High-stability functional beverage based on citric acid and maltodextrin dynamic cross-linked microencapsulated spirulina and preparation method of high-stability functional beverage

Abstract

The invention discloses a high-stability functional beverage based on citric acid and maltodextrin dynamic cross-linked microencapsulated spirulina and a preparation method of the high-stability functional beverage, and belongs to the technical field of functional food processing. Aiming at the problems of flavor defect, easy degradation of active ingredients, poor storage stability, narrow system adaptability and the like of the existing spirulina beverage, the invention initiates a citric acid and maltodextrin dynamic crosslinking wall material system, constructs a core-shell structure microcapsule, and combines a synergistic process of spray drying, gradient homogenization, staged sterilization and the like to prepare the spirulina beverage. The efficient embedding and function maintenance of the spirulina in various beverage substrates are realized. A dense ester bond network is formed on the basis of dynamic esterification reaction of maltodextrin hydroxyl and citric acid carboxyl, a cross-linking degree detection method is optimized, and nonlinear improvement of a synergistic technical effect is realized. The process is stable and controllable, the microcapsule embedding rate is high, the method is suitable for multiple systems such as yoghourt, fruit juice and vegetable protein beverages, and the method can be widely applied to the field of functional foods and has remarkable industrialization value.

Description

Technical Field

[0001] This invention relates to the field of functional food processing technology, and in particular to a highly stable functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin, and its preparation method. Background Technology

[0002] Spirulina ( Spirulina Spirulina (sp.) is a high-protein, highly active microalgae resource, rich in phycocyanin, gamma-linolenic acid, chlorophyll, and various minerals. It possesses physiological functions such as antioxidation, anti-inflammation, and immune enhancement, making it an ideal nutritional fortifier for functional beverages. For example, Chinese invention patent CN106343020A provides a spirulina yogurt and its production method. This invention mixes raw milk with spirulina powder in a specific ratio. By adding spirulina, the nutrients in the spirulina are mixed with the raw milk, resulting in a yogurt rich in protein, polysaccharides, fatty acids, vitamins, and trace elements. However, existing spirulina beverages face three major technological bottlenecks in industrial application: First, the fishy smell (trimethylamine, aldehydes) and bitterness (phycocyanin degradation products) are difficult to mask, resulting in poor flavor when directly added and mixed. Existing single encapsulation technologies (such as sodium alginate encapsulation alone) only achieve a 50-60% odor masking rate, leading to low consumer acceptance. Second, the active ingredients are sensitive to heat and oxygen. Ordinary processing techniques (such as single high-temperature sterilization) result in a 40-60% loss rate of phycocyanin, and the activity retention rate is less than 60% after 7 days of storage. Third, spirulina particles have a high density (1.2-1.3 g / cm³). 3 It is prone to settling in beverages, has poor system compatibility, and its product shelf life is generally shorter than 7 days.

[0003] In order to improve the stability of the components of spirulina in the liquid system, the microcapsule embedding method is usually used in the prior art, and polysaccharides or protein substances (such as gum arabic, gelatin, etc.) are used as wall materials to prepare microcapsule powder through physical adsorption, covalent cross-linking or spray drying. For example, the Chinese invention patent with the publication number CN115844006A discloses a kale spirulina microcapsule, a preparation method and application. The invention uses a new microcapsule preparation process to prepare a microcapsule product with spirulina powder and kale powder as the first embedding core raw material and dietary fiber as the second embedding core raw material. However, the invention uses sodium alginate, konjac glucomannan and calcium carbonate for static embedding. Static embedding is usually a one-time reaction at a fixed temperature / pH, and the molecular dynamics activity is low, the ester bond formation is uneven, the wall material has poor compactness (the ester bond density is only 71% of the dynamic cross-linking), and the dual protection of odor and activity cannot be achieved. In addition, the existence of a large amount of protein, pigment and polysaccharide and other reactive functional groups in the spirulina powder body makes the chemical reaction of the system uneven, and the cross-linking density is difficult to accurately control, resulting in significant differences in the stability of the obtained microcapsules.

[0004] In summary, in view of the technical problems existing in the prior art, a functional beverage based on spirulina is designed and provided, which realizes the synergistic improvement of the flavor, stability and functionality of the spirulina beverage, and has important significance for expanding the application of spirulina. SUMMARY

[0005] In view of the above-mentioned defects of the prior art, in the first aspect of the present application, a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and malt dextrin is provided, which comprises a composite beverage base and dynamic cross-linking microencapsulated spirulina powder dispersed therein; the dynamic cross-linking microencapsulated spirulina powder comprises a core material and a dynamic cross-linking material as a wall material; wherein the core material is spirulina powder, and the dynamic cross-linking material is an ester bond cross-linking network formed by citric acid and malt dextrin.

[0006] Preferably, the effective content of spirulina in the functional beverage is 0.8-2.5 g / 100 mL.

[0007] Preferably, the average particle size of the dynamic cross-linking microencapsulated spirulina powder is 2-8 μm, the embedding rate is ≥92%, and the absolute value of Zeta potential is ≥30 mV.

[0008] Preferably, the mass ratio of spirulina to malt dextrin is 1:1.2-1:1.8, and the addition amount of citric acid is 8%-12% of the weight of spirulina.

[0009] Preferably, the dynamic crosslinking material has an ester bond characteristic absorption peak at 1735 cm -1 Preferably, the dynamic crosslinking material has an ester bond characteristic absorption peak at 1735 cm

[0010] Preferably, the dynamic crosslinking material has an ester bond characteristic absorption peak at 1735 cm

[0011] Preferably, the composite beverage base includes at least one of a yogurt base, a fruit juice base, a plant protein beverage base, and a sports beverage base.

[0012] Compared with the traditional static esterification network, the dynamic crosslinking system of the present application can maintain good dispersibility and storage stability in different pH, electrolyte strength and protein / polysaccharide complex environments, and has broad spectrum applicability and system compatibility. For the yogurt base, in the acidic high-protein environment, the traditional static crosslinking microcapsule is easily affected by protein and polycarboxyl competitive adsorption, and aggregation or flocculation occurs; while the dynamic reversible ester bond network of the present application can reversibly reorganize intramolecularly at low pH, and maintain uniform particle size through micro-dynamic adjustment of crosslinking density, with suspension stability > 30 d without obvious sedimentation, and the system appearance is uniform and delicate. For the fruit juice base, the dynamic crosslinking network has the structure recovery characteristics of acid self-adaptation, and can maintain > 85% of the complete embedding rate and the optical stability of the transparent system in the fruit acid medium, significantly improving the shelf life stability of the fruit type functional beverage. For the plant protein base, due to the presence of a large number of hydrophobic residues and negative charge groups in the plant protein system, the traditional microcapsule is easy to occur surface adsorption and aggregation; the dynamic crosslinking structure constructed by the reversible ester bond and hydrogen bond in the present application shows the interface strain self-adaptation ability, and can maintain a narrow particle size distribution in the protein and polysaccharide coexisting system, without obvious stratification or agglomeration after storage for 14 d. For the sports beverage base, in the high ionic strength system, the charge shielding effect of the conventional static microcapsule leads to a significant decrease in stability, while the ion adaptability of the dynamic crosslinking microcapsule of the present application makes it maintain a uniform particle size distribution in the Na + / K +The particle size remains stable, the Zeta potential is maintained in the range of 35-40 mV, and the system does not show sedimentation or stratification after being stored for 30 days. The dynamic cross-linking microcapsule powder prepared in the application exhibits excellent structural self-adaptability, thermal oxygen stability and dispersion uniformity in various systems of acid, protein, fructose and electrolyte, and realizes the universal stability that cannot be achieved by traditional static cross-linking systems in multi-substrate beverages. In addition, a suitable food-grade stabilizer can be added according to actual conditions or production needs, including single or complex types.

