A method for counting protein aggregate particles in yogurt

Abstract

The present invention provides a method for counting protein aggregated particles in yogurt, comprising the following steps: dispersing a yogurt sample with a solvent so that the non-particle part in the yogurt sample is dissolved and the particle part is dispersed to form a mixed solution; taking a sample picture of the mixed solution using an imaging device; performing interference elimination processing on the sample picture in the imaging device; and partitioning and counting the sample picture after the interference elimination processing. The counting method of the present invention can effectively evaluate the severity of protein aggregated white particles in the production and sales process of yogurt products for quantitative analysis, and then formulate appropriate quality standards, providing a scientific basis for improving the protein aggregated particle problem of yogurt products.

Description

Technical Field

[0001] The invention belongs to the field of food detection, and in particular relates to a method for counting protein aggregate particles in yogurt. Background Art

[0002] During the production and sales process of yogurt products, the protein aggregates and forms white particles due to the increase of acidity, temperature changes, and violent shaking. Figure 1 When these white particles aggregate large enough, they can pose a risk to the quality of yogurt products.

[0003] Yogurt products have a thick texture and can suspend large particles such as fruit particles and fruit fibers. When white particles of protein flocculation appear in the product, it is impossible to analyze the problem through natural sedimentation, centrifugal sedimentation, etc. At present, there is no clear evaluation method for protein aggregated particles on the market, and it is impossible to quantify the quality problem of protein aggregated particles, and then it is impossible to formulate quality standards, and improvement verification cannot be effectively evaluated. Summary of the invention

[0004] The object of the present invention is to provide a method for evaluating and detecting protein aggregate particles in yogurt products, by which the severity of protein aggregate particles in yogurt products can be effectively evaluated and quantitative analysis can be achieved.

[0005] According to one aspect of the present invention, a method for counting protein aggregate particles in yogurt is provided, comprising the following steps:

[0006] The yogurt sample is dispersed with a solvent so that the non-particle part of the yogurt sample is dissolved.

[0007] The particles are partially dispersed to form a mixed solution;

[0008] Using an imaging device to take a sample picture of the mixed solution;

[0009] performing interference elimination processing on the sample image in the imaging device; and

[0010] The sample images after interference elimination are divided into partitions and counted.

[0011] Preferably, in the counting method, the imaging device is an optical microscope.

[0012] Preferably, the interference elimination process includes using microscope software to perform background elimination on the sample image.

[0013] Preferably, the background elimination includes setting the elimination radius to 400-600 by using microscope software so that interfering particles are eliminated.

[0014] Preferably, the partition design includes performing a grid design of equal proportions on the sample image.

[0015] Preferably, the counting comprises counting the protein aggregated particles in each grid separately and then calculating the total number.

[0016] Preferably, the dispersion treatment is performed by mechanical stirring.

[0017] Preferably, the solvent is water, or an alcohol organic solvent.

[0018] Preferably, the microscope software is Zeiss ZEIZZ optical microscope software ZEN.

[0019] The counting method according to the present invention adopts a simple sample processing method, the counting process is accurate, the risk of protein aggregate particles being missed is reduced, and it is easy to trace the experimental results later. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will now be more clearly described with reference to the following drawings.

[0021] Figure 1 Shows the protein flocculated white particles appearing in the yogurt.

[0022] Figure 2 The sample processing method according to the counting method of the present invention is shown.

[0023] Figure 3 and Figure 4 The process of picture interference elimination processing according to the counting method of the present invention is shown. DETAILED DESCRIPTION

[0024] In order to more clearly understand the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now further described in detail. It should be understood that the following specific embodiments are only exemplary, and the technical solution of the present invention is not limited to the specific embodiments listed below.

[0025] The invention provides a method for counting white particles in yogurt. The particles detected by the method of the invention refer to white granular substances formed by protein flocculation in yogurt.

[0026] The counting method of the present invention comprises a sample processing step, a picture taking step, a picture processing step and a counting step.

[0027] The sample processing step adopted by the present invention utilizes mechanical stirring to evenly disperse the yogurt sample, dissolve the non-particle part and disperse the particle part in the yogurt sample, and expose the insoluble particles to the solution. Generally, water or an alcohol organic solvent (such as methanol, ethanol, propanol, butanol, etc.) is used as a solvent, and water is preferably used for the sample processing step.

[0028] Figure 2 The sample processing method according to one embodiment of the present invention is shown, in which a magnetic stirrer is used to mechanically disperse yogurt. Yogurt and water are added to a container 2, which is placed on a magnetic stirrer 1. A magnetic rotor 3 is placed in the container 2, and a mixed solution 4 is formed after magnetic stirring. Usually, a non-magnetic vessel is selected as the container 2. A magnetic stirrer with a rotation speed in the range of 0-1500rpm and a power of 20W is usually selected.

[0029] The weight ratio of the yogurt to water can be (0.1-0.2):(50-100), and purified water is preferably used.

