A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products

Abstract

The present invention relates to the field of food. Addressing the problem of the lack of quality grade classification of xanthan gum in actual sample systems, the present invention provides a method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products. The method comprises first preparing a feed solution using cooled milk obtained from whole milk powder, a stabilizer solution obtained by mixing CMC, xanthan gum, and white sugar, a salt solution obtained by mixing sodium tripolyphosphate and sodium citrate, and an acid solution obtained by mixing citric acid monohydrate and lactic acid. The feed solution is then sterilized after high-speed shearing treatment and cooled to room temperature to obtain a sample. The sample is then subjected to centrifugal sedimentation measurement to calculate the centrifugal sedimentation percentage S. S≤2.0 is considered a high grade, suitable for the production of fermented acidic dairy products; 2.0<S≤3.0 is considered a medium grade, suitable for the production of formulated acidic dairy products; and S>3.0 is considered a low grade, suitable for the production of other products. The present invention can directly and efficiently screen out xanthan gum that can provide good stability in acidic dairy products.

Description

Technical Field

[0001] The invention relates to the field of food, in particular to a method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products. Background Art

[0002] Xanthan gum has a repeating pentasaccharide structure and a fibrous backbone composed of two D-glucose molecules linked by β(1→4) glycosidic bonds. Every other glucose residue is linked to a trisaccharide side chain at the C3 position of the backbone. The side chains are mannose at the beginning and end, with glucuronic acid in the middle. An acetyl group is attached to the C6 position of the mannose near the backbone, and pyruvic acid is condensed at the C4 and C6 positions of the terminal mannose. The glucuronic and pyruvic acid groups on the side chains give xanthan gum a negative charge. The interactions between these negatively charged side chains and between them and the polymer backbone determine the excellent properties of xanthan gum solutions.

[0003] CMC is widely used in the production of acidic milk beverages in my country. However, CMC alone cannot stabilize the product system and the product tastes poor. Xanthan gum, due to its excellent properties, is widely used in actual production to stabilize the system and enhance taste.

[0004] GB 1886.41-2015 National Food Safety Standard for Xanthan Gum, a food additive, specifies general xanthan gum specifications, such as viscosity, shear strength, and pyruvic acid content. However, it does not specify specific xanthan gum application indicators, specifically the quality grading method for xanthan gum when used with sodium carboxymethylcellulose in different acidic dairy products. Existing research techniques primarily focus on xanthan gum quality evaluation indicators such as the rheological properties of xanthan gum solutions, pyruvic acid content, and calcium ion content. However, no research has been conducted on the quality grading of xanthan gum in actual sample systems. Therefore, an ideal solution suitable for the production of acidic dairy beverages is needed. Summary of the Invention

[0005] The present invention aims to address the technical problem of evaluating the grade of xanthan gum in different types of acidic dairy products. It provides a method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products. Based on the product formula and production process, laboratory pilot production is conducted for different acidic dairy product systems. The xanthan gum raw material quality is ultimately graded using the centrifugal sedimentation rate indicator to ensure product stability throughout its shelf life. This method, designed based on the product formula and production process, is more targeted, direct, and efficient.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products comprises the following steps:

[0008] 1) Preparation of the feed solution: adding whole milk powder to water, shearing and hydrating until completely dissolved, and then cooling to 20-25° C. to obtain a cooled milk solution; weighing CMC, xanthan gum, and white sugar, mixing them evenly, adding them to water, shearing them until completely dissolved, and after the solution becomes transparent, cooling them to 20-25° C. to obtain a stabilizer solution; weighing sodium tripolyphosphate and sodium citrate, dissolving them in water to obtain a salt solution; weighing citric acid monohydrate and lactic acid, dissolving them in water to obtain an acid solution; under emulsified shearing conditions, adding the cooled milk solution to the stabilizer solution, stirring until thoroughly mixed, then adding the salt solution, stirring, and then adding the acid solution to the solution, and continuing to stir until uniformly mixed, to obtain the feed solution;

[0009] 2) High-speed shear test: The liquid was heated to 85-95°C and subjected to high-speed shear treatment. After the test, it was sterilized and cooled to room temperature.

[0010] 3) Determination of test results: After the sample is left for 15-25 hours, shake it well and perform centrifugal sedimentation determination. Calculate the centrifugal sedimentation percentage S;

[0011] 4) Evaluation criteria: Raw materials are graded according to the centrifugal sedimentation rate grade S. S ≤ 2.0 is a high grade, suitable for the production of fermented acidic dairy products; 2.0 < S ≤ 3.0 is a medium grade, suitable for the production of formulated acidic dairy products; S > 3.0 is a low grade, suitable for the production of other products.

