±0.5, and a caffeine content of 5000-12000 mg / kg.

[0049] (2) The selection, acceptance, and milk purification standards and treatments of raw milk in the following examples and comparative examples are as follows:

[0050] Healthy dairy cows from large-scale pasture breeding bases are selected, and fresh milk is squeezed from healthy cow udders using mechanized milking equipment. The protein, fat, non-fat milk solids, acidity, pH value and total bacteria count in fresh milk are tested. The acceptance criteria meet the national standard GB19301 "Raw Milk". Qualified raw milk is stored in a cold chain at 4°C. The raw milk is cold-cleaned and filtered using a 200-mesh screen to remove impurities in the milk. The raw milk is centrifuged and cleaned by a centrifugal purifier. The temperature is controlled at 6°C and the milk is centrifuged at 5800rpm to remove impurities in the milk.

[0051] (3) The raw milk used in the following examples and comparative examples refers to whole milk from the pasture, with 3.2% protein and 3.8% fat. Skim milk refers to pure milk with 3.2% protein and 0% fat. Whole milk refers to pure milk with 3.2% protein and 3.8% fat.

[0052] (4) The pore size of the ultrafiltration membrane used in the following examples and comparative examples is 6000 Daltons, and the filtration temperature of the ultrafiltration membrane is 4°C;

[0053] The pore size of the nanofiltration membrane used in the nanofiltration treatment is 500MW, the filtration temperature of the nanofiltration membrane is 6°C, and the membrane pressure is 6 bar;

[0054] The reverse osmosis membrane system is an organic reverse osmosis membrane with a concentration ratio of 1.2; the temperature of the reverse osmosis membrane filtration is 6° C. The temperature of the permeate entering the reverse osmosis membrane concentration system does not exceed 10° C., and the temperature at the outlet does not exceed 20° C.

[0055] Example 1

[0056] The steps for preparing coffee milk are as follows:

[0057] (1) Testing the physical and chemical indicators of raw milk, and using separation technology to purify the raw milk that passes the test to remove impurities in the raw milk;

[0058] (2) passing the raw milk after impurities removal in step (1) through an ultrafiltration membrane to obtain a permeate;

[0059] (3) the permeate obtained in step (2) is fed into a reverse osmosis membrane system for treatment to obtain a permeate concentrate;

[0060] (4) The coffee milk product is prepared by adding 89 wt% of raw milk, 8 wt% of coffee concentrate, and 3 wt% of the permeate concentrate;

[0061] (5) The prepared product is homogenized at 30 / 180 bar and 60°C, and sterilized at 138°C and 4S. After sterilization, it is cooled to 5°C for aseptic filling.

[0062] Example 2

[0063] The steps for preparing coffee milk are as follows:

[0064] (1) to (3): Same as in Example 1;

[0065] (4) The coffee milk product is formulated according to the following ingredients: 85 wt% of skimmed milk, 9 wt% of coffee concentrate, and 6 wt% of the permeate concentrate.

[0066] (5): Same as Example 1.

[0067] Example 3

[0068] The steps for preparing coffee milk are as follows:

[0069] (1): Same as Example 1;

[0070] (2) passing the raw milk after impurities removal in step (1) through a nanofiltration membrane to obtain a permeate;

[0071] (3) the permeate obtained in step (2) is fed into a reverse osmosis membrane system for treatment to obtain a permeate concentrate;

[0072] (4) The coffee milk product is prepared by adding 82 wt% of whole milk, 7 wt% of coffee concentrate, and 11 wt% of the permeate concentrate;

[0073] (5): Same as Example 1.

[0074] Example 4

[0075] The steps for preparing coffee milk are as follows:

[0076] (1) to (3): Same as in Example 1;

[0077] (4) The coffee milk product is prepared by adding 87 wt% of raw milk, 8 wt% of coffee concentrate, and 5 wt% of the permeate concentrate;

[0078] (5): Same as Example 1.

