Preparation method of instant stevioside RM

Abstract

The invention discloses a preparation method of instant stevioside RM, and belongs to the technical field of food processing. The method comprises the following steps: (1) respectively dissolving a stevioside RM raw material and a wall material (preferably Arabic gum), and mixing and homogenizing according to a mass ratio of 1: (0.1-0.3); (2) carrying out spray drying and microencapsulation (the temperature of an inlet is 150-160 DEG C and the temperature of an outlet is 75-80 DEG C); (3) dissolving an adhesive (hydroxypropyl methyl cellulose and the like), a disintegrating agent (carboxymethyl starch sodium and the like), an emulsifying agent (lecithin and the like) and a defoaming agent in water to form an auxiliary material solution B; (4) adding the auxiliary material solution B according to 30-40% of the mass of the microencapsulated stevioside, and performing wet granulation (blade 10-20Hz / cutter 25-30Hz); (5) carrying out segmented boiling drying (60-62 DEG C in the first 10 minutes and 63-65 DEG C in the second 10-20 minutes); and (6) crushing to 80-100 meshes. According to the preparation method, three-stage processes of microencapsulation, wet granulation and segmented drying are cooperated, so that the defects of slow dissolution (more than 270 seconds) and heavy bitter taste (score is more than or equal to 3.5 scores) of the conventional RM are overcome, the dissolution time of the obtained product is less than or equal to 200 seconds, the bitter taste score is less than or equal to 0.7 score, and the stability in an environment with pH of 3-8 is more than 98%.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing and specifically discloses a preparation method of instant steviol glycoside RM. Background Art

[0002] Rebaudioside M (RM), the natural sweetener with the highest sweetness (200-300 times that of sucrose) and the least bitter aftertaste among the steviol glycoside family, offers significant advantages in the health food sector. However, the hydrophobic groups in its molecular structure result in extremely low water solubility (conventional products require over 270 seconds to fully dissolve), and even in high-concentration applications, it still releases trace amounts of bitter precursors, resulting in an unacceptable "grassy bitter aftertaste."

[0003] Existing technologies attempt to improve this through two approaches:

[0004] 1) Microencapsulation: Although encapsulation with wall materials such as gelatin and sodium alginate can improve initial dispersibility, the spray-dried powder is prone to secondary aggregation in the liquid, resulting in limited improvement in solubility (for example, the dissolution time in Comparative Example 1 is still 240 seconds);

[0005] 2) Wet granulation: Directly adding disintegrants to granulate can shorten the dissolution time, but cannot mask the bitter taste (the product of Comparative Example 1 has obvious bitterness).

[0006] The aforementioned methods all rely on single-step improvements, failing to simultaneously address the fundamental conflict between optimizing solubility and taste. Existing RM products, in particular, suffer from delayed dissolution and bitterness in high-acid / high-temperature beverages (such as tea and coffee). Summary of the Invention

[0007] In order to solve the above-mentioned problems in the prior art, the present invention discloses a method for preparing instant steviol glycoside RM.

[0008] To achieve the above objectives, the present invention includes the following technical solutions.

[0009] A method for preparing instant steviol glycoside RM comprises the following steps:

[0010] (1) Dissolve the stevioside RM raw material and the wall material in water respectively, and stir to form a stevioside solution and a wall material solution;

[0011] (2) Mixing the stevioside solution and the wall material solution in a mass ratio of 1:(0.1-0.3) and homogenizing at 2000-3000 rpm;

[0012] (3) spray drying the mixed solution at an inlet temperature of 150-160° C., an outlet temperature of 75-80° C., and an atomizer speed of 8000-10000 rpm to obtain microencapsulated stevioside;

[0013] (4) dissolving a binder, a disintegrant, an emulsifier, and a defoaming agent in water to form an excipient solution B;

[0014] (5) Place the microencapsulated stevioside into a wet granulator, add excipient solution B at 30-40% of the mass of the microencapsulated stevioside, and slowly add the solution to granulate at a blade frequency of 10-20 Hz and a cutter frequency of 25-30 Hz;

[0015] (6) Boiling drying of the granules at 60-65°C for 20-30 min;

[0016] (7) Grinding to 80-100 mesh to obtain instant stevioside RM.

[0017] Furthermore, in the above method, the wall material in step (1) is gum arabic, the concentration of the steviol glycoside solution is 5-10% (w / w), the concentration of the wall material solution is 0.5-2% (w / w), and the stirring conditions are 800-1000 rpm, 20-25° C., and 0.5-1 h.

[0018] Furthermore, in the above method, in the spray drying step (3), the atomizer speed is 9000-10000 rpm, and the solid content of the mixed solution is controlled at 8-12% (w / w).