[0030] After the above sample treatment, the yogurt sample is fully dispersed and dissolved in water, so that the insoluble protein aggregate particles do not stick to each other and form single particles.

[0031] According to a specific embodiment, the sample processing step may include: weighing 0.1-0.2g of yogurt sample into a 1000mL beaker 2, adding 50-100mL of pure water to form a mixed solution 4, placing it on a magnetic stirrer 1, placing a 30-40mm magnetic rotor 3 in the beaker, adjusting the speed of the magnetic stirrer to 800-1000rpm, and processing for 3-5min to fully disperse and dissolve the yogurt sample in the pure water.

[0032] The mixed solution obtained in the above sample processing step is allowed to stand, and after the particles are completely precipitated, a sample image of the mixed solution is taken using an imaging device.

[0033] The imaging device applicable to the present invention may be a microscope, preferably an optical microscope with an image processing function, such as a Zeiss ZEIZZ optical microscope installed with software ZEN.

[0034] After the sample image is obtained by using the imaging device, it is necessary to further use the imaging device to perform image processing on the sample image, such as performing interference elimination processing.

[0035] like Figure 3 and Figure 4 The process of using an image device to perform interference elimination processing on a picture is shown. Using an image device, such as software installed in an optical microscope, such as ZEN software, background elimination 5 is set, and preferably the elimination radius range 6 is set to 400-600. Here, 1 unit of the elimination radius is a specified unit in the processing software, which is usually equivalent to 0.0254 pixel units.

[0036] After the interference elimination process, the small interfering particles 9 in the picture are eliminated, making the protein aggregated particles 8 more obvious and easy to count subsequently. Usually, the interfering particles 9 are flaky irregular particles with a small diameter and a lighter color (white); the protein white particles are solid regular particles with larger particles and a darker color (white). In terms of texture, the interfering particles are flocculent and fragile, and can be broken by vigorous shaking or stirring. In contrast, the protein aggregated particles to be detected are hard particles that need to be squeezed to break.

[0037] The counting step includes performing a grid design on the image after the interference elimination process 7, usually performing an equal-proportion grid design, that is, dividing the image into a number of identical squares. The protein aggregate particles in each square in the image are counted separately, and the number of each square is summed up to obtain the total number of protein aggregate particles.

[0038] According to the counting method of the present invention, the influence of interfering particles 9 on the test results can be eliminated through sample processing and image processing steps, the accuracy of the counting process of protein aggregated particles 8 can be ensured, the risk of missing protein aggregated particles is reduced, and it is easy to trace the experimental results later.

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0040] The methods used in the following examples are conventional methods unless otherwise specified, and the reagents used are commercially available reagents unless otherwise specified.

[0041] Example

[0042] Example 1

[0043] The yogurt sample processing steps include: weighing 0.12g of the yogurt sample into a 1000mL beaker, adding 100mL of pure water to form a mixed solution, placing it on a magnetic stirrer, placing a 30mm magnetic rotor in the beaker, adjusting the speed of the magnetic stirrer to 900rpm, processing for 4min, so that the yogurt sample is fully dispersed and dissolved in the pure water to obtain a mixed solution.

[0044] The mixed solution was allowed to stand until the particles were completely precipitated. Sample images were taken using a Zeiss ZEIZZ optical microscope equipped with the ZEN software.

[0045] The software ZEN was used to set the image background removal, and the removal radius was set to 500. A grid was designed for the image after interference removal, and the number of protein aggregate particles that were not eliminated in each grid was calculated (interference particles were not included), and the total number was calculated. The test results are shown in Table 1.

[0046] Table 1

[0047]

[0048] Comparative Example 1

[0049] The protein aggregate particle count was performed in the same manner as in Example 1, except that the conditions shown in Table 2 below were followed. The test results are shown in Table 2.

[0050] Table 2

[0051]

[0052] It can be seen from Table 2 above that the rotor model used in Comparative Example 1 is lower than the protection range of 30-40 mm, the shearing ability of the rotor on the particles is reduced, the larger curd blocks are not fully broken, the number of particles is low, and the maximum particle size is large.

[0053] Comparative Example 2

[0054] The protein aggregate particle count was performed in the same manner as in Example 1, except that the conditions shown in Table 3 below were followed. The test results are shown in Table 3.

[0055] Table 3

[0056]

[0057] It can be seen from Table 3 above that the rotor model used in Comparative Example 2 is 30-40 mm higher than the protection range, the shearing capacity of the rotor on the particles is increased, the number of particles is reduced, and the maximum particle size has no significant change.

[0058] Comparative Example 3

[0059] The protein aggregate particle count was performed in the same manner as in Example 1, except that the conditions shown in Table 4 below were followed. The test results are shown in Table 4.

[0060] Table 4

[0061]

[0062]

[0063] It can be seen from Table 4 above that the rotation speed used in Comparative Example 3 is lower than the protection range of 800-1000 mm, the shearing ability of the rotor on the particles is reduced, the larger curd blocks are not fully broken, the number of particles is low, and the maximum particle size is large.

