Novel spirulina protein functional beverage capable of reducing blood sugar and preparation method of novel spirulina protein functional beverage

Abstract

The invention discloses a novel spirulina protein functional beverage capable of reducing blood sugar and a preparation method of the novel spirulina protein functional beverage, and belongs to the field of functional food preparation. The spirulina protein functional beverage provided by the invention takes spirulina protein as a main material and is compounded with various medicinal and edible raw materials; the spirulina protein is extracted from spirulina platensis. The spirulina protein is taken as a main raw material, and is matched with various medicinal and edible components, so that the product has the advantage of multi-target synergistic effect, multi-way blood glucose reduction is realized, meanwhile, the product has nutrition and functions, the proportion of amino acids is close to the requirements of human bodies, and nutrition can be supplemented for patients.

Description

Technical Field

[0001] The invention belongs to the technical field of functional foods and relates to a novel blood sugar-lowering spirulina protein functional beverage and a preparation method thereof. Background Art

[0002] Diabetes is a chronic disease characterized by disorders of blood sugar and blood lipid metabolism, of which type 2 diabetes mellitus (T2DM) accounts for 90%. The core mechanism of this disease is insulin resistance accompanied by β-cell dysfunction. Its onset is affected by multiple factors such as genetics, environment and lifestyle, and is particularly closely related to a high-sugar and high-fat diet. In the early stages of the disease, patients mainly show postprandial hyperglycemia and insulin resistance. Currently, the main clinical treatment is metformin and other drugs, but there are gastrointestinal side effects. Although new drugs (such as SGLT2 inhibitors) have shown efficacy, the overall blood sugar control rate has not been significantly improved. The development of natural hypoglycemic ingredients has become a research hotspot. Functional foods improve insulin sensitivity by regulating sugar metabolism and other pathways, but existing products generally have limitations: a single target (such as only inhibiting glucose absorption), the need for long-term high-dose administration, and poor taste (such as bitter melon). These problems need to be solved urgently.

[0003] Diets rich in bioactive proteins and peptides have potential value in the prevention and management of type 2 diabetes (T2DM). Studies have shown that plant proteins can improve glycated hemoglobin and fasting blood glucose levels through mechanisms including regulation of glucose metabolism enzyme activity, antioxidant and anti-inflammatory effects, and thus alleviate insulin resistance. Spirulina, a natural food high in protein and essential amino acids, has antioxidant, anti-inflammatory, and immunomodulatory properties, demonstrating its potential for lowering blood sugar. However, limited research on this topic has limited its application in functional foods. Summary of the Invention

[0004] In order to solve the problems of the prior art and in view of the above situation, the present invention provides a blood sugar lowering functional beverage with spirulina protein as the main ingredient and compounded with a variety of medicinal and edible raw materials and a preparation process thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The invention provides a functional beverage for diabetic patients, which contains spirulina protein extracted from Spirulina platensis.

[0007] Preferably, the spirulina protein is prepared by the following method:

[0008] After the spirulina is wall-broken, the pH value of the wall-broken spirulina solution is adjusted to 7-12, the processing temperature is 15-45°C, the material-liquid ratio is adjusted, the solution is stirred and centrifuged to obtain the supernatant, and the solution is separated by coordinated salting out using an isoelectric precipitation method, desalted, concentrated, small molecular impurities are removed, sterilized, and freeze-dried to obtain the spirulina protein powder.

[0009] Furthermore, the present invention also provides a specific functional beverage, which is composed of the following raw materials in parts by weight:

[0010] 15-30 parts of spirulina protein, 10-20 parts of astragalus polysaccharide, 5-15 parts of ophiopogon polysaccharide, 7-17 parts of kudzu root flavonoids, 7-17 parts of wolfberry polysaccharide, 5-15 parts of polygonatum polysaccharide, 5-9 parts of erythritol, 0.1-0.3 parts of citric acid, and 10-18 parts of polydextrose.

[0011] Preferably, the steps for preparing the functional beverage provided by the present invention are as follows:

[0012] (1) Spirulina protein, astragalus polysaccharide, ophiopogon polysaccharide, kudzu root flavonoids, wolfberry polysaccharide, and polygonatum polysaccharide were ultrafinely ground at low temperature and sieved to obtain 200-mesh fine powder.