[0019] Furthermore, in the above method, the mass percentages of the components in the auxiliary material solution B in step (4) are: binder 0.5-1.5%, disintegrant 1-2%, emulsifier 0.1-0.3%, defoamer 0.05-0.1%, and the balance is water.

[0020] Furthermore, in the above method, the binder in the excipient solution B is selected from hydroxypropyl methylcellulose or sodium carboxymethyl cellulose, the disintegrant is selected from sodium carboxymethyl starch, the emulsifier is selected from lecithin, and the defoaming agent is a silicone defoaming agent.

[0021] Furthermore, in the above method, the granulation time in step (5) is 5-10 min, and the addition rate of the auxiliary material solution B is controlled to be 10-15 mL / min per 100 g of microencapsulated stevioside.

[0022] Furthermore, in the above method, step (6) of boiling drying adopts segmented temperature control: the temperature is maintained at 60-62°C for the first 10 minutes and then raised to 63-65°C for the next 10-20 minutes.

[0023] The present invention also discloses an instant stevioside RM product, which is prepared by any of the above methods, has a microencapsulation rate of 92-95%, a particle size D90 of 80-120 μm, and a dissolution stability change rate of less than 5% within the pH range of 3-8.

[0024] Furthermore, the instant stevioside RM product has a dispersion time of ≤105 seconds and a dissolution time of ≤200 seconds in water at 25°C, and has no bitter taste according to sensory evaluation.

[0025] Furthermore, the above-mentioned instant stevioside RM product, when added to coffee or tea beverages, has a bitterness intensity score of ≤1.0 out of 10; and the equivalent sweetness of sucrose is more than 200 times.

[0026] Compared with the prior art, the present invention has the following outstanding beneficial effects:

[0027] 1) Solubility performance is greatly improved

[0028] The microencapsulation step (gum arabic wall material) significantly improved initial dispersibility, with Example 7 dispersing in only 98 seconds (compared to 135 seconds for the stevioside RM raw material).

[0029] During wet granulation, sodium starch glycolate produces capillary disintegration, shortening the dissolution time to 192 seconds (compared to 275 seconds for stevioside RM raw material), breaking through the bottleneck of stevioside solubility performance.

[0030] 2) Significant bitterness masking effect

[0031] The lecithin emulsifier encapsulates the bitter molecules, and combined with the flavor-masking effect of gum arabic, the bitterness score is reduced from 3.8 points of conventional RM to 0.7 points (sensory indiscernible level);

[0032] Staged boiling drying (low temperature in the front section to prevent surface hardening, high temperature in the back section to completely remove water) avoids the residue of bitter precursors. Compared with static drying (Comparative Example 2), the bitterness score is reduced by 75%.

[0033] 3) Comprehensive improvement in processing applicability

[0034] pH stability: The microencapsulation layer blocks H + / OH- erosion, the ingredient retention rate is 98.2% in the pH 3-8 environment (stevioside RM raw material is only 85.3%), solving the precipitation problem in acidic beverage applications;

[0035] Sweetness efficiency: The process further protects the sweet molecular structure, and the sweetness reaches 210 times that of sucrose (180 times that of stevioside RM raw material), the highest known value;

[0036] Process compatibility: Boiling drying time is 20-30 minutes, which is more than 50% shorter than traditional methods such as freeze drying.

[0037] 4) Significant economic benefits

[0038] Dissolution time is shortened by more than 30%, reducing stirring energy consumption in beverage production;

[0039] Eliminating bitterness reduces the amount of taste masking agents (such as fructose, etc.), and the formulation cost drops by about 15%.

[0040] In summary, this invention, for the first time, uses the "microencapsulation-directional disintegration granulation-thermodynamic drying control" process chain to simultaneously solve the three major technical bottlenecks of solubility, taste, and stability in the industrialization of stevioside RM, providing a high-quality sweetener solution for healthy foods. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0042] Table 1 Raw materials

[0043]

[0044]

[0045] Example 1

[0046] Gelatin system

[0047] (1) Dissolution: 100 g of stevioside RM raw material + 900 g of water (10%), 10 g of gelatin + 990 g of water (1%) (forming wall material solution), 900 rpm / 23°C / 0.8 h;

[0048] (2) Mixing: Stevioside solution: wall material solution = 1:0.1, homogenization at 2500 rpm for 0.5 h;

[0049] (3) Microencapsulation: spray drying (inlet 155°C / outlet 78°C / atomizer 8500 rpm, solid content 11%);

[0050] (4) Dissolving: 0.8 g hydroxypropyl methylcellulose + 1.2 g sodium starch glycolate + 28 g water (excipient solution B, accounting for 30% of the mass of microencapsulated stevioside);

[0051] (5) Granulation: feeding rate 12 mL / min, paddle 15 Hz / cutter 28 Hz, granulation 8 min;

[0052] (6) Boiling drying: 62°C / 25 min;

[0053] (7) Crushing: 90 mesh.

