Soluble fiber solid beverage and preparation method thereof

Abstract

The invention belongs to the technical field of nutritious food, discloses a soluble fiber solid beverage and a preparation method thereof, and solves the problems of single component, lack of functional synergy and insufficient universality of the existing soluble fiber solid beverage. The soluble fiber solid beverage is prepared from the following components in parts by weight: 1 to 2 parts of alginate oligosaccharide, 25 to 40 parts of resistant dextrin, 20 to 30 parts of inulin, 15 to 25 parts of polydextrose, 10 to 20 parts of fructo-oligosaccharide, 3 to 5 parts of stachyose and 0.1 to 0.3 part of stevioside. The total soluble fiber content can reach 88.5%, the dissolution time is only 2.3 s, the particle size of undissolved particles is smaller than or equal to 5 microns, the abdominal distension occurrence rate is 6.0%, the gas production rate is 10.0%, and the low-sugar-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low-fat-content low

Description

Technical Field

[0001] This invention belongs to the field of nutritional food technology, and in particular relates to a soluble fiber solid beverage and its preparation method. Background Technology

[0002] According to data from the Chinese Dietary Guidelines (2022), the average daily dietary fiber intake of Chinese residents is only 10.8g, far below the recommended intake of 25-30g. As a result, the incidence of chronic constipation and intestinal flora imbalance is 18.1% and 23.5%, respectively. Long-term insufficient intake will also increase the risk of metabolic diseases such as type 2 diabetes and hyperlipidemia (cited from Chinese Journal of Epidemiology, Vol. 44, No. 5, 2023).

[0003] There are three major defects in existing soluble fiber solid beverages: (1) Single ingredients: Most products are based on fructooligosaccharides (single prebiotics) or inulin (single polysaccharide fiber), which can only achieve the single function of "relieving constipation" or "promoting the proliferation of beneficial bacteria", and cannot meet the multidimensional needs of intestinal health.

[0004] (2) Lack of functional synergy: Some compound formulations are not designed based on intestinal physiological mechanisms. For example, the difference in fermentation rate of different fibers is not considered (e.g., the fermentation cycle of fructooligosaccharides is 2-4 hours, and the fermentation cycle of resistant dextrin is 8-12 hours), which can easily lead to excessive gas production in the intestine in a short period of time, with an bloating rate of over 30%.

[0005] (3) Insufficient universality: Most sweeteners use erythritol (the daily tolerance level is ≤30g, and excessive use can easily cause osmotic diarrhea), and gas production control is not optimized for people with irritable bowel syndrome (IBS). At the same time, the total soluble fiber content is generally less than 75%, resulting in insufficient efficacy. Summary of the Invention

[0006] One objective of this invention is to provide a soluble fiber solid beverage that effectively solves the problems of single ingredients, lack of functional synergy, and insufficient universality in existing soluble fiber solid beverages.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a soluble fiber solid beverage, comprising the following components by weight: 1-2 parts of fucoidan, 25-40 parts of resistant dextrin, 20-30 parts of inulin, 15-25 parts of polydextrose, 10-20 parts of fructooligosaccharide, 3-5 parts of stachyose, and 0.1-0.3 parts of steviol glycosides.

[0008] Furthermore, by weight, it includes the following components: 1.5 parts of fucoidan, 34.3 parts of resistant dextrin, 24 parts of inulin, 20 parts of polydextrose, 16 parts of fructooligosaccharide, 4 parts of stachyose, and 0.2 parts of steviol glycosides.

[0009] Another objective of this invention is to provide a method for preparing the soluble fiber solid beverage described in the above embodiments, comprising the following steps: Step 1, raw material pretreatment; weighing each raw material according to the formula: fucoidan, resistant dextrin, inulin, polydextrose, fructooligosaccharide, stachyose and steviol glycoside, wherein fucoidan, resistant dextrin, inulin, polydextrose, fructooligosaccharide and stachyose are vacuum dried to a moisture content ≤3%, and the dried raw materials are passed through a 120-mesh standard sieve.

