Cheese product and preparation method thereof

Abstract

The invention provides a cheese product and a preparation method thereof. According to the cheese product, the flavor of the cheese product is improved through a combined enzymolysis technology of protease and lipase, so that essence is prevented from being added; meanwhile, under the condition that the fat content of the cheese product is low, the taste of the product is improved through the synergistic effect of the inulin and the konjaku flour.

Description

Technical Field

[0001] The present invention relates to a cheese product, and particularly to a cheese product and a preparation method thereof, belonging to the food field. Background Art

[0002] Cheese is a solid dairy product made by coagulating fresh milk under the action of a starter and rennet, and contains rich nutrients such as protein, calcium, fat, phosphorus and vitamins, and is deeply loved by consumers.

[0003] However, the fat content in cheese is generally relatively high, which causes a greater burden on human health. Currently, existing low-fat cheeses have a rough texture, insufficient flavor and poor taste. At the same time, in order to increase the flavor of cheese products, flavors are usually used, which also does not meet the current people's pursuit of no additives, clean labels, natural and healthy.

[0004] A cheese product with low fat content, good flavor and taste and no use of flavors is relatively lacking in the existing market. Summary of the Invention

[0005] The present invention provides a cheese product, which does not contain flavors, has natural and healthy ingredients, low fat content, good flavor and taste.

[0006] The present invention also provides a preparation method of the above cheese product. The preparation method has a simple process and is convenient to operate. Through this preparation method, a cheese product with good flavor, excellent taste and low fat content can be obtained, and the cheese product has natural and healthy ingredients.

[0007] On the one hand, the present invention provides a cheese product, wherein the raw materials of the cheese product include, by percentage content: 20-60% of cheese, 5-15% of lipid products, 1-5% of inulin, 1-2% of konjac powder, 1-5% of protein powder, 0.2-2% of enzyme preparation, 0.2-1% of emulsifying salt, 0.4-1% of stabilizer, and the balance is water; wherein, the enzyme preparation includes protease and lipase, and the mass ratio of the protease to the lipase is 0.5-1:0.5-3.

[0008] The cheese product as described above, wherein the raw materials of the cheese product include, by percentage content: 35-45% of cheese, 6-12% of lipid products, 4-5% of inulin, 1.5-2% of konjac powder, 4-5% of protein powder, 1.4-1.6% of enzyme preparation, 0.5-1.0% of emulsifying salt, 0.4-0.6% of stabilizer, and the balance is water; wherein, the enzyme preparation includes protease and lipase, and the mass ratio of the protease to the lipase is 0.5-1:0.75-2.

[0009] The cheese product as described above, wherein the protease comprises at least one of papain, neutral protease, alkaline protease, and flavor protease.

[0010] The cheese product as described above, wherein the lipase comprises at least one of animal lipase, plant lipase, and microbial lipase.

[0011] The cheese product as described above, wherein the raw materials of the cheese product further comprise at least one of granulated sugar and calcium salt.

[0012] The cheese product as described above, wherein the emulsifying salt comprises at least one of sodium hexametaphosphate, sodium tripolyphosphate, trisodium phosphate, sodium citrate, potassium citrate, sodium phosphate, and potassium phosphate.

[0013] The cheese product as described above, wherein the stabilizer comprises at least one of carrageenan, locust bean gum, gelatin, xanthan gum, sodium carboxymethyl cellulose, and pectin.

[0014] The cheese product as described above, wherein the lipid product comprises at least one of butter, cream, shortening, and palm kernel stearin.

[0015] On the other hand, the present invention provides a method for preparing a cheese product, which comprises the following steps:

[0016] 1) Mix the raw material system comprising the cheese, lipid product, and water with the enzyme preparation, and sequentially carry out enzymatic hydrolysis and enzyme inactivation treatment to obtain a first material;

[0017] 2) Add the inulin, konjac powder, protein powder, emulsifying salt, and stabilizer to the first material and mix to obtain the cheese product.

[0018] The preparation method as described above, wherein in step 2), it further comprises heating the mixed system to 85 - 100 °C at a rotation speed of 1000 - 2500 rpm, holding for 1 - 3 min, and then reducing the rotation speed to 100 - 800 rpm and stirring for 0.5 - 2.5 min.