[0054] Example 2

[0055] Gum Arabic Basics

[0056] (1) Dissolution: 100g Stevioside RM raw material + 950g water, 15g gum arabic + 1485g water (1%)

[0057] (2) Mixing: solution ratio 1:0.15, homogenization at 2800 rpm

[0058] (3) Microencapsulation: inlet 158°C / outlet 77°C / atomizer 9200 rpm (solid content 9.8%)

[0059] (4) Dissolution: 1.2g sodium carboxymethyl cellulose + 1.5g microcrystalline cellulose + 32.3g water (35%)

[0060] (5) Granulation: feeding rate 14 mL / min, paddle 18 Hz / cutter 30 Hz, granulation 6 min

[0061] (6) Boiling drying: 63℃ / 22min

[0062] (7) Crushing: 95 mesh

[0063] Example 3

[0064] Sodium alginate system

[0065] (1) Dissolve: 100g of stevioside RM raw material (8% solution), 8g of sodium alginate (1.2% solution)

[0066] (2) Mixing: solution ratio 1:0.12, homogenization at 2200 rpm

[0067] (3) Microencapsulation: inlet 152°C / outlet 76°C / atomizer 9500 rpm (solid content 10.5%)

[0068] (4) Dissolution: Hydroxypropyl methylcellulose 1.0g + sodium starch glycolate 1.0g + water 28g (32%)

[0069] (5) Granulation: feeding rate 10 mL / min, paddle 10 Hz / cutter 25 Hz, granulation 10 min

[0070] (6) Boiling drying: 60℃ / 30min

[0071] (7) Crushing: 100 mesh

[0072] Example 4

[0073] Tween 80 emulsifier

[0074] (1)-(3) Same as Example 2

[0075] (4) Dissolution: Hydroxypropyl methylcellulose 0.8g + microcrystalline cellulose 1.5g + Tween 80 0.2g + silicone defoamer 0.08g + water 27.42g (total weight 30g, accounting for 32%)

[0076] (5) Granulation: feeding rate 12 mL / min, paddle 15 Hz / cutter 28 Hz, granulation 8 min

[0077] (6) Boiling drying: 62℃ / 25min

[0078] (7) Crushing: 80 mesh

[0079] Example 5

[0080] Sodium carboxymethyl cellulose binder

[0081] (1)-(3) Same as Example 2

[0082] (4) Dissolution: Sodium carboxymethyl cellulose 1.2g + microcrystalline cellulose 1.8g + Tween 80 0.25g + silicone defoamer 0.1g + water 31.65g (total weight 35g, accounting for 38%)

[0083] (5) Granulation: feeding rate 14 mL / min, paddle 18 Hz / cutter 30 Hz, granulation 6 min

[0084] (6) Boiling drying: 63℃ / 22min

[0085] (7) Crushing: 95 mesh

[0086] Example 6

[0087] Sodium starch glycolate disintegrant

[0088] (1)-(3) Same as Example 2

[0089] (4) Dissolution: Hydroxypropyl methylcellulose 1.0g + sodium starch glycolate 1.5g + Tween 80 0.15g + silicone defoamer 0.06g + water 27.29g (total weight 30g, accounting for 35%)

[0090] (5) Granulation: feeding rate 13 mL / min, paddle 12 Hz / cutter 26 Hz, granulation 7 min

[0091] (6) Boiling drying: 64℃ / 28min

[0092] (7) Crushing: 100 mesh

[0093] Example 7

[0094] Best Mode

[0095] (1)-(3) Same as Example 2

[0096] (4) Dissolution: Hydroxypropyl methylcellulose 1.2g + sodium starch glycolate 1.8g + lecithin 0.25g + silicone defoamer 0.07g + water 26.68g (component mass percentage: HPMC 1.2% / disintegrant 1.8% / emulsifier 0.25% / defoamer 0.07%)

[0097] (5) Granulation: feeding rate 15 mL / min, paddle 20 Hz / cutter 30 Hz, granulation 5 min

[0098] (6) Boiling drying: staged temperature control - 61°C for the first 10 minutes / 64°C for the last 15 minutes

[0099] (7) Crushing: 90 mesh.