[0010] Step 2: Perform three mixing steps; the first mixing step involves mixing resistant dextrin, inulin, and polydextrose to obtain the first mixture, with a coefficient of variation (CV) ≤ 5%; the second mixing step involves adding fructooligosaccharides and stachyose to the first mixture and mixing to obtain the second mixture, with a coefficient of variation (CV) ≤ 3%; the third mixing step involves adding fucoidan and steviol glycosides to the second mixture and mixing to obtain the final mixture with a coefficient of variation (CV) ≤ 2%.

[0011] Step 3: Package the product to obtain the soluble fiber solid beverage.

[0012] Furthermore, in step one, the vacuum drying conditions are: drying in a vacuum drying oven at 60±2℃ and a vacuum degree of -0.09MPa until the moisture content is ≤3%.

[0013] Furthermore, in step one, the dried raw material is screened using a vibrating screen with an amplitude of 3mm and a frequency of 50Hz to ensure that the particle size distribution range of the raw material is 80-120μm.

[0014] Furthermore, in step two, all three mixing processes are completed in a multi-directional motion mixer. The first mixing process is carried out at a speed of 30 rpm for 10 minutes, the second mixing process is carried out at a speed of 30 rpm for 6 minutes, and the third mixing process is carried out at a speed of 25 rpm for 4 minutes.

[0015] Compared with existing technologies, the beneficial technical effects of this invention are as follows: the total soluble fiber content of the soluble fiber solid beverage provided by this invention can reach 88.5%, which is far higher than mainstream composite fiber products and conventional products, meets the "high dietary fiber" food standard and has a compound synergistic effect; the dissolution time is only 2.3s, and the undissolved particle size is ≤5μm, which is better than all commercially available composite fiber products and close to the benchmark single fiber products; the incidence of bloating is 6.0%, and the gas production rate is 10.0%, which is significantly lower than similar commercially available products (16.0%-35.0%), and is especially well tolerated by patients with mild IBS.

[0016] In summary, this invention achieves optimal synergy in three core indicators: total soluble fiber content, solubility, and intestinal tolerance, outperforming similar products on the market. Detailed Implementation

[0017] Example 1: A soluble fiber solid beverage comprises the following components (by weight): 1-2 parts of fucoidan, 25-40 parts of resistant dextrin, 20-30 parts of inulin, 15-25 parts of polydextrose, 10-20 parts of fructooligosaccharide, 3-5 parts of stachyose, and 0.1-0.3 parts of steviol glycosides.

[0018] In this embodiment, the soluble fiber solid beverage comprises the following components (by weight): 1.5 parts of fucoidan, 34.3 parts of resistant dextrin, 24 parts of inulin, 20 parts of polydextrose, 16 parts of fructooligosaccharide, 4 parts of stachyose, and 0.2 parts of steviol glycosides.

[0019] The soluble fiber solid beverage provided in this embodiment has the following core advantages.

[0020] (1) Total soluble fiber content: The test was conducted according to the AOAC 991.43 standard method. The test results showed that the total soluble fiber content in the soluble fiber solid beverage provided in this embodiment was ≥88%, which meets the requirements of the "high dietary fiber" food standard (GB28050). GB28050 stipulates that a dietary fiber content of ≥6g per 100g of food is considered "high content", while the product provided in this embodiment contains 88g of dietary fiber per 100g, which far exceeds the standard.

[0021] The current benchmark high-fiber product on the market: Xiyun Dietary Fiber Fruit Juice Beverage, which uses patented fiber raw materials, has the highest soluble fiber content of approximately 91% (labeled as 91% Fibersol®-2 content). However, this product uses a single fiber raw material and lacks synergistic effects. The current mainstream composite fiber product: WonderLab Fruit and Vegetable Dietary Fiber Solid Beverage contains 41g of dietary fiber per 100g (approximately 80% soluble fiber, equivalent to 32.8g of soluble fiber), which is only 37.4% of the product provided in this example. Current ordinary compliant products: Most commercially available products only meet the minimum standard of GB28050 "High Dietary Fiber" (≥6g / 100g), such as konjac gum dietary fiber solid beverages and imported inulin solid beverages. Their soluble fiber content is mostly between 6-3.3g / 100g, and some products are even below 10g / 100g.

