Thick milk and preparation method thereof

Abstract

The invention relates to the technical field of dairy products, and provides thick milk and a preparation method thereof.The preparation method of the thick milk comprises the steps that a first raw material containing raw milk and a stabilizer is sheared until an image of obtained feed liquid is observed to be qualified under a polarizing microscope, then mixing, volume metering, homogenizing, sterilizing, cooling and filling are conducted, and the thick milk is obtained; the stabilizer comprises microcrystalline cellulose and / or sodium carboxymethyl cellulose; if the image is qualified, the white short-rod-shaped graphs observed in the image are not aggregated. According to the method, the stability of the thick milk product obtained according to a specific formula can be rapidly judged through the polarizing microscope during first-step material melting of experiments and production ingredients, the stability observation time of the thick milk product added with microcrystalline cellulose and sodium carboxymethyl cellulose can be effectively shortened, the research and development period is shortened, and the research and development efficiency is improved. The blank of quickly judging the stability of the thick milk is filled.

Description

Technical Field

[0001] The invention relates to the technical field of dairy products, in particular to thick milk and a preparation method thereof, and in particular to high-protein and high-fat thick milk and a preparation method thereof. Background Art

[0002] Thick milk is a dairy product obtained through a specific processing technique. It has a higher milk fat content and is significantly different from ordinary milk or milk beverages in taste and texture. The milk fat content of thick milk is usually higher than that of ordinary milk, which gives it a rich milky aroma and mellow taste. In addition, thick milk has a thick texture, which allows it to be mixed with other ingredients more effectively during food processing. For example, in coffee preparation, thick milk can bring a richer taste level; in baked goods, thick milk can make the finished product more moisturizing. The mellow taste of thick milk is created by the high milk fat content and special processing technology, bringing consumers a unique taste experience.

[0003] In recent years, the trend of thick milk has been strong. Thick milk has good flavor and mellow taste. However, due to the high fat content of thick milk protein, the product is prone to fat floating and protein precipitation during the shelf life. At present, adding stabilizers is a common method in the preparation of thick milk. Commonly used stabilizers include microcrystalline cellulose and sodium carboxymethyl cellulose.

[0004] Microcrystalline cellulose is a kind of microcrystalline cellulose made from wood cellulose. It is a white powder with good chemical stability and water solubility. It has strong water absorption and has the ability to form a gel after strong shearing in an aqueous medium. Sodium carboxymethyl cellulose is an ionic polymer material that can effectively increase the viscosity and stability of aqueous solutions. In food production, sodium carboxymethyl cellulose can be used as a thickener, emulsifier and adhesive. It has good thickening effect and stability, and can improve the taste and quality of food. In food, it can be used as a thickener, stabilizer, dispersant, extender and solid agent. It can be widely used in dairy products, juices, chocolate, beverages and lactic acid cheese as a stabilizing dispersant. The compound of microcrystalline cellulose and sodium carboxymethyl cellulose can be dispersed in milk beverages to form a three-dimensional network structure, which improves the stability of thick milk without affecting the viscosity and rheology of thick milk, and plays a certain role in fat replacement.

[0005] However, when using the above stabilizers, some products still have unstable phenomena such as fat floating, protein precipitation, flocculation, stratification, etc. during the shelf life. Therefore, it is of great significance to provide a thick milk with a good shelf life and stable product state. Summary of the invention

[0006] The present invention provides a thick milk and a preparation method thereof, which are used to solve the problem that thick milk products containing stabilizers such as microcrystalline cellulose and / or sodium carboxymethyl cellulose in the prior art have unstable phenomena such as fat floating, protein precipitation, flocculation, stratification, etc. during the shelf life. The present invention controls the characteristics of the feed liquid by monitoring the specific parameters of the feed liquid during the batching stage, so as to avoid the occurrence of unstable product during the shelf life.

[0007] Specifically, in a first aspect, the present invention provides a method for preparing thick milk, comprising: shearing a first raw material comprising raw cow milk and a stabilizer until the resulting liquid has a qualified image observed under a polarizing microscope, and then mixing, fixing the volume, homogenizing, sterilizing, cooling and filling to obtain the thick milk; The stabilizer includes microcrystalline cellulose and / or sodium carboxymethyl cellulose; The qualified image includes: there is no aggregation of white short stick-shaped figures observed in the image.