[0012] Acidic milk-containing products are divided into fermented acidic milk-containing products and formulated acidic milk-containing products. Formulated acidic milk-containing products refer to products prepared by adding water, sugar solution, organic acid, etc. to fresh milk or dairy products as raw materials; fermented acidic milk-containing products refer to products prepared by adding water, sugar solution, etc. to the emulsion obtained by culturing and fermenting lactic acid bacteria with fresh milk or dairy products as raw materials. Due to the preparation characteristics, the protein particles of fermented acidic milk-containing products are larger and more easily precipitated than those of formulated acidic milk-containing products, so the quality requirements for xanthan gum are also higher. For the needs of actual production, the present invention is based on the standard of being applicable to different types of dairy products, and the quality grades of xanthan gum are artificially divided, filling the gap in the existing xanthan gum research quality evaluation index for its quality grade division in the actual sample system, which can provide guidance for actual production applications and avoid the problems such as instability of the acidic milk products produced during the shelf life.

[0013] This study has developed a method for grading xanthan gum raw material quality using centrifugal sedimentation rate after laboratory pilot production. This method has the following advantages: 1. It is more targeted, direct, and efficient, based on product formulation and production process design; 2. Compared to existing particle size detection methods, the centrifugal sedimentation instrument can operate continuously, is less expensive, and offers good reproducibility and a wider testing range.

[0014] To ensure that quality grade corresponds to the sedimentation rate, the inventors conducted extensive experiments and ultimately determined that a sedimentation rate S ≤ 2.0 indicates a relatively stable product, meeting the stability requirements of fermented acidic dairy products, as these products have larger particles. A centrifugal sedimentation rate S > 3.0 degrades the product, making it unsuitable for the production of formulated acidic dairy products and limiting its use to other products. These values ​​are not disclosed in the prior art and represent the inventors' original work.

[0015] Preferably, the conditions for preparing the cooled milk in step 1) are: the concentration of whole milk powder is 0.2-0.3 g whole milk powder per gram of water, the water temperature is 40-60° C., and the shearing process is first high-speed shearing for 10-20 minutes and then low-speed shearing for 15-25 minutes.

[0016] Preferably, the conditions for preparing the stabilizer solution in step 1) are: the mass ratio of CMC, xanthan gum, white sugar and water is (4-6):(0.1-0.3):(30-50):(500-700), the water temperature is 50-60°C, and the shearing process is first high-speed shearing for 5-10 minutes and then low-speed shearing for 20-25 minutes.

[0017] Preferably, the high-speed shearing speed in step 1) or step 2) is 4000-5000 rpm, and the low-speed shearing speed is 1500-2000 rpm.

[0018] Preferably, the conditions for preparing the salt solution in step 1) are: the mass ratio of sodium tripolyphosphate, sodium citrate and water is (0.3-0.5):(0.4-0.6):(40-60).

[0019] Preferably, the conditions for preparing the acid solution in step 1) are: the mass ratio of citric acid monohydrate, lactic acid and water is (3-3.5):(1-1.5):(20-40).

[0020] Preferably, the sterilization treatment conditions in step 2) are: packaging the liquid feed and placing it in a 95±2° C. water bath for 30-40 minutes.

[0021] Preferably, the method for determining the centrifugal sedimentation in step 3) is as follows: first weigh the weight of the centrifuge tube m1, then weigh m grams of sample and place it in the centrifuge tube for centrifugal determination, setting the centrifugation conditions to 2880g for 30 minutes; after the centrifugation is completed, discard the upper solution, place the centrifuge tube upside down for 20-40 minutes, and then weigh the centrifugal sediment and the total weight of the centrifuge tube m2; calculate the centrifugal sedimentation percentage S according to the formula, which is S = (m2-m1) / m*100%.

[0022] Therefore, the present invention has the following beneficial effects: for different acidic dairy product systems, according to product formula and production process, laboratory small-scale trial production products are carried out, and the quality grade of xanthan gum raw materials is finally determined by the centrifugal sedimentation rate index to evaluate it, thereby ensuring the stability of the product during the shelf life, providing guidance for actual production applications, and avoiding the problems of instability of the produced acidic dairy products during the shelf life. The present invention is designed based on the product formula and production process, is more targeted, more direct and efficient, and compared with the particle size detection method in the prior art, the instrument for the centrifugal sedimentation operation can be operated continuously, is relatively low in price, and has good method repeatability and a large test range. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below through specific embodiments.

