Preparation method of calcium-chelated casein coagulated yoghurt

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a preparation method of calcium-chelated casein solidified yoghurt. The preparation method comprises the following steps: selecting a micelle casein milk-based ingredient as a raw material, chelating casein by using trisodium citrate, preparing calcium chelated casein powder through spray drying, and preparing the calcium chelated casein powder by using the obtained calcium chelated casein powder as a raw material and glucolactone as an acidifying agent. The stability and compactness of a gel network structure are optimized by using glutamine transferase, so that the novel set yogurt is prepared. Different from traditional fermented yoghurt, the calcium-chelated casein powder gel can be formed under the condition that no gel is contained, and belongs to high-protein and zero-fat set yoghurt, so that the requirements of consumers on low-fat or zero-fat diet are met, and the calcium-chelated casein powder gel is prepared by using calcium-chelated casein as a protein source. The protein content and the nutritional value of the yoghourt are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and particularly relates to a method for preparing calcium-chelated casein-set yogurt. Background Art

[0002] With the enhancement of people's health awareness, the requirements for the nutritional components and health benefits of food are getting higher and higher, and the demand for protein is also increasing. Compared with most plant-based proteins, the nutritional quality of milk protein is generally higher. This nutritional advantage is fully reflected in dairy products, especially products made through processes such as pasteurization and fermentation, which have greater health value. Yogurt, as a dairy product rich in nutrition, easy to digest, and with a unique taste, is deeply loved by consumers. However, traditional yogurt preparation usually adds a certain amount of fat, which does not meet the needs of consumers who pursue a low-fat or fat-free diet. In the production process of traditional set yogurt, in order to improve the taste and texture of yogurt, a certain amount of colloid substances, such as gelatin, pectin, etc., are usually added. However, the addition of these colloid substances not only increases the production cost, but may also have an adverse impact on the health of some consumers, such as causing allergic reactions. In addition, the protein source in traditional yogurt is relatively single, and high-quality protein resources are often not fully utilized. This not only limits the nutritional value of yogurt and cannot meet the consumers' demand for diversified nutrition, but also puts traditional yogurt at a disadvantage when competing with emerging products rich in multiple proteins in the market.

[0003] Milk protein, as an important ingredient in many foods, has various functions and nutritional properties. Milk protein powder is a complex system composed of different proportions of casein, whey protein, lactose, fat, and minerals, and the specific proportions depend on the degree of separation before dehydration. Casein accounts for about 80% of the total protein content in milk, and the rest is whey protein, and natural casein usually presents in the form of micelles. In yogurt, casein is the main structural component and can form a gel network, but milk powder rich in casein micelles often has low solubility, and its solubility problem during the hydration process becomes a major limiting factor in applications in the food and beverage fields, so a reconstitution process must be carried out before producing yogurt. And the rate at which casein micelles are released from powder particles into the solution is extremely slow, which is also the key rate-limiting step affecting casein solubility. In recent years, many studies have proven that measures can be taken to improve the rehydration performance of casein micelles. The current main treatment methods include physical processing methods and chemical modification methods. Among them, physical processing methods include high-shear, high-pressure processing, ultrasonic treatment, membrane filtration, etc. Chemical modification methods include adjusting the pH during membrane filtration, treating with calcium chelating salts (citrates, phosphates) before spray drying or increasing the ionic strength (such as adding NaCl), using enzyme modification, introducing other food ingredients, etc. However, during physicochemical improvement processes such as acidification or adding rennet, significant structural changes will occur in casein micelles, resulting in irreversible gelation of milk, which is not conducive to powder production.

[0004] During the fermentation process of traditional yogurt, the activity of lactic acid bacteria causes the pH value to decrease, resulting in the disintegration of the κ-casein layer on the surface of casein micelles when approaching the isoelectric point (pI = 4.6), and then a three-dimensional casein particle network gel is formed, which constitutes the main structure of yogurt. However, the formed gel is still very weak because the physical isolation effect of the collapse of the κ-casein layer leads to weak connections between particles, and the interfaces between closely located particles still remain hydrated. Therefore, the incorporation of other substances can promote the formation of connections between caseins and strengthen the stability of the casein network. For example, the electrostatic shielding and calcium bridge formation of Ca 2+ are beneficial to the formation of protein gels. Calcium chelating agents reduce the concentration of free calcium ions by sequestering calcium in the aqueous phase and dissociate casein micelles by changing the calcium balance, thereby improving the hydration of casein and changing the functional properties of casein powder.