[0019] The cheese product provided by the present invention uses the enzymatic hydrolysis technology of protease and lipase to enhance the flavor of the product, avoids the use of flavors, has a low fat content, and at the same time improves the fat taste of the product through the synergistic effect of using inulin and konjac powder with the product formulation. The above synergism makes the cheese product of the present invention have the advantages of low fat content, natural and healthy ingredients, good flavor and taste. Detailed implementation mode

[0020] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0021] In the first aspect of the present invention, a cheese product is provided. The raw materials of the cheese product include, by percentage content: 20 - 60% of cheese, 5 - 15% of lipid products, 1 - 5% of inulin, 1 - 2% of konjac powder, 1 - 5% of protein powder, 0.2 - 2% of enzyme preparation, 0.2 - 1% of emulsifying salt, 0.4 - 1% of stabilizer, and the balance is water; wherein, the enzyme preparation includes protease and lipase, and the mass ratio of protease to lipase is 0.5 - 1:0.5 - 3.

[0022] The present invention does not make special limitations on the above-mentioned cheese. The above-mentioned cheese may include at least one of fresh cheese, cream cheese, quark, and mascarpone.

[0023] In some embodiments, the above-mentioned cream cheese is commercially available refrigerated cream cheese, cut into uniformly sized blocks.

[0024] The present invention does not make special limitations on lipid products, emulsifying salts and stabilizers. The functions of the above components are to provide a basic fat taste, emulsifying effect and stabilizing effect for the cheese product of the present invention.

[0025] The above-mentioned protein powder may include at least one of whole milk powder, skim milk powder, concentrated milk protein powder, and whey powder.

[0026] The present invention defines that the above-mentioned enzyme preparation includes protease and lipase, and the mass ratio of protease to lipase is 0.5 - 1:0.5 - 3. The enzyme preparation uses the combination of protease and lipase to enzymatically hydrolyze proteins and fats in the raw materials of the above-mentioned cheese product, fully exert the aroma-producing ability of proteins and fats in cheese and lipid products. The enzymatic hydrolysis reaction helps the occurrence of the reaction for generating the main flavor substances in the cheese product, can significantly improve the aroma intensity of the cheese product, make the characteristic aroma more prominent, enhance the aroma of the cheese product, and thus make the flavor of the cheese product more intense.

[0027] Inulin is a type of fructan widely present in nature. It is an excellent fat substitute, containing a large number of hydroxyl groups, and has strong water-holding and moisturizing properties. During food processing, it can effectively reduce water loss and can be used as a water-retaining agent in yogurt production, meat product processing, and chocolate processing to extend the shelf life of food. Konjac flour is a high-molecular polysaccharide that cannot be hydrolyzed by digestive enzymes in the human gastrointestinal tract, so it is considered an indigestible dietary fiber with no calories. It has a strong water-binding ability itself and is a commonly used thickening agent in food processing, showing a synergistic effect on protein gelation and water binding in meat products. When inulin and konjac flour are respectively applied to the preparation of cheese products at mass percentages of 1 - 5% and 1 - 2% in the raw materials of cheese products, and act synergistically with the double-enzyme hydrolysis technology of the above enzyme preparation, while the double-enzyme hydrolysis technology enhances the flavor of cheese products, it avoids the deterioration of the texture or taste of cheese products caused by the reduction of fat or protein content. These two components and the above enzyme preparation can synergistically improve the flavor, texture, and taste of cheese products. In addition, inulin, as a dietary fiber rich in prebiotic components, is often used as a standard control for studying the effects of other prebiotics and has various physiological functions such as antibacterial, improving the intestinal microecology, regulating blood sugar levels, and reducing blood lipids. At the same time, it is reported that konjac flour has functions such as preventing and improving constipation, regulating lipid metabolism, improving glucose metabolism, and reducing the occurrence of diabetes and heart diseases. Therefore, inulin and konjac flour can also synergistically increase the health attributes of cheese products.

[0028] The cheese product of the present invention has a strong cheese aroma, a harmonious overall flavor, good texture, suitable taste, does not contain flavorings, has a low fat content, is natural, healthy, and additive-free, has a high health value, can achieve the differentiation of cheese products, and improves the market competitiveness of products.