[0008] The non-aggregation of the white short stick-shaped figures in the present invention means that: there are no more than 4 white short stick-shaped figures gathered and / or stacked together in the picture measured by the polarizing microscope, or the white short stick-shaped figures are separated from each other in the picture measured by the polarizing microscope, and there are gaps between any adjacent white short stick-shaped figures.

[0009] According to the method for preparing the thick emulsion provided by the present invention, the qualified image further comprises: the equivalent diameters of the regular or irregular granular graphics observed in the image are all smaller than the equivalent diameter of the white short stick graphics.

[0010] According to the preparation method of the thick milk provided by the present invention, the protein content of the thick milk is ≥3.5%, and the fat content is ≥10.0%.

[0011] Compared with other methods, the method of the present invention is more conducive to controlling the shelf life stability of the above-mentioned type of thick milk.

[0012] According to the preparation method of the thick milk provided by the present invention, the content of microcrystalline cellulose in the thick milk is 0.1-2.0%.

[0013] According to the preparation method of the thick milk provided by the present invention, the content of sodium carboxymethyl cellulose in the thick milk is 0.1-2.0%.

[0014] Generally, the higher the content of microcrystalline cellulose and sodium carboxymethyl cellulose in thick milk, the easier it is to aggregate in the liquid. Studies have found that when the content of microcrystalline cellulose and sodium carboxymethyl cellulose is within the above range, the thick milk obtained by the method of the present invention has better stability during the shelf life.

[0015] According to the preparation method of the thick milk provided by the present invention, based on 100 parts by weight, the raw materials of the thick milk include: 70-80 parts of cow's milk, 10-20 parts of condensed milk, 5-10 parts of milk fat, 0.1-2.0 parts of microcrystalline cellulose, 0.1-2.0 parts of sodium carboxymethyl cellulose, 0.1-1 parts of emulsifier, 0.1-1 parts of buffer salt and the balance of water.

[0016] Preferably, the emulsifier is selected from one or more of mono- and di-glycerol fatty acid esters, sucrose fatty acid esters, soybean lecithin, Tween 80, polyglycerol fatty acid esters, diacetyl tartaric acid mono- and di-glycerides, and lactic acid fatty acid glycerides.

[0017] Further preferably, the emulsifier comprises mono- and di-glycerol fatty acid esters and / or sucrose fatty acid esters.

[0018] In the thick emulsion, the dispersion degree of each material is related to the emulsifier and its content in the liquid. Studies have found that when the thick emulsion of the present invention adopts the above formula, the obtained thick emulsion has better stability during the shelf life.

[0019] According to the method for preparing the thick emulsion provided by the present invention, the process of observing a qualified image of the obtained liquid under a polarizing microscope comprises: Placing the feed liquid on a glass slide, and covering the glass slide with a cover slip to obtain sample slices; placing the sample slice on the stage of a polarizing microscope; The image is obtained by adjusting the objective lens, eyepiece, polarizer and light source of the polarizing microscope.

[0020] Although polarizing microscopes are commonly used to observe microstructures, there is no known method in the art to use polarizing microscope detection as a means of monitoring shelf stability of dairy products. The present invention has found through a large number of experiments that, compared with other similar low-light testing methods, the polarizing microscope used in the present invention has the comprehensive advantages of being fast, accurate, and efficient.

[0021] More importantly, the present invention can observe the liquid material in the first step of batching, so as to predict the shelf life stability of the obtained thick milk product. The method of the present invention can effectively shorten the stability observation time, shorten the research and development cycle, and fill the gap in the rapid determination of the stability of thick milk. The method has been verified to have good accuracy and reproducibility in the scheme of the present invention.

[0022] According to the method for preparing the thick emulsion provided by the present invention, the step of observing a qualified image of the obtained liquid under a polarizing microscope comprises: (1) Place the slurry on a glass slide, cover the glass slide with a cover slip to obtain a sample slice, and then place it on the stage of a polarizing microscope.

[0023] (2) Select a low-power objective lens of the polarizing microscope and align it with the light aperture. Adjust the coarse focusing knob to bring the objective lens close to the sample slice and adjust the eyepiece.

[0024] (3) Insert a polarizing filter into the filter slot of the polarizing microscope.

[0025] (4) Rotate the eyepiece to adjust the color and eliminate glare.

[0026] (5) Use the focus wheel on the polarizing microscope to adjust the clarity and magnify to obtain the image.