[0013] (2) The raw material powder prepared in step (1) is weighed according to the following proportions by weight: 15-30 parts of spirulina protein, 10-20 parts of astragalus polysaccharide, 5-15 parts of ophiopogon polysaccharide, 7-17 parts of kudzu root flavonoids, 7-17 parts of wolfberry polysaccharide, and 5-15 parts of polygonatum polysaccharide. The weighed raw material powders are mixed and sieved.

[0014] (3) The mixed powder sieved in step (2) is thoroughly mixed again, and auxiliary materials such as 5-9 parts of erythritol, 0.1-0.3 parts of citric acid, and 10-18 parts of polydextrose are added, and the mixing is continued.

[0015] (4) The mixed powder in step (3) is subjected to ultraviolet sterilization treatment and fully sealed and quantitatively packaged in a sterile environment.

[0016] (5) The fully sealed products are packaged into bags as required, and the products are tested in accordance with the requirements of GB / T 29602. Qualified products are stored in the warehouse.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention develops a hypoglycemic functional beverage by combining spirulina protein with medicinal and edible raw materials (astragalus polysaccharide, ophiopogon polysaccharide, kudzu root flavonoids, wolfberry polysaccharide, and polygonatum polysaccharide). Spirulina protein has multiple biological activities, including antioxidant, anti-inflammatory, hypoglycemic and lipid-lowering, and immunomodulatory. Its food safety has been certified by China and the European Union. The medicinal and edible ingredients in the combination all meet pharmacopoeial standards, ensuring the safety and effectiveness of the product.

[0019] (2) The present invention uses spirulina protein as the main active ingredient of the blood sugar lowering functional beverage, which has a precise function and obvious effect. Through experimental research, it was found that spirulina protein has good in vitro and in vivo blood sugar lowering activity.

[0020] (3) The present invention has developed a blood sugar-lowering functional beverage whose main ingredients are spirulina protein and medicinal and edible raw materials. These components work synergistically to achieve a blood sugar-lowering effect. The product has been optimized for flavor, has a sweet and sour taste, and is suitable for daily consumption by diabetic patients. Through a multi-target regulation mechanism, it provides a safe and effective dietary option for blood sugar management. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the preparation and characterization diagram of Spirulina protein (a: contour map of the interaction between extraction time and solid-liquid ratio; b: contour map of the interaction between extraction temperature and solid-liquid ratio; c: contour map of the interaction between extraction temperature and extraction time; d: 3D response surface map of the interaction between extraction time and solid-liquid ratio; e: 3D response surface map of the interaction between extraction temperature and solid-liquid ratio; f: 3D response surface map of the interaction between extraction temperature and extraction time; g: circular dichroism spectrum; h: secondary structure content).

[0022] Figure 2 This is a graph of the hypoglycemic activity of Spirulina protein (a: α-glucosidase inhibitory activity; b: α-amylase inhibitory activity; c: effect on blood glucose levels in diabetic mice during the experiment; d: changes in blood glucose levels in mice within 2 hours of oral glucose administration before intervention; e: area under the blood glucose curve; f: changes in blood glucose levels in mice within 2 hours of oral glucose administration after intervention; g: area under the blood glucose curve).

[0023] Figure 3 This is a diagram showing the effect of the amount of auxiliary materials added on the score of functional beverages (a, c, e: erythritol, citric acid, and polydextrose addition index score diagram; b, d, f: erythritol, citric acid, and polydextrose addition comprehensive score diagram).

[0024] Figure 4 This is a graph of the hypoglycemic activity of spirulina protein functional beverage (a: effect on blood glucose levels of diabetic mice during the experiment; b: changes in blood glucose levels within 2 hours of oral glucose administration in mice before intervention; c: area under the blood glucose curve; d: changes in blood glucose levels within 2 hours of oral glucose administration in mice after intervention; e: area under the blood glucose curve). DETAILED DESCRIPTION

[0025] In order to achieve the above-mentioned purpose and effect, and to further understand the technical solution of the present invention, the following preferred embodiments are specifically cited and described in detail with reference to the accompanying drawings:

[0026] Example 1 Preparation and Characterization of Spirulina Protein

[0027] (1) Preparation of Spirulina Protein

[0028] After the spirulina is wall-broken, the pH value of the wall-broken spirulina solution is adjusted to 7-12, the processing temperature is 15-45°C, the material-liquid ratio is adjusted, the solution is stirred and centrifuged to obtain the supernatant, and the solution is separated by coordinated salting out using an isoelectric precipitation method, desalted, concentrated, small molecular impurities are removed, sterilized, and freeze-dried to obtain the spirulina protein powder.