[0100] Comparative Example 1

[0101] No microencapsulation

[0102] (1) Dissolve: Hydroxypropyl methylcellulose 1.2g + sodium starch glycolate 1.8g + lecithin 0.25g + water 26.75g

[0103] (2) Granulation: Add 100g of stevioside directly, granulate at 20Hz for 5min with blade and 30Hz for cutting.

[0104] (3) Boiling drying: same as in Example 7

[0105] (4) Crushing: 90 mesh

[0106] Comparative Example 2

[0107] Unconventional drying

[0108] (1)-(5) Same as Example 7

[0109] (6) Drying: static drying in an oven at 60°C for 3.5 minutes

[0110] (7) Crushing: 90 mesh

[0111] Comparative Example 3

[0112] No wet granulation

[0113] (1)-(3) Same as Example 2

[0114] (4) Skip the step of adding excipient solution B

[0115] (5) Boiling drying: same as in Example 2

[0116] (6) Crushing: 95 mesh

[0117] Test Case

[0118] The products obtained in Examples 1-7 and Comparative Examples 1-3 were tested.

[0119] 1. Test items and methods.

[0120] 1). Determination of dispersion time

[0121] The test was conducted in accordance with the national standard GB / T 36392-2018, "Determination of Powder Solubility." Accurately weigh 1.00 g of sample and add it to 100 mL of distilled water maintained at 25°C. Immediately stir at 200 rpm. Visually observe and record the time (in seconds) required for the sample particles to be completely wetted and free of floating debris. Repeat three times and take the average value.

[0122] 2). Dissolution time determination

[0123] Refer to ISO 2173:2003, "Determination of Solubility of Foods." Continue stirring after the dispersion time is complete. Monitor the particle size distribution in real time using a laser particle size analyzer (Malvern Mastersizer 3000). Complete dissolution is determined when the D90 value (90% particle diameter) is ≤50 μm. Record the time (in seconds) from sample addition until the dissolution reaches the target.

[0124] 3) Bitterness intensity score

[0125] The test was conducted blindly in an independent sensory laboratory by a panel of 10 professionally trained sensory assessors in accordance with GB / T 16860-2018, "Sensory Analysis - Flavor Profile Test." Samples were prepared as 0.05% aqueous solutions (25°C) and scored on a 0-10 scale (0 = no bitterness, 10 = extremely bitter). Results are presented as mean ± SD.

[0126] 4). Microencapsulation rate detection

[0127] High-performance liquid chromatography (HPLC) combined with an internal standard method was used for quantification. Chromatographic conditions: C18 reverse-phase column (4.6×250 mm, 5 μm), mobile phase acetonitrile-water (65:35, v / v), flow rate 1.0 mL / min, detection wavelength 210 nm. Free steviol glycosides were separated by surface washing, and the microencapsulation efficiency was calculated according to the formula:

[0128] Microencapsulation rate (%) = (1-surface free stevioside mass / total stevioside mass) × 100%

[0129] 5). Determination of sweetness multiple

[0130] Based on the three-point comparison method of ISO 22935-3:2009 "Sensory Evaluation of Dairy Products", a series of sample solutions with a sweetness of 5% sucrose solution were prepared. The sensory evaluation panel determined the sample concentration that was equal in sweetness to the reference solution. The sweetness multiple was calculated using the following formula:

[0131] Sweetness multiple = (5% / concentration of equal sweet sample) × 100

[0132] 6). pH stability test

[0133] Refer to the general stability test method of the 2020 edition of the Chinese Pharmacopoeia. Dissolve the sample in a solution of pH 3.0 (citrate buffer), pH 5.0 (acetate buffer), and pH 8.0 (phosphate buffer) at a concentration of 0.1 mg / mL. After being placed at 25°C for 24 hours, the change in the main peak area of ​​stevioside RM was detected by HPLC, and the content retention rate was calculated:

[0134] Retention rate (%) = (main peak area after 24 hours / main peak area at 0 hours) × 100%

[0135] 2. Results

[0136] The results are shown in Table 1

[0137] Table 1 Performance test results (mean ± SD, n = 3)

[0138]

[0139] In summary, by systematically comparing the performance data of Examples 1-7, Comparative Examples 1-3, and the stevioside RM raw material, the following conclusions can be drawn:

[0140] 1. Process integrity determines instant solubility:

[0141] Although Comparative Example 3 (microencapsulation only, no granulation) achieved a high microencapsulation rate of 94.7%, the lack of a wet granulation step resulted in a dissolution time of >600 seconds (compared to only 192 seconds in Example 7), demonstrating that the seven-step process chain of the present invention cannot be reduced. Wet granulation, which disrupts microcapsule aggregates through the capillary disintegration of sodium starch glycolate, is the key to achieving instant dissolution.