[0013] Preferably, the dynamic cross-linking microencapsulated spirulina powder has pH-responsive sustained-release properties in a simulated gastrointestinal environment.

[0014] The index of the above-mentioned pH-responsive sustained-release properties includes that the release rate of the active ingredient is ≤30% in a stomach environment with a pH value of 1.2 and containing 0.3% pepsin for 2 h, and the release rate of the active ingredient is ≥70% in an intestinal environment with a pH value of 7.4 and containing 0.5% trypsin for 4 h.

[0015] In the second aspect of the application, a preparation method of a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina of citric acid and malt dextrin is provided, including the following steps: (1) Preparation of dynamic cross-linking microcapsule powder: First, weigh each raw material according to the proportion, mix spirulina powder, malt dextrin and water until completely dissolved; add citric acid and complete the dynamic cross-linking reaction; secondly, characterize the Fourier transform infrared spectrum and acid swelling degree of the dynamic cross-linking product to meet the production indicators; finally, the qualified dynamic cross-linking liquid is prepared by spray drying and detection to obtain the dynamic cross-linking microcapsule powder; (2) Pretreatment of composite beverage substrate: According to the type of the selected beverage, the composite beverage substrate is pretreated to stabilize the system; the pretreatment includes at least one of pasteurization, homogenization and pH adjustment; (3) Beverage compounding and synergistic post-treatment: First, based on the target spirulina effective content, the dynamic cross-linking microcapsule powder is mixed with the composite beverage substrate to make it uniformly dispersed; then, treatment is carried out under gradient pressure to complete homogenization; further, antioxidant is added after pasteurization and ultra-high temperature instant sterilization; finally, sterile filling is carried out; (4) Quality detection: the product is subjected to quality detection to obtain a qualified product, i.e. a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina of citric acid and malt dextrin.

[0016] Preferably, in step (1), the pH of the dynamic cross-linking reaction is 4.0-4.5, the reaction temperature is 50-55 ℃, and the reaction time is 20-30 min.

[0017] In the present application, the spirulina powder meeting the raw material index can be directly used, or the spirulina raw powder can be processed into spirulina powder meeting the raw material index by pretreatment. For example, the spirulina raw powder is vacuum dried at 60-65 ℃ and a vacuum degree of -0.08 to -0.09 MPa for 4-6 h until the moisture content is ≤5%, and then the powder is crushed by a super micro grinder and sieved through a 200-mesh sieve (particle size ≤75 μm). For the spirulina raw powder, the drying and crushing steps are conventional pretreatment processes, and the main purpose is to improve the uniformity of the powder and the subsequent reaction contact efficiency, which can be adjusted within the range without affecting the performance of the final product.

[0018] In the dynamic cross-linking reaction process, the mass ratio of spirulina to maltodextrin, the addition amount of citric acid, pH, temperature and reaction time are key parameters for realizing the stability of the present application. For example, when the citric acid is less than 6% or the pH is higher than 5.0, the network of ester bonds cannot be formed, and the cross-linking density of the microcapsule wall material is insufficient; when the temperature exceeds 60 ℃ or the reaction time exceeds 40 min, protein denaturation and a decrease in the embedding rate are easily caused; therefore, the above parameters have significant technical relevance to the formation of a cross-linked structure with excellent acid resistance and stability. Under the above process conditions, a person skilled in the art can adjust the pH of the system within the target range by appropriate means, for example, by using 1 mol / L of HCl or NaOH, etc.

[0019] In the detection and property control of the cross-linked structure, a person skilled in the art can detect the acid swelling degree by the swelling equilibrium method. For example, in actual operation, 0.5 g of dried powder after cross-linking is taken, 10 mL of citric acid-sodium citrate buffer with a pH of 3.0 is added, and the mixture is oscillated in a 37 ℃ constant temperature water bath for 2 h (oscillation rate 150 rpm), and then centrifuged at 3000 rpm for 10 min, and the sediment volume (V1) is measured. V 1) and the initial loose volume (V0) are determined, and the acid swelling degree is calculated according to the formula "acid swelling degree = (V1-V0) / V0 x 100%". V V V V 0×100%" is calculated, and the result meeting the ≤55% index of the present application is qualified.

[0020] Preferably, in the step (3), the step of gradient homogenization comprises: first homogenizing twice at a pressure of 18-22 MPa, each time for 5-8 min, and then homogenizing once at a pressure of 30-35 MPa for 3-5 min, and the homogenization temperature is controlled at 40-45 ℃.

[0021] Preferably, in the step (3), the step of segmented sterilization comprises: first pasteurizing the beverage at 65 ℃ for 20-30 min, and then ultra-high temperature instant sterilizing for 5-10 s at 135 ℃, and rapidly cooling the sterilized beverage to below 25 ℃.​​​

[0022] Unlike traditional single-stage homogenization, the gradient homogenization of the present application can induce the dynamic ester bond network of the microcapsule wall material to partially and reversibly break at a medium pressure (18-22 MPa) under the action of grading pressure and temperature control, forming a transient rheological window; the subsequent high-pressure stage promotes the rapid recombination of the reversible ester bond, thereby achieving structural self-repair at the microscale, allowing the microcapsule to maintain an intact morphology in a strong shear environment. As presented in one or more embodiments of the present application, the microcapsule breakage rate after the process is ≤3%, which is significantly lower than that of a conventional crosslinking system (breakage rate of about 15-20%), and the system stability is improved by about 3 times. In addition, the reversibility of the dynamic crosslinking structure exhibits a molecular slip effect under high pressure, avoiding the brittle fracture of conventional static ester bond structures; this feature exhibits good universality in yogurt-type, juice-type, and high-electrolyte sports drinks, allowing the finished beverage to have no sedimentation or flocculation phenomenon within 30 d of storage. In the beverage compounding and synergistic post-processing step, the gradient homogenization pressure and the number of stages are key process parameters that directly affect the dispersion of the microcapsule and the breakage rate of the wall material; when the homogenization pressure is lower than 18 MPa, the dispersion is uneven, and when it is higher than 35 MPa, the microcapsule wall material is prone to breakage. After controlling the above parameters, the microcapsule breakage rate is ≤3%, and the stability of the beverage system is significantly improved.

[0023] In the present process, the combination of "low-temperature pasteurization + high-temperature instant" sterilization is a key step that can maximize the maintenance of phycocyanin activity while ensuring microbial safety; the sterilization temperature and time should be adjusted within the above range, and exceeding this range will result in a significant decrease in activity. The dynamic crosslinking microcapsule powder exhibits excellent thermal stability and oxygen protection during the above-mentioned segmented sterilization process, and its dynamic recombination characteristics of ester bonds allow it to self-regulate the intermolecular stress distribution under high-temperature instantaneous conditions, thereby reducing wall material breakage and core material leakage, improving the encapsulation rate, and reducing the loss rate of phycocyanin activity.