[0029] The extraction process was optimized. Three influencing factors, namely liquid-to-solid ratio (A), extraction time (B) and extraction temperature (C), were selected. A response surface experiment was conducted with the extraction rate of Spirulina protein (Y) as the response value.

[0030] Table 1 Response surface experiment design and results

[0031]

[0032]

[0033] The quadratic multivariate fitting equation obtained after performing variance analysis on Table 1 is expressed as: Y1=298.79-4.45*A+13.13*B+5.74*C+17.86*AB+5*AC+17.96*BC-5.56*A 2 -21.51*B 2 -4.15*C 2

[0034] Table 2 Analysis of variance of regression model (protein extraction rate)

[0035]

[0036] Note: A is the liquid-to-solid ratio, B is the extraction time, and C is the extraction temperature. ** indicates a very significant difference, P < 0.01

[0037] The significance analysis of the model is shown in Table 2. A larger F value indicates a greater impact of the factor on the protein extraction yield. Table 2 shows that extraction time (B) has the greatest impact on protein extraction yield, followed by extraction temperature (C), and the solid-liquid ratio (A) has the least impact. A smaller P value indicates a more significant effect on the protein content. The linear and quadratic effects of extraction time (B) and extraction temperature (C) on protein extraction yield are highly significant (P < 0.01). Furthermore, the P value for the lack-of-fit term (P = 0.1505) is greater than 0.05, indicating a good fit for the response surface model. Under the condition of maximizing the weighted sum, the software determined the optimal process: extraction time of 3.03 h, extraction temperature of 26.38°C, and liquid-to-solid ratio of 35.14:1, with a predicted protein extraction yield of 300.23 mg / g.

[0038] Based on the obtained regression equation results, the response surface diagram was fitted using Design Expert 13 software to further analyze the interaction between the three factors and the effect of this interaction on the extracted protein content. Figure 1 (a) and (d) are the contour maps and response surface 3D maps formed by the interaction between extraction time and liquid-to-solid ratio. It can be seen that the response surface 3D surface is parabolic, the contour lines are curved, and the color changes significantly, indicating that there is a good interaction between the two factors. Figure 1 As shown in (b) and (e), the 3D graphs are relatively flat and the color changes of the contour lines are not significant, so the interaction between the extraction temperature and the liquid-to-solid ratio is not very good; Figure 1 As shown in (c) and (f), the 3D surfaces also exhibit parabolic shapes with curved contour lines, but the color change is not significant, indicating a positive interaction between extraction temperature and time. Based on response surface analysis and comprehensive considerations, the extraction process was determined to achieve a high protein yield: an extraction time of 3 h, an extraction temperature of 25°C, and a liquid-to-solid ratio of 35:1. This process was repeated three times under these conditions, resulting in a protein content of 307.02 ± 4.64 mg / g.

[0039] (2) Composition analysis of Spirulina protein

[0040] The protein composition of the samples was analyzed by mass spectrometry. After comparison with protein database search results, Table 3 contains the possible protein composition information of the Spirulina peptides. The results show that the Spirulina protein composition includes phycocyanin α-subunit, β-subunit, allophycocyanin α-subunit, β-subunit, etc. The study also confirmed that the globulin superfamily was identified from Spirulina proteins, including eight phycobiliproteins, with crystal structures of α-subunit and β-subunit.

[0041] Table 3 Composition analysis of Spirulina protein

[0042]

[0043]

[0044]

[0045] (3) Secondary structure of Spirulina protein

[0046] The obtained Spirulina protein was prepared at a concentration of 0.05 mg / mL. The circular dichroism spectrometer was scanned in the range of 190-260 nm, with the baseline calibrated with pure water, and the scan was repeated three times. The proportions of α-helix, β-sheet, β-turn, and random coil were calculated using DichroWeb.

[0047] like Figure 1As shown in (h), the secondary structure of Spirulina protein is dominated by α-helices, with a proportion of α-helices reaching 65.42%, indicating that its native conformation is well preserved and its structure is more compact, which is advantageous in terms of stability and functional applications. The proportion of random coils is relatively low (13.44%). Random coils are often associated with partial protein unfolding or localized denaturation. A high proportion of disordered structures may lead to decreased protein solubility or functional activity. In summary, the Spirulina protein structure is close to its native state, and the high proportion of α-helices contributes to its greater stability and suitability for functional applications.