[0029] Furthermore, when the raw materials of the above cheese product include, by percentage: 35 - 45% cheese, 6 - 12% lipid products, 4 - 5% inulin, 1.5 - 2% konjac flour, 4 - 5% protein powder, 1.4 - 1.6% enzyme preparation, 0.5 - 1.0% emulsifying salt, 0.4 - 0.6% stabilizer, and the balance is water; wherein, the enzyme preparation includes protease and lipase, and the mass ratio of protease to lipase is 0.5 - 1:0.75 - 2. The cheese product prepared according to the above formula has a more intense cheese aroma, a more harmonious flavor, and better texture and taste.

[0030] The mass ratio of the above protease to lipase can also be 0.5 - 1:1 - 3, preferably 0.5 - 1:1.5, which is more conducive to exerting the effect of double-enzyme hydrolysis to enhance the flavor of cheese products.

[0031] The above proteases include at least one of papain, neutral protease, alkaline protease, and flavor protease. These proteases are beneficial to the enzymatic hydrolysis of proteins in the raw materials, and thus are beneficial to improving the flavor and taste of cheese products.

[0032] The above lipases include at least one of animal lipase, plant lipase, and microbial lipase. Small molecule substances such as aldehydes, ketones, alcohols, and acids produced by the enzymatic hydrolysis of fats by these lipases are the main providers of the flavor of cheese products, which is beneficial to further reducing the fat content of cheese products. More importantly, it can improve the cheese aroma and flavor of cheese products.

[0033] Generally, the raw materials of the above cheese products further include at least one of granulated sugar and calcium salt. Granulated sugar can provide a sweet taste and viscosity for cheese products, and calcium salt is beneficial to increasing the calcium content of the product and at the same time is beneficial to stabilizing the gel network system of cheese products, helping to improve the stability of the product, and being helpful for the texture and taste of the product.

[0034] In the raw materials of cheese products, the mass percentage content of the above granulated sugar is generally 0-15%, and the mass percentage content of calcium salt is generally 0.8-2%.

[0035] Furthermore, the above calcium salt can be at least one of tricalcium phosphate and calcium lactate, which is beneficial to increasing the calcium salt content of cheese products and is also helpful for maintaining the texture of cheese products.

[0036] The above emulsifying salts include at least one of sodium hexametaphosphate, sodium tripolyphosphate, trisodium phosphate, sodium citrate, potassium citrate, sodium phosphate, and potassium phosphate. The above emulsifying salts have a significant impact on the quality of cheese products. Through emulsification, calcium chelation, pH adjustment and buffering effects, and effects on the dispersion and hydration of proteins, etc., and synergistic effects with the above enzyme preparations, inulin, konjac flour, etc., the quality of cheese products is significantly improved.

[0037] The above stabilizers include at least one of carrageenan, locust bean gum, gelatin, xanthan gum, sodium carboxymethyl cellulose, and pectin, which is beneficial to reducing the oil separation rate of cheese products and improving the stability of cheese products.

[0038] The above lipid products include at least one of butter, cream, shortening, and palm kernel stearin, which can provide basic fat for cheese products and is beneficial to maintaining the good taste and flavor of cheese products.

[0039] The second aspect of the present invention provides a preparation method of the cheese product of the first aspect, including the following steps:

[0040] 1) Mix the raw material system including cheese, lipid products, and water with an enzyme preparation, and sequentially perform enzymatic hydrolysis and enzyme inactivation treatment to obtain a first material;

[0041] 2) Mix inulin, konjac powder, protein powder, emulsifying salts, and stabilizers into the above-mentioned first material and mix them to obtain the above-mentioned cheese product.

[0042] In step 1) above, the raw material system including cheese, lipid products, and water can be first mixed evenly and then the enzyme preparation is added for mixing, which is beneficial to improving the effect of enzymatic hydrolysis.

[0043] The present invention does not limit the place of the above reaction. For example, the mixing can be carried out in a chopping pan, and the enzymatic hydrolysis can be carried out in an enzymatic hydrolysis tank.