[0024] Based on the above technical solutions and process descriptions, the design concept and principle of the present application are as follows: The present application adopts a process of dynamic crosslinking of spirulina with citric acid and maltodextrin, constructing a self-regulating crosslinking network suitable for spirulina systems. This network has both stable ester bonds and dynamic exchangeable bonds (such as carboxylate and hydroxyl hydrogen bond pairs) in its molecular structure. This feature allows the system to have molecular rearrangement ability during subsequent drying, dissolution, homogenization, and other processes, automatically repairing crosslinking defects, thereby significantly improving the integrity and compactness of the microcapsule membrane, and solving the following technical problems of traditional processes: (1) Because the components such as proteins, pigments and polysaccharides in spirulina are prone to non-selective side reactions with cross-linking agents, resulting in uneven distribution of cross-linking density; this invention establishes a controllable dynamic cross-linking system of citric acid and maltodextrin under complex biological matrix conditions, and achieves adjustable cross-linking density and uniform structure through process parameter optimization, thus avoiding non-selective cross-linking. (2) In view of the problems that traditional FTIR detection is easily interfered with by the absorption peaks of phycocyanin and lipid carbonyl, and it is difficult to quantitatively determine the degree of ester bond formation and the integrity of cross-linking network; this invention constructs a detection system that can accurately identify and verify the formation of dynamic ester bond network, realize the quantitative correlation between dynamic cross-linking degree and product physical stability, and provide controllable indicators for the production process. (3) By improving the dispersibility and thermo-oxidative stability of spirulina in acidic beverages through dynamic cross-linked microcapsule structure, the technical problems of sedimentation, flocculation and activity loss are effectively reduced, thereby obtaining functional beverage base with high encapsulation rate, uniform appearance and stable shelf life.

[0025] This invention, based on beverage compounding and synergistic post-processing, achieves high dispersibility, high activity retention, and excellent shelf-life stability in microalgae functional beverage systems through the synergistic combination of dynamic cross-linked microcapsule structure design, gradient homogenization pressure control, and segmented sterilization protection mechanisms. It solves the technical problems of traditional microcapsules being prone to structural collapse and severe activity loss in high-shear, high-temperature, and acidic systems, and has significant technological advancements and industrial application value.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention overcomes the bottleneck of achieving homogenized crosslinking in the complex environment of Spirulina and constructs a dynamically self-regulating crosslinking system. By introducing a dynamic and reversible ester bond and hydrogen bond synergistic network, the crosslinking system possesses molecular self-rearrangement and defect self-repair capabilities in complex environments such as Spirulina proteins, pigments, and polysaccharides. This structure can dynamically adjust the crosslinking density according to the pH and temperature of the reaction system, achieving homogenization of crosslinking and improved network integrity. FTIR ester bond peak quantitative results show that the esterification absorption intensity is increased by about 40%, and the acid swelling degree is reduced by more than 30%, which is significantly better than the traditional system.

[0027] This invention achieves broad-spectrum adaptation and stable dispersion of dynamically cross-linked microcapsule powder in various types of beverage substrates. The prepared dynamically cross-linked microencapsulated spirulina powder maintains stable particle size, absolute Zeta potential ≥30 mV, and shows no sedimentation after 30 days of storage in yogurt, fruit juice, plant protein, and sports drinks under different pH, electrolyte concentrations, and high protein environments. Furthermore, its reversible ester bond network can spontaneously recombine under acidic conditions and maintain charge shielding balance in high ionic strength environments, exhibiting excellent structural self-adaptation and system compatibility. This comprehensively solves the key problems of easy flocculation, easy stratification, and severe activity loss in microalgae functional beverages.

[0028] The application proposes a synergistic mechanism of gradient homogenization and dynamic crosslinking structure, realizing self-repair and structural integrity of microcapsules under high shear conditions. Gradient homogenization with hierarchical pressure control induces partial reversible fracture of dynamic ester bond network at the medium pressure stage, forming a transient rheological window; at the high pressure stage, it promotes rapid recombination of ester bonds, realizing structural self-repair at the micro level. Thus, the microcapsule breakage rate is ≤3%, which is significantly lower than that of conventional systems, and the system viscosity is stable after homogenization, and the dispersion is excellent. The synergistic design of gradient homogenization and dynamic crosslinking belongs to a new mechanism of "dynamic reconfiguration rheological stabilization" in theory, which has theoretical innovation.

[0029] The application establishes a segmented sterilization protection mechanism suitable for dynamic crosslinking systems, realizing the dual maintenance of phycocyanin activity and wall material structure. By using the segmented sterilization process combined with the reversibility of the crosslinking network, the wall material can quickly rearrange molecules under thermal stress to disperse local stress, thereby reducing core material leakage and membrane layer fracture. The phycocyanin activity retention rate and embedding rate after sterilization are high, realizing the compatibility of high-temperature sterilization and high-activity maintenance, and providing key technical support for the industrialization of microalgae beverages. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 : The sample prepared according to the embodiment 1 of the application. DETAILED DESCRIPTION

[0031] The application will be further described by way of examples, but the application is not limited to the examples. The experimental methods in the following examples are not specified, and the methods are selected according to conventional methods and conditions, or according to the instructions of the commodity.

[0032] In the following examples, the raw material selection and standards are shown in Table 1: Table 1: Raw material selection and standards

[0033] In the examples, each raw material is selected to meet the requirements of food safety, nutritional value, etc.

[0034] In the examples, the preparation method of the high-stability functional beverage based on dynamic crosslinking microcapsulation of spirulina with citric acid and maltodextrin is as follows: (1) Preparation of dynamic crosslinking microcapsule powder Spirulina powder pretreatment: Spirulina raw powder was spread on the tray of vacuum drying box (thickness 1 cm), the temperature was set to 60-65℃, the vacuum degree was set to -0.08 to -0.09 MPa, and drying was performed for 4-6 h; the powder was turned over every 2 h to avoid local clumping, and the moisture content after drying was ≤5% (5 g of sample was taken, the moisture content was determined by a rapid moisture meter, three times in parallel, and the error was ≤0.2%). The dried powder was put into a super micro grinder (rotating speed 30000 rpm) and ground for 15-20 min; 25℃ cooling air was introduced to prevent the powder from overheating (the denaturation temperature of phycocyanin is ≥70℃). Further, a 200 mesh standard sieve (pore size 75 μm) was used for screening for 10 min (frequency 50 Hz); the residues (particle size >75 μm) on the sieve were returned to the grinder for regrinding to ensure that the passing rate was ≥95%.

[0035] Dynamic cross-linking solution preparation: Spirulina powder and malt dextrin were weighed according to a mass ratio of 1:1.2-1.8, distilled water was added (solid-liquid ratio 1:10-1:15), and the mixture was poured into a constant temperature water bath stirring tank, the temperature was set to 40-50℃, the rotating speed was set to 300-500 rpm, and stirring was performed for 30-40 min until the solution was uniform and transparent (no residue was found after 40 mesh sieve filtration). Further, 8%-12% of citric acid based on the weight of spirulina was added, and 1 mol / L HCl / NaOH was used to adjust the pH value to 4.0-4.5; then, the temperature was increased to 50-55℃, the rotating speed was kept at 300 rpm, and constant temperature reaction was performed for 20-30 min to form an ester bond cross-linking network.