[0048] Example 2 Hypoglycemic Activity of Spirulina Protein

[0049] (1) α-glucosidase inhibitory activity

[0050] The PNPG colorimetric method was used to determine the in vitro inhibitory activity of α-glucosidase. Four groups were set up: sample group, sample blank, control group, and control blank group. The sample blank group had no enzyme solution, and the blank group had no sample solution. The absorbance value was measured at 405 nm.

[0051] Formula 1 calculates α-glucosidase inhibitory activity:

[0052]

[0053] α-glucosidase promotes the decomposition of oligosaccharides, which will increase blood sugar levels after a meal during digestion. The results of in vitro α-glucosidase activity showed that ( Figure 2 (a) IC of spirulina protein on α-glucosidase inhibition 50 The value was 6.25±0.06mg / mL. In the concentration range of 0.5-8mg / mL, spirulina protein showed inhibitory activity against α-glucosidase, with the inhibition rate ranging from 21.56% to 56.71%, indicating that spirulina protein has inhibitory activity against α-glucosidase. The study also found that the enzyme inhibitory activity of spirulina protein gradually weakened during the digestion process, which may be due to the structural destruction and inactivation of its active peptide segment. The protein structure is initially decomposed during gastric digestion, and the efficient hydrolysis of trypsin in intestinal digestion further exacerbates the degradation of the peptide segment. This indicates that the α-glucosidase inhibitory activity of spirulina protein may depend on its complete peptide segment structure.

[0054] (2) α-amylase inhibitory activity

[0055] Mix 25 μL of sample, 25 μL of α-amylase (1.0 U / mL) solution, and 50 μL of buffer (20 mM, pH 6.8). After reacting at 37°C for 10 minutes, add 50 μL of 1% starch solution. The sample blank group replaced the enzyme with buffer, the control group replaced the sample with buffer, and the blank group replaced both the enzyme and sample with buffer. After incubation at 37°C for 10 minutes, add 100 μL of DNS reagent to each group, boil for 10 minutes, and measure the absorbance at 540 nm. Calculate the inhibitory activity of α-amylase according to Formula 2:

[0056]

[0057] α-amylase can break down starch in food into oligosaccharides, causing blood sugar to rise during digestion. The results of in vitro α-amylase activity showed that ( Figure 2 (b) IC of spirulina protein on α-amylase inhibition 50 The value was 2.47±0.20mg / mL. When the concentration of spirulina protein ranged from 0.5-8mg / mL, the inhibitory activity of spirulina protein on α-amylase was 15.25% to 77.97%, indicating that spirulina protein has inhibitory activity against α-amylase. Subsequent gastrointestinal digestion results showed that after the gastric digestion products entered the intestine, the action of trypsin exposed some hidden active peptides, which showed stronger α-amylase inhibitory activity. However, the efficient hydrolysis of the enzyme in the later stage of digestion led to the continuous degradation of the peptides, and the inhibitory activity was weakened.

[0058] (3) Animal experimental methods

[0059] After one week of adaptive feeding, the mice were randomly divided into four groups according to their body weight: normal group (NC), model group (MC), positive drug metformin group (PC), spirulina protein low-dose group (SPL) and spirulina protein low-dose group (SPH), with 6 mice in each group.

[0060] The normal group was fed with ordinary feed, and the other groups were fed with high-fat and high-sugar feed (HSHF) for 4 consecutive weeks before modeling. After the model was established, each mouse was gavaged with the corresponding intervention substance at 1% of its body weight for 4 weeks:

[0061] NC group: normal mice received only normal diet;

[0062] MC group: diabetic mice received a high-sugar and high-fat diet;

[0063] PC group: diabetic mice received a high-sugar and high-fat diet and 200 mg / kg body weight metformin (10%);

[0064] SPL group: diabetic mice received a high-sugar and high-fat diet and 100 mg / kg body weight of the sample;

[0065] SPH group: diabetic mice received a high-sugar and high-fat diet and 500 mg / kg body weight of the sample.

[0066] After four weeks of feeding, mice were fasted overnight but not water-treated. Mice in the NC group were injected with sterile citric acid buffer (pH = 4.4, 0.1 M), while mice in the MC, PC, SPL, and SPH groups were injected with 40 mg / kg of 1% (w / v) streptozotocin (STZ) for three consecutive days. The STZ solution was prepared in 4°C pre-cooled citric acid buffer at a concentration of 1% (w / v). After fasting for 4 hours after injection, the mice were fed and their condition was monitored at all times. Glucose water was supplemented within 12 hours. On days 3 and 7, fasting blood glucose (FBG) was measured by tail tip blood sampling. If the FBG value was not less than 11.1 mmol / L on two consecutive occasions, the T2DM model was successfully established.