[0064] Comparative Example 4

[0065] Protein aggregate particle counting was performed in the same manner as in Example 1, except that the conditions shown in the following Table 5 were followed. The test results are shown in Table 5.

[0066] Table 5

[0067]

[0068] It can be seen from Table 5 above that the rotation speed used in Comparative Example 4 is higher than the protection range of 800-1000 mm, the shearing capacity of the rotor on the particles is increased, the number of particles is reduced, and the maximum particle size has no obvious change.

[0069] Comparative Example 5

[0070] Protein aggregate particle counting was performed in the same manner as in Example 1, except that the conditions shown in the following Table 6 were followed. The test results are shown in Table 6.

[0071] Table 6

[0072]

[0073] It can be seen from Table 6 above that the processing time used in Comparative Example 5 is lower than the protection range of 3-5 min, the shearing ability of the rotor on the particles is reduced, the larger curd blocks are not fully broken, the number of particles is low, and the maximum particle size is large.

[0074] Comparative Example 6

[0075] Protein aggregate particle counting was performed in the same manner as in Example 1, except that the conditions shown in the following Table 7 were followed. The test results are shown in Table 7.

[0076] Table 7

[0077]

[0078] It can be seen from Table 7 above that the processing time used in Comparative Example 6 is higher than the protection range of 3-5 min, the shearing capacity of the rotor on the particles is increased, and the number of particles and the maximum particle size have no obvious changes.

[0079] Comparative Example 7

[0080] Protein aggregate particle counting was performed in the same manner as in Example 1, except that the conditions shown in the following Table 8 were followed. The test results are shown in Table 8.

[0081] Table 8

[0082]

[0083] It can be seen from Table 8 above that the sample weight used in Comparative Example 7 is lower than the protection range of 0.1-0.2 g, the sample concentration is reduced, the number of particles is significantly reduced, and the maximum particle size is reduced.

[0084] Comparative Example 8

[0085] Protein aggregate particle counting was performed in the same manner as in Example 1, except that the conditions shown in the following Table 9 were followed. The test results are shown in Table 9.

[0086] Table 9

[0087]

[0088] It can be seen from Table 9 above that the sample weight used in Comparative Example 8 is higher than the protection range of 0.1-0.2 g, the sample concentration increases, the particle recognition decreases, the number of particles increases significantly, and the maximum particle size does not change significantly.

[0089] Comparative Example 9

[0090] Protein aggregate particle counting was performed in the same manner as in Example 1, except that the conditions shown in the following Table 10 were followed. The test results are shown in Table 10.

[0091] Table 10

[0092]

[0093] It can be seen from Table 10 above that the elimination radius range used in Comparative Example 9 is lower than the protection range of 400-600, the photo recognition is increased, the number of particles increases, and the purpose of eliminating interference is not achieved; the maximum particle size does not change significantly.

[0094] Comparative Example 10

[0095] The protein aggregate particle count was performed in the same manner as in Example 1, except that the conditions shown in the following Table 11 were followed. The test results are shown in Table 11.

[0096] Table 11

[0097]

[0098]

[0099] It can be seen from Table 11 above that the elimination radius range used in Comparative Example 10 is higher than the protection range of 400-600, the photo recognition is reduced, the number of particles is reduced, the interference removal effect is too strong; the maximum particle size does not change significantly.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that, without departing from the spirit and essence of the present invention, those skilled in the art may make various modifications, combinations, changes or substitutions to the details and features of the present invention. These modifications, combinations, changes or substitutions should also be understood to be included in the scope of protection claimed by the present invention.

Claims

1. A method for counting protein aggregate particles in yogurt, characterized in that: The following steps are involved: The yogurt sample is dispersed with a solvent so that the non-particle part of the yogurt sample is dissolved, the particle part is dispersed, and the insoluble particles are exposed to the solution to form a mixed solution; Using an imaging device to take a sample picture of the mixed solution; performing interference elimination processing on the sample image in the imaging device; as well as Design partitions for the sample images after interference elimination and count them; The dispersion treatment is carried out by mechanical stirring; The solvent is water or an alcohol organic solvent.

2. The counting method according to claim 1, wherein the imaging device is an optical microscope.

3. The counting method according to claim 2, wherein the interference elimination process comprises using microscope software to eliminate the background of the sample image.

4. The counting method according to claim 3, wherein the background elimination comprises using microscope software to set an elimination radius of 400-600 so that interfering particles are eliminated.

5. According to the counting method according to claim 1, the partition design includes designing a grid of equal proportions for the sample image.

6. The counting method according to claim 5, wherein the counting comprises counting the protein aggregate particles in each grid separately and then calculating the total number.

7. The counting method according to claim 4, wherein the microscope software is Zeiss ZEIZZ optical microscope software ZEN.

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