[0036] Cross-linking structure detection and property control: Fourier transform infrared spectrometer and acid swelling degree method were used to detect the cross-linking effect, specifically as follows: Fourier transform infrared spectrometer detection: 2 mL of cross-linking solution was taken, and vacuum drying was performed at 60℃ until the weight was constant; 1 mg of dried powder was ground with 100 mg of KBr (spectral purity) to make a tablet (10 MPa, 30 s); Fourier transform infrared spectrometer scanning (4000-400 cm -1 , resolution 4 cm -1 -1), 1735 cm -1 -1 ester bond peak absorbance ≥0.8 was qualified; Acid swelling degree detection: 0.5 g of cross-linked dry powder was taken, 10 mL of citric acid-sodium citrate buffer (0.1 mol / L) with a pH value of 3.0 was added; constant temperature water bath oscillation was performed at 37℃ for 2 h (150 rpm), and centrifugation was performed at 3000 rpm for 10 min; the volume of the precipitate (1) and the initial loose volume (0) were determined, and the acid swelling degree was calculated according to the formula "acid swelling degree=(1-0) / 0x100%" (result ≤55% was qualified). V V V V V ​​​​​

[0037] Spray drying: Start the centrifugal spray dryer, set the inlet temperature 160-175℃, outlet temperature 92-98℃, inlet air speed 30-35 m / s, outlet air speed 15-20 m / s, atomization pressure 0.2-0.3 MPa; after the temperature is stable (fluctuation ≤2℃), feed. The crosslinking liquid is introduced by peristaltic pump, and the feeding rate is controlled at 6-7 mL / min (speed up when the outlet temperature >98℃, and slow down when <92℃); clean the residual powder on the tower wall every 30 min to avoid caking. Collect the powder through a 100 mesh sieve, detect the average particle size, embedding rate and Zeta potential of the undersize powder, and place it in a vacuum dryer (humidity ≤30%) for standby. The specific detection method is: Average particle size: detected by laser diffraction particle size analyzer, particle size in 2-8 μm is qualified; Embedding rate: free phycocyanin is measured by ultraviolet spectrophotometer (620 nm), and embedding rate ≥92% is qualified; Zeta potential: measured by Malvern potential instrument, when the absolute value ≥30 mV, it is qualified.

[0038] (2) Pretreatment of composite beverage base: Yogurt base: fresh milk (milk protein ≥3.0%, fat 1.0%-3.0%) is sterilized at 95℃ for 5 min, then inoculated with Lactobacillus bulgaricus and Streptococcus thermophilus (1:1, inoculation amount 2%-3%) after cooling to 43℃, and fermented at 42-43℃ for 4-6 h to pH 4.2-4.4. After fermentation, break emulsion at 100-150 rpm for 10-15 min, and viscosity is controlled at 2000-3000 mPa·s.

[0039] Juice base: juice stock (soluble solids ≥15 °Brix) is diluted to stock content ≥25%, and adjusted to soluble solids ≥12 °Brix. Then, homogenize once at 60-70℃, 15-20 MPa, and measure the clarity ≥90% by 620 nm spectrophotometer.

[0040] Plant protein base: plant protein liquid (protein ≥2.5%) is added with 0.1-0.3% of compound stabilizer (xanthan gum: guar gum = 1:2), and stirred at 70-75℃ for 30 min (300 rpm) until dissolved. Then, homogenize once at 60-70℃, 15-20 MPa, to ensure no particulate feeling.

[0041] Sports drink base: Dissolve glucose (2.0-3.0%), sodium chloride (0.05-0.08%), potassium chloride (0.02-0.03%), stir at 40 ℃ for 10 min (200 rpm). Adjust pH to 3.8-4.5 with 1 mol / L citric acid, and filter to clarify with a 0.45 μm microporous filter membrane.

[0042] According to the selected beverage type (yogurt, juice, plant protein or sports drink), the system is pretreated by adopting conventional processes such as pasteurization, homogenization and pH adjustment, etc.

[0043] (3) Beverage compounding and synergistic post-treatment Compounding and dispersion: Add the dynamic cross-linking microcapsule powder to the pretreated base at a ratio of 0.8-2.5 g / 100 mL (e.g. 1000 mL of yogurt plus 20 g of powder), stirring (200-300 rpm) while adding to avoid agglomeration. Then stir at 30-40 ℃ for 15-20 min to ensure full dispersion.

[0044] Gradient homogenization: Use a high-pressure homogenizer for step-by-step gradient processing: first homogenize at 18-22 MPa for 2 times (5-8 min each time), then perform secondary intensive homogenization at 30-35 MPa for 1 time (3-5 min), and complete the fine mixing of microcapsules and beverage base at 40-45 ℃.

[0045] Segmented sterilization and filling: First pasteurize at 65 ℃ for 30 min to kill non-heat-resistant bacteria (total bacterial count ≤100 CFU / mL), and avoid denaturation of phycocyanin through mild treatment; then perform 10 s of ultra-high temperature instantaneous sterilization at 135 ℃ to effectively kill heat-resistant spore bacteria while maintaining an activity retention rate of phycocyanin ≥85%. After sterilization, quickly cool to below 25 ℃, add 0.02-0.05% ascorbyl palmitate (food grade) as a fat-soluble antioxidant, stir uniformly, and then use a sterile filling machine (filling environment cleanliness ≥100 grade) for filling, with a product volume error ≤±2%.

[0046] (4) Quality testing: Perform quality testing on the product, with the following indicators and methods: 1) 30-day storage stability Settlement observation: No visible settlement at 25 ℃ for 30 days, and centrifugal sedimentation rate ≤1.5% (3000 rpm / 10 min).

[0047] Viscosity change: The rate of change in viscosity measured by a rotational viscometer is ≤10%.

[0048] 2) Activity and flavor detection Phycocyanin retention rate: HPLC measurement of 30-day content, retention rate ≥ 85%.

[0049] DPPH scavenging rate: UV spectrophotometer (517 nm) measurement of scavenging rate ≥ 50%.

[0050] Flavor score: 10-person professional group score (color 20 points + flavor 40 points + mouthfeel 30 points + appearance 10 points), total score ≥ 85 points.

[0051] 3) Microcapsule pH-responsive sustained-release property The prepared microcapsules were added to simulated gastric juice environment (hydrochloric acid solution with pH value of 1.2 + 0.3% pepsin, 37°C) and intestinal juice environment (phosphate buffer with pH value of 7.4 + 0.5% trypsin, 37°C), and the release rate of phycocyanin after 2 h in gastric environment and 4 h in intestinal environment was measured.

[0052] According to the performance verification index, the qualified product, i.e. the high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and malt dextrin, was obtained.

[0053] Example 1 The present example provides a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and malt dextrin, which is a yogurt-based spirulina beverage prepared by the above process, and the parameters of each step are as follows: (1) Preparation of dynamic cross-linking microcapsule powder: Raw material preparation: Spirulina powder: protein content 62%, vacuum dried at 63°C and -0.085 MPa for 5 h (turn over every 2 h), ultra-micro pulverized (30000 rpm, 18 min, 25°C cooling air), and then passed through a 200-mesh sieve with a pass rate of 96% and a moisture content of 4.8%; Malt dextrin: DE value 12, in line with GB / T 20882.6-2021; Citric acid: purity 99.6%, in line with GB 1886.235-2016; Ascorbic acid palmitate: purity 98.5%, in line with GB 1886.230-2016.