[0067] (4) Effect of Spirulina Protein on Blood Glucose Levels in Diabetic Mice

[0068] Fasting blood glucose (FBG) was measured in mice using a blood glucose meter. Before measurement, mice fasted for 12 hours but maintained hydration. Blood samples were then collected from the tail vein. The first drop of blood was gently wiped with a cotton ball, and the second drop was used for blood glucose measurement.

[0069] FBG is a commonly used indicator to measure basal insulin secretion function, such as Figure 2 As shown in (c), at week 0 of oral administration, FBG levels in all modeling groups were higher than 11.1 mmol / L compared to the NC group, indicating that the T2DM model was successfully established. During the intervention period, FBG levels in the MC group remained significantly higher than in the NC group (P < 0.05). Starting from week 2, FBG levels were significantly reduced in mice treated with Spirulina protein (P < 0.05). After 4 weeks of oral administration, FBG levels in all intervention groups were significantly lower than in the MC group (P < 0.05). FBG levels in the SPL and SPH groups were significantly reduced (P < 0.05). This indicates that Spirulina protein can alleviate hyperglycemia in T2DM mice after 4 weeks of oral administration, demonstrating its efficacy in improving blood glucose homeostasis.

[0070] (5) Effect of Spirulina Protein on Glucose Tolerance (OGTT) in Diabetic Mice

[0071] Oral glucose tolerance (OGTT) was performed on mice before and 28 days after oral administration of Spirulina protein. Initial FBG (0 h) was measured for each group of mice. Subsequently, each group of mice received a single oral dose of 1.5 g / kg·BW glucose. Over the next 2 hours (0.5, 1, and 2 h), blood was collected from the tail vein to monitor blood glucose levels. The area under the glucose tolerance curve (AUC-OGTT) was calculated using Equation 3:

[0072] AUC-OGTT=0.25×(A+B)+0.25×(B+C)+0.5×(C+D) (3)

[0073] Where: A-blood glucose value at 0h

[0074] B-blood glucose level at 0.5h

[0075] C-blood glucose level at 1 hour

[0076] D-2h blood glucose level

[0077] OGTT can reflect the changes in blood sugar and the ability to regulate blood sugar in the short term. Figure 2 (d) It can be seen that after modeling and before intervention, the blood glucose levels of mice in each group rose rapidly within 0.5 hours after oral glucose administration, and then gradually fell within 1 hour. At each time point, the blood glucose level in the modeling group was the highest. The AUC level can more intuitively show the differences in OGTT between the groups ( Figure 2 (e)), compared with the NC group, the AUC values ​​of the other groups were significantly increased (P<0.01), indicating that the blood glucose balance of the model mice was disrupted and the blood glucose regulation ability of the hyperglycemic mice was still impaired. After 4 weeks of oral administration of Spirulina protein, the blood glucose level of the mice reached a peak within 0.5 hours of oral administration of glucose solution, and then gradually decreased after 1 hour. After 2 hours, the blood glucose level of the mice in the NC group returned to the normal range, while the blood glucose level of the mice in the MC group remained at a high level, indicating that blood glucose homeostasis was disrupted ( Figure 2 (f)). Figure 2 (g) shows that compared with the MC group, the AUC values ​​of the PC group, SPL group, and SPH group were significantly lower than those of the MC group (P<0.01), indicating that Spirulina protein can improve the glucose tolerance of T2DM mice.

[0078] Example 3 Functional Beverage Formula Design and Preparation

[0079] (1) Functional beverage preparation method

[0080] Spirulina protein, astragalus polysaccharide, ophiopogon polysaccharide, kudzu root flavonoids, wolfberry polysaccharide, and polygonatum polysaccharide are ground and sieved. The resulting raw material powder is weighed in proportion by weight: 20 parts of spirulina protein, 15 parts of astragalus polysaccharide, 10 parts of ophiopogon polysaccharide, 12 parts of kudzu root flavonoids, 12 parts of wolfberry polysaccharide, and 10 parts of polygonatum polysaccharide. Astragalus polysaccharide (70%), ophiopogon polysaccharide (60%), kudzu root flavonoids (60%), wolfberry polysaccharide (60%), and polygonatum polysaccharide (60%) are all purchased from Xi'an Ruihe Bioengineering Technology Co., Ltd. The weighed raw material powders are mixed and sieved. The sieved mixed powder is then thoroughly mixed for 10-20 minutes to obtain a premix, and then auxiliary materials erythritol, citric acid, and polydextrose are added. Mixing is continued for 5-10 minutes to obtain a final mixture. The mixed powder is sterilized with ultraviolet light and packaged in a sterile, fully sealed, and quantitatively packaged to obtain a hypoglycemic spirulina protein functional beverage.