[0027] According to the method for preparing the thick emulsion provided by the present invention, the eyepiece is a 10x eyepiece.

[0028] According to the method for preparing thick emulsion provided by the present invention, the low-magnification objective lens is a 5x to 40x objective lens.

[0029] According to the method for preparing the thick emulsion provided by the present invention, a polarizing lens is placed on the eyepiece.

[0030] The present invention adopts the above detection parameters to realize accurate and efficient monitoring of the feed liquid.

[0031] According to the method for preparing thick milk provided by the present invention, the steps of preparing the thick milk include: (1) Shearing: After heating a portion of raw milk, add microcrystalline cellulose, sodium carboxymethyl cellulose and an emulsifier thereto, and shear the material until the resulting liquid has a qualified image observed under a polarizing microscope; Preferably, the heating temperature is 60-80°C; Preferably, the chemical concentration is less than 5%; (2) Mixing: adding condensed milk, milk fat and remaining raw milk to the material obtained in step (1) in sequence; (3) Fixed volume; (4) Homogenization and cooling: After heating the material, homogenize it under a pressure of 0-250 bar, cool it after homogenization, and let it stand for 10-60 minutes; Preferably, the material is heated to 60-70°C and then homogenized; Preferably, the homogenization is followed by cooling to 4-20°C; (5) Sterilization: Sterilize at 72-145°C for 3-90 seconds; (6) Cooling and canning: The material is canned after cooling.

[0032] In a third aspect, the present invention also provides thick milk prepared by the thick milk preparation method as described above.

[0033] Preferably, the thick emulsion has a qualified image when observed under a polarizing microscope.

[0034] When the image of the obtained thick milk product is observed to be qualified under a polarizing microscope, the stability of the thick milk product during the shelf life is better. Observing the thick milk product at this stage is also conducive to predicting the stability of the thick milk product during the shelf life.

[0035] The thick milk and the preparation method thereof provided by the present invention can quickly determine the stability of the thick milk product obtained by a specific formula during the first step of experiment and production of ingredients by using a polarizing microscope. The method of the present invention can effectively shorten the stability observation time and the research and development cycle for thick milk products added with microcrystalline cellulose and sodium carboxymethyl cellulose, thus filling the gap in quickly determining the stability of thick milk. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a process flow chart of thick milk in Example 1 provided by the present invention.

[0038] Figure 2 It is a qualified image in the test example 1 provided by the present invention.

[0039] Figure 3 This is an image of the liquid obtained by shearing the material in Example 1 provided by the present invention.

[0040] Figure 4 This is an image of the thick breast of Example 1 provided by the present invention.

[0041] Figure 5 This is an image of the liquid obtained by shearing the material in Example 2 provided by the present invention.

[0042] Figure 6 This is an image of the thick breast of Example 2 provided by the present invention.

[0043] Figure 7 This is an image of the liquid obtained by shearing the material in Example 3 provided by the present invention.

[0044] Figure 8 This is an image of the thick breast of Example 3 provided by the present invention.

[0045] Fig. 9 This is an image of the thick breast of Example 4 provided by the present invention.

[0046] Fig.10 This is an image of the liquid obtained by shearing the material in Comparative Example 1 provided by the present invention.

[0047] Fig.11 It is an image of the thick milk of Comparative Example 1 provided by the present invention.

[0048] Fig.12 This is an image of the liquid obtained by shearing the material in Comparative Example 2 provided by the present invention.

[0049] Fig.13 It is an image of the thick milk of Comparative Example 2 provided by the present invention.

[0050] Fig.14 This is an image of the liquid obtained by shearing the material in Comparative Example 3 provided by the present invention.

[0051] Fig.15 It is an image of the thick milk of Comparative Example 3 provided by the present invention.

[0052] Fig.16 It is an image of the thick milk of Comparative Example 4 provided by the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Combine the following Figure 1-Figure 16 The thick milk of the present invention and the preparation method thereof are described.

[0055] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0056] This embodiment first provides a method for preparing thick milk, comprising: shearing a first raw material comprising raw cow milk and a stabilizer until the resulting liquid has a qualified image observed under a polarizing microscope, and then mixing, volume fixing, homogenizing, sterilizing, cooling and filling to obtain the thick milk; The stabilizer includes microcrystalline cellulose and / or sodium carboxymethyl cellulose; The qualified image includes: there is no aggregation of white short stick-shaped figures observed in the image.