[0044] Specifically, after adding the raw material system including cheese, lipid products, and water to the above-mentioned chopping pan and mixing evenly, for example, chop and mix at a speed of 1000 - 2500 rpm for 1 - 3.5 min to promote the full mixing of the above raw material system. After adding the above enzyme preparation to the raw material system and mixing evenly, transfer it to an enzymatic hydrolysis tank, and adjust the temperature of the raw material system according to the characteristics of the enzyme preparation for enzymatic hydrolysis. For example, the temperature can be adjusted to 40 - 60 °C, and this temperature range is suitable for most proteases and lipases to carry out enzymatic hydrolysis.

[0045] When the enzyme preparation is 0.2 - 2% by mass percentage, the enzyme preparation includes protease and lipase, and the mass ratio of protease to lipase is 0.5 - 1:0.5 - 3 for enzymatic hydrolysis of cheese with a mass percentage of 20 - 60% and lipid products with a mass percentage of 5 - 15%, generally the enzymatic hydrolysis time can be controlled within 1 - 2 h, which can fully exert the ability of proteins and fats in cheese and lipid products to increase flavor and aroma, and significantly increase the cheese aroma and flavor of the cheese product.

[0046] In order to avoid excessive enzymatic hydrolysis of the enzyme preparation or enzymatic hydrolysis of the remaining added materials, an enzyme inactivation treatment should be carried out after the above enzymatic hydrolysis to obtain the first material.

[0047] Transfer the above-mentioned first material to a chopping pan, add inulin, konjac powder, protein powder, emulsifying salts, and stabilizers to the above-mentioned first material, and mix evenly to obtain the cheese product of the present invention.

[0048] The above preparation method is simple to operate. By using an enzymatic hydrolysis process combining protease and lipase, it fully exerts the aroma-producing ability of proteins and fats in cheese and lipid products, significantly improves the aroma intensity of the cheese product, makes the characteristic aroma more prominent. The above enzymatic hydrolysis process can also reduce the fat content of the cheese product, and cooperate with inulin and konjac powder to maintain the flavor, texture, taste, and quality of the product, making up for the deficiencies of insufficient aroma, strong essence flavor, and poor sensory quality of the cheese products produced by the existing technology, increasing the health attributes of the cheese product. The above preparation method is an industrial method suitable for the further development and utilization of cheese products.

[0049] In industrial production, the above preparation method further includes filling, wherein the filling temperature is ≥78°C.

[0050] In step 2), it also includes heating the mixed system to 85 - 100°C at a rotational speed of 1000 - 2500 rpm, holding for 1 - 3 min, and then reducing the rotational speed to 100 - 800 rpm and stirring for 0.5 - 2.5 min, which can effectively improve the mixing effect of the materials, facilitate the full mixing and reaction of the above components, and further obtain a cheese product with good flavor, texture and taste.

[0051] Hereinafter, the cheese product of the present invention and its preparation method will be introduced in more detail through specific examples.

[0052] Example 1

[0053] A cheese product of this example includes raw materials with the following mass percentages:

[0054] Cream cheese 40%, butter 10%, inulin 5%, konjac flour 2%, concentrated milk protein powder 5%, neutral protease 0.5%, microbial lipase 1%, compound emulsifying salt (sodium hexametaphosphate, sodium tripolyphosphate) 0.9%, carrageenan 0.5%, granulated sugar 8%, tricalcium phosphate 0.1%, and the balance is water;

[0055] The preparation method of the above cheese product includes the following steps:

[0056] 1) After uniformly mixing the raw material system including cream cheese, butter and water at a rotational speed of 1000 - 2500 rpm, adding neutral protease and microbial lipase and mixing evenly, adjusting the temperature to 40 - 60°C and stirring for enzymatic hydrolysis for 1 - 2 h, and then heating to 80°C to inactivate the enzyme for 10 min to obtain the first material;

[0057] 2) Adding inulin, konjac flour, concentrated milk protein powder, compound emulsifying salt (sodium hexametaphosphate, sodium tripolyphosphate), carrageenan, granulated sugar and tricalcium phosphate to the above first material, heating the mixed system to 85 - 100°C at a rotational speed of 1000 - 2500 rpm, holding for 2 - 3 min, and then reducing the rotational speed to 100 - 800 rpm and stirring for 0.5 - 2.5 min, and cooling to obtain the cheese product of the present invention.

[0058] Example 2

[0059] This example is basically the same as Example 1, the difference is:

[0060] The inulin is 1%, and the balance is water.