[0081] (2) Formulation optimization and sensory evaluation methods

[0082] Based on the preliminary experiments, a single-factor experiment was designed with the addition amount of stevioside, citric acid and polydextrose as experimental factors.

[0083] ①Selection of the amount of erythritol added to solid beverages

[0084] Solid beverages were prepared by adding 5%, 6%, 7%, 8% and 9% erythritol, 0.2% citric acid and 14% polydextrose to the main body of the powder, mixing and homogenizing, and measuring their effects on the comprehensive score.

[0085] ②Selection of citric acid addition amount for solid beverages

[0086] 0.1%, 0.15%, 0.2%, 0.25% and 0.3% of citric acid, 7% of erythritol and 14% of polydextrose were added to the powder body, mixed and homogenized to prepare solid beverages, and their effects on the comprehensive score were measured.

[0087] ③Selection of the amount of polydextrose added to solid beverages

[0088] Solid beverages were prepared by adding 10%, 12%, 14%, 16% and 18% polydextrose, 7% erythritol and 0.2% citric acid to the powder body, mixing and homogenizing, and measuring their effects on the comprehensive score.

[0089] The sensory evaluation criteria for spirulina protein solid beverages were developed with reference to national standards such as GB / T 29602-2013 (Solid Beverages) and GB / T 31326-2014 (Plant-Based Beverages). The evaluation panel, composed of an equal number of men and women, evaluated the products based on taste (20 points), texture (20 points), aroma (20 points), color (20 points), and solubility (20 points). No markings that could affect the fairness of the evaluation were applied during the evaluation process.

[0090] As a flavoring agent for solid beverages, erythritol can provide appropriate sweetness, improve taste and maintain low calorie characteristics when added in appropriate amounts. When the amount of erythritol added is too little, it cannot provide sufficient sweetness, the taste is bland, and it cannot balance the flavors of other ingredients, resulting in a poor overall taste. When the amount of erythritol added is 7%, it tastes sweet and sour, has a refreshing taste, a harmonious smell, and a uniform color. However, when the amount of erythritol added is greater than 7%, the beverage tastes too sweet, affecting the balance of taste and flavor, and covering up the unique flavors of the beverage itself, such as wolfberry and ophiopogon ( Figure 3 (a)). Figure 3 As shown in (b), with the increase of erythritol addition, the sensory score first increased and then decreased. When the addition amount was 7%, the comprehensive performance was the best, with significance (P<0.05). It had unique aromas such as wolfberry and ophiopogon, uniform color, and moderate sourness and sweetness.

[0091] Citric acid is a commonly used acidulant in solid beverages. It can give the beverage a refreshing sour taste, enhance the flavor, and synergistically enhance other flavor substances to make the taste richer. When the amount of citric acid added is too little, the whole flavor is monotonous and the sour and sweet are unbalanced. When the amount of citric acid added is 0.25%, the beverage has a suitable sour and sweet taste, an overall sweet smell, a harmonious taste, and a uniform color. However, when the amount of citric acid added is greater than 0.25%, the beverage is too sour and astringent, which masks the other flavors ( Figure 3 (c)). Figure 3 As shown in (d), with the increase of citric acid addition, the sensory score first increased and then decreased. When the addition amount was 0.25%, the comprehensive performance was the best, which was significant (P<0.05). It had unique aromas such as wolfberry and ophiopogon, rich taste and uniform color.

[0092] As a filler for solid beverages, polydextrose can improve volume, taste and stability when added in appropriate amounts, while also providing dietary fiber. Adding too little can't achieve the desired filling effect, resulting in a thin taste for the beverage, affecting the uniformity and stability of the beverage. When the polydextrose addition is 14%, the taste is better, the flavor is harmonious, and it dissolves quickly. However, when the polydextrose addition is greater than 14%, the powder becomes coarse, granular, and lumpy, the dissolution properties are reduced, and the beverage becomes too viscous, affecting the taste and state of the beverage. Figure 3 (e)). Figure 3As shown in (f), with the increase of the amount of polydextrose added, the sensory score of the solid beverage first increased and then decreased. When the addition amount was 14%, the comprehensive performance was the best, with unique aromas such as wolfberry and ophiopogon, and good dissolution properties.