[0142] 2. Components synergistically optimize taste and stability:

[0143] Gum Arabic wall material: Example 2 (108 seconds to disperse) showed a 22.2% improvement in dispersion efficiency compared to Example 3 (sodium alginate, 132 seconds) due to the accelerated wetting of the hydrophilic colloid.

[0144] Lecithin emulsifier: Example 7 had a bitterness score of 0.7, which was 82% lower than that of Comparative Example 1 (no microencapsulation, 3.5 points). This may be because lecithin encapsulates bitter molecules and blocks taste bud recognition.

[0145] Staged boiling drying: Example 7 compared to Comparative Example 2 (static drying) showed a 75% reduction in bitterness score (0.7 vs 2.8). This was because the first stage (61°C) softened the particles to prevent surface hardening and locking of bitterness, while the second stage (64°C) completely removed water to prevent residual water.

[0146] 3. Improved solubility performance:

[0147] The dissolution time of 192 seconds (Example 7) was 44.7% higher than that of the stevioside RM raw material (275 seconds);

[0148] The pH stability of 98.2% (Example 7) far exceeds that of the stevioside RM raw material (85.3%), because the microcapsule layer can effectively block H + / OH- erosion.

[0149] The above are only a few preferred embodiments of the present invention, and their description is relatively specific and detailed, but it should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and such modifications and improvements are within the scope of protection of the present invention.

Claims

1. A method for preparing instant steviol glycoside RM, characterized in that: The following steps are involved: (1) Dissolve the stevioside RM raw material and the wall material in water respectively, and stir to form a stevioside solution and a wall material solution; (2) mixing the stevioside solution and the wall material solution in a mass ratio of 1:(0.1-0.3) and homogenizing at 2000-3000 rpm; (3) spray drying the mixed solution at an inlet temperature of 150-160° C., an outlet temperature of 75-80° C., and an atomizer speed of 8000-10000 rpm to obtain microencapsulated stevioside; (4) dissolving a binder, a disintegrant, an emulsifier, and a defoaming agent in water to form an excipient solution B; (5) Place the microencapsulated stevioside into a wet granulator, add excipient solution B at 30-40% of the mass of the microencapsulated stevioside, and slowly add the solution to granulate at a blade frequency of 10-20 Hz and a cutter frequency of 25-30 Hz; (6) Boiling drying of the granules at 60-65°C for 20-30 min; (7) Grinding to 80-100 mesh to obtain instant stevioside RM.

2. The method according to claim 1, wherein: In step (1), the wall material is gum arabic, the concentration of the steviol glycoside solution is 5-10% (w / w), the concentration of the wall material solution is 0.5-2% (w / w), and the stirring conditions are 800-1000 rpm, 20-25° C., and 0.5-1 h.

3. The method according to claim 1, wherein: In the spray drying step (3), the atomizer rotation speed is 9000-10000 rpm, and the solid content of the mixed solution is controlled at 8-12% (w / w).

4. The method according to claim 1, wherein: The mass percentages of the components in the auxiliary material solution B in step (4) are: binder 0.5-1.5%, disintegrant 1-2%, emulsifier 0.1-0.3%, defoamer 0.05-0.1%, and the balance is water.

5. The method according to claim 4, characterized in that: In the auxiliary material solution B, the binder is selected from hydroxypropyl methylcellulose or sodium carboxymethyl cellulose, the disintegrant is selected from sodium carboxymethyl starch, the emulsifier is selected from lecithin, and the defoaming agent is a silicone defoaming agent.

6. The method according to claim 1, wherein: The granulation time in step (5) is 5-10 min, and the addition rate of the auxiliary material solution B is controlled to be 10-15 mL / min per 100 g of microencapsulated stevioside.

7. The method according to claim 1, wherein: Step (6) boiling drying adopts segmented temperature control: maintain 60-62°C for the first 10 minutes and then increase to 63-65°C for the next 10-20 minutes.

8. An instant stevioside RM product, characterized by: The invention is prepared by the method according to any one of claims 1 to 7, wherein the microencapsulation rate is 92-95%, the particle size D90 is 80-120 μm, and the dissolution stability change rate is less than 5% within the pH range of 3-8.

9. The product according to claim 8, characterized in that: The product has a dispersion time of ≤105 seconds and a dissolution time of ≤200 seconds in water at 25° C., and has no bitter taste according to sensory evaluation.

10. The product according to claim 8, characterized in that: When the product is added to coffee or tea beverages, the bitterness intensity score is ≤1.0 out of 10; and the equivalent sweetness of sucrose is more than 200 times.

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