[0057] In a specific embodiment of the present invention, the qualified image further comprises: the equivalent diameters of the regular or irregular granular graphics observed in the image are all smaller than the equivalent diameter of the white short stick graphics.

[0058] In a specific embodiment of the present invention, the protein content of the thick milk is ≥3.5%, and the fat content is ≥10.0%.

[0059] In a specific embodiment of the present invention, the content of microcrystalline cellulose in the thick milk is 0.1-2.0%; In a specific embodiment of the present invention, the content of sodium carboxymethyl cellulose in the thick milk is 0.1-2.0%.

[0060] In a specific embodiment of the present invention, the raw materials of the thick milk include, based on 100 parts by weight: 70-80 parts of cow's milk, 10-20 parts of condensed milk, 5-10 parts of milk fat, 0.1-2.0 parts of microcrystalline cellulose, 0.1-2.0 parts of sodium carboxymethyl cellulose, 0.1-1 parts of emulsifier, 0.1-1 parts of buffer salt and the balance of water; In a specific embodiment of the present invention, the emulsifier includes diglycerol fatty acid ester and / or sucrose fatty acid ester.

[0061] In a specific embodiment of the present invention, the process of observing a qualified image of the obtained slurry under a polarizing microscope comprises: Placing the feed liquid on a glass slide, and covering the glass slide with a cover slip to obtain sample slices; placing the sample slice on the stage of a polarizing microscope; The image is obtained by adjusting the objective lens, eyepiece, polarizer and light source of the polarizing microscope.

[0062] In a specific embodiment of the present invention, the step of observing a qualified image of the obtained slurry under a polarizing microscope comprises: (1) placing the slurry on a glass slide, placing a cover glass on the glass slide to obtain a sample slice, and then placing the sample slice on the stage of a polarizing microscope; (2) Select the low-power objective lens of the polarizing microscope and align it with the light aperture. Adjust the coarse focusing knob to bring the objective lens close to the sample slice and adjust the eyepiece. (3) Insert a polarizing filter into the filter slot of the polarizing microscope; (4) Rotate the eyepiece to adjust the color and eliminate glare.

[0063] (5) Use the focus wheel on the polarizing microscope to adjust the clarity and magnify to obtain the image.

[0064] In a specific embodiment of the present invention, the eyepiece is a 10x eyepiece.

[0065] In a specific embodiment of the present invention, the low-magnification objective lens is 5 times to 40 times.

[0066] In a specific embodiment of the present invention, a polarizing lens is mounted on the eyepiece.

[0067] In a specific embodiment of the present invention, the steps of preparing the thick milk include: (1) Shearing: After heating a portion of raw milk, add microcrystalline cellulose, sodium carboxymethyl cellulose and an emulsifier thereto, and shear the material until the resulting liquid has a qualified image observed under a polarizing microscope; Preferably, the heating temperature is 60-80°C; Preferably, the chemical concentration is less than 5%; (2) Mixing: adding condensed milk, milk fat and remaining raw milk to the material obtained in step (1) in sequence; (3) Fixed volume; (4) Homogenization and cooling: After heating the material, homogenize it under a pressure of 0-250 bar, cool it after homogenization, and let it stand for 10-60 minutes; Preferably, the material is heated to 60-70°C and then homogenized; Preferably, the homogenization is followed by cooling to 4-20°C; (5) Sterilization: Sterilize at 72-145°C for 3-90 seconds; (6) Cooling and canning: The material is canned after cooling.

[0068] This embodiment also provides thick milk prepared by the method for preparing thick milk as described above; In a specific embodiment of the present invention, the thick emulsion has a qualified image when observed under a polarizing microscope.

[0069] This embodiment also provides a method for predicting the shelf life stability of thick milk, the preparation process of the thick milk comprising: subjecting a first raw material comprising raw milk and a stabilizer to shearing, mixing, volume fixing, homogenizing, sterilizing and cooling and filling to obtain the thick milk; the stabilizer comprises microcrystalline cellulose and / or sodium carboxymethyl cellulose; the prediction method further comprises: sampling at the discharge port of the sheared material, and observing the image of the obtained sample under a polarizing microscope; The less the aggregation state of the white short stick-shaped figures observed in the image, the better the stability of the thick milk corresponding to the image during the shelf life.