[0022] (2) Solubility: The soluble fiber solid beverage provided in this embodiment dissolves in water at room temperature (20-25℃) (solid-liquid ratio 1:5) in ≤3s. The undissolved particles in the solution are ≤5μm in diameter, and there are no visible clumps. Dissolution time refers to the time from when the sample is added to when it is completely dissolved (no visible particles).

[0023] Currently available fast-dissolving products: Jiaocun barley grass juice solid beverage, which claims to dissolve automatically in 3 minutes, actually dissolves in approximately 90-120 seconds and contains a small amount of visible plant fiber residue. Current conventional composite fiber products: Most products dissolve in 30-60 seconds. At a solid-liquid ratio of 1:5, they are prone to suspension and clumping, requiring continuous stirring for 10-15 seconds to disperse. Laser particle size analyzers show that undissolved particles are mostly between 20-50 μm in size. Current low-soluble products: Mixed formulations containing insoluble fibers (such as those with added fruit and vegetable powders or wheat bran) often dissolve in more than 2 minutes. After standing, they easily separate and precipitate, requiring reconstitution with water above 40℃ to improve solubility.

[0024] (3) Intestinal tolerance: The soluble fiber solid beverage provided in this embodiment was verified through a human trial experiment with 100 people (including 20 patients with mild IBS). The incidence of bloating was ≤6%, and the gas production rate was reduced by 40% compared with the single fiber formula. Incidence of bloating = number of people with bloating symptoms / total number of people × 100%; Gas production rate = number of people who felt increased gas production / total number of people × 100%.

[0025] Currently available compound fiber products generally have a bloating rate of 15%-30%. Products containing single oligosaccharides (such as pure fructooligosaccharides or pure inulin) have a bloating rate as high as 25%-40%, with some consumers reporting significant gas production and discomfort after consumption. Products targeting sensitive populations: A few products labeled "low gas production" have a bloating rate of approximately 10%-15%, but these have not been specifically validated for mild IBS patients, and the gas production rate is only 15%-20% lower than single-fiber formulas. Currently available high-fiber products: Commercially available products with a fiber content ≥50% often have a bloating rate exceeding 30% due to the lack of optimized fiber blend ratios. Some products recommend consumption 2-3 times daily due to tolerability issues, making them inconvenient to use.

[0026] The functions and synergistic mechanisms of each component in the soluble fiber solid beverage provided in this embodiment are as follows.

[0027] (a) Single component function.

[0028] (1) Alginate: By binding to adhesion molecules on the surface of intestinal epithelial cells, it increases the expression of tight junction proteins (occludin, claudin-1) (Western Blot analysis showed a 2.3-fold increase in expression), enhances the integrity of the intestinal mucosal barrier, and can inhibit the adhesion of harmful bacteria such as Escherichia coli and Salmonella (antibacterial rate ≥50%, referring to GB4789.2-2022 "National Food Safety Standard for Microbiological Examination of Food - Determination of Total Colony Count"); its small molecular characteristics (molecular weight ≤1000Da) allow it to be partially absorbed in the upper part of the small intestine, and its metabolites can be detected in the blood within 1 hour, making up for the "slow onset" defect of polysaccharide fiber.

[0029] (2) Resistant dextrin: It is resistant to digestive enzyme decomposition in the stomach and small intestine (digestibility ≤10%). After entering the large intestine, it is slowly fermented by Bifidobacterium and Clostridium difficile (fermentation rate 0.8 mmol / (h·g)) to continuously generate short-chain fatty acids (SCFA, mainly acetic acid, propionic acid and butyric acid in a ratio of 3:1:1). Butyric acid can serve as the main energy source for colonic epithelial cells (energy supply ≥70%), maintaining the vitality of intestinal epithelial cells.

[0030] (3) Inulin: In addition to promoting the proliferation of Bifidobacteria (proliferation multiple ≥ 10), 3 In addition to being detected by real-time quantitative PCR, it can enhance the solubility of Ca²⁺ and Mg²⁺ in the intestine through chelation (the absorption rate is increased by 25% and 18% respectively, as detected by AOAC985.35 method). At the same time, its long chain structure (DP≥20) can increase fecal volume (each 10g of inulin can increase fecal volume by 50mL).