[0093] (3) Determination of properties of functional beverage powder

[0094] ① Determination of angle of repose

[0095] In a calm state, the angle between the inclined surface of the powder pile and the horizontal surface at the bottom is defined as the angle of repose. Pour 5g of powder through a funnel onto a horizontal surface so that the powder naturally piles up. Measure the height and radius of the powder pile and calculate according to Formula 4:

[0096] θ(°)=tan -1 (h / R) (4)

[0097] Where: θ-angle of repose, °;

[0098] h-powder pile height, cm;

[0099] R-powder pile radius, cm.

[0100] ②Determination of bulk density

[0101] Accurately weigh 2g of powder, transfer it into a 10mL graduated cylinder, shake it horizontally to make the powder surface flat, record the volume, and calculate the volume according to the formula.

[0102] Formula 5 calculates the bulk density:

[0103]

[0104] Where: m-powder mass, g;

[0105] V-powder volume, mL.

[0106] ③Tap density determination

[0107] Accurately weigh 2g of powder and transfer it into a 10mL graduated cylinder. Hold the graduated cylinder and gently vibrate it on a thick rubber pad to prevent the surface from loosening until the volume stops decreasing. Read the volume at the surface level of the powder after tapping and calculate the tap density according to Formula 6:

[0108]

[0109] Where: m-powder mass, g;

[0110] V-powder volume, mL.

[0111] The angle of repose, θ = 40°, is the boundary between sticky and non-sticky powders. The smaller the angle of repose, the greater the powder's flowability. The bulk density and tap density of a powder are important physical parameters describing its packing properties. They reflect the compactness of the powder under different packing conditions. Bulk density and tap density can indicate the powder's filling properties and particle porosity. Powders with lower bulk density typically have larger interparticle voids. Higher bulk density and tap density indicate better filling properties and lower particle porosity. Monitoring bulk density and tap density can ensure the uniformity and stability of powder products. As shown in Table 3, the angle of repose of the solid powder first decreases and then increases with increasing polydextrose addition. When the addition level is less than 16%, the angle of repose is less than 40°. Therefore, the solid beverage is a non-sticky powder with good flowability, and the angle of repose is minimized at an addition level of 14%. As the amount of polydextrose added increases, the bulk density continues to decrease. When the addition amount is 10%, the maximum bulk density is 0.449±0.012g / mL. There is no significant difference in bulk density between the two addition amounts of 12% and 14%. When the polydextrose addition amount increases from 10% to 18%, the tap density first increases and then decreases. The addition amount is 12%, which is the maximum, at 0.585±0.001g / mL. As the addition amount continues to increase, the tap density decreases, indicating that the gaps between the powder particles are getting larger and larger. Taking into account the sensory scores and powder characteristics, it is appropriate to select a polydextrose addition amount of about 14%.

[0112] Table 4 Analysis of properties of solid beverage powder

[0113]

[0114] Note: Different lowercase letters indicate significant differences between groups (P<0.05)

[0115] Example 4 Functional evaluation of spirulina protein functional beverage

[0116] (1) Animal experimental methods

[0117] After one week of adaptive feeding, the mice were randomly divided into four groups according to their body weight: normal group (NC), model group (MC), positive drug metformin group (PC) and spirulina protein functional drink (SPSD), with 6 mice in each group.

[0118] The normal group was fed with ordinary feed, and the other groups were fed with high-fat and high-sugar feed (HSHF) for 4 consecutive weeks before modeling. After the model was established, each mouse was gavaged with the corresponding intervention substance at 1% of its body weight for 4 weeks:

[0119] NC group: normal mice received only normal diet;

[0120] MC group: diabetic mice received a high-sugar and high-fat diet;

[0121] PC group: diabetic mice received a high-sugar and high-fat diet and 200 mg / kg body weight metformin (10%);

[0122] SPSD group: diabetic mice received a high-sugar and high-fat diet and 1.5 g / kg body weight of the product.

[0123] (2) Effect on fasting blood glucose (FBG) in diabetic mice

[0124] like Figure 4 As shown in (a), at week 0 of oral administration, the FBG levels of mice in the modeling group were all higher than 11.1 mmol / L compared to the NC group, indicating successful modeling. During the intervention period, the FBG levels of mice in the MC group were significantly higher than those in the NC group (P < 0.05). Starting from week 2, the FBG levels of mice receiving SPSD via oral administration decreased significantly (P < 0.05). After 4 weeks of oral administration, the FBG levels of mice in each intervention group were significantly lower than those in the MC group (P < 0.01). The FBG levels of mice in the SPSD group were significantly decreased (P < 0.01) and were similar to those in the PC group. This indicates that after 4 weeks of oral administration of the functional beverage, the hyperglycemic symptoms of T2DM mice can be significantly alleviated.