[0070] In the present invention, the aggregation state of the white short stick-shaped figures refers to a shape formed by four or more white short stick-shaped figures gathered and / or stacked together in the picture measured by the polarizing microscope.

[0071] Specifically, the method for determining whether the image of the slurry involved in the embodiment of the present invention is qualified when observed under a polarizing microscope is as follows: (1) Place the test liquid on a glass slide, cover the slide with a cover glass to obtain a sample slice, and then place it on the stage of a polarizing microscope; (2) Select the 10× objective lens of the polarizing microscope and align it with the light aperture. Adjust the coarse focusing knob to bring the objective lens close to the sample slice. Adjust the 10× eyepiece and put a polarizing lens on the eyepiece. Rotate the eyepiece to eliminate glare.

[0072] (3) Insert a polarizing filter into the filter slot of the polarizing microscope to eliminate glare and obtain a clear image.

[0073] (4) Use the focus wheel on the polarizing microscope to adjust the clarity and magnify to obtain an image.

[0074] When white short stick-shaped figures can be observed in the image in step (4), and the observed white short stick-shaped figures are not aggregated, such as Figure 2 If the image is qualified, the liquid material can enter the next process. If the equivalent diameter of the regular or irregular particle-shaped graphics observed in the image is smaller than the equivalent diameter of the white short stick-shaped graphics, the image corresponds to a better liquid material state and can enter the next process.

[0075] The present invention can quickly and efficiently determine whether the thick milk product system is stable by using a polarizing microscope to detect the microstructure and distribution state of the feed liquid, thereby providing a fast, simple and highly economical detection method for adjusting the thick milk process and selecting appropriate auxiliary ingredients.

[0076] The use of polarized digital microscopes can not only overcome the complex observation problems of existing electron microscopes and optical microscopes, provide a relatively simple observation method, and reduce the tedious steps of sample preparation. It can also solve the problem that existing observations are not intuitive enough, and use the characteristics of polarized microscopes to present microscopic features more clearly and improve the visualization of observations.

[0077] The thick milk and the preparation method thereof of the present invention are described below in conjunction with specific implementation examples of the present invention.

[0078] Example 1 This embodiment provides a method for preparing thick milk, the process flow is as follows Figure 1 As shown, the steps are as follows: Based on 100 parts by weight, there are 70 parts by weight of raw milk, 10 parts by weight of milk fat, 15 parts by weight of condensed milk, emulsifiers (0.25 parts by weight of mono- and di-glycerol fatty acid esters, 0.05 parts by weight of sucrose fatty acid esters), stabilizers (0.1 parts by weight of sodium carboxymethyl cellulose, 0.1 parts by weight of microcrystalline cellulose, 0.005 parts by weight of carrageenan), and the balance is water.

[0079] The thick milk preparation process of the present embodiment is as follows: (1) Shearing: Weigh 20 parts of raw milk, heat to 70°C, add microcrystalline cellulose, sodium carboxymethyl cellulose and emulsifier, the concentration of the emulsifier is less than 5%, and shear the emulsifier for 10 minutes to obtain a mixture A. Sampling is performed, and the obtained liquid is observed under a polarizing microscope according to the method of Test Example 1. The image is qualified. Figure 3 shown.

[0080] (2) Mixing and volume determination: According to the product formula, accurately weigh the condensed milk, milk fat, mixture A and the remaining raw milk in sequence. After weighing, determine the volume.

[0081] (4) Homogenization and cooling: Heat the material to 65°C and then homogenize it. The homogenization pressure is 20 MPa. After homogenization, cool the material to 10°C and let it stand for 15 minutes.

[0082] (5) Sterilization: Sterilize the sample. Sterilization procedure: sterilization temperature: 140℃, 4s.

[0083] (6) Cooling packaging: After sterilization, the sample is cooled and aseptically filled at a filling temperature of 20°C to obtain thick milk.

[0084] The thick milk prepared in this embodiment has a protein content of 4.0-4.2% and a fat content of 10.0-10.2%.

[0085] Before the thick emulsion enters the shelf life, a sample is taken, and the resulting liquid is observed under a polarizing microscope according to the method of Test Example 1 to obtain a qualified image. Figure 4 shown.