[0054] Spirulina powder and malt dextrin were weighed according to the mass ratio of 1:1.5, distilled water was added (solid-liquid ratio 1:12), stirred at 45°C and 400 rpm for 35 min, and filtered through a 40-mesh sieve without residue; 10% of the weight of spirulina was added with citric acid, and the pH value was adjusted to 4.2 with 1 mol / L HCl, and the temperature was raised to 52°C and reacted at 300 rpm for 25 min. Cross-linking effect detection: Fourier transform infrared spectrometer scanning, 1735 cm -1Ester bond peak absorbance 0.85; acid swelling degree test results 52%, all qualified.

[0055] Centrifugal spray dryer parameters: inlet temperature 168°C, outlet temperature 95°C, air inlet speed 32 m / s, air outlet speed 18 m / s, atomization pressure 0.25 MPa, feed rate 6.5 mL / min (outlet temperature stabilized at 94-96°C), clean the tower wall every 30 min.

[0056] Powder detection: pass through a 100 mesh sieve, average particle size 5 μm, embedding rate 94%, Zeta potential absolute value 32 mV, placed in a humidity 28% vacuum dryer for standby.

[0057] (2) Yogurt base pretreatment: Take milk protein 3.2%, fat 2.0% fresh milk, 95°C sterilization for 5 min, cool to 43°C, inoculate Lactobacillus bulgaricus: Streptococcus thermophilus = 1:1 strain (inoculum 2.5%), 42.5°C fermentation for 5 h to pH 4.3, 120 rpm stirring for 12 min to break emulsion, viscosity 2500 mPa·s.

[0058] (3) Beverage compounding and synergistic post-treatment: Compound dispersion: add microcapsule powder to the yogurt base at a ratio of 2.0 g / 100 mL, stir at 250 rpm, stir at 35°C for 18 min, observe under 100x optical microscope without agglomeration.

[0059] Gradient homogenization: high-pressure homogenizer first 20 MPa for 2 times (6 min each time), then 32 MPa for 1 time (4 min), temperature 42°C, microcapsule breakage rate 2.5%.

[0060] Segmented sterilization and aseptic filling: 65°C pasteurization for 30 min (total bacterial count 80 CFU / mL), 135°C ultra-high temperature instantaneous sterilization for 10 s, quickly cooled to 22°C, added 0.03% ascorbyl palmitate, filled in 100-level sterile environment, volume error ±1.5%.

[0061] (4) Quality detection: Obtained qualified product, i.e. high stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin (yogurt base spirulina beverage), as shown in Figure 1 .

[0062] 30-day storage stability: no visible sedimentation at 25°C, centrifugal sedimentation rate 1.2%, viscosity change rate 8%.

[0063] Activity and flavor: phycocyanin retention rate 88%, DPPH clearance rate 53%, 10-person professional group score 88 points (color 18 points + flavor 38 points + texture 27 points + appearance 5 points).

[0064] Microcapsule pH response slow-release property: 15% phycocyanin release rate in stomach environment for 2 h, and 82% release rate in intestinal environment for 4 h.

[0065] Example 2 This example provides a high-stability functional beverage based on dynamic cross-linking microencapsulation of spirulina with citric acid and malt dextrin, which is a fruit juice-based spirulina beverage prepared by the above process flow, and the parameters of each step are as follows: (1) Preparation of dynamic cross-linking microcapsule powder: Raw material preparation: same as example 1.

[0066] Spirulina powder and malt dextrin were weighed according to the mass ratio of 1:1.3, distilled water was added (solid-liquid ratio 1:11), stirred at 45 ℃ and 400 rpm for 35 min, and filtered through a 40-mesh screen without residue; 8.5% citric acid based on the weight of spirulina was added, and the pH value was adjusted to 4.1 with 1 mol / L HCl, and the temperature was raised to 51 ℃ and reacted at 300 rpm for 22 min. Cross-linking effect detection: Fourier transform infrared spectrometer scanning, 1735 cm -1 ester bond peak absorbance 0.82; acid swelling degree detection result 54%, all qualified.

[0067] Centrifugal spray dryer parameters: inlet temperature 165 ℃, outlet temperature 93 ℃, inlet air speed 31 m / s, outlet air speed 16 m / s, atomization pressure 0.22 MPa, feeding rate 6.2 mL / min (outlet temperature stable at 94-96 ℃), clean the tower wall every 30 min.

[0068] Powder detection: pass through a 100-mesh screen, average particle size 4 μm, embedding rate 93%, Zeta potential absolute value 31 mV, placed in a humidity 28% vacuum dryer for standby.

[0069] (2) Pretreatment of fruit juice base: The fruit juice (soluble solids 16 °Brix) was diluted to 28% original juice content and 13 °Brix soluble solids, homogenized once at 65 ℃ and 18 MPa, and the clarity was 92%.

[0070] (3) Beverage compounding and synergistic post-treatment: Compound dispersion: add microcapsule powder to the fruit juice base at a ratio of 1.5 g / 100 mL, stir at 220 rpm, and stir at 32 ℃ for 16 min, and observe under a 100x optical microscope without agglomerates.

[0071] Gradient homogenization: 2 times of 19 MPa homogenization (5.5 min each time), 1 time of 31 MPa homogenization (3.5 min), temperature 41 ℃, microcapsule breakage rate 2.8%.

[0072] Segmented sterilization and sterile filling: 65 ℃ pasteurization for 30 min, 135 ℃ ultra-high temperature instant sterilization for 10 s, rapid cooling to 22 ℃, addition of 0.025% ascorbyl palmitate, 100-level sterile environment filling, volume error ±1.8%.

[0073] (4) Quality detection: The qualified product, i.e., a high-stability functional beverage (juice-based spirulina beverage) based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin, is obtained.

[0074] 30-day storage stability: no visible sedimentation at 25 ℃, centrifugal sedimentation rate 1.3%, viscosity change rate 9%.

[0075] Activity and flavor: phycocyanin retention rate 86%, DPPH clearance rate 51%, 10-person professional group score 86 points.

[0076] Microcapsule pH response slow-release property: 14% of phycocyanin release rate in stomach environment for 2 h, 80% of release rate in intestinal environment for 4 h.

[0077] Example 3 The present example provides a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin, which is a plant protein-based spirulina beverage, prepared by using the above process flow, and the parameters of each step are as follows: (1) Dynamic cross-linking microcapsule powder preparation: Raw material preparation: same as example 1.

[0078] Spirulina powder and maltodextrin were weighed according to the mass ratio of 1:1.7, distilled water was added (solid-liquid ratio 1:14), stirred at 45 ℃ and 400 rpm for 35 min, and filtered through a 40-mesh sieve without residue; 11% of the weight of spirulina was added citric acid, and the pH value was adjusted to 4.4 with 1 mol / L HCl, and the temperature was raised to 54 ℃ and reacted at 300 rpm for 28 min. Cross-linking effect detection: Fourier transform infrared spectrometer scanning, 1735 cm -1 ester bond peak absorbance 0.87; acid swelling degree detection result 50%, all qualified.

[0079] Centrifugal spray dryer parameters: inlet temperature 172°C, outlet temperature 97°C, inlet air speed 34 m / s, outlet air speed 19 m / s, atomization pressure 0.28 MPa, feed rate 6.8 mL / min (outlet temperature stabilized at 94-96°C), clean the tower wall every 30 min.

[0080] Powder detection: pass through a 100-mesh sieve, average particle size 7 μm, embedding rate 95%, Zeta potential absolute value 33 mV, placed in a humidity 28% vacuum dryer for standby.