[0005] In view of the above-mentioned many problems existing in the preparation process of traditional yogurt, it is necessary to further optimize the preparation method of yogurt in order to promote the development of the yogurt industry in a healthier and more competitive direction and meet the increasingly diverse and refined needs of consumers. Summary of the Invention

[0006] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for preparing calcium-chelated casein-set yogurt, which not only meets the needs of consumers for low-fat or zero-fat diets, but also improves the protein content and nutritional value of yogurt by using calcium-chelated casein as a protein source.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a method for preparing calcium-chelated casein-set yogurt, which comprises the following steps:

[0009] S1. Prepare calcium-chelated casein powder: Dissolve micellar casein milk-based ingredients in water, and then add trisodium citrate, so that trisodium citrate acts as a calcium chelating agent to combine with calcium ions in casein to form calcium-chelated casein, and then use spray drying technology to dry the calcium-chelated casein into powder form;

[0010] Using trisodium citrate as a calcium chelating agent to treat micellar casein by calcium chelation to destroy its micellar structure is beneficial to improving the functional properties of casein, especially the hydration of casein. Through calcium chelation, casein micelles are dissociated into smaller particle sizes, which is beneficial to the dissolution of the powder and can quickly arrange, connect and crosslink to form a uniform gel structure.

[0011] S2. Prepare a calcium-chelated casein complex solution: Dissolve the calcium-chelated casein powder prepared in S1 in water to form a calcium-chelated casein solution. By adjusting the concentration of the casein solution, the protein content in the final yogurt can be controlled.

[0012] S3. Add transglutaminase to the calcium-chelated casein solution in S2, and after the reaction, add glucono-delta-lactone and stir well to make the glucono-delta-lactone evenly distributed;

[0013] Adding transglutaminase to the casein solution, transglutaminase promotes the covalent bond binding of proteins by catalyzing the cross-linking reaction between casein molecules, thereby further optimizing the stability and compactness of the gel network structure. At the same time, adding glucono-delta-lactone to the casein solution in a certain proportion, glucono-delta-lactone as an acidifying agent can cause casein to coagulate under suitable pH conditions, thereby forming set yogurt. Due to the special properties of calcium-chelated casein, it can undergo a gel reaction after being mixed with glucono-delta-lactone, while untreated casein cannot gel with it.

[0014] S4. Homogenization and sterilization: Homogenize the mixture obtained in S3 to improve the taste and texture of the yogurt; then, sterilize the mixture to ensure the hygienic safety of the yogurt.

[0015] S5, Fermentation and Cooling: Ferment the mixed liquid processed in S4 until the yogurt solidifies. After fermentation is completed, cool the yogurt for preservation and consumption.

[0016] This invention selects micellar casein milk-based ingredients as raw materials, and its protein content is about 91% (based on dry matter). When preparing micellar casein milk-based ingredients, the microfiltration method will be adopted. During this process, the whey protein in skim milk will be removed, and at the same time, lactose and minerals will also be significantly reduced, finally obtaining a product rich in casein micelles, which usually contains 91% protein (w / w). In the micellar casein milk-based ingredients, casein mainly exists in the form of micellar casein containing colloidal calcium phosphate. Subsequently, trisodium citrate is used to chelate casein, and calcium-chelated casein powder is prepared by spray drying. Then, using the obtained calcium-chelated casein powder as raw materials, together with transglutaminase and glucono-delta-lactone, a set-type yogurt is prepared. Different from traditional fermented yogurt, the calcium-chelated casein powder gel of this invention can be formed without the addition of gum, and the obtained yogurt is a high-protein zero-fat type yogurt, which improves the protein content and nutritional value of yogurt and meets the needs of consumers for low-fat or zero-fat diets.

[0017] Preferably, in S1, the mass concentration of micellar casein is 15 - 25%, and the final concentration of trisodium citrate is 10 - 60 mM.

[0018] Preferably, in S1, the inlet temperature of spray drying is 170 - 190 °C, the feeding rate is 10 - 20 mL / min, and the fan speed is 85 - 95%.

[0019] Preferably, in S2, the mass concentration of the calcium-chelated casein solution is 7 - 15%.

[0020] Preferably, in S2, the usage amount of transglutaminase is 0.7 - 2% of the mass of calcium-chelated casein.

[0021] Preferably, in S2, the usage amount of glucono-delta-lactone is 4% - 6% of the mass of the calcium-chelated casein solution.

[0022] Preferably, in S4, the conditions for the homogenization treatment are homogenization at 1000 r / min for 3 - 5 min.