[0086] Example 2 This embodiment provides a method for preparing thick milk, the process flow is as follows Figure 1 As shown, the steps are as follows: Based on 100 parts by weight, there are 80 parts by weight of raw milk, 15 parts by weight of milk fat, 10 parts by weight of condensed milk, emulsifier (0.3 parts by weight of mono- and di-glycerol fatty acid esters, 0.02 parts by weight of soybean lecithin), stabilizer (0.2 parts by weight of sodium carboxymethyl cellulose, 0.1 parts by weight of microcrystalline cellulose, 0.005 parts by weight of carrageenan), and the balance is water.

[0087] The thick milk preparation process of the present embodiment is as follows: (1) Shearing: Weigh 20 parts of raw milk, heat to 70°C, add microcrystalline cellulose, sodium carboxymethyl cellulose and emulsifier, the concentration of the emulsifier is less than 5%, and shear the emulsifier for 10 minutes to obtain a mixture A. Sampling is performed, and the obtained liquid is observed under a polarizing microscope according to the method of Test Example 1. The image is qualified. Figure 5 shown.

[0088] (2) Mixing and volume determination: According to the product formula, accurately weigh the condensed milk, milk fat, mixture A and the remaining raw milk in sequence. After weighing, determine the volume.

[0089] (4) Homogenization and cooling: Heat the material to 65°C and then homogenize it. The homogenization pressure is 20 MPa. After homogenization, cool the material to 10°C and let it stand for 15 minutes.

[0090] (5) Sterilization: Sterilize the sample. Sterilization procedure: sterilization temperature: 140℃, 4s.

[0091] (6) Cooling packaging: After sterilization, the sample is cooled and aseptically filled at a filling temperature of 20°C to obtain thick milk.

[0092] The thick milk obtained in Example 2 has a protein content of 5.5-5.7% and a fat content of 12.4-12.6%.

[0093] Before the thick emulsion enters the shelf life, a sample is taken, and the resulting liquid is observed under a polarizing microscope according to the method of Test Example 1 to obtain a qualified image. Figure 6 shown.

[0094] Example 3 This embodiment provides a method for preparing thick milk, the process flow is as follows Figure 1 As shown, the steps are as follows: based on 100 parts by weight, 80 parts by weight of raw milk, 15 parts by weight of milk fat, 10 parts by weight of condensed milk, emulsifier (0.3 parts by weight of mono- and di-glycerol fatty acid esters, 0.02 parts by weight of soybean lecithin), stabilizer (0.2 parts by weight of sodium carboxymethyl cellulose, 0.1 parts by weight of microcrystalline cellulose, 0.005 parts by weight of carrageenan), and the balance of water.

[0095] The thick milk preparation process of the present embodiment is as follows: (1) Shearing: Weigh 9 parts of raw milk, heat to 70°C, add microcrystalline cellulose, sodium carboxymethyl cellulose and emulsifier, the concentration of the emulsifier is less than 5%, and shear the emulsifier for 10 minutes to obtain mixture A. Sampling is performed, and the obtained liquid is observed under a polarizing microscope according to the method of Test Example 1. The image is qualified. Figure 7 shown.

[0096] (2) Mixing and volume determination: According to the product formula, accurately weigh the condensed milk, milk fat, mixture A and the remaining raw milk in sequence. After weighing, determine the volume.

[0097] (4) Homogenization and cooling: Heat the material to 65°C and then homogenize it. The homogenization pressure is 20 MPa. After homogenization, cool the material to 10°C and let it stand for 15 minutes.

[0098] (5) Sterilization: Sterilize the sample. Sterilization procedure: sterilization temperature: 140℃, 4s.

[0099] (6) Cooling packaging: After sterilization, the sample is cooled and aseptically filled at a filling temperature of 20°C to obtain thick milk.

[0100] The thick milk obtained in Example 3 has a protein content of 5.5-5.7% and a fat content of 12.4-12.6%.

[0101] Before the thick emulsion enters the shelf life, a sample is taken, and the resulting liquid is observed under a polarizing microscope according to the method of Test Example 1 to obtain a qualified image. Figure 8 shown.

[0102] Example 4 Example 4 is a commercially available thick milk product, characterized in that the ingredients are water, raw milk, cream, white sugar, sodium caseinate, microcrystalline cellulose, sodium carboxymethyl cellulose, and the protein content is 3.5% and the fat content is 12.5%. The shelf life is 4 months. The thick milk product is observed under a polarizing microscope. Fig. 9 As shown, compared with the example, the observed image is qualified and its condition is observed to be good.