[0024] The various embodiments of the present invention measure the quality of xanthan gum raw materials from different suppliers and different batches. In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art.

[0025] Except for xanthan gum raw material, other raw materials used must undergo corresponding testing, and the reproducibility and stability of the test results must meet the requirements.

[0026] Shearing equipment: High-speed shearing machine, Silverson, UK, model L4R. The high-speed shearing speed described below is 4000-5000 rpm, and the low-speed shearing speed is 1500-2000 rpm.

[0027] The formula for calculating the centrifugal sedimentation rate S is S = (m2-m1) / m*100% (m1-centrifuge tube mass, m2-sample mass, m3-total mass of centrifuge tube and sample after centrifugation)

[0028] Example 1

[0029] A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products comprises the following steps:

[0030] 1) Preparation of the feed solution: Add 230 g of whole milk powder to water and dissolve it in 1000 g of warm water at 50°C under shear conditions in an emulsifier. Maintain high shear speed for 15 minutes and low shear hydration for 20 minutes during the dissolution process. After complete dissolution, cool it to 22°C in a cold water bath. Weigh 307 g of the cooled milk solution for later use.

[0031] Weigh 5.0g of CMC, 0.2g of xanthan gum, and 40g of white sugar, mix well, and add to 600g of 55°C hot water under emulsification shear conditions. Maintain high-speed shearing for 5 minutes and low-speed shearing for 20 minutes until completely dissolved. When the solution becomes transparent, cool it to 25°C in a cold water bath to prepare a stabilizer solution for later use.

[0032] Weigh 0.4g sodium tripolyphosphate and 0.5g sodium citrate, dissolve in 50g room temperature water to prepare a salt solution for later use;

[0033] Weigh 3.1g of citric acid monohydrate and 1.30g of lactic acid, dissolve in 30g of room temperature water to prepare acid solution for later use;

[0034] Under emulsification shear conditions, add the cooled milk to the stabilizer solution, stir at low speed for 20 minutes, and after thorough mixing, add the prepared salt solution and stir for 2 minutes. Then, slowly add the prepared acid solution to the solution and continue stirring for 15 minutes until evenly mixed. Then, stop stirring to obtain the liquid to be tested.

[0035] 2) High-speed shear test: Preheat the water bath to 95°C, place the prepared liquid in the water bath and heat it to 90°C, then remove it. Place the liquid heated to 90°C in a high-speed shear machine and perform high-speed thermal shear treatment for 15 minutes. After the high-speed shear test, pour the liquid into HDPE plastic bottles, seal them, and sterilize them in a water bath at 95±2°C for 35 minutes. After heating, cool the sample to room temperature with tap water.

[0036] 3) Test result determination: After the sample is placed for 20 hours, it is vigorously shaken and centrifuged to determine the centrifugal sedimentation rate S. The centrifugal sedimentation rate (S) determination method is as follows: weigh the weight of a 50ml centrifuge tube (m1), accurately weigh 50.0g (m) of sample in a centrifuge tube for centrifugal determination, and set the centrifugation condition to 2880g for 30min. After the centrifugation is completed, discard the upper solution (be careful not to destroy the bottom sedimentation state), place the centrifuge tube upside down for 30min, and then weigh the centrifugal sedimentation and the centrifuge tube weight (m2). According to the formula, the centrifugal sedimentation rate S is 1.6%, indicating that the xanthan gum being tested is of high grade and is suitable for the production of fermented acidic dairy products.

[0037] The xanthan gum used in this example is used in the production of fermented acidic milk-containing products. The obtained acidic milk beverage has good stability and does not produce whey separation during the shelf life.

[0038] Example 2

[0039] A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products comprises the following steps:

[0040] 1) Preparation of the feed solution: Add 200g of whole milk powder to water and dissolve it in 1000g of warm water at 40°C under shear conditions of an emulsifier. Maintain high shear speed for 10 minutes and low shear hydration for 15 minutes during the dissolution process. After complete dissolution, cool it to 20°C in a cold water bath. Weigh 300g of the cooled milk solution for later use.

[0041] Weigh 4.0g of CMC, 0.1g of xanthan gum, and 30g of white sugar, mix well, and add to 500g of 50°C hot water under emulsification shear conditions. Maintain high-speed shearing for 10 minutes and low-speed shearing for 25 minutes until completely dissolved. When the solution becomes transparent, cool it to 25°C in a cold water bath to prepare a stabilizer solution for later use.