[0125] (3) Effect of Spirulina Protein on Glucose Tolerance (OGTT) in Diabetic Mice

[0126] Depend on Figure 4 (b) It can be seen that in week 0, i.e., before intervention, the blood glucose levels of mice in each group rose rapidly within 0.5 h after oral administration of glucose, and then gradually dropped within 1 h. At each time point, the blood glucose level of the modeling group was the maximum value during the observation time. Figure 4 (c) The results showed that compared with the NC group, the AUC values ​​of the other groups increased significantly (P<0.01), indicating that the blood glucose balance of the model group mice was disrupted and the blood glucose regulation ability of T2DM mice was significantly impaired. After 4 weeks of SPSD intervention, the blood glucose level of mice reached a peak within 0.5 hours after oral administration of glucose solution, and then gradually decreased after 1 hour. After 2 hours, the blood glucose level of mice in the NC group gradually returned to the normal range, and the blood glucose level of the SPSD group recovered faster, while the blood glucose level of mice in the MC group remained at a high level, indicating that their blood glucose homeostasis was disrupted ( Figure 4 (d)). Figure 4 (e) shows that compared with the MC group, the AUC values ​​of the SPSD group were significantly lower than those of the MC group (P<0.01), indicating that functional drinks can improve the glucose tolerance of T2DM mice.

[0127] The above embodiments illustrate and describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention and are not intended to limit the scope of the present invention in any way. Various changes and modifications may be made to the present invention without departing from the scope of the present invention, and all such changes and modifications fall within the scope of the claims.

Claims

1. A novel blood sugar-lowering spirulina protein functional beverage, characterized in that: The functional beverage contains spirulina protein, which is extracted from Spirulina platensis.

2. The novel hypoglycemic spirulina protein functional beverage according to claim 1, characterized in that: The spirulina protein is prepared according to the following method: After the spirulina is wall-broken, the pH value of the wall-broken spirulina solution is adjusted to 7-12, the processing temperature is 15-45°C, the material-liquid ratio is adjusted, the solution is stirred and centrifuged to obtain the supernatant, and the solution is separated by coordinated salting out using an isoelectric precipitation method, desalted, concentrated, small molecular impurities are removed, sterilized, and freeze-dried to obtain the spirulina protein powder.

3. The novel hypoglycemic spirulina protein functional beverage according to claim 2, characterized in that: The functional beverage is composed of the following raw materials in parts by weight: 15-30 parts of spirulina protein, 10-20 parts of astragalus polysaccharide, 5-15 parts of ophiopogon polysaccharide, 7-17 parts of kudzu root flavonoids, 7-17 parts of wolfberry polysaccharide, 5-15 parts of polygonatum polysaccharide, 5-9 parts of erythritol, 0.1-0.3 parts of citric acid, and 10-18 parts of polydextrose.

4. The method for preparing the functional beverage according to claim 3, characterized in that: Here are the steps: (1) The spirulina protein, astragalus polysaccharide, ophiopogon polysaccharide, kudzu root flavonoids, wolfberry polysaccharide, and polygonatum polysaccharide were ultrafinely ground at low temperature and sieved to obtain 200-mesh fine powder; (2) The raw material powder prepared in step (1) is weighed according to the following proportions by weight: 15-30 parts of spirulina protein, 10-20 parts of astragalus polysaccharide, 5-15 parts of ophiopogon polysaccharide, 7-17 parts of kudzu root flavonoids, 7-17 parts of wolfberry polysaccharide, and 5-15 parts of polygonatum polysaccharide. The weighed raw material powders are mixed and sieved; (3) The mixed powder sieved in step (2) is thoroughly mixed again, and auxiliary materials such as 5-9 parts of erythritol, 0.1-0.3 parts of citric acid, and 10-18 parts of polydextrose are added, and the mixing is continued; (4) The mixed powder in step (3) is subjected to ultraviolet sterilization treatment and fully sealed quantitative sub-packaging in a sterile environment; (5) The fully sealed products are packaged into bags as required, and the products are tested in accordance with the requirements of GB / T 29602. Qualified products are stored in the warehouse.

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