[0031] (4) Polydextrose: The calories are only 1 kcal / g (far lower than 4 kcal / g of sucrose), and the glycemic index (GI) is ≤15 (determined by in vitro digestion model combined with high performance liquid chromatography), which meets the standard of "low GI food". Its branched structure can adsorb free cholesterol (adsorption amount ≥20mg / g) and bile acid (adsorption amount ≥35mg / g) in the intestine and excrete them through feces, thus helping to regulate blood lipids.

[0032] (5) Fructooligosaccharides + Stachyose: Fructooligosaccharides have a strong selective proliferation ability of lactic acid bacteria (multiplication rate ≥ 10). 2 Stachyose has higher specificity for Bifidobacteria (the proportion of Bifidobacteria increased from 15% to 40%). When the two are combined in a 3:1 ratio (12 parts fructooligosaccharide: 4 parts stachyose), the number of beneficial intestinal bacteria increased from 4 to 7 (16S rRNA gene sequencing results), the microbial diversity index (Shannon index) increased by 0.8, and more intestinal microecological functions were covered.

[0033] (6) Steviosides: The sweetness is 200-300 times that of sucrose, and the calories are close to 0. Verified by the oral glucose tolerance test (OGTT), the blood glucose fluctuation within 2 hours after ingesting 0.15g of steviol glycosides is ≤0.5mmol / L, and it does not affect insulin secretion. At the same time, it can mask the fishy taste of brown algae oligosaccharides and the bitter taste of polydextrose. According to the sensory evaluation (out of 9 points), the product taste score increased from 5.2 points to 8.1 points.

[0034] (ii) Synergistic mechanism of each component.

[0035] (1) Synergistic regulation of fermentation rate by polysaccharides and oligosaccharides: resistant dextrin (slow fermentation) and inulin (medium-speed fermentation) can slow down the fermentation process of oligofructose and stachyose (fast fermentation), stabilize the SCFA generation rate in the large intestine at 0.5-0.7 mmol / (h·g), avoid excessive gas production in a short period of time (H2 generation is reduced from 80 mL / d to 30 mL / d), and prolong the action time of SCFA (from 4 h to 8 h).

[0036] (2) Synergistic absorption of fiber and minerals: The chelating effect of inulin can improve the solubility of Ca²⁺ and Mg²⁺, and the branched structure of polydextrose can delay the residence time of minerals in the intestine (the residence time is extended from 2h to 4h). The synergistic effect of the two can increase the mineral absorption rate by more than 30%, solving the problem of single fiber "promoting absorption but short residence time".

[0037] (3) Stevioside-fiber synergistic reduction of gas production: Experiments have shown that 0.1-0.2 parts of steviol glycoside can inhibit the activity of gas-producing bacteria (such as Clostridium perfringens) in the intestine (colony count from 10). 6 CFU / g decreased to 10 4 The CFU / g ratio, in synergy with the fermentation rate regulation of fiber, reduces the gas production rate of the product by 20% compared to the formula without steviosides, and controls the incidence of bloating to within 6%.

[0038] The quality indicators of the soluble fiber solid beverage provided in this embodiment are as follows.

[0039] (a) Solubility and stability.

[0040] (1) Solubility: When dissolved in water at room temperature of 20-25℃, the solid-liquid ratios are 1:1 (20g / 20mL), 1:5 (20g / 100mL), and 1:10 (20g / 200mL). The complete dissolution time is 2.8s, 2.2s, and 2.0s respectively, and the solution is transparent with no visible particles.

[0041] (2) Stability: After the solution was prepared, it was left to stand for 24 hours at 25℃ and 4℃. The solution was then tested by centrifugation (3000 rpm, 10 min). There was no stratification or precipitation, and the clarity of the supernatant did not change (transmittance ≥95%, detected by UV spectrophotometer at 600 nm wavelength).

[0042] (ii) Security.

[0043] (1) Acute toxicity test: Referring to GB15193.3-2014 "National Food Safety Standard Acute Oral Toxicity Test", SPF grade ICR mice (weight 20±2g) were subjected to a gavage test. When the dose reached 20g / kg·bw, the mice did not die or exhibit any abnormal behavior (such as diarrhea or lethargy) within 7 days, and their weight gain was normal (average daily increase of 0.5-1.0g). The LD50 was >20g / kg·bw, which is considered "practically non-toxic".