[0079] Example 5

[0080] The steps for preparing coffee milk are as follows:

[0081] (1) to (3): Same as in Example 1;

[0082] (4) The coffee milk product is prepared by adding 86 wt% of raw milk, 8 wt% of coffee concentrate, and 6 wt% of the permeate concentrate;

[0083] (5): Same as Example 1.

[0084] Example 6

[0085] The steps for preparing coffee milk are as follows:

[0086] (1): Same as Example 1;

[0087] (2) passing the raw milk after impurities removal in step (1) through an ultrafiltration membrane to obtain a permeate;

[0088] (3) the permeate obtained in step (2) is fed into a reverse osmosis membrane system for treatment to obtain a permeate concentrate;

[0089] (4) The coffee milk product is prepared by adding 87 wt% of raw milk, 5 wt% of coffee concentrate, and 8 wt% of the permeate concentrate;

[0090] (5): Same as Example 1.

[0091] Comparative Example 1

[0092] The steps for preparing coffee milk are as follows:

[0093] (1): Same as Example 1;

[0094] (2) The coffee milk product is prepared by adding 92 wt% of raw milk and 8 wt% of coffee concentrate;

[0095] (3): Same as step (5) in Example 1.

[0096] Comparative Example 2

[0097] The steps for preparing coffee milk are as follows:

[0098] (1): Same as Example 1;

[0099] (2) The coffee milk product is formulated according to the following ingredients: 91 wt% of raw milk, 8 wt% of coffee concentrate, and 1 wt% of a compound stabilizer (mono- and di-glycerol fatty acid esters, monoglyceride succinate, microcrystalline cellulose, sodium tripolyphosphate, dipotassium hydrogen phosphate, xanthan gum, sodium hexametaphosphate, and sodium carboxymethyl cellulose); wherein the mass ratio of mono- and di-glycerol fatty acid esters: monoglyceride succinate: microcrystalline cellulose: sodium tripolyphosphate: dipotassium hydrogen phosphate: xanthan gum: sodium hexametaphosphate: and sodium carboxymethyl cellulose is 1.5:1.0:1.0:0.7:0.8:0.5:0.5:0.5.

[0100] (3): Same as step (5) in Example 1.

[0101] Comparative Example 3

[0102] The steps for preparing coffee milk are as follows:

[0103] (1): Same as Example 1;

[0104] (2) The coffee milk product is prepared by adding 91 wt% of whole milk and 9 wt% of coffee concentrate;

[0105] (3) Same as step (5) in Example 1.

[0106] Comparative Example 4

[0107] The steps for preparing coffee milk are as follows:

[0108] (1) to (3): Same as in Example 1;

[0109] (4) The coffee milk product is prepared by adding 91.5 wt% of raw milk, 8 wt% of coffee concentrate, and 0.5 wt% of the permeate concentrate;

[0110] (5): Same as step (5) in Example 1.

[0111] Comparative Example 5

[0112] The steps for preparing coffee milk are as follows:

[0113] (1) to (3): Same as in Example 1;

[0114] (4) The coffee milk product is prepared by adding 77 wt% of raw milk, 8 wt% of coffee concentrate, and 15 wt% of the permeate concentrate;

[0115] (5): Same as step (5) in Example 1.

[0116] Comparative Example 6

[0117] The steps for preparing coffee milk are as follows:

[0118] (1): Same as Example 1;

[0119] (2) The coffee milk product is prepared by adding 90 wt% skim milk and 10 wt% coffee concentrate;

[0120] (3): Same as step (5) in Example 1.

[0121] Experimental results and analysis:

[0122] 1. Product sensory evaluation

[0123] In order to better illustrate the beneficial effects of the present invention, the coffee milk of Examples 1-6 and Comparative Examples 1-6 was subjected to sensory evaluation, and 15 g of each product was taken for sensory evaluation. The sensory evaluation was performed by professionals (20 people, 10 men and 10 women) to evaluate the products, and the scoring criteria were implemented according to Table 1, and the average score was finally taken. The results of the sensory evaluation test are shown in Table 2.