[0023] Preferably, in S4, the sterilization treatment is pasteurization treatment.

[0024] Preferably, in S5, the temperature of fermentation is 35 - 40 °C, and the time is 3 - 5 hours.

[0025] Compared with the prior art, the beneficial effects of this invention are:

[0026] The present invention selects a micellar casein milk-based ingredient as the raw material, chelates casein with trisodium citrate, and prepares calcium-chelated casein powder by spray drying. Then, using the obtained calcium-chelated casein powder as the raw material and glucono delta-lactone as the acidifying agent, the stability and compactness of the gel network structure are optimized by transglutaminase, and thus a new type of set yogurt is made. Different from traditional fermented yogurt, the calcium-chelated casein powder gel of the present invention can be formed without the addition of gums, and since its protein source is obtained by microfiltration of skim milk and the protein content is as high as 91%, this yogurt belongs to a set yogurt with high protein and zero fat, which not only meets the needs of consumers for low-fat or zero-fat diets, but also improves the protein content and nutritional value of the yogurt by using calcium-chelated casein as the protein source. The present invention has the following advantages:

[0027] (1) The present invention uses a micellar casein milk-based ingredient as the protein source, which has a protein content of about 91% and has the nutritional characteristics of high protein, low fat, and low lactose content.

[0028] (2) The present invention uses trisodium citrate as the calcium ion chelating agent, and its usage level is within a safe and green range.

[0029] (3) The method for preparing calcium-chelated casein powder in the present invention is simple and rapid, does not require expensive precision instruments, has a low cost, is suitable for large-scale industrial production, and provides a new direction for the deep processing of casein. Moreover, the requirements for storing calcium-chelated casein powder are simple and it is convenient to be applied in food production.

[0030] (4) The high-protein and zero-fat set yogurt prepared in the present invention is easy to operate, has a low cost, good rheological properties, can be prepared within a short time and within a wide temperature range, is a safe, green, edible yogurt rich in high-quality protein, and meets the dual needs of consumers for low-fat or zero-fat diets and high-protein nutrition. Description of the Drawings

[0031] Figure 1 It is a flowchart for the preparation of set casein yogurt;

[0032] Figure 2 It is a picture of the appearance of the calcium-chelated casein powder re-solution / casein powder re-solution;

[0033] Figure 3 It is a picture of the appearance of casein yogurt during the coagulation process;

[0034] Figure 4 It is a picture of the appearance of set casein yogurt at different angles;

[0035] Figure 5Top view appearance diagram of solidified casein yogurt;

[0036] Figure 6 Viscosity measurement results of calcium-chelated casein powder complex solution / casein powder complex solution;

[0037] Figure 7 Rheological mechanics test result diagram of casein yogurt during solidification treatment;

[0038] Figure 8 Rheological mechanics test result diagram of casein yogurt during solidification treatment. Detailed implementation manners

[0039] The following further describes the detailed implementation manners of the present invention. It should be noted here that the description of these implementation manners is used to help understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the various implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The experimental methods in the following examples are all conventional methods unless otherwise specified, and the test materials used in the following examples are all available through conventional commercial channels unless otherwise specified.

[0041] Example 1: Preparation method of a solidified yogurt

[0042] (1) Dissolve micellar casein powder in water at a mass concentration of 10% to form a casein solution (casein complex solution, as Figure 2 shown).

[0043] (2) Add transglutaminase to the casein solution at a ratio of 1% of the casein mass, stir evenly and react at 40 °C for 1 h, then add glucono-delta-lactone to the casein solution at a ratio of 5% of the casein solution mass, and stir well to make the glucono-delta-lactone evenly distributed.

[0044] (3) Homogenize the obtained mixture (homogenize at 1000 r / min for 3 - 5 min), and then perform pasteurization treatment to kill the microorganisms in the mixture. Then ferment at 38 °C for 4 hours until the yogurt solidifies ( Figure 3 ). After fermentation is completed, store the yogurt under refrigerated conditions. The appearance of the obtained yogurt (denoted as MC1) is as Figure 4 , 5 shown.

[0045] Example 2: Preparation method of a calcium-chelated casein solidified yogurt

[0046] According to Figure 1The process flow chart shown, the preparation method includes the following steps:

[0047] (1) Dissolve micellar casein powder in deionized water to prepare a 20% casein solution. Without adding sodium citrate (the final concentration of sodium citrate is recorded as 0 mM), using spray drying technology, at an inlet temperature of 180 °C, dry the casein into powder (feed rate is 15 mL / min, fan speed is 90%), and the obtained calcium-chelated casein powder is called spray-dried casein powder (TCC-0).