[0044] (2) Microbiological indicators: total bacterial count ≤1000 CFU / g, coliform bacteria ≤10 CFU / g, mold and yeast ≤20 CFU / g, no pathogenic bacteria (Salmonella, Staphylococcus aureus, Shigella) detected, meeting the requirements of GB14881-2013 "National Food Safety Standard General Hygiene Specifications for Food Production".

[0045] Example 2: A method for preparing a soluble fiber solid beverage as described in Example 1, comprising the following steps: Step 1: Raw material pretreatment.

[0046] Weigh out the following raw materials according to the formula: fucoidan, resistant dextrin, inulin, polydextrose, fructooligosaccharide, stachyose and steviol glycoside. Place the fucoidan, resistant dextrin, inulin, polydextrose, fructooligosaccharide and stachyose in a vacuum drying oven and dry for 2 hours at 60±2℃ and a vacuum degree of -0.09MPa until the moisture content is ≤3%.

[0047] After drying, the raw material is passed through a 120-mesh standard sieve (sieve aperture size is 125μm) and screened using a vibrating sieve machine (amplitude 3mm, frequency 50Hz) to remove large particle impurities and ensure that the raw material has a uniform particle size distribution range of 80-120μm.

[0048] Step 2: Three-stage mixing process (based on mixing uniformity verification).

[0049] First mixing: Add resistant dextrin (30 parts), inulin (22 parts), and polydextrose (18 parts) to a multi-directional motion mixer (model SYH-100), set the speed to 30 rpm, and the mixing time to 10 min. Use the "five-point sampling method" to check the mixing uniformity. The coefficient of variation (CV) should be ≤5% to ensure that the polysaccharide fiber is mixed evenly.

[0050] Second mixing: Continue adding fructooligosaccharides (12 parts) and stachyose (4 parts) to the multi-directional motion mixer, maintaining a speed of 30 rpm, and continue mixing for 6 minutes. Take another sample for testing; CV ≤ 3% ensures that the oligosaccharides and polysaccharides are evenly mixed.

[0051] Third mixing: Add 1.5 parts of fucoidan and 0.15 parts of steviol glycosides, reduce the speed to 25 rpm (to prevent small molecule components from agglomerating due to centrifugal force), and mix for 4 minutes. The final mixture CV is ≤2%, which meets the requirements for the uniformity of solid beverage mixing.

[0052] Step 3: Package the product to obtain the soluble fiber solid beverage.

[0053] The product is packaged using an automatic packaging machine (model DXD-40), with a net content of 20g per bag and an allowable deviation of ±5% (in accordance with JJF1070-2005 "Rules for Measurement and Inspection of Net Content of Quantitatively Packaged Commodities").

[0054] The packaging material is an aluminized composite film (PET / AL / PE structure, 80μm thick), which has good barrier properties (oxygen permeability ≤5cm³ / (m²·24h·0.1MPa), water vapor permeability ≤2g / (m²·24h)), which can prevent the product from absorbing moisture and oxidizing.

[0055] After packaging, the product is stored at a temperature of 25±2℃ and a relative humidity of ≤60%, with a shelf life of 18 months. During this period, regular sampling and testing are conducted, and there are no significant changes in physicochemical and microbiological indicators.

[0056] To verify the performance of the soluble fiber solid beverage prepared in Example 2, the following experiments were conducted.

[0057] (1) Solubility comparison experiment.

[0058] The soluble fiber solid beverage (20g) prepared in Example 2 was used as the experimental group, a commercially available single fructooligosaccharide solid beverage (20g, total fiber content 70%) was used as control group 1, and a commercially available composite fiber solid beverage (20g, containing inulin and polydextrose, total fiber content 80%) was used as control group 2. The solubility of the experimental group, control group 1, and control group 2 was tested under the conditions of 25℃ room temperature water, a solid-liquid ratio of 1:5 (20g / 100mL), and magnetic stirring (500rpm). The results showed that the dissolution time of the experimental group was 2.2s with no clumping; the dissolution time of control group 1 was 8.5s with a clumping rate of 15%; and the dissolution time of control group 2 was 12.3s with a clumping rate of 25%. These results indicate that the soluble fiber solid beverage prepared in Example 2 has superior solubility.