[0042] Weigh 0.5g sodium tripolyphosphate and 0.6g sodium citrate, dissolve in 60g room temperature water to prepare a salt solution for later use;

[0043] Weigh 3.0g of citric acid monohydrate and 1.0g of lactic acid, dissolve in 20g of room temperature water to prepare acid solution for later use;

[0044] Under emulsification shear conditions, add the cooled milk to the stabilizer solution, stir at low speed for 20 minutes, and after thorough mixing, add the prepared salt solution and stir for 2 minutes. Then, slowly add the prepared acid solution to the solution and continue stirring for 15 minutes until evenly mixed. Then, stop stirring to obtain the liquid to be tested.

[0045] 2) High-speed shear test: Preheat the water bath to 95°C, place the prepared liquid in the water bath and heat it to 85°C, then remove it. Place the liquid heated to 85°C in a high-speed shear machine and perform high-speed thermal shear treatment for 15 minutes. After the high-speed shear test, pour the liquid into HDPE plastic bottles, seal them, and sterilize them in a water bath at 95±2°C for 30 minutes. After heating, cool the sample to room temperature with tap water.

[0046] 3) Test result judgment: After the sample is placed for 15 hours, it is shaken vigorously, and the centrifugal sedimentation is measured, and the centrifugal sedimentation percentage S is calculated. The centrifugal sedimentation rate (S) determination method is: weigh the weight (m1) of a 50ml centrifuge tube, accurately weigh 50.0g (m) sample centrifuge tube and carry out centrifugal determination, and set the centrifugal condition to 2880g 30min. After centrifugation is complete, discard the upper solution (note that the bottom sedimentation state cannot be destroyed), after the centrifuge tube is placed upside down for 30min, weigh the centrifugal sedimentation and the centrifuge tube weight (m2). According to the formula, the centrifugal sedimentation percentage S is 2.8%, indicating that the xanthan gum being tested belongs to a medium grade and is applicable to the production of formulated acidic dairy products.

[0047] When the xanthan gum used in this example was used in the actual production of fermented acidic milk-containing products, the resulting acidic milk beverage had average stability, with 2.5% of the products experiencing whey separation during shelf life. However, when the xanthan gum used in this example was used in the actual production of formulated acidic milk-containing products, the resulting acidic milk beverage had excellent stability and did not experience whey separation during shelf life.

[0048] Example 3

[0049] A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products comprises the following steps:

[0050] 1) Preparation of the feed solution: Add 300 g of whole milk powder to water and dissolve it in 1000 g of warm water at 60°C under shear conditions of an emulsifier. Maintain high shear speed for 20 minutes and low shear hydration for 25 minutes during the dissolution process. After complete dissolution, cool it to 25°C in a cold water bath. Weigh 320 g of the cooled milk solution for later use.

[0051] Weigh 6.0g of CMC, 0.3g of xanthan gum, and 60g of white sugar, mix well, and add to 600g of 55℃ hot water under emulsification shear conditions. Maintain high-speed shear for 5 minutes and low-speed shear for 20 minutes until completely dissolved. After the solution becomes transparent, cool it to 25℃ in a cold water bath to prepare a stabilizer solution for later use.

[0052] Weigh 0.3g sodium tripolyphosphate and 0.4g sodium citrate, dissolve in 40g room temperature water to prepare a salt solution for later use;

[0053] Weigh 3.5g of citric acid monohydrate and 1.5g of lactic acid and dissolve them in 40g of room temperature water to prepare acid solution for later use;

[0054] Under emulsification shear conditions, add the cooled milk to the stabilizer solution, stir at low speed for 20 minutes, and after thorough mixing, add the prepared salt solution and stir for 2 minutes. Then, slowly add the prepared acid solution to the solution and continue stirring for 15 minutes until evenly mixed. Then, stop stirring to obtain the liquid to be tested.

[0055] 2) High-speed shear test: Preheat the water bath to 95°C, place the prepared liquid in the water bath and heat it to 95°C, then remove it. Place the liquid heated to 95°C in a high-speed shear machine and perform high-speed thermal shear treatment for 15 minutes. After the high-speed shear test, pour the liquid into HDPE plastic bottles, seal them, and sterilize them in a water bath at 95±2°C for 40 minutes. After heating, cool the sample to room temperature with tap water.