[0048] (2) Dissolve the casein powder prepared in step (1) in water at a mass concentration of 10% to form a casein solution (calcium-chelated casein re-solution, as Figure 2 shown).

[0049] (3) Add transglutaminase to the casein solution in step (2) at a ratio of 1% of the casein mass, stir evenly and react at 40 °C for 1 h, then add glucono-delta-lactone to the casein solution at a ratio of 5% of the casein solution mass, and stir well to make the glucono-delta-lactone evenly distributed.

[0050] (4) Homogenize the mixture obtained in step (3) (homogenize at 1000 r / min for 3 - 5 min), and then perform pasteurization treatment to kill the microorganisms in the mixture.

[0051] (5) Place the mixture treated in step (4) at 38 °C and ferment for 4 hours until the yogurt solidifies( Figure 3 ). After fermentation is completed, store the yogurt under refrigerated conditions. The appearance of the obtained yogurt (recorded as TCC-0) is as Figure 4 、 5 shown.

[0052] Example 3: A preparation method of calcium-chelated casein set yogurt

[0053] According to Figure 1 the process flow chart shown, the preparation method includes the following steps:

[0054] (1) Dissolve micellar casein powder in deionized water to prepare a 20% casein solution. Then add trisodium citrate to the casein solution, the final concentration of sodium citrate is 10 mM, stir well to combine the trisodium citrate with the colloidal calcium phosphate in the casein to form calcium-chelated casein. Then, using spray drying technology, at an inlet temperature of 180 °C, dry the calcium-chelated casein into powder (feed rate is 15 mL / min, fan speed is 90%), and the obtained calcium-chelated casein powder is called trisodium citrate-casein powder (TCC-10).

[0055] (2) Dissolve the sodium citrate-casein powder prepared in step (1) in water at a mass concentration of 10% to form a casein solution (calcium-chelated casein complex solution, as Figure 2 shown).

[0056] (3) Add transglutaminase to the casein solution in step (2) at a ratio of 1% of the casein mass. After stirring evenly, react at 40 °C for 1 h. Then, add glucono-delta-lactone to the casein solution at a ratio of 5% of the casein solution mass, and stir well to make the glucono-delta-lactone evenly distributed.

[0057] (4) Homogenize the mixture obtained in step (3) (homogenize at 1000 r / min for 3 - 5 min), and then perform pasteurization to kill the microorganisms in the mixture.

[0058] (5) Place the mixture treated in step (4) at 38 °C and ferment for 4 hours until the yogurt solidifies ( Figure 3 ). After fermentation is completed, store the yogurt under refrigerated conditions. The appearance of the obtained yogurt (denoted as TCC-10) is as Figure 4 , 5 shown.

[0059] Example 4: A preparation method of calcium-chelated casein set yogurt

[0060] According to Figure 1 the process flow chart shown, the preparation method includes the following steps:

[0061] (1) Dissolve micellar casein powder in deionized water to prepare a 20% casein solution. Then add sodium citrate to the casein solution, and the final concentration of sodium citrate is 20 mM. Stir well to make sodium citrate combine with the colloidal calcium phosphate in casein to form calcium-chelated casein. Then, use spray drying technology to dry the calcium-chelated casein into powder at an inlet temperature of 180 °C (the feeding rate is 15 mL / min, and the fan speed is 90%). The obtained calcium-chelated casein powder is called sodium citrate-casein powder (TCC-20).

[0062] (2) Dissolve the casein powder prepared in step (1) in water at a mass concentration of 10% to form a casein solution. (Calcium-chelated casein complex solution, as Figure 2 shown)

[0063] (3) Add transglutaminase to the casein solution in step (2) at a ratio of 1% of the casein mass. After stirring evenly, react at 40 °C for 1 h. Then, add glucono-delta-lactone to the casein solution at a ratio of 5% of the casein solution mass, and stir well to make the glucono-delta-lactone evenly distributed.

[0064] (4) Homogenize the mixture obtained in step (3) (homogenize at 1000 r / min for 3 - 5 min), and then perform pasteurization to kill the microorganisms in the mixture.

[0065] (5) Place the mixture processed in step (4) at 38 °C and ferment for 4 hours until the yogurt solidifies ( Figure 3 ). After fermentation is completed, store the yogurt under refrigerated conditions. The appearance of the obtained yogurt (denoted as TCC - 20) is as shown in Figure 4 、 5 .