[0081] (2) Pretreatment of plant protein base: Plant protein liquid (protein 2.7%) plus 0.2% compound stabilizer (xanthan gum: guar gum = 1:2), 72°C, 300 rpm stirring for 30 min, 68°C, 19 MPa homogenization once, no particulate feeling.

[0082] (3) Beverage compounding and synergistic post-treatment: Compound dispersion: add microcapsule powder to plant protein base at a ratio of 2.2 g / 100 mL, stir at 280 rpm, stir at 38°C for 19 min, observe under 100x optical microscope, no agglomerates.

[0083] Gradient homogenization: high-pressure homogenizer first 21 MPa for 2 times (7 min each time), then 34 MPa for 1 time (4.5 min), temperature 44°C, microcapsule breakage rate 2.3%.

[0084] Segmented sterilization and aseptic filling: 65°C pasteurization for 30 min, 135°C ultra-high temperature instant sterilization for 10 s, quickly cooled to 22°C, add 0.04% ascorbyl palmitate, fill in 100-level sterile environment, volume error ±1.6%.

[0085] (4) Quality detection: Obtain qualified products, i.e. high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin (plant protein base spirulina beverage).

[0086] 30-day storage stability: no visible sedimentation at 25°C, centrifugal sedimentation rate 1.1%, viscosity change rate 7%.

[0087] Activity and flavor: phycocyanin retention rate 90%, DPPH clearance rate 55%, 10-person professional group score 90 points.

[0088] Microcapsule pH-responsive sustained-release property: phycocyanin release rate in stomach environment for 2 h is 13%, release rate in intestinal environment for 4 h is 85%.

[0089] Example 4 The embodiment provides a high-stability functional beverage based on dynamic crosslinking microencapsulated spirulina with citric acid and malt dextrin, which is a spirulina beverage based on a sports beverage, and is prepared by using the above process flow, and parameters of each step are as follows. (1) Dynamic crosslinking microcapsule powder preparation: Raw material preparation: same as example 1.

[0090] Spirulina powder and malt dextrin are weighed according to a mass ratio of 1:1.4, distilled water (solid-liquid ratio 1:13) is added, stirring is carried out at 45 DEG C and 400 rpm for 35 min, and no residue is filtered through a 40-mesh screen; 9.5% of the spirulina by weight is added citric acid, 1 mol / L HCl is used to adjust the pH value to 4.3, and the temperature is raised to 53 DEG C, and constant temperature reaction is carried out at 300 rpm for 26 min. Crosslinking effect detection: Fourier transform infrared spectrometer scanning, 1735 cm -1 Ester bond peak absorbance 0.84; acid swelling degree detection result 53%, all qualified.

[0091] Centrifugal spray dryer parameters: inlet temperature 170 DEG C, outlet temperature 96 DEG C, air inlet speed 33 m / s, air outlet speed 17 m / s, atomization pressure 0.26 MPa, feeding rate 6.6 mL / min (outlet temperature is stabilized at 94~96 DEG C), and the tower wall is cleaned every 30 min.

[0092] Powder detection: pass through a 100-mesh screen, the average particle size is 6 μm, the embedding rate is 94%, and the Zeta potential absolute value is 32 mV, and it is placed in a humidity 28% vacuum dryer for standby.

[0093] (2) Sports beverage base pretreatment: Dissolve 2.5% of glucose, 0.06% of sodium chloride and 0.025% of potassium chloride, stir at 40 DEG C and 200 rpm for 10 min, adjust the pH value to 4.2 by 1 mol / L citric acid, and filter and clarify by a 0.45 μm microporous filter membrane.

[0094] (3) Beverage compounding and synergistic post-treatment: Compound dispersion: according to the proportion of 1.0 g / 100 mL, the microcapsule powder is added to the sports beverage base, 230 rpm stirring, 34 DEG C stirring for 17 min, and 100 times optical microscope observation shows no agglomerates.

[0095] Gradient homogenization: the high-pressure homogenizer is first homogenized at 18 MPa for 2 times (6.5 min each time), and then homogenized at 33 MPa for 1 time (3.8 min), and the temperature is 43 DEG C, and the microcapsule breakage rate is 2.9%.

[0096] Segmented sterilization and sterile filling: pasteurization at 65 ℃ for 30 min, ultra-high temperature instant sterilization at 135 ℃ for 10 s, rapid cooling to 22 ℃, addition of 0.035% ascorbyl palmitate, grade 100 sterile environment filling, volume error ±1.7%.

[0097] (4) Quality detection: The qualified product, i.e., a high-stability functional beverage (a sports drink base spirulina beverage) based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin, is obtained.

[0098] 30-day storage stability: no visible sedimentation at 25 ℃, centrifugal sedimentation rate 1.4%, viscosity change rate 9%.

[0099] Activity and flavor: phycocyanin retention rate 87%, DPPH clearance rate 52%, score of 10-person professional group 87.

[0100] Microcapsule pH response release property: phycocyanin release rate in stomach environment for 2 h is 16%, and release rate in intestinal environment for 4 h is 81%.

[0101] Example 5 The example provides a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin, which is a compound fruit and vegetable juice base spirulina beverage, prepared by using the above process flow, and the parameters of each step are as follows: (1) Preparation of dynamic cross-linking microcapsule powder: Raw material preparation: spirulina powder is the same as in Example 1; fruit juice is apple juice (soluble solids 17 °Brix) and carrot juice (soluble solids 14 °Brix) compounded at a ratio of 3:1.

[0102] Spirulina powder and maltodextrin are weighed at a mass ratio of 1:1.6, distilled water (solid-liquid ratio 1:13.5) is added, stirring at 45 ℃ and 400 rpm for 35 min, and no residue is filtered through a 40-mesh sieve; 10.5% of citric acid by weight of spirulina is added, and the pH value is adjusted to 4.25 with 1 mol / L HCl, and the temperature is raised to 53 ℃ and 300 rpm for constant temperature reaction for 27 min. Cross-linking effect detection: Fourier transform infrared spectrometer scanning, 1735 cm -1 ester bond peak absorbance 0.86; acid swelling degree detection result 51%, both qualified.

[0103] Centrifugal spray dryer parameters: inlet temperature 166 ℃, outlet temperature 94 ℃, inlet air speed 32.5 m / s, outlet air speed 17.5 m / s, atomization pressure 0.25 MPa, feeding rate 6.4 mL / min (outlet temperature stable at 94-96 ℃), and tower wall cleaning every 30 min.

[0104] Powder detection: 100 mesh sieve, average particle size 4.8 μm, embedding rate 94%, Zeta potential absolute value 32 mV, placed in a humidity 28% vacuum dryer for standby.

[0105] (2) Compound fruit and vegetable juice base pretreatment: Compound fruit juice diluted to 30% of the original juice content (soluble solids 12.5 °Brix), homogenized at 68 ℃ and 19 MPa for 1 time, clarity 93% (carrot juice pigment did not affect clarity).

[0106] (3) Beverage compounding and synergistic post-treatment: Compound dispersion: add microcapsule powder to the compound fruit and vegetable juice base at a ratio of 1.6 g / 100 mL, stir at 230 rpm, and stir at 33 ℃ for 16.5 min. No agglomerates were observed under 100x optical microscopy.

[0107] Gradient homogenization: high-pressure homogenizer first homogenized at 20 MPa for 2 times (6 min each time), then homogenized at 32 MPa for 1 time (3.8 min), temperature 42 ℃, microcapsule breakage rate 2.7%.