[0061] Example 3

[0062] This example is basically the same as Example 1, with the difference that:

[0063] The inulin is 3%, the konjac flour is 1%, and the balance is water.

[0064] Example 4

[0065] This example is basically the same as Example 1, with the difference that:

[0066] The neutral protease is 0.7%, the microbial lipase is 1.3%, and the balance is water.

[0067] Example 5

[0068] This example is basically the same as Example 1, with the difference that:

[0069] The neutral protease is 0.25%, the microbial lipase is 0.75%, and the balance is water.

[0070] Example 6

[0071] This example is basically the same as Example 1, with the difference that:

[0072] The neutral protease is 1%, the microbial lipase is 0.5%, and the balance is water.

[0073] Example 7

[0074] This example is basically the same as Example 1, with the difference that:

[0075] The konjac flour is 5%, the inulin is 2%, and the balance is water.

[0076] Example 8

[0077] This example is basically the same as Example 1, with the difference that:

[0078] The concentrated milk protein powder is 1%, and the balance is water.

[0079] Example 9

[0080] This example is basically the same as Example 1, with the difference that:

[0081] The cream cheese is 30%, and the balance is water.

[0082] Comparative Example 1

[0083] A kind of cheese product in this comparative example comprises raw materials with the following mass percentages:

[0084] The cream cheese is 40%, the butter is 10%, the inulin is 5%, the konjac flour is 2%, the concentrated milk protein powder is 5%, the compound emulsifying salt (sodium hexametaphosphate, sodium tripolyphosphate) is 0.9%, the carrageenan is 0.5%, the granulated sugar is 8%, the tricalcium phosphate is 0.1%, and the balance is water;

[0085] The preparation method of the above-mentioned cheese product comprises the following steps:

[0086] Mix the above-mentioned cream cheese, butter, inulin, konjac powder, concentrated milk protein powder, compound emulsifying salt (sodium hexametaphosphate, sodium tripolyphosphate), carrageenan, granulated sugar, tricalcium phosphate and water, and heat the mixed system to 85 - 100 °C at a rotation speed of 1000 - 2500 rpm, keep warm for 2 - 3 min, then reduce the rotation speed to 100 - 800 rpm, stir for 0.5 - 2.5 min, and obtain the cheese product of the present invention after cooling.

[0087] Comparative Example 2

[0088] This comparative example is basically the same as Example 1, the difference lies in:

[0089] It does not include inulin and konjac powder, and the balance is water.

[0090] Comparative Example 3

[0091] This comparative example is basically the same as Example 1, the difference lies in:

[0092] Inulin is 10%, and the balance is water.

[0093] Comparative Example 4

[0094] This comparative example is basically the same as Example 1, the difference lies in:

[0095] Neutral protease is 2%, and microbial lipase is 3%, and the balance is water.

[0096] Comparative Example 5

[0097] This comparative example is basically the same as Example 1, the difference lies in:

[0098] Neutral protease is 2%, and microbial lipase is 1%, and the balance is water.

[0099] Test Example

[0100] 1. Detect the following parameters for the above-mentioned examples and comparative examples:

[0101] 1) Oil separation rate: The oil separation rate of the cheese is measured by the filter paper method. Specifically, a cheese sample with a diameter of 35 mm and a height of 30 mm is taken with a special sampler, the cheese sample is placed on a chemical analysis filter paper, and then it is taken out after being placed in a refrigerator at 10 °C for 2 h. At this time, an oil ring is formed. Each product is operated in parallel four times, and the area of the oil ring formed is the average value of the four parallel tests. The oil separation rate is the ratio of the area of the newly formed oil ring after the storage ends to the area of the oil ring when the cheese is just placed on the filter paper. The specific results are shown in Table 1;

[0102] 2) Sensory analysis of products: The products on the fifth day of shelf life were subjected to sensory analysis in terms of texture, taste, color and flavor. The specific results are shown in Table 1.