[0103] Comparative Example 1 The same as Example 1, except that the shearing time in step (2) is shortened to 5 min. The images of the slurry and thick emulsion sample obtained in step (2) under a polarizing microscope are as follows: Figures 10-11 As shown, compared with Example 1, the observed images are unqualified regardless of the sample after chemical material shearing or the thick emulsion sample.

[0104] Comparative Example 2 The method is basically the same as Example 1, except that the shearing time in step (2) is extended to 30 min. The images of the slurry and thick emulsion sample obtained in step (2) under a polarizing microscope are as follows: Figures 12-13 As shown, compared with Example 1, the observed images are unqualified regardless of the sample after chemical material shearing or the thick emulsion sample.

[0105] Comparative Example 3 The method is basically the same as Example 1, except that the concentration of the chemical in step (2) is increased to >5%. The images of the slurry and thick emulsion sample obtained in step (2) under a polarizing microscope are as follows: Figures 14 and 15 As shown, compared with Example 1, the observed images are unqualified regardless of the sample after chemical material shearing or the thick emulsion sample.

[0106] Comparative Example 4 Comparative Example 4 is a commercially available thick milk product, whose ingredients are raw milk, cream, mono- and diglycerol fatty acid values, microcrystalline cellulose, and white sugar, with a protein content of 4.0% and a fat content of 11.5%. The shelf life is 3 months. The thick milk product is observed under a polarizing microscope. Fig.16 As shown, compared with Example 1, the observed image is unqualified, and its state is observed to have obvious gel and fat floating phenomenon.

[0107] Furthermore, the thick milk of the above-mentioned embodiment and comparative example was subjected to shelf life tracking, and its product status, viscosity growth rate and fat floating rate were tested. The results are shown in Tables 1, 2 and 3 below.

[0108] Table 1

[0109] It can be seen from Table 1 that the thick milk sample has good stability in the short term (within 60 days), but as time goes by, the product will show different degrees of instability, such as gel and fat floating. Different embodiments show differences in long-term stability. Overall, during the entire test period, the product status of Example 1, Example 2, Example 3 and Example 4 is better than that of other embodiments, which corresponds to the observation results of the polarizing microscope.

[0110] Table 2

[0111] It can be seen from Table 2 that during the tracking period, the room temperature viscosity of the thick milk sample increases with time. There are differences in the viscosity of different embodiments. During the entire test period, the viscosity growth rates of Example 1, Example 2, Example 3, and Example 4 are all relatively low, at 35.5%, 32.4%, 30.5%, and 16.5%, respectively. The viscosity growth rate of Comparative Example 3 is relatively high, at 50.7%. This may be because microcrystalline cellulose and sodium carboxymethyl cellulose aggregate, and due to their own structural characteristics and interactions in the system, a large number of physical crosslinks or molecular entanglements will be formed, thereby increasing the internal friction and consistency of the system, causing the viscosity to rise rapidly. As time goes by, phenomena such as fat floating and protein aggregation will gradually intensify. On the whole, in this shelf life tracking, the product status of Example 1, Example 2, Example 3, and Example 4 is better than that of other comparative examples, with the lowest room temperature viscosity growth rate and the best performance effect; consistent with the results of polarizing microscope observations, it can provide a reference example for adjusting the thick milk formula and process.

[0112] Table 3

[0113] It can be seen from Table 3 that during the tracking period, the fat floating rate of the thick milk sample increased with time. There are differences in the fat floating rates of different embodiments. During the entire test period, the fat floating rates of Example 1, Example 2, Example 3, and Example 4 are all relatively low, at 11.5%, 10.5%, 12.6%, and 5.1%, respectively. The fat floating rate of Comparative Example 3 is relatively high, at 34.0%. Microcrystalline cellulose and sodium carboxymethyl cellulose can be dispersed in milk beverages to form a three-dimensional network structure, which improves the stability of thick milk without affecting the rheological properties of thick milk. The high fat floating rate may be because microcrystalline cellulose and sodium carboxymethyl cellulose have poor shear dispersion in the system, and no three-dimensional network structure is formed, or the formed network structure gradually disperses over time, resulting in increased fat floating. On the whole, in this shelf life tracking, the product status of Example 1, Example 2, Example 3, and Example 4 is better than that of other comparison examples, with the lowest fat floating rate and the best performance effect; this is consistent with the results of polarizing microscope observations, and can provide a reference example for adjusting the thick milk formula and process.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing thick milk, characterized in that: include: The first raw material including raw milk and a stabilizer is sheared until the obtained liquid has a qualified image observed under a polarizing microscope, and then mixed, fixed volume, homogenized, sterilized, cooled and filled to obtain the thick milk; The stabilizer includes microcrystalline cellulose and / or sodium carboxymethyl cellulose; The qualified image includes: there is no aggregation of white short stick-shaped figures observed in the image.