[0108] Segmented sterilization and aseptic filling: pasteurized at 65 ℃ for 30 min, ultra-high temperature instant sterilized at 135 ℃ for 10 s, quickly cooled to 22 ℃, added 0.028% ascorbyl palmitate, filled in a 100-level sterile environment, volume error ±1.5%.

[0109] (4) Quality detection: A qualified product was obtained, i.e. a high-stability functional beverage based on dynamic cross-linking microencapsulated spirulina with citric acid and maltodextrin (compound fruit and vegetable juice base spirulina beverage).

[0110] 30-day storage stability: no visible sedimentation at 25 ℃, centrifugal sedimentation rate 1.25%, viscosity change rate 8.2%.

[0111] Activity and flavor: phycocyanin retention rate 88% (fruit and vegetable juice antioxidant component auxiliary protection), DPPH clearance rate 54%, 10-person professional group score 89 points (compound fruit and vegetable flavor and spirulina flavor fusion better).

[0112] Microcapsule pH-responsive sustained-release property: phycocyanin release rate in stomach environment for 2 h was 13.8%, and release rate in intestinal environment for 4 h was 83%.

[0113] Comparative Example 1 This comparative example is a spirulina beverage without dynamic cross-linking process.

[0114] The preparation process of this comparative example is as follows: Except for the absence of dynamic cross-linking step (directly mixing spirulina powder with maltodextrin, without adding citric acid, without cross-linking reaction), the remaining steps (spray drying, base pretreatment, compounding, gradient homogenization, segmented sterilization) are the same as Example 1.

[0115] Performance test results: 30-day storage stability: 30-day centrifugal sedimentation rate 4.8% (insufficient homogenization leading to particle aggregation and sedimentation), viscosity change rate 18%.

[0116] Activity and flavor: phycocyanin retention rate 72% (part of the microcapsules are not fully dispersed and are easily oxidized and degraded), DPPH clearance rate 41%, professional group score 73 points (slight particle feeling in taste, poor flavor integration).

[0117] Sustained-release property: 2 h release rate in stomach environment 68%, 4 h release rate in intestinal environment 90% (no obvious sustained-release effect).

[0118] Compared with Example 1, the present comparative example lacks a dynamic cross-linking process, and there is no complete ester bond cross-linking network (Example 1 ester bond peak absorbance 0.85, the present comparative example has no ester bond peak), which leads to: (1) a significant decrease in storage stability, the 30-day centrifugal sedimentation rate is 7 times that of Example 1, and the viscosity change rate is 3 times that of Example 1, as there is no cross-linking network to fix the spirulina powder, which is prone to sedimentation; (2) the phycocyanin retention rate is only 63% of Example 1, and the DPPH clearance rate is only 60% of Example 1, as there is no wall material embedding, and the active ingredients are directly exposed to the oxidation environment; (3) the sustained-release effect of Comparative Example 1 is poor due to the absence of a cross-linking network to resist gastric acid. The above shows that the dynamic cross-linking process is the core technology for achieving high stability, high activity retention, and pH-responsive sustained-release property of the product.

[0119] Comparative Example 2 The present comparative example is a spirulina beverage lacking a gradient homogenization process The preparation process of the present comparative example is as follows: Only a single 20 MPa homogenization (8 min) is used instead of gradient homogenization, and the remaining steps (dynamic cross-linking, spray drying, yogurt base pretreatment, compounding, segmented sterilization) are exactly the same as Example 1.

[0120] Performance test results: 30-day storage stability: 30-day centrifugal sedimentation rate 4.8% (insufficient homogenization leading to particle aggregation and sedimentation), viscosity change rate 18%.

[0121] Activity and flavor: phycocyanin retention rate 72% (part of the microcapsules are not fully dispersed and are easily oxidized and degraded), DPPH clearance rate 41%, professional group score 73 points (slight particle feeling in taste, poor flavor integration).

[0122] Microcapsule breakage rate: 8.2% (single homogenization pressure cannot balance the dispersion effect and microcapsule integrity).

[0123] Compared with Example 1, the comparative example, due to the absence of the gradient homogenization process, only single low-pressure homogenization is used, resulting in: (1) due to the single low pressure, the microcapsules cannot be fully dispersed, resulting in a significant decrease in storage stability, the 30-day centrifugal precipitation rate is 4 times that of Example 1, and the viscosity change rate is 2.25 times that of Example 1; (2) the microcapsule breakage rate is 3.3 times that of Example 1, and the undispersed microcapsules are exposed to the system, the phycocyanin retention rate is only 82% of Example 1, and the DPPH clearance rate is only 77% of Example 1; (3) the taste is reduced due to the decrease in particle sensation score, and the professional group score is 15 points lower than Example 1. Therefore, the gradient homogenization process, through the synergistic effect of "low-pressure pre-dispersion-high-pressure densification", can not only ensure the integrity of the microcapsules, but also achieve system uniformity, which is the key step to improve product stability, activity retention and taste.

[0124] Comparative Example 3 This comparative example is a spirulina beverage that lacks the segmented sterilization process.

[0125] The preparation process of the comparative example is as follows: Only 135°C ultra-high temperature instantaneous sterilization for 10 seconds is used, without pasteurization step, and the remaining steps are the same as Example 1.

[0126] Performance test results: 30-day storage stability: the total number of colonies increased to 1000 CFU / mL (only ultra-high temperature sterilization cannot completely kill non-heat-resistant bacteria), odour and stratification appeared, and it could not be stored continuously.

[0127] Activity and flavor: phycocyanin retention rate 70% (ultra-high temperature has certain damage to protein), DPPH clearance rate 39%, professional group score 70 points (odour seriously affects flavor, color slightly yellow due to microbial reproduction).

[0128] Microbial safety: does not meet the food hygiene standard (total number of colonies exceeds the standard).

[0129] Compared with Example 1, the comparative example, due to the absence of the pasteurization step, only relies on ultra-high temperature instantaneous sterilization, resulting in: (1) microbial control failure, Example 1 can achieve 30-day total number of colonies ≤80 CFU / mL, while the comparative example exceeds the standard to 1000 CFU / mL on the 15th day; (2) the phycocyanin retention rate is 20% lower than Example 1, and the microbial reproduction may accelerate the degradation of active ingredients. Therefore, the segmented sterilization process can not only ensure microbial safety, but also reduce the damage to active ingredients and flavor, which is a necessary guarantee for the product to achieve a 30-day storage period.

[0130] Comparative Example 4 This comparative example is a spirulina beverage with dynamic cross-linking pH deviating from the optimized range.

[0131] The preparation process of the present comparative example is as follows: In the dynamic crosslinking step, the pH value is adjusted to 3.5 (lower than the optimized range of 4.0-4.5) with 1 mol / L HC1, and the remaining steps (spray drying, substrate pretreatment, compounding, etc.) are exactly the same as in Example 1.

[0132] Performance test results: Crosslinking effect: 1735 cm -1 Ester bond peak absorbance 0.65 (not up to standard, insufficient ester bond formation), acid swelling degree 72% (far exceeding the standard of ≤55%, incomplete crosslinking network).

[0133] 30-day storage stability: obvious sedimentation occurred on the 8th day, 30-day centrifugal sedimentation rate 9.8%, viscosity change rate 28% (incomplete crosslinking leading to easy breakage of microcapsules).