[0103] 2. Test results

[0104] Table 1 Oil precipitation rate and sensory analysis of products

[0105]

[0106]

[0107] From the results in Table 1, it can be seen that the dual-enzyme hydrolysis process helps to increase the flavor of the product itself and give the product a milky aroma. The addition of dietary fiber makes up for the lack of product texture caused by fat and protein hydrolysis. The two complement each other and synergistically improve the flavor, texture and taste of the product. It can be seen from Examples 1 to 10 that with the increase in the amount of protease added, a partial Maillard reaction will occur, affecting the sensory organs and flavor of the product, and adding a Maillard flavor to the product. However, Comparative Example 5 shows that excessive enzyme content will cause the product to have a darker color, a heavier roasted taste, and an overall unharmonious flavor; dietary fiber has a certain improvement effect on the texture of the product after enzymatic hydrolysis, and as its content increases, the oil precipitation rate decreases and the texture gradually becomes harder; the effect of konjac flour and inulin synergistically improving the texture and taste of the product is more significant, which is more significant than the effect of using them alone. Combined with the evaluation results of texture, taste, color and flavor and oil precipitation rate, when the enzyme preparation addition amount is 0.2-2%, inulin is 1-5%, and konjac flour is 1-2%, the above-mentioned qualities of the product are significantly improved. Among them, the preferred range is when the enzyme preparation addition amount is 1.5% (0.5% protease + 1% lipase) and the dietary fiber addition amount is 7% (5% inulin + 2% konjac flour), the obtained product has better flavor and better hardness and taste.

[0108] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary technical means in the art that are not disclosed by the present invention.

Claims

1. A cheese product, characterized in that, the raw materials of the cheese product include, by percentage content: 20 - 60% of cheese, 5 - 15% of lipid products, 1 - 5% of inulin, 1 - 2% of konjac powder, 1 - 5% of protein powder, 0.2 - 2% of enzyme preparation, 0.2 - 1% of emulsifying salt, 0.4 - 1% of stabilizer, and the balance is water; wherein, the enzyme preparation includes protease and lipase, and the mass ratio of the protease to the lipase is 0.5 - 1:0.5 - 3.

2. The cheese product according to claim 1, characterized in that, the raw materials of the cheese product include, by percentage content: 35 - 45% of cheese, 6 - 12% of lipid products, 4 - 5% of inulin, 1.5 - 2% of konjac powder, 4 - 5% of protein powder, 1.4 - 1.6% of enzyme preparation, 0.5 - 1.0% of emulsifying salt, 0.4 - 0.6% of stabilizer, and the balance is water; wherein, the enzyme preparation includes protease and lipase, and the mass ratio of the protease to the lipase is 0.5 - 1:0.75 - 2.

3. The cheese product according to claim 1 or 2, characterized in that, the protease includes at least one of papain, neutral protease, alkaline protease, and flavor protease.

4. The cheese product according to any one of claims 1 - 3, characterized in that, the lipase includes at least one of animal lipase, plant lipase, and microbial lipase.

5. The cheese product according to any one of claims 1 - 4, characterized in that, the raw materials of the cheese product further include at least one of granulated sugar and calcium salt.

6. The cheese product according to any one of claims 1 - 5, characterized in that, the emulsifying salt includes at least one of sodium hexametaphosphate, sodium tripolyphosphate, trisodium phosphate, sodium citrate, potassium citrate, sodium phosphate, and potassium phosphate.

7. The cheese product according to any one of claims 1 - 6, characterized in that, the stabilizer includes at least one of carrageenan, locust bean gum, gelatin, xanthan gum, sodium carboxymethyl cellulose, and pectin.

8. The cheese product according to any one of claims 1 - 7, characterized in that, the lipid products include at least one of butter, cream, shortening, and palm kernel stearin.

9. A method for preparing the cheese product according to any one of claims 1 - 8, characterized in that, it includes the following steps: 1) Mix the raw material system including the cheese, lipid products, and water with the enzyme preparation, and successively carry out enzymatic hydrolysis and enzyme inactivation treatment to obtain a first material; 2) Add the inulin, konjac powder, protein powder, emulsifying salt, and stabilizer to the first material and mix to obtain the cheese product.

10. The preparation method according to claim 9, characterized in that, in step 2), it further includes heating the mixed system to 85 - 100°C at a rotation speed of 1000 - 2500 rpm, holding for 1 - 3 min, and then reducing the rotation speed to 100 - 800 rpm and stirring for 0.5 - 2.5 min.

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