[0124] Table 1

[0125]

[0126]

[0127] Table 2

[0128]

[0129] From the above experimental results, it can be seen that compared with Examples 1-6 and Comparative Examples 1-6, the overall preference of the Examples is better than that of the Comparative Examples. The above sensory evaluation shows that the coffee milk prepared by the present invention has good stability and almost no precipitation. At the same time, the coffee flavor is mellow, the ingredients are pure and healthy, the taste is full and thick, there is no obvious rough granularity, and it has a light milky aroma. The combination is coordinated, giving the product a full, rich and smooth taste.

[0130] Compared with Comparative Example 1, Examples 1, 4, and 5 use raw cow milk instead of the concentrated solution of ultrafiltration permeate, and the sensory evaluation scores are all lower than those of the example, indicating that the addition of the concentrated solution of ultrafiltration permeate can significantly improve the product flavor of coffee milk. Compared with Comparative Example 2, Examples 1-6 add concentrated solutions of ultrafiltration or nanofiltration permeate to coffee milk, which can significantly improve the stability of the product system. However, compared with the addition of multiple composite stabilizers in Comparative Example 2, the coffee milk of the present invention has no additional additives, and can achieve the effect of clean label and health attributes. Compared with Comparative Examples 4 and 5, the concentrated solution of ultrafiltration permeate with too low or too high concentration in Examples 1, 4, and 5 cannot improve the flavor of the product.

[0131] 2. Product stability evaluation

[0132] The product stability was tested using a Lumisizer stability analyzer (2000 rpm / min, 25°C) for 4 hours, with the instability coefficient as the evaluation index. The pH of the product was tested using a pH meter. The test results are recorded in Table 3.

[0133] It should be noted that the product stability here is measured by Lumisizer stability analyzer. During the test, an accelerated experiment is performed by centrifugation to simulate the state of the product being placed for a long time.

[0134] Table 3

[0135] product Instability coefficient PH Example 1 0.12 6.77 Example 2 0.13 6.81 Example 3 0.14 6.90 Example 4 0.11 6.85 Example 5 0.10 6.87 Example 6 0.13 6.89 Comparative Example 1 0.22 6.48 Comparative Example 2 0.11 6.88 Comparative Example 3 0.21 6.37 Comparative Example 4 0.20 6.55 Comparative Example 5 0.22 6.86 Comparative Example 6 0.23 6.31

[0136] The main factors that affect the length of the shelf life of a product include flavor, microorganisms, and stability. Among them, stability is the most intuitive thing for consumers. If a product floats or precipitates, it will inevitably affect consumers' purchasing decisions. Therefore, for most products, floating and precipitation cannot occur during the shelf life. Without considering the influence of flavor and microorganisms, the less likely a product is to float and precipitate, the longer the shelf life of the product can be marked. For example, a product showed obvious floating and precipitation on the 7th day. The Lumisizer Stability Analyzer can accelerate the simulation of the stability state of a product during the shelf life by centrifugation. Within the same experimental time, the larger the instability coefficient, the more floating and precipitation there are in the product, the worse the stability of the product, and the floating and precipitation phenomenon will appear faster on the shelf. The smaller the instability coefficient, the longer the shelf life of the product can be marked.

[0137] From the results in Table 3, it can be seen that after adding the concentrated solution of ultrafiltration or nanofiltration permeate, the product can achieve or even surpass the effect of adding a stabilizer to the product, can ensure the stability of the system, and can be maintained in a relatively neutral environment. According to Examples 1-6 and Comparative Examples 1, 3, and 6, the product without adding the concentrated solution of ultrafiltration or nanofiltration permeate has poor stability. According to Examples 1-6 and Comparative Examples 4 and 5, the product with too low or too high content of ultrafiltration permeate added also has poor stability.