[0134] Activity and flavor: phycocyanin retention rate 52% (excessive acidity leading to protein denaturation), DPPH clearance rate 30%, professional group score 58 points (sour taste, unacceptable).

[0135] Microcapsule pH-responsive release: 2h release rate in stomach environment 75%, no sustained-release effect (crosslinking network cannot resist gastric acid erosion).

[0136] Compared with Example 1 (dynamic crosslinking pH=4.2), the present comparative example deviates from the optimized range of pH, leading to: (1) insufficient crosslinking reaction, ester bond peak absorbance is only 76% of Example 1, acid swelling degree is 1.4 times of Example 1, as too low pH will inhibit the esterification reaction of citric acid and maltodextrin, and an intact crosslinking network cannot be formed; (2) poor storage stability, 30-day centrifugal sedimentation rate is 8.2 times of Example 1, and sedimentation occurs as early as the 8th day, as the incomplete crosslinking network cannot support the microcapsule structure, which is easy to break during storage; (3) phycocyanin retention rate is only 59% of Example 1, on the one hand, excessive acidity directly leads to protein denaturation, on the other hand, broken microcapsules expose active ingredients to oxidation, and the sour taste leads to a 30-point lower professional group score than Example 1; (4) release rate in stomach environment is 5 times of Example 1, and the active ingredient cannot be targeted released in the intestinal tract. It is proved that the optimized range of dynamic crosslinking pH value of 4.0-4.5 is the core parameter to ensure the integrity of the crosslinking network and the normal function of the microcapsule, and deviation from this range will lead to the failure of the invention purpose.

[0137] In summary, the present application aims at the technical difficulties of existing spirulina beverage, such as flavor defects, easy degradation of active ingredients, poor storage stability and narrow system adaptability. The present application first creates a wall material system of "dynamic cross-linking of citric acid and malt dextrin" in the microalgae food system, and combines spray drying, gradient homogenization, and segmented sterilization to construct a core-shell structure microcapsule (average particle size 2-8 μm), realizing efficient embedding of spirulina in multiple beverage substrates and maintaining its function. The core technology of the present application is "dynamic cross-linking of citric acid and malt dextrin, spray drying, gradient homogenization, and segmented sterilization". Through precise control of dynamic cross-linking reaction, standardized detection, and optimization of synergistic process, the present application realizes the synergistic improvement of flavor, stability, and functionality of spirulina beverage.

[0138] Specifically, the present application realizes the dynamic esterification reaction of malt dextrin hydroxyl and citric acid carboxyl through precise pH control (4.0-4.5), forming a dense ester bond network, and the ester bond density is increased by more than 40% compared with ordinary static cross-linking. FTIR detection determines the ester bond characteristic peak at 1735 cm -1 The present application optimizes the cross-linking degree detection method, with an absorbance value of ≥0.8. The storage rate of phycocyanin is ≥85% after 30 days of storage, which is increased by 42% compared with the non-embedded group. The DPPH free radical scavenging rate is ≥50%, and the flavor acceptance score is ≥85 points, realizing the nonlinear improvement of synergistic technical effect. The present application also clarifies the protection effect of gradient homogenization and segmented sterilization process on the integrity of microcapsules, with a breakage rate of less than 3%, and the product does not settle after 30 days of storage. The process of the present application is stable and controllable, with a microcapsule embedding rate of ≥92%, which is suitable for multiple systems such as yogurt, fruit juice, and plant protein beverage, and can be widely applied in the field of functional food, with significant industrial value.

[0139] The above detailed the preferred embodiments of the present application. It should be understood that those skilled in the art can make many modifications and changes without creative labor based on the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A highly stable functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin, characterized in that, include: A complex beverage base and dynamically cross-linked microencapsulated spirulina powder dispersed therein; the dynamically cross-linked microencapsulated spirulina powder includes a core material and a dynamically cross-linked material as a wall material; wherein the core material is spirulina powder, and the dynamically cross-linked material is an ester bond cross-linked network formed by citric acid and maltodextrin.

2. The high-stability functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin according to claim 1, characterized in that: The effective content of spirulina in the functional beverage is 0.8~2.5 g / 100 mL.

3. The high-stability functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin according to claim 1, characterized in that: The average particle size of the dynamically cross-linked microencapsulated spirulina powder is 2~8 μm, the encapsulation rate is ≥92%, and the absolute value of the Zeta potential is ≥30 mV.

4. The high-stability functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin according to claim 1, characterized in that: The mass ratio of spirulina to maltodextrin is 1:1.2 to 1:1.8, and the amount of citric acid added is 8% to 12% of the weight of spirulina.

5. The high-stability functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin according to claim 1, characterized in that: The dynamic cross-linked material was detected by Fourier transform infrared spectroscopy at 1735 cm⁻¹. -1 It exhibits characteristic absorption peaks of ester bonds, with an absorbance ≥0.8; the acid swelling degree of the dynamically crosslinked material is ≤55%.

6. The high-stability functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin according to claim 1, characterized in that: The composite beverage base includes at least one of yogurt base, fruit juice base, plant protein beverage base, and sports drink base.

7. The high-stability functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin according to claim 1, characterized in that: The dynamically cross-linked microencapsulated spirulina powder exhibits pH-responsive sustained-release properties in a simulated gastrointestinal environment.

8. A method for preparing a highly stable functional beverage based on dynamically cross-linked microencapsulated spirulina using citric acid and maltodextrin as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Preparation of dynamic cross-linked microcapsule powder: First, weigh each raw material according to the ratio, mix spirulina powder, maltodextrin and water until completely dissolved; add citric acid to complete the dynamic cross-linking reaction; second, characterize the Fourier transform infrared spectrum and acid swelling degree of the dynamic cross-linked product to meet the production indicators; finally, the qualified dynamic cross-linked liquid is spray-dried and tested to obtain dynamic cross-linked microcapsule powder. (2) Pretreatment of the compound beverage base: According to the type of beverage selected, the compound beverage base is pretreated to stabilize the system; the pretreatment includes at least one of pasteurization, homogenization and pH adjustment; (3) Beverage compounding and synergistic post-processing: First, based on the effective content of the target spirulina, the dynamic cross-linked microcapsule powder is mixed with the compound beverage base to make it evenly dispersed; then it is processed under gradient pressure to complete homogenization; after pasteurization and ultra-high temperature instantaneous sterilization, antioxidants are added, and finally aseptic filling is carried out. (4) Quality inspection: The product is inspected to obtain a qualified product, namely a high-stability functional beverage based on spirulina microencapsulated by dynamic cross-linking of citric acid and maltodextrin.

9. The preparation method according to claim 8, characterized in that: In step (1), the pH of the dynamic crosslinking reaction is 4.0~4.5, the reaction temperature is 50~55 ℃, and the reaction time is 20~30 min.

10. The preparation method according to claim 8, characterized in that: In step (3), the gradient homogenization step includes: first homogenizing twice at a pressure of 18~22 MPa for 5~8 min each time, and then homogenizing once at a pressure of 30~35 MPa for 3~5 min, with the homogenization temperature controlled at 40~45 ℃; the segmented sterilization step includes: the beverage is first pasteurized at 65 ℃ for 20~30 min, then subjected to ultra-high temperature instantaneous sterilization at 135 ℃ for 5~10 s, and then rapidly cooled to below 25 ℃ after sterilization.

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