[0056] 3) Test result determination: After the sample is placed for 25 hours, it is vigorously shaken and centrifuged to determine the centrifugal sedimentation rate S. The centrifugal sedimentation rate (S) determination method is as follows: weigh the weight of a 50ml centrifuge tube (m1), accurately weigh 50.0g (m) of sample in a centrifuge tube for centrifugation determination, and set the centrifugation condition to 2880g for 30min. After the centrifugation is completed, discard the upper solution (be careful not to destroy the bottom sediment state), place the centrifuge tube upside down for 30min, and then weigh the centrifugal sedimentation and the centrifuge tube weight (m2). According to the formula, the centrifugal sedimentation rate S is 3.9%, indicating that the xanthan gum tested is of low grade and suitable for the production of other products.

[0057] When the xanthan gum used in this example was used in a fermented acidic milk-containing product, the resulting acidic milk beverage had poor stability, with 60.1% of the products experiencing whey separation during their shelf life.

[0058] It can be seen from the results of the above examples that the evaluation results obtained using the method of the present invention are consistent with the product stability results in the actual production process, which proves that the method of the present invention can effectively evaluate the quality grade of xanthan gum raw materials, thereby applying it to the preparation of different acidic dairy products to ensure the stability of the products during their shelf life.

Claims

1. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products, characterized in that: The following steps are involved: 1) Preparation of the feed solution: Add whole milk powder to water, shear and hydrate until completely dissolved, and then cool to 20-25°C to obtain a cooled milk solution. Weigh CMC, xanthan gum, and white sugar, mix thoroughly, add to water, shear until completely dissolved, and after the solution becomes transparent, cool to 20-25°C to obtain a stabilizer solution. Weigh sodium tripolyphosphate and sodium citrate and dissolve them in water to obtain a salt solution. Weigh citric acid monohydrate and lactic acid and dissolve them in water to obtain an acid solution. Under emulsified shear conditions, add the cooled milk solution to the stabilizer solution and stir until thoroughly mixed. Then, add the salt solution and stir. Then, add the acid solution to the solution and continue stirring until evenly mixed to obtain the feed solution. 2) High-speed shear test: Heat the liquid to 85-95°C and perform high-speed shear treatment. After the test, sterilize and cool to room temperature. 3) Determination of test results: After the sample is left for 15-25 hours, shake it well, perform centrifugal sedimentation determination, and calculate the centrifugal sedimentation percentage S; 4) Evaluation criteria: Raw materials are graded according to the centrifugal sedimentation percentage S. S ≤ 2.0% is considered high grade, suitable for the production of fermented acidic dairy products; 2.0% < S ≤ 3.0% is considered medium grade, suitable for the production of formulated acidic dairy products; S > 3.0% is considered low grade.

2. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 1, characterized in that: The conditions for preparing the cooled milk in step 1) are as follows: the concentration of whole milk powder is 0.2-0.3 g whole milk powder per gram of water, the water temperature is 40-60°C, and the shearing process is first high-speed shearing for 10-20 minutes and then low-speed shearing for 15-25 minutes.

3. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 1, characterized in that: The conditions for preparing the stabilizer solution in step 1) are as follows: the mass ratio of CMC, xanthan gum, white sugar and water is (4-6):(0.1-0.3):(30-50):(500-700), the water temperature is 50-60°C, and the shearing process is first high-speed shearing for 5-10 minutes and then low-speed shearing for 20-25 minutes.

4. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 2 or 3, characterized in that: The high-speed shearing speed in step 1) is 4000-5000 rpm, and the low-speed shearing speed is 1500-2000 rpm.

5. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 1, characterized in that: The conditions for preparing the salt solution in step 1) are: the mass ratio of sodium tripolyphosphate, sodium citrate and water is (0.3-0.5):(0.4-0.6):(40-60).

6. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 1, characterized in that: The conditions for preparing the acid solution in step 1) are: the mass ratio of citric acid monohydrate, lactic acid and water is (3-3.5):(1-1.5):(20-40).

7. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 1, characterized in that: Step 2) Sterilization conditions are as follows: After packaging the liquid, place it in a 95±2°C water bath for 30-40 minutes.

8. A method for evaluating the quality grade of xanthan gum raw materials in acidic dairy products according to claim 1, characterized in that: Step 3) The centrifugal sedimentation determination method is as follows: first weigh the centrifuge tube m1, then weigh a sample of m weight and place it in the centrifuge tube for centrifugation determination, setting the centrifugation conditions at 2880 g for 30 min. After the centrifugation is complete, the upper solution is discarded, the centrifuge tube is inverted and placed for 20-40 minutes, and then the centrifuged sediment and the total weight of the centrifuge tube m2 are weighed; Calculate the centrifugal sedimentation percentage S according to the formula: S=(m2-m1) / m*100%.