[0138] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0139] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A coffee milk, characterized in that: The coffee milk comprises: coffee, raw milk and permeate concentrates; Among them, based on the total mass of the coffee milk as 100%, the added amount of the coffee is 1-9wt.%; the added amount of the raw cow's milk is 80-91wt.%; the added amount of the permeate concentrate is 1-11wt.%; the permeate concentrate is: the permeate obtained by ultrafiltration or nanofiltration of raw cow's milk, and the permeate concentrate obtained by concentrating the permeate.

2. The coffee milk according to claim 1, characterized in that: The raw milk needs to be treated with impurities before ultrafiltration or nanofiltration, and the impurity removal process includes filtering and centrifuging the raw milk.

3. The coffee milk according to claim 2, characterized in that: The impurity removal process comprises: The raw milk is first passed through a bag filter with mesh size of 80-600, and then centrifuged at a temperature of 2-10°C and a speed of 4000-6000 rpm.

4. The coffee milk according to claim 1, characterized in that: The coffee includes at least one of coffee concentrate and coffee powder.

5. The coffee milk according to claim 1, characterized in that: The pore size of the ultrafiltration membrane used in the ultrafiltration treatment is 5000-8000 Daltons, and the temperature of the ultrafiltration membrane filtration is 2-6°C; The pore size of the nanofiltration membrane used in the nanofiltration treatment is 200-800 MW, the filtration temperature of the nanofiltration membrane is 4-15° C., and the membrane pressure is 2-6 bar.

6. The coffee milk according to claim 1, characterized in that: The method for concentrating the permeate is: concentrating the permeate through a reverse osmosis membrane.

7. The coffee milk according to claim 6, characterized in that The reverse osmosis membrane is an organic reverse osmosis membrane roll, the concentration ratio of the reverse osmosis membrane is 1.1-1.3; the filtration temperature of the reverse osmosis membrane is 2-6°C.

8. The method for preparing coffee milk according to any one of claims 1 to 7, characterized in that: The preparation method comprises: The raw milk is ultrafiltered or nanofiltered to obtain a permeate, and the permeate is concentrated to obtain a permeate concentrate; the permeate concentrate, raw milk and coffee are mixed, homogenized and sterilized to obtain the coffee milk.

9. The preparation method according to claim 8, characterized in that: The preparation method comprises the following steps: (1) removing impurities from raw milk: first passing the raw milk through a bag filter with a mesh size of 80-600, and then centrifuging at a temperature of 2-10° C. and a speed of 4000-6000 rpm; (2) ultrafiltration or nanofiltration is performed on the raw milk after the impurity removal treatment in step (1) to obtain a permeate; the pore size of the ultrafiltration membrane of the ultrafiltration treatment is 5000-8000 Daltons, and the filtration temperature of the ultrafiltration membrane is 2-6° C.; the pore size of the nanofiltration membrane of the nanofiltration treatment is 200-800 MW, and the filtration temperature of the nanofiltration membrane is 4-15° C., and the membrane pressure is 2-6 bar; (3) Concentrating the permeate in step (2) to obtain a permeate concentrate, wherein the concentration method is: concentrating the permeate through a reverse osmosis membrane, wherein the reverse osmosis membrane is an organic reverse osmosis membrane, the concentration ratio of the reverse osmosis membrane is 1.1-1.3, and the filtration temperature of the reverse osmosis membrane is 2-6° C.; (4) The permeate concentrate, raw milk and coffee in step (3) are mixed, homogenized and sterilized to obtain the coffee milk.

10. The preparation method according to claim 9, characterized in that: The homogenization treatment in step (4) is a two-stage homogenization, wherein the pressure of the first-stage homogenization is 30-40 bar, the pressure of the second-stage homogenization is 170 bar-230 bar, and the homogenization temperature is 50-65°C.

Images