[0059] (2) Experiment on intestinal conditioning effect.

[0060] A randomized, controlled, double-blind experimental design was used to select 60 volunteers with chronic constipation (meeting the Rome IV diagnostic criteria: ≤3 bowel movements per week for ≥3 months), aged 25-55 years, with an equal number of males and females, excluding patients with diabetes or organic intestinal diseases. The experimental group and the control group each had 30 participants. The experimental group consumed the soluble fiber solid beverage prepared in Example 2 (20g / day, mixed with 100mL of water, consumed 30 minutes after breakfast); the control group consumed a single fructooligosaccharide beverage (20g / day, mixed with 100mL of water). The experimental period was 4 weeks.

[0061] The following parameters were measured in the experimental and control groups: bowel movement frequency (weekly), fecal water content (measured by drying method), incidence of bloating (daily recording), and gut microbiota structure (16S rRNA sequencing). The results are shown in Table 1. Compared with the control group, the experimental group that consumed the soluble fiber solid beverage prepared in Example 2 of this invention showed significantly increased bowel movement frequency and fecal water content, significantly decreased incidence of bloating, and significantly increased proportion of Bifidobacteria.

[0062] Table 1. Experimental results of intestinal conditioning effects In summary, this invention achieves optimal synergy in three core indicators: total soluble fiber content, solubility, and intestinal tolerance, outperforming similar products on the market. It is suitable for people with insufficient dietary fiber intake, people with intestinal dysfunction, and people who need to control blood sugar and lipids, and meets the definition of "high dietary fiber" food in GB28050-2011 "National Food Safety Standard for General Rules for Nutrition Labeling of Prepackaged Foods".

[0063] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A soluble fiber solid beverage, characterized in that, By weight, it includes the following components: 1-2 parts of fucoidan, 25-40 parts of resistant dextrin, 20-30 parts of inulin, 15-25 parts of polydextrose, 10-20 parts of fructooligosaccharides, 3-5 parts of stachyose, and 0.1-0.3 parts of steviol glycosides.

2. A soluble fiber solid beverage according to claim 1, characterized in that, By weight, it includes the following components: 1.5 parts of fucoidan, 34.3 parts of resistant dextrin, 24 parts of inulin, 20 parts of polydextrose, 16 parts of fructooligosaccharide, 4 parts of stachyose, and 0.2 parts of steviol glycosides.

3. A method for preparing a soluble fiber solid beverage according to any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Raw material pretreatment; Weigh out the following raw materials according to the formula: fucoidan, resistant dextrin, inulin, polydextrose, fructooligosaccharide, stachyose and steviol glycosides. Among them, fucoidan, resistant dextrin, inulin, polydextrose, fructooligosaccharide and stachyose are vacuum dried to a moisture content of ≤3%. After drying, the raw materials are passed through a 120-mesh standard sieve. Step 2: Mix three times; The first mixing involved blending resistant dextrin, inulin, and polydextrose to obtain a first mixture, with a coefficient of variation (CV) ≤ 5%. The second mixing involved adding fructooligosaccharides and stachyose to the first mixture and blending to obtain a second mixture, with a CV ≤ 3%. The third mixing involved adding fucoidan and steviol glycosides to the second mixture and blending to obtain a final mixture with a CV ≤ 2%. Step 3: Package the product to obtain the soluble fiber solid beverage.

4. The method for preparing a soluble fiber solid beverage according to claim 3, characterized in that, In step one, the vacuum drying conditions are: drying in a vacuum drying oven at 60±2℃ and a vacuum degree of -0.09MPa until the moisture content is ≤3%.

5. The method for preparing a soluble fiber solid beverage according to claim 4, characterized in that, In step one, the dried raw material is screened using a vibrating screen with an amplitude of 3 mm and a frequency of 50 Hz to ensure that the particle size distribution range of the raw material is 80-120 μm.

6. The method for preparing a soluble fiber solid beverage according to claim 5, characterized in that, In step two, all three mixing processes are completed in a multi-directional motion mixer. The first mixing process is carried out at a speed of 30 rpm for 10 minutes, the second mixing process is carried out at a speed of 30 rpm for 6 minutes, and the third mixing process is carried out at a speed of 25 rpm for 4 minutes.

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