[0066] Example 5: A method for preparing calcium - chelated casein set - type yogurt

[0067] According to the process flow chart shown in Figure 1 , the preparation method includes the following steps:

[0068] (1) Dissolve micellar casein powder in deionized water to prepare a 20% casein solution. Then add trisodium citrate to the casein solution, and the final concentration of trisodium citrate is 40 mM. Stir well to combine trisodium citrate with the colloidal calcium phosphate in casein to form calcium - chelated casein. Then, using spray - drying technology, at an inlet temperature of 180 °C, dry the calcium - chelated casein into a powder form (the feeding rate is 15 mL / min, and the fan speed is 90%). The obtained calcium - chelated casein powder is called trisodium citrate - casein powder (TCC - 40).

[0069] (2) Dissolve the casein powder prepared in step (1) in water at a mass concentration of 10% to form a casein solution (calcium - chelated casein re - solution, as shown in Figure 2 ).

[0070] (3) Add transglutaminase to the protein solution in step (2) at a ratio of 1% of the casein mass, stir evenly and react at 40 °C for 1 h. Then add glucono - δ - lactone to the casein solution at a ratio of 5% of the casein solution mass, and stir well to make glucono - δ - lactone evenly distributed.

[0071] (4) Homogenize the mixture obtained in step (3) (homogenize at 1000 r / min for 3 - 5 min), and then perform pasteurization to kill the microorganisms in the mixture.

[0072] (5) Place the mixture processed in step (4) at 38 °C and ferment for 4 hours until the yogurt solidifies ( Figure 3 ). After fermentation is completed, store the yogurt under refrigerated conditions. The appearance of the obtained yogurt (denoted as TCC - 40) is as shown in Figure 4, 5 as shown.

[0073] Example 6: A preparation method of calcium-chelated casein coagulated yogurt

[0074] According to Figure 1 the process flow chart shown, the preparation method includes the following steps:

[0075] (1) Dissolve micellar casein powder in deionized water to prepare a 20% casein solution. Then add trisodium citrate to the casein solution, and the final concentration of trisodium citrate is 60 mM. Stir well to combine trisodium citrate with colloidal calcium phosphate in casein to form calcium-chelated casein. Then, using spray drying technology, at an inlet temperature of 180 °C, dry the calcium-chelated casein into powder form (feed rate is 15 mL / min, fan speed is 90%). The obtained calcium-chelated casein powder is called trisodium citrate-casein powder (TCC-60).

[0076] (2) Dissolve the casein powder prepared in step (1) in water at a mass concentration of 10% to form a casein solution (calcium-chelated casein re-solution, as Figure 2 shown).

[0077] (3) Add transglutaminase to the casein solution in step (2) at a ratio of 1% of the casein mass. After stirring evenly, react at 40 °C for 1 h. Then add glucono-delta-lactone to the casein solution at a ratio of 5% of the casein solution mass, and stir well to make glucono-delta-lactone evenly distributed.

[0078] (4) Homogenize the mixture obtained in step (3) (homogenize at 1000 r / min for 3 - 5 min), and then perform pasteurization to kill microorganisms in the mixture.

[0079] (5) Place the mixture treated in step (4) at 38 °C and ferment for 4 hours until the yogurt coagulates ( Figure 3 ). After fermentation is completed, store the yogurt under refrigerated conditions. The appearance of the obtained yogurt (denoted as TCC-60) is as Figure 4 , 5 shown.

[0080] Experimental example: Rheological test of yogurt

[0081] Rheological tests were carried out using a HAAKE MARS 40 rheometer (Thermo Scientific Inc., Germany), which is equipped with a water circulation temperature control system. A 35 mm geometric plate was selected for the test, and the specific operation is as follows: Add a few drops of the samples in Examples 1-6 to the sample platform of the rheometer. Set the gap between the upper geometry and the lower platform plate to 500 μm. When adding the sample, a few drops of the sample need to be added to the platform to fill the gap. After the geometry moves down to the set position, wipe off the excess solution. Then, apply oil to the edge of the gap between the geometry and the platform to prevent the solution from evaporating.

[0082] To eliminate the influence of the solution shear history, first pre-shear at 30 °C for 10 s at 6 s -1 , and then equilibrate for 1 min, during which the "zero velocity" setting is completed. Finally, through the "peak hold" mode, measure the viscosity at 30 °C for 1 min at a shear rate of 100 s -1 , with a measurement interval of 1 s.