2. The method for preparing thick milk according to claim 1, characterized in that: The qualified image also includes: the equivalent diameter of the regular or irregular granular graphics observed in the image is smaller than the equivalent diameter of the white short stick graphics.

3. The method for preparing thick milk according to claim 1 or 2, characterized in that: The thick milk has a protein content of ≥3.5% and a fat content of ≥10.0%.

4. The method for preparing thick milk according to any one of claims 1 to 3, characterized in that: The content of microcrystalline cellulose in the thick milk is 0.1-2.0%; And / or, the content of sodium carboxymethyl cellulose in the thick milk is 0.1-2.0%.

5. The method for preparing thick milk according to any one of claims 1 to 4, characterized in that: Based on 100 parts by weight, the raw materials of the thick milk include: 70-80 parts of cow's milk, 10-20 parts of condensed milk, 5-10 parts of milk fat, 0.1-2.0 parts of microcrystalline cellulose, 0.1-2.0 parts of sodium carboxymethyl cellulose, 0.1-1 parts of emulsifier, 0.1-1 parts of buffer salt and the balance of water; Preferably, the emulsifier is selected from one or more of mono- and di-glycerol fatty acid esters, sucrose fatty acid esters, soybean lecithin, Tween 80, polyglycerol fatty acid esters, diacetyl tartaric acid mono- and di-glycerides, and lactic acid fatty acid glycerides; Further preferably, the emulsifier comprises mono- and di-glycerol fatty acid esters and / or sucrose fatty acid esters.

6. The method for preparing thick milk according to any one of claims 1 to 5, characterized in that: The process of observing a qualified image of the obtained slurry under a polarizing microscope comprises: Placing the feed liquid on a glass slide, and covering the glass slide with a cover slip to obtain sample slices; placing the sample slice on the stage of a polarizing microscope; The image is obtained by adjusting the objective lens, eyepiece, polarizer and light source of the polarizing microscope.

7. The method for preparing thick milk according to any one of claims 1 to 6, characterized in that: The step of observing a qualified image of the obtained slurry under a polarizing microscope comprises: (1) placing the slurry on a glass slide, placing a cover glass on the glass slide to obtain a sample slice, and then placing the sample slice on the stage of a polarizing microscope; (2) Select the low-power objective lens of the polarizing microscope and align it with the light aperture. Adjust the coarse focusing knob to bring the objective lens close to the sample slice and adjust the eyepiece. (3) Insert a polarizing filter into the filter slot of the polarizing microscope; (4) Rotate the eyepiece to adjust the color and eliminate glare; (5) Use the focus wheel on the polarizing microscope to adjust the clarity and obtain the above image.

8. The method for preparing thick milk according to claim 8, characterized in that: The eyepiece is a 10x eyepiece; and / or, the low-magnification objective lens is a 5x to 40x objective lens; And / or, a polarizing lens is placed over the eyepiece.

9. The method for preparing thick milk according to any one of claims 1 to 7, characterized in that: The preparation steps of the thick milk include: (1) Shearing: After heating a portion of raw milk, add microcrystalline cellulose, sodium carboxymethyl cellulose and an emulsifier thereto, and shear the material until the resulting liquid has a qualified image observed under a polarizing microscope; preferably, the concentration of the material is less than 5%; (2) Mixing: adding condensed milk, milk fat and remaining raw milk to the material obtained in step (1) in sequence; (3) Fixed volume; (4) Homogenization and cooling: After heating the material, homogenize it under a pressure of 0-250 bar, cool it after homogenization, and let it stand for 10-60 minutes; (5) Sterilization: Sterilize at 72-145°C for 3-90 seconds; (6) Cooling and canning: The material is canned after cooling.

10. Thick milk obtained by the method for preparing thick milk according to any one of claims 1 to 9; Preferably, the thick emulsion has a qualified image when observed under a polarizing microscope.

Images