[0083] After completing the viscosity measurement, immediately proceed to the next step of the oscillatory rheology program to measure the gelation process (characterized by the storage modulus G' value and the loss modulus G" value). The oscillatory program performs a time scan at 25 °C for 35 min, and the control variable settings are as follows: the strain is 0.1%, and the angular frequency is 6.280 rad / s.

[0084] According to the experimental results of Examples 1-6, compared with the casein powder complex solutions prepared in Examples 1 and 2, the calcium-chelated casein powder complex solutions prepared in Examples 3-6 have a higher initial viscosity. As the concentration of trisodium citrate increases, the viscosity of the calcium-chelated casein complex solution shows an increasing trend ( Figure 6 ). Among them, Example 6 has the highest viscosity value of 5.13 mPa·s, while the complex solution of Example 1 has the lowest viscosity, about 2.26 mPa·s, and the viscosity of Example 2 is slightly higher than that of Example 1, with a viscosity value of about 2.75 mPa·s. The high-viscosity complex solution is beneficial for forming a dense network that can better lock in moisture, avoid whey separation on the surface of the finished product, and extend the shelf life. At the same time, the G' and G" values of Examples 2-6 show a gradually increasing trend after the start of gelation and gradually tend to the plateau value over time. Among them, G' of Example 5 > 80, and the gel strength of Example 5 is better than that of other examples. The higher gel strength endows the yogurt with a uniform and dense three-dimensional network structure, avoiding a loose texture or a granular feeling and enhancing the smooth taste. Examples 2-6 respectively show a crossover point at 15.53, 14.01, 33.34, 3.98, and 21.03 min, and these times are the times when the samples form gels ( Figure 7 、 8)。The reason for the above results is as follows: The chelation of trisodium citrate with colloidal calcium phosphate destroys the structure of casein micelles. Removing colloidal calcium phosphate can increase the fluidity of casein, thereby increasing the contact area of casein particles during gelation. When the chelation degree of colloidal calcium phosphate is low, the flexibility of the molecules increases and the cross-linking formed between the chains is enhanced, which indirectly increases the strength of the gel. When the content of trisodium citrate is high, due to the loss of colloidal calcium phosphate cross-linking and the dispersion of casein, the bond formation rate is low. When most of the colloidal calcium phosphate is removed, the micelles are dispersed and the gel properties deteriorate, resulting in a delay in the gelation time. Among them, the gel time of Example 5 is much faster than that of other examples, which is beneficial to shortening the production cycle, reducing the occupation time of the fermenter, improving the production line efficiency, and reducing the energy consumption required for constant temperature control.

[0085] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. A method for preparing calcium chelated casein coagulated yogurt, characterized in that: The following steps are involved: S1. Preparing calcium chelated casein powder: dissolving micellar casein milk-based ingredients in water, and then adding trisodium citrate, so that the trisodium citrate acts as a calcium chelating agent and combines with calcium ions in casein to form calcium chelated casein, and then drying the calcium chelated casein into powder by spray drying technology; S2. preparing a calcium chelated casein complex solution: dissolving the calcium chelated casein powder prepared in S1 in water to form a calcium chelated casein solution; S3, adding glutaminase to the calcium chelated casein solution of S2, adding gluconolactone after the reaction, and stirring thoroughly to make the gluconolactone evenly distributed; S4, homogenization and sterilization: homogenizing the mixed solution obtained in S3, and then sterilizing the mixed solution to ensure the hygiene and safety of the yogurt; S5, fermentation and cooling: fermenting the mixed solution treated in S4 until the yogurt solidifies. After the fermentation is completed, the yogurt is cooled for storage and consumption.

2. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S1, the mass concentration of micellar casein is 15-25%, and the final concentration of trisodium citrate is 10-60 mM.

3. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S1, the inlet temperature of the spray drying is 170-190°C, the feed rate is 10-20 mL / min, and the fan speed is 85-95%.

4. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S2, the mass concentration of the calcium chelated casein solution is 7-15%.

5. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S2, the amount of transglutaminase used is 0.7-2% of the mass of calcium chelated casein.

6. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S2, the amount of gluconolactone used is 4%-6% of the mass of the calcium chelated casein solution.

7. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S4, the homogenization treatment condition is 1000r / min homogenization for 3-5min.

8. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S4, the sterilization treatment is pasteurization treatment.

9. The method for preparing a calcium chelated casein coagulated yogurt according to claim 1, characterized in that: In S5, the fermentation temperature is 35-40° C. and the fermentation time is 